30 Jan
2011
30 Jan
'11
7:38 p.m.
In the US, two separate 110 legs are delivered to the house. When we
need 220, the magic of constructive interference is applied, and we
get 220. The 220 is delivered to the appliance as two separate 110
wires, a neutral wire, and sometimes a separate ground wire for
safety.
Because of this arrangement, sometimes appliances (I believe, maybe
I'm wrong) will pull 110 from one of the legs to power electronics in
the appliance.
But I think european 220 doesn't work this way. Is one 220 leg
delivered to the house? And the electronics work off that 220 leg?
Or are two 110 lines delivered and every outlet gets the sum of those
two 110 lines?
If it's not two separate legs, I'm thinking that it will be impossible
to wire an american 220 appliance to work with european 220. Is this
right?
brian
30 Jan
30 Jan
7:52 p.m.
On Sunday, January 30, 2011, Brian Lanning wrote:
In the US, two separate 110 legs are delivered to the
house. When we
need 220, the magic of constructive interference is applied, and we
get 220. The 220 is delivered to the appliance as two separate 110
wires, a neutral wire, and sometimes a separate ground wire for
safety.
Some things don't have a separate neutral line, in which case they don't
require 120V power.
Because of this arrangement, sometimes appliances (I
believe, maybe
I'm wrong) will pull 110 from one of the legs to power electronics in
the appliance.
Yes, some do that. You can always wire in a 240V to 120V step-down
transformer to run the extra bits. It's rarely much power (timers,
clocks, etc), so you probably could get away with a 100W or so step-down
transformer, which should be pretty cheap.
But I think european 220 doesn't work this way.
Is one 220 leg
delivered to the house? And the electronics work off that 220 leg?
Or are two 110 lines delivered and every outlet gets the sum of those
two 110 lines?
Right, it's ~240V to ground instead of ~120V to ground. As I understand
it, you're a lot more likely to run into 3 phase power (415/240V) than
split-phase single phase power (480/240V), because of how power is
usually distributed.
If it's not two separate legs, I'm thinking
that it will be
impossible to wire an american 220 appliance to work with european
220. Is this right?
No, usually at most you need a small step-down transformer. OTOH, it
may not be legal to connect such an appliance to european power, for
safety reasons, so check your local codes. :)
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
31 Jan
31 Jan
12:26 p.m.
On Sunday, January 30, 2011, Brian Lanning wrote:
I thought there used to be an (IMHO dangerous) bit in the US elcectircal
regualtiosns which allowed cookers to have a 3 wire mains cable (the 2
phases and protective gorund., the last being wired ot the metal frame of
the cooker) but they coulsd still have a 110V timer wired from one phase
to the _protective ground_ wire.
Taht wouldn't work in Europe (since the 2 sides of the 230V mains are not
balanced about ground), and anyway AFAIK making the protecive ground wire
carry any current under normal conditions is totally forbidden.
In the US, two separate 110 legs are delivered to
the house. When we
need 220, the magic of constructive interference is applied, and we
get 220. The 220 is delivered to the appliance as two separate 110
wires, a neutral wire, and sometimes a separate ground wire for
safety.
Some things don't have a separate neutral line, in which case they don't
require 120V power. Because of this arrangement, sometimes appliances
(I believe, maybe
I'm wrong) will pull 110 from one of the legs to power electronics in
the appliance.
Yes, some do that. You can always wire in a 240V to 120V step-down
transformer to run the extra bits. It's rarely much power (timers,
clocks, etc), so you probably could get away with a 100W or so step-down
transformer, which should be pretty cheap.
1:28 p.m.
On Monday 31 January 2011, Tony Duell wrote:
Sort of. Technically, there was no "ground" wire, and the appliance
chassis (if connected) was connected to the neutral line. This is no
longer allowed. As long as there's no electrical faults, neutral and
ground should be at the same potential (but obviously for safety
reasons, one shouldn't assume this). They're usually bonded together at
the service entrance - wherever the main circuit breaker (which may
actually be up to 6 breakers for separate loads) is.
In any case, that's not allowed in new construction or appliances
anymore, only grandfathered in, in existing situations.
One thing to watch for is that clocks, etc, may well use the mains
freuqency as a timing refernece (electromechanical clocks almost
certainly use xsynchronous motors, electronci ones may well use the
mains as the timing input). US mains is 60Hz, European mains is
50Hz. Such clocks, fed froma step-down transofmrmer, will run slow
in Europe.
-tony
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
On Sunday,
January 30, 2011, Brian Lanning wrote:
I thought there used to be an (IMHO dangerous) bit in the US
elcectircal regualtiosns which allowed cookers to have a 3 wire
mains cable (the 2 phases and protective gorund., the last being
wired ot the metal frame of the cooker) but they coulsd still have a
110V timer wired from one phase to the _protective ground_ wire. In the US, two separate 110 legs are delivered to
the house.
When we need 220, the magic of constructive interference is
applied, and we get 220. The 220 is delivered to the appliance
as two separate 110 wires, a neutral wire, and sometimes a
separate ground wire for safety.
Some things don't have a separate neutral line, in which case they
don't require 120V power. Taht wouldn't work in Europe (since the 2 sides of
the 230V mains are
not balanced about ground), and anyway AFAIK making the protecive
ground wire carry any current under normal conditions is totally
forbidden.
Right. Like I said, the chassis was bonded to neutral, not neutral
bonded to ground. I guess it's the same situation as an 120V appliance
whose chassis is bonded to the neutral line in a 2-wire, non-grounded
plug.
Though, ground carrying some current isn't all that uncommon. There are
plenty of things that have a non-trivial leakage current (eg, MOV or
other surge protector devices). I've seen some computer equipment with
warnings about having a "high leakage current".
Because of this arrangement, sometimes appliances (I
believe,
maybe I'm wrong) will pull 110 from one of the legs to power
electronics in the appliance.
Yes, some do that. You can always wire in a 240V to 120V step-down
transformer to run the extra bits. It's rarely much power (timers,
clocks, etc), so you probably could get away with a 100W or so
step-down transformer, which should be pretty cheap.
1 Feb
1 Feb
10:53 a.m.
Taht
wouldn't work in Europe (since the 2 sides of the 230V mains are
not balanced about ground), and anyway AFAIK making the protecive
ground wire carry any current under normal conditions is totally
forbidden.
Right. Like I said, the chassis was bonded to neutral, not neutral
bonded to ground. I guess it's the same situation as an 120V appliance
whose chassis is bonded to the neutral line in a 2-wire, non-grounded
plug.
Though, ground carrying some current isn't all that uncommon. There are
plenty of things that have a non-trivial leakage current (eg, MOV or
other surge protector devices). I've seen some computer equipment with
warnings about having a "high leakage current".
Yes, you're right. I am sure there;s a limit to the mazximum permitted
leackage current. It's not zero, but ti's probably not that high either.
Mins filters often have cpaciaotrs from the power-carrying wires to
ground, and they will pass some AC current.
-tony
2:36 p.m.
On 01/02/2011 18:53, Tony Duell wrote:
Yes, you're right. I am sure there;s a limit to
the mazximum permitted
leackage current. It's not zero, but ti's probably not that high either.
Mins filters often have cpaciaotrs from the power-carrying wires to
ground, and they will pass some AC current.
The RCDs on the supplies into our data centre are settable; they can be
set at least as low as 30mA but normally they're set to over an amp and
can be set as high as 6.3A residual current. What's allowed depends on
the context (and that includes the time they take as well as the current).
--
Pete Peter Turnbull
Network Manager
University of York
3:54 p.m.
On Tuesday, February 01, 2011, Pete Turnbull wrote:
On 01/02/2011 18:53, Tony Duell wrote:
The ground fault breaker (RCD by you) on the 480V supply the work's main
datacenter (which is rated at 1MVA, or 1200A currently - an upgrade to
5MW is coming this year) was tripping on us when it was set to 200-300A,
and is now set higher. IIRC, the tripping was caused by current spikes
to ground from "leaky" motors, and probably some capacitors or other
power filter equipment.
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
Yes, you're right. I am sure there;s a limit
to the mazximum
permitted leackage current. It's not zero, but ti's probably not
that high either. Mins filters often have cpaciaotrs from the
power-carrying wires to ground, and they will pass some AC
current.
The RCDs on the supplies into our data centre are settable; they can
be set at least as low as 30mA but normally they're set to over an
amp and can be set as high as 6.3A residual current. What's allowed
depends on the context (and that includes the time they take as well
as the current).
2 Feb
2 Feb
12:10 a.m.
The ground fault breaker (RCD by you) on the 480V
supply the work's main
datacenter (which is rated at 1MVA, or 1200A currently - an upgrade to
5MW is coming this year) was tripping on us when it was set to 200-300A,
and is now set higher. IIRC, the tripping was caused by current spikes
to ground from "leaky" motors, and probably some capacitors or other
power filter equipment.
That's pretty extreme. To me, that sounds vry strange -- 200A leakage
current on a total of 1200A load current is a huge proportion. Our
feeds are 630A (and that's three-phase at twice your voltage) and our
RCDs don't trip -- though admittedly we're not drawing nything like the
full 630A. I wonder if it's something to do with the duration of
switch-on surges, or something of the sort?
--
Pete Peter Turnbull
Network Manager
University of York
10:39 a.m.
The ground fault breaker (RCD by you) on the 480V
supply the work's main
datacenter (which is rated at 1MVA, or 1200A currently - an upgrade to
5MW is coming this year) was tripping on us when it was set to 200-300A,
Dop you mean that? 200A (not mA) of earth leakage wouldappear to be
dangerously high in any installation.
-tony
1:54 p.m.
On Wednesday, February 02, 2011, Tony Duell wrote:
Yes, I mean 200A.
When you're dealing with high-ish voltage (277V to ground), and lots of
power being used (about 1000 amps per phase), leakages can add up
quickly... And, it's most likely a spike, not a continuous leakage
current, eg, a short-lived arc to ground from some worn out insulating
parts.
In any case a 200A short-term fault isn't all that huge. Ratings for
typical US house circuit breakers are around 10,000A interrupting
capability.
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
The ground
fault breaker (RCD by you) on the 480V supply the work's
main datacenter (which is rated at 1MVA, or 1200A currently - an
upgrade to 5MW is coming this year) was tripping on us when it was
set to 200-300A,
Dop you mean that? 200A (not mA) of earth leakage wouldappear to be
dangerously high in any installation. 
3:18 p.m.
On Wed, 2 Feb 2011, Patrick Finnegan wrote:
In any case a 200A short-term fault isn't all that
huge. Ratings for
typical US house circuit breakers are around 10,000A interrupting
capability.
You appear to be confusing 2 numbers... interrupting capacity is the
maximum current that the breaker is rated to interrupt, not the minimum
current at which it interrupts (which is the number that it makes sense to
compare to your RCD's 200A setting). For US house breakers the latter is
typically 15A or 20A.
Alexey
3 Feb
3 Feb
1:57 p.m.
On Wednesday, February 02, 2011, Tony Duell wrote:
Yes, I mean 200A.
Ouch. I how most of that is either for a short duration (switch-on
surges) on in quatrature to the supply so that no real power is being
consumed.
The
ground fault breaker (RCD by you) on the 480V supply the work's
main datacenter (which is rated at 1MVA, or 1200A currently - an
upgrade to 5MW is coming this year) was tripping on us when it was
set to 200-300A,
Dop you mean that? 200A (not mA) of earth leakage wouldappear to be
dangerously high in any installation.
When you're dealing with high-ish voltage (277V to ground), and lots of
power being used (about 1000 amps per phase), leakages can add up
Even so, it's high. It's around 1/15 of the total current, which, pro
rata would be a leakage of 1A on a medium-sizedd PDP11, say. If my PDP11
had that sort of leak, I would be repairing it. Period.
quickly... And, it's most likely a spike, not a
continuous leakage
current, eg, a short-lived arc to ground from some worn out insulating
parts.
That is precisely the sort of thing I would repair and not just turn up
the breakers to get round it! Worn-out isulation (whatever that may
mean) is not something I am going to trust.
In any case a 200A short-term fault isn't all that huge. Ratings for
typical US house circuit breakers are around 10,000A interrupting
capability.
That is surely the maximum fault current they will safely break. Not the
current they carry before they trip. Over here most decent domestic MCBs
will break 16kA safely -- that is the peak current that might flow if
there's a dead short across the mains. But said breakers will trip on a
current of 32A, say.
-tony
8:17 p.m.
On Thursday, February 03, 2011, Tony Duell wrote:
Yes. Things would have heated up quickly and/or blown fuses if it was
long-duration.
Yes, it's high.
I'd agree. The problem is convincing people to spend the time tracking
down an intermittent fault somewhere within more than a dozen possible
pieces of equipment. Sometimes it's easier to just wait for it to go
BANG!, and pick up the pieces. There's nothing irreplacable or unique
that it could destroy, and the equipment is generally designed to
contain such a problem to avoid hurting a person who's nearby when it
happens.
Yes, I do understand the difference. My point is that a fault that's
200A on a supply that can probably supply a fault current nearing 100kA,
isn't that big compared to what's possible, (eg, not a "dead short").
And for whatever it's worth, unless it's a special purpose breaker, a
circuit breaker doesn't trip as soon as the current crosses its rated
current, where "soon" can be as long as minutes depending on the breaker
if you're only overloading by 10% or so. I was amazed at how long
(10-15 minutes) a particular 20A breaker sustained a 25A load before it
tripped. Then again, the thermal response of a breaker tends to match
the effects of wires (that it's protecting) to keep them from
overheating.
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
On Wednesday,
February 02, 2011, Tony Duell wrote:
Yes, I mean 200A.
Ouch. I how most of that is either for a short duration (switch-on
surges) on in quatrature to the supply so that no real power is being
consumed. The
ground fault breaker (RCD by you) on the 480V supply the
work's main datacenter (which is rated at 1MVA, or 1200A
currently - an upgrade to 5MW is coming this year) was
tripping on us when it was set to 200-300A,
Dop you mean that? 200A (not mA) of earth leakage wouldappear to
be dangerously high in any installation. When
you're dealing with high-ish voltage (277V to ground), and
lots of power being used (about 1000 amps per phase), leakages can
add up
Even so, it's high. It's around 1/15 of the total current, which, pro
rata would be a leakage of 1A on a medium-sizedd PDP11, say. If my
PDP11 had that sort of leak, I would be repairing it. Period. quickly...
And, it's most likely a spike, not a continuous leakage
current, eg, a short-lived arc to ground from some worn out
insulating parts.
That is precisely the sort of thing I would repair and not just turn
up the breakers to get round it! Worn-out isulation (whatever that
may mean) is not something I am going to trust. In any case a
200A short-term fault isn't all that huge. Ratings
for typical US house circuit breakers are around 10,000A
interrupting capability.
That is surely the maximum fault current they will safely break. Not
the current they carry before they trip. Over here most decent
domestic MCBs will break 16kA safely -- that is the peak current
that might flow if there's a dead short across the mains. But said
breakers will trip on a current of 32A, say. 
8:44 p.m.
I'd agree. ?The problem is convincing people to
spend the time tracking
down an intermittent fault somewhere within more than a dozen possible
pieces of equipment. ?Sometimes it's easier to just wait for it to go
BANG!, and pick up the pieces. ?There's nothing irreplacable or unique
that it could destroy, and the equipment is generally designed to
contain such a problem to avoid hurting a person who's nearby when it
happens.
Also, the machines are generally designed to avoid hurting themselves.
The big higher end stuff tends to have enough protection circuitry
that power supply (and environmental) failures do not end up
destroying the rest of the electronics.
IBM mainframe and midrange equipment has an unbelievable amount of
extra stuff in the power supplies. I do not worry much at all about
turning on some old bit of IBM gear - if there is a problem, the
machine will give a power check (or temperature check), shut down
safely, and will let me know to pull out the Big Blue Binder with the
repair instructions.
--
Will
4 Feb
4 Feb
11:30 a.m.
Also, the machines are generally designed to avoid
hurting themselves.
The big higher end stuff tends to have enough protection circuitry
that power supply (and environmental) failures do not end up
destroying the rest of the electronics.
My view is that protective devices, whether to protect the machine or a
person, are there to do their job if there is an unforseen failure. They
are not there to protect against probably known problems.
In other words, of coruse I fi a mains fuse of the correct rating in
every machine I run. It will hopefully protect the rest of the machine,
and maybe prevent a fire if there's a mahor PSU failure. But if I know I
have PSU problems, I don;t rely on that fuse alone. I will use a series
light bulb to limit the current.
I wil lhappily use an RCD t protect against me touching a live part when
working o nthe machine. But this doesn't mean I will be careless and work
on the machine while still plguged in.
IBM mainframe and midrange equipment has an unbelievable amount of
extra stuff in the power supplies. I do not worry much at all about
turning on some old bit of IBM gear - if there is a problem, the
It's your machine, you can do what you like. But I won't go along with it.
machine will give a power check (or temperature
check), shut down
safely, and will let me know to pull out the Big Blue Binder with the
repair instructions.
Which if it's anything like any other IBM 'service' manual I've seen,
it'll tell you to rpelace FRU <foo? and won't actually help you to find
the problem.
-tony
11:25 a.m.
quickly... And, it's most likely a spike, not a
continuous leakage
current, eg, a short-lived arc to ground from some worn out
insulating parts.
That is precisely the sort of thing I would repair and not just turn
up the breakers to get round it! Worn-out isulation (whatever that
may mean) is not something I am going to trust. that it could destroy, and the equipment is generally
designed to
contain such a problem to avoid hurting a person who's nearby when it
happens.
Perhaps you can explain to me the point of an earth-leakage breaker under
thsoe conditions... It's nvercurent device (that is, a derive that cuts
th emains if the current in the power-carying conductors exceeds a
certain value). The normal reason for having them over here is to protect
people in the event of an insulation breakdown, the unbalanced current
flowing throughj the person to ground will trip the breaker.
I doubt that 200A would flow though a person touvhing a live conductor
(if it would,then there'd be no point in the RCD in most isntalations,
the nromal current-operated breakers would trip). And if it fif, that
person would not notice it. Ever.
So I am seriosu. What fault is the 200A earth-leakage breaker protecting
against?
In any
case a 200A short-term fault isn't all that huge. Ratings
for typical US house circuit breakers are around 10,000A
interrupting capability.
That is surely the maximum fault current they will safely break. Not
the current they carry before they trip. Over here most decent
domestic MCBs will break 16kA safely -- that is the peak current
that might flow if there's a dead short across the mains. But said
breakers will trip on a current of 32A, say.
And for whatever it's worth, unless it's a special purpose breaker, a
circuit breaker doesn't trip as soon as the current crosses its rated
current, where "soon" can be as long as minutes depending on the breaker
if you're only overloading by 10% or so. I was amazed at how long
(10-15 minutes) a particular 20A breaker sustained a 25A load before it
tripped. Then again, the thermal response of a breaker tends to match
the effects of wires (that it's protecting) to keep them from
overheating.
The same is true of fuses, of course. A 20A fuse does not melt the
instant the currnet rises over 20A.
The currnet agianst time (I-t) characteristics of fuses and circuit
breakers are specified i nthe data sheets (and at least over here there
are British Standards giving hte ones ocmmonly used). It's often
important to allow a higher-than-normal inrush current. I am sure we've
all used anti-surge fuses, for example.
However, I didn;t think that earth-leakage brekaers (RCDs, etc) had much
of a time delay as standard. The idea being that there really shouldn't
be an earth leakage current, not even fopr a faraction of a second.
-tony
12:51 p.m.
On 04/02/2011 19:25, Tony Duell wrote:
The currnet agianst time (I-t) characteristics of
fuses and circuit
breakers are specified i nthe data sheets (and at least over here there
are British Standards giving hte ones ocmmonly used). It's often
important to allow a higher-than-normal inrush current. I am sure we've
all used anti-surge fuses, for example.
Yes... the standard circuit breakers used in homes, offices, etc are
usually A-curve or (more often) B-curve, but for IT installations (lots
of switchmode power supplies) and installations with motors, usually
C-curve or D-curve to handle quite long inrush currents. And they're EN
standards, so international (sorry, I don't remember the EN number).
However, I didn;t think that earth-leakage brekaers
(RCDs, etc) had much
of a time delay as standard. The idea being that there really shouldn't
be an earth leakage current, not even fopr a faraction of a second.
Usually l about one cycle of the mains, 20ms here (with 50Hz mains),
occasionally one half-cycle, though as I may have mentioned when
describing our big RCDs in the data centres, those can be set for longer
times too: up to one second I think.
--
Pete Peter Turnbull
Network Manager
University of York
2:37 p.m.
On Friday 04 February 2011, Tony Duell wrote:
I'd agree. The problem is convincing people to spend the time
tracking down an intermittent fault somewhere within more than a
dozen possible pieces of equipment. Sometimes it's easier to just
wait for it to go BANG!, and pick up the pieces. There's nothing
irreplacable or unique
I see.. There's never time or money to do it right. nut there is time
and moneyu to bodge it when things finally fail catestrophically.
And youwonder wheat's wrong with the world...
"Do it right" is subjective. You may easily spend hundreds of man hours
hunting down a problem that won't show up until there's a major fault,
which costs maybe a few man-hours to fix, and is simple to find once it
has gone "boom".
Basically, an equipment fault which causes current to flow to ground,
but which isn't enough to trip a breaker or blow a fuse.
It's actually required by the US National Electrical Code to have such a
ground-fault interrupter on any power distribution system that exceeds
800A.
I believe that part of the reasoning is that you can have a "dead short"
that's through a thin enough conductor (or strand of multi-stranded
conductor), that you won't draw enough current to blow a fuse (possibly
hundreds of amps), but which you don't want to trip from 90deg out of
phase loads from capacitors or inductors that are acting as power
filters.
Yes, I do understand the difference. My point is that a fault
that's 200A on a supply that can probably supply a fault current
nearing 100kA, isn't that big compared to what's possible, (eg, not
a "dead short").
Ture enough. But what fault would trip this breaker nad not a
current-operated one? What is it protecting against?
Say you have a 18AWG or so "strand" of a thick stranded copper wire, on
a circuit that's fused for 400A or more. The strand (shorted to ground)
will quickly heat up to dangerous levels, and probably won't cause a
high enough current draw to blow the fuse.
Wire insulation that has been knicked by a metal burr in conduit can
cause a similar situation.
Yes, but breakers tend to emulate "slow-blo" fuses more than
"fast-blo"
ones.
quickly...
And, it's most likely a spike, not a continuous
leakage current, eg, a short-lived arc to ground from some worn
out insulating parts.
That is precisely the sort of thing I would repair and not just
turn up the breakers to get round it! Worn-out isulation
(whatever that may mean) is not something I am going to trust. that it could
destroy, and the equipment is generally designed to
contain such a problem to avoid hurting a person who's nearby when
it happens.
Perhaps you can explain to me the point of an earth-leakage breaker
under thsoe conditions... It's nvercurent device (that is, a derive
that cuts th emains if the current in the power-carying conductors
exceeds a certain value). The normal reason for having them over
here is to protect people in the event of an insulation breakdown,
the unbalanced current flowing throughj the person to ground will
trip the breaker.
I doubt that 200A would flow though a person touvhing a live
conductor (if it would,then there'd be no point in the RCD in most
isntalations, the nromal current-operated breakers would trip). And
if it fif, that person would not notice it. Ever.
So I am seriosu. What fault is the 200A earth-leakage breaker
protecting against? In any case a
200A short-term fault isn't all that huge.
Ratings for typical US house circuit breakers are around
10,000A interrupting capability.
That is surely the maximum fault current they will safely break.
Not the current they carry before they trip. Over here most
decent domestic MCBs will break 16kA safely -- that is the peak
current that might flow if there's a dead short across the mains.
But said breakers will trip on a current of 32A, say. And for
whatever it's worth, unless it's a special purpose breaker,
a circuit breaker doesn't trip as soon as the current crosses its
rated current, where "soon" can be as long as minutes depending on
the breaker if you're only overloading by 10% or so. I was amazed
at how long (10-15 minutes) a particular 20A breaker sustained a
25A load before it tripped. Then again, the thermal response of a
breaker tends to match the effects of wires (that it's protecting)
to keep them from overheating.
The same is true of fuses, of course. A 20A fuse does not melt the
instant the currnet rises over 20A. The currnet agianst time (I-t) characteristics of
fuses and circuit
breakers are specified i nthe data sheets (and at least over here
there are British Standards giving hte ones ocmmonly used). It's
often important to allow a higher-than-normal inrush current. I am
sure we've all used anti-surge fuses, for example.
However, I didn;t think that earth-leakage brekaers (RCDs, etc) had
much of a time delay as standard. The idea being that there really
shouldn't be an earth leakage current, not even fopr a faraction of
a second.
Yes, high-current GFIs work the same way.
In addition, high-current breakers usually have a magnetic trip
(possibly with a settable trip point somewhere around 2-4x the rating of
the breaker) that will trip with just a cycle or two of abnormally high
current (eg, short circuit) in addition to the thermal breaker part,
which trips on circuit overload.
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
5 Feb
5 Feb
7:23 a.m.
"Do it right" is subjective. You may easily
spend hundreds of man hours
True enough...
However, I don't think that turning up circuit breakers (whether
over-currnet ones or RCDs) to get over intermittant breakdown of old
insulation is ever 'doing it right'.
Similarly, it's hard to think of a case where increasing the currnt
rating of a protective device for no good reason is 'doing it right'. If
the device is trippign becauseo f a genuine current surge that yuu know
about and can show is safe, then fine. But otherwise, IMHO you need to
find why the deive is tripping, not just turn it up and hope the problem
goes away.
hunting down a problem that won't show up until
there's a major fault,
which costs maybe a few man-hours to fix, and is simple to find once it
has gone "boom".
Given the sort of energies you are dealing with, I am not at all
convicves it will go 'boom' safely.
So I am
seriosu. What fault is the 200A earth-leakage breaker
protecting against?
Basically, an equipment fault which causes current to flow to ground,
but which isn't enough to trip a breaker or blow a fuse.
It's actually required by the US National Electrical Code to have such a
ground-fault interrupter on any power distribution system that exceeds
800A. I believe that part of the reasoning is that you can
have a "dead short"
that's through a thin enough conductor (or strand of multi-stranded
conductor), that you won't draw enough current to blow a fuse (possibly
hundreds of amps), but which you don't want to trip from 90deg out of
phase loads from capacitors or inductors that are acting as power
filters.
[...]
Say you have a 18AWG or so "strand" of a
thick stranded copper wire, on
a circuit that's fused for 400A or more. The strand (shorted to ground)
will quickly heat up to dangerous levels, and probably won't cause a
high enough current draw to blow the fuse.
Hang on a second. Your RCD trips at 200A or so. What if you have an earth
fault that sould only carry 100A. It will not trip either breker, but it
certian;y could dispate enoguh power to do a lot of damage.
Yes, but breakers tend to emulate "slow-blo"
fuses more than "fast-blo"
ones.
Depends a lot on the breakers and how they work.
Electromagnetically-operated circuit breakers tend to be fast-tripping,
thermal ones slower/ Both types are made (or were made last time I looked
at them).
-tony
1 Feb
1 Feb
3:22 a.m.
On Mon, 31 Jan 2011, Tony Duell wrote:
Taht wouldn't work in Europe (since the 2 sides of
the 230V mains are not
balanced about ground), and anyway AFAIK making the protecive ground wire
carry any current under normal conditions is totally forbidden.
In new installations, maybe. But many older houses have just that, they
use the neutral wire as protective ground (called "klassische Nullung" or
TN-C system as opposed to a TN-C-S system, see
http://en.wikipedia.org/wiki/Earthing_system)
Christian
1:32 p.m.
On 01/02/2011 11:22, Christian Corti wrote:
On Mon, 31 Jan 2011, Tony Duell wrote:
Both TN-C and TN-C-S are allowed here, but those terms refer
specifically only to building wiring, and where the neutral is connected
to earth (as it always is, somewhere). But Tony was writing about
appliance wiring, and he's right about that; the protective conductor is
not permitted to carry any load current under normal conditions, whether
it's a fixed appliance or portable.
--
Pete Peter Turnbull
Network Manager
University of York
Taht wouldn't work in Europe (since the 2
sides of the 230V mains are not
balanced about ground), and anyway AFAIK making the protecive ground wire
carry any current under normal conditions is totally forbidden.
In new installations, maybe. But many older houses have just that, they
use the neutral wire as protective ground (called "klassische Nullung"
or TN-C system as opposed to a TN-C-S system, see
http://en.wikipedia.org/wiki/Earthing_system)
1:29 p.m.
On Sun, Jan 30, 2011 at 9:52 PM, Patrick Finnegan
<pat at computer-refuge.org> wrote:
On Sunday, January 30, 2011, Brian Lanning wrote:
ok, so considering this one:
http://www.cmadishmachines.com/files/8-2008/UC50e/Kromo%20Wire%20Diagram.pdf
I would look at this and say that since there's no electronics, I can
wire up any old 220 line (assuming the line had the appropriate
current rating). Does that sound right? It looks to me like it
combines the two 110 lines right at the screw terminal where the power
comes in.
brian
In the US, two separate 110 legs are delivered to
the house. ?When we
need 220, the magic of constructive interference is applied, and we
get 220. ?The 220 is delivered to the appliance as two separate 110
wires, a neutral wire, and sometimes a separate ground wire for
safety.
Some things don't have a separate neutral line, in which case they don't
require 120V power.
Because of this arrangement, sometimes appliances
(I believe, maybe
I'm wrong) will pull 110 from one of the legs to power electronics in
the appliance.
Yes, some do that. ?You can always wire in a 240V to 120V step-down
transformer to run the extra bits. ?It's rarely much power (timers,
clocks, etc), so you probably could get away with a 100W or so step-down
transformer, which should be pretty cheap. 
2:51 p.m.
On 2011 Feb 1, at 1:29 PM, Brian Lanning wrote:
http://www.cmadishmachines.com/files/8-2008/UC50e/
Kromo%20Wire%20Diagram.pdf
I would look at this and say that since there's no electronics, I can
wire up any old 220 line (assuming the line had the appropriate
current rating). Does that sound right? It looks to me like it
combines the two 110 lines right at the screw terminal where the power
comes in.
Looking at the wiring digram, to my interpretation, it's not combining
two 115V lines, all the loads in the unit appear to run from 230V.
The way it is labelled with 'Neutral and 230V' suggests it was meant
for a European type supply or a commercial 230V supply, that is: single
phase 230V relative to a 0V neutral, along with a protective ground.
However, both wires (230V and Neutral) in the unit have control devices
(switches, relays) in them, so it would appear to (should) be OK to run
from the two hot legs of a North American residential
supply 230V
(split-phase 115-neutral-115 with protective ground, with no need for
the neutral connection).
The spec sheet also mentions 208V which is another voltage supplied in
North America to commercial or light industrial consumers (2 legs of
120V 3-phase Y connection).
Clear as mud?
2 Feb
2 Feb
5:51 p.m.
On Tue, Feb 1, 2011 at 4:51 PM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
Looking at the wiring digram, to my interpretation,
it's not combining two
115V lines, all the loads in the unit appear to run from 230V.
The way it is labelled with 'Neutral and 230V' suggests it was meant for a
European type supply or a commercial 230V supply, that is: single phase 230V
relative to a 0V neutral, along with a protective ground.
However, both wires (230V and Neutral) in the unit have control devices
(switches, relays) in them, so it would appear to (should) be OK to run from
the two hot legs of a North American residential supply 230V (split-phase
115-neutral-115 with protective ground, with no need for the neutral
connection).
The spec sheet also mentions 208V which is another voltage supplied in North
America to commercial or light industrial consumers (2 legs of ?120V 3-phase
Y connection).
Clear as mud?
It's a commercial dish washer that's actually hooked up and running in
my kitchen now. I installed a subpanel and ran a separate 30 amp 220
line. It works great. I was just wondering whether it would work on
european power.
brian
4 Feb
4 Feb
4:42 p.m.
On 2011 Feb 2, at 5:51 PM, Brian Lanning wrote:
On Tue, Feb 1, 2011 at 4:51 PM, Brent Hilpert
<hilpert at cs.ubc.ca>
wrote:
The real-world difference between North American 240V and Euro 240V is
the maximum potential relative to ground:
NA: 120 VRMS, 170V peak
Euro: 240 VRMS, 340V peak
Of course, the lower potential to ground is precisely why NA uses the
split-phase 120/240: it is much safer for humans but you still have 240
for heavy loads.
For equipment, in theory, there could be a problem if the insulation
rating of some component (e.g. caps) could not handle the higher
potential to ground. In practice, it's somewhat unlikely a manufacturer
would build anything such that that would be a problem.
Looking at the wiring digram, to my
interpretation, it's not
combining two
115V lines, all the loads in the unit appear to run from 230V.
The way it is labelled with 'Neutral and 230V' suggests it was meant
for a
European type supply or a commercial 230V supply, that is: single
phase 230V
relative to a 0V neutral, along with a protective ground.
However, both wires (230V and Neutral) in the unit have control
devices
(switches, relays) in them, so it would appear to (should) be OK to
run from
the two hot legs of a North American residential supply 230V
(split-phase
115-neutral-115 with protective ground, with no need for the neutral
connection).
The spec sheet also mentions 208V which is another voltage supplied
in North
America to commercial or light industrial consumers (2 legs of ?120V
3-phase
Y connection).
Clear as mud?
It's a commercial dish washer that's actually hooked up and running in
my kitchen now. I installed a subpanel and ran a separate 30 amp 220
line. It works great. I was just wondering whether it would work on
european power.
5 Feb
5 Feb
2:05 a.m.
On 05/02/2011 00:42, Brent Hilpert wrote:
The real-world difference between North American 240V
and Euro 240V is
the maximum potential relative to ground:
NA: 120 VRMS, 170V peak
Euro: 240 VRMS, 340V peak
Of course, the lower potential to ground is precisely why NA uses the
split-phase 120/240: it is much safer for humans but you still have 240
for heavy loads.
I believe that's debatable.
Now, I expect most of us would agree that voltage below about 70-90V
peak (around 55V RMS) is much safer, on the grounds that while it might
give a person an unpleasant surprise, a shock, even across the body, is
unlikely to be fatal. Hence the SELV rules and our use of RLV 110V AC
centre tapped to ground on building sites, giving a maximum of 55V RMS.
(According to the standards bodies like IET, that means a maximum
around 40V for indirect contact shock protection, well below the
accepted standard safe touch voltage and therefore we don't need to
limit earth loop impedances and worry about RCDs on building sites.)
Nevertheless, I've often heard it argued that voltages around 230V RMS
are safer than, say, 110V RMS, on the grounds that a casual brush with a
230V live conductor will cause a very rapid reaction in humans, often
jerking the contact free, whereas voltages around the 100-150V range
don't. I can't remember where I read supporting evidence, but it's
certainly something I've often heard mentioned, and is one reason we
think American voltages are actually more dangerous than ours. All that
said, either can give a potentially fatal shock, as both are sufficient
to overcome initial skin resistance.
Actually, the main reason America uses split phase 120/240 is that given
a 120V single-phase main supply, it's much easier and cheaper to provide
120/240 than an additional 240V single (non-split) phase or 3-phase.
Just as in Europe, 240 is preferred over 120V mainly for reasons of
efficiency rather than safety.
--
Pete Peter Turnbull
Network Manager
University of York
7:16 a.m.
Nevertheless, I've often heard it argued that
voltages around 230V RMS are
safer than, say, 110V RMS, on the grounds that a casual brush with a 230V
live conductor will cause a very rapid reaction in humans, often jerking the
contact free, whereas voltages around the 100-150V range don't. ?I can't
remember where I read supporting evidence, but it's certainly something I've
often heard mentioned, and is one reason we think American voltages are
actually more dangerous than ours.
This reasoning sounds really flawed. A jolt of unexpected 120 V AC
will certainly make the muscles do uncontrolled things.
It is the "uncontrolled things" that cause nearly all the injuries and
deaths - things like falling off ladders, whacking elbows against
walls, hitting oneself in the face with tools, etc..
--
Will
9:45 a.m.
On 05/02/2011 15:16, William Donzelli wrote:
I think there's something in it, but I agree that just about any shock
will make muscles do uncontrolled things. I certainly wouldn't take
less care on a 230V circuit than a 120V one, OR vice versa. OTOH I've
had a shock from a slightly lower voltage that was painful (and
potentially dangerous) but not sharp enough to jerk my fingers off the wire.
--
Pete Peter Turnbull
Network Manager
University of York
Nevertheless,
I've often heard it argued that voltages around 230V RMS are
safer than, say, 110V RMS, on the grounds that a casual brush with a 230V
live conductor will cause a very rapid reaction in humans, often jerking the
contact free, whereas voltages around the 100-150V range don't. I can't
remember where I read supporting evidence, but it's certainly something I've
often heard mentioned, and is one reason we think American voltages are
actually more dangerous than ours.
This reasoning sounds really flawed. A jolt of unexpected 120 V AC
will certainly make the muscles do uncontrolled things. 
10:15 a.m.
On 5 Feb 2011 at 17:45, Pete Turnbull wrote:
I think there's something in it, but I agree that
just about any shock
will make muscles do uncontrolled things. I certainly wouldn't take
less care on a 230V circuit than a 120V one, OR vice versa. OTOH I've
had a shock from a slightly lower voltage that was painful (and
potentially dangerous) but not sharp enough to jerk my fingers off the
wire.
Hmm, you'd think that someone would have thought of powering
"universal motor" tools, such as saws and drills used on construction
sites with DC as a safety measure. The current level at which one
loses muscle control is substantially higher with DC than with AC.
Many power tools sold in the US have no 3rd wire for grounding at
all, instead, a "double insulated" method of construction is used.
What's curious is that such tools often employ the "large blade =
neutra, small blade = line" polarized plugs.
--Chuck
10:27 a.m.
On 05/02/2011 18:15, Chuck Guzis wrote:
Many power tools sold in the US have no 3rd wire for
grounding at
all, instead, a "double insulated" method of construction is used.
Same here (most are DI) but it doesn't stop them getting wet, or stop
cables getting frayed.
--
Pete Peter Turnbull
Network Manager
University of York
11:06 a.m.
On 5 Feb 2011 at 18:27, Pete Turnbull wrote:
Same here (most are DI) but it doesn't stop them
getting wet, or stop
cables getting frayed.
That's always bothered me a bit. I've replaced the 2-wire cord in a
drill with a 3-wire one, attaching the ground wire to the field coil
laminations. While not perfect, it's probably better than nothing.
On electronic (i.e. personal computer) gear, I wonder if the role of
the ever-present ground wire isn't more for RF noise than actual
safety protection.
--Chuck
1:11 p.m.
On 5 Feb 2011 at 14:10, William Donzelli wrote:
Ever have to pre-drill and drive 500 4" deck screws with a cordless?
It can be done, but you'd better have a pile of charged batteries.
Battery-powered circular saws are also a joke--I've yet to see one
that could hold its own against my worm-drive Skilsaw.
I have several cordless drills and drivers, including hammer drills
and impact wrenches. They're okay for small jobs, but don't hold up
under heavy use. (Much like trying to mow the meadow in front of my
house with a cordless lawn mower...)
I've also popped the power FETs in a couple of cordless drills after
heavy use. They probably gave out because their cooling mostly
consists of having a small heatsink in a confined space--but stupid
design is a completely different topic.
--Chuck
That's
always bothered me a bit. ?I've replaced the 2-wire cord in a
drill with a 3-wire one, attaching the ground wire to the field coil
laminations. ?While not perfect, it's probably better than nothing.
Get a cordless.
2:08 p.m.
Ever have to pre-drill and drive 500 4" deck
screws with a cordless?
It can be done, but you'd better have a pile of charged batteries.
Two batteries and a good quality tool will do just fine.
Battery-powered circular saws are also a
joke--I've yet to see one
that could hold its own against my worm-drive Skilsaw.
Get a modern one.
Cordless tools have changed a lot in the past ten years. Technology marches on.
--
Will, who this weekend will be drill and screwing lots of things with
a modern Hilti.
2:26 p.m.
On 5 Feb 2011 at 17:08, William Donzelli wrote:
I don't believe it. If that were the case, the contractors around
here would be gobbling them up like hotcakes and nobody would own a
corded saw or drill.
Got any figures for how much 4x fir a modern cordless circular saw
will rip (not crosscut) on a charge?
I'm prepared to be proved wrong, but if a 7" cordless saw can cut a
shift's worth of framing lumber on a single charge, I'll seriously
consider buying one.
--Chuck
Battery-powered circular saws are also a joke--I've yet to see one
that could hold its own against my worm-drive Skilsaw.
Get a modern one.
2:37 p.m.
I'm prepared to be proved wrong, but if a 7"
cordless saw can cut a
shift's worth of framing lumber on a single charge, I'll seriously
consider buying one.
Who expects any of those tools to work all day on a single charge?
Go to any construction site, and you will find a bank of chargers for
all the tools. Whether it is once a day or twenty times a day, the
guys will simply walk over and swap out the exhausted batteries.
Yes, there are still applications for corded tools on the site (big
ass hammer drills, serious saws, conduit benders, etc..), but these
days 95 percent of the hand work can be done nicely with cordless
tools.
--
Will
6 Feb
6 Feb
7:54 a.m.
On 5 Feb 2011 at 14:10, William Donzelli wrote:
Ever have to pre-drill and drive 500 4" deck screws with a cordless?
It can be done, but you'd better have a pile of charged batteries.
Personally, I hate rechargeable batteries in anything. Every type I've
used (including modern ones) has a ridiculously high self-discharge rate
and a fairly long (hours) charging time, Which emans if you want to use
something powered by such a battery that you've not used for a couple of
months, if you're lucky the battery will only need charging and you'll be
held up until it's charged. if you're unlucky, the battery will ned
replacing.
That's always bothered me a bit. =A0I've replaced the 2-wire cord in a
drill with a 3-wire one, attaching the ground wire to the field coil
laminations. =A0While not perfect, it's probably better than nothing.
Get a cordless. I have several cordless drills and drivers, including
hammer drills
and impact wrenches. They're okay for small jobs, but don't hold up
I can;t see the point of cordless tools in my workshop. Small jobs I will
do by hand, for anything larger, I don't mind having to plug the cable
in.
My father wanted a powered screwdriver recently. In the end he did manage
to find a mains-powered one (110V). All I will say is that it's a lot
nicer than any cordless one I've ever tried.
-tony
11:33 a.m.
On 6 Feb 2011 at 15:54, Tony Duell wrote:
> I can;t see the point of cordless tools in my
workshop. Small jobs
I
will do by hand, for anything larger, I don't mind
having to plug the
cable in.
On the subject of plugs and receptacles, quite a number of
professional building contractors around here use 3-prong "twist-
lock" aka "Hubbel" connectors for their corded tools. One advantage
is that the plugs won't simply pull out. The twist-lock connectors
are also quite common in things such as RV hookups and portable
generators and can be had in various sizes of 3 and 4 prong versions.
They were quite common in comptuer data centers, but I don't know if
that's still true.
--Chuck
11:52 a.m.
On the subject of plugs and receptacles, quite a
number of
professional building contractors around here use 3-prong "twist-
lock" aka "Hubbel" connectors for their corded tools. One advantage
Ove here, 'Hubbel connector' is used as a generic term for _any_
American-type mains connector by some people. Hubbel make a lot mroe than
twist-n-lock plugs after all. I think most of the 230V plugs in my
PDP11s were made by Hubbel, for example.
But I guess it's like the example Philip (I think) stated of calling the
BS4343 plugs 'Commando Plugs'.
is that the plugs won't simply pull out. The
twist-lock connectors
are also quite common in things such as RV hookups and portable
generators and can be had in various sizes of 3 and 4 prong versions.
They were quite common in comptuer data centers, but I don't know if
that's still true.
I'e seen the odd one or two, I think. maybe one of my old paper tape
units has a twist-n-lock connector for the mains input, I think some BRPE
punches did, for example. That would be a 3 contact one with a central
earth pin and 2 different-sized curved hooked plades for the live and
neutral wires.
They are certainly not commonly used in the UK.
-tony
12:13 p.m.
On 6 Feb 2011 at 19:52, Tony Duell wrote:
But I guess it's like the example Philip (I think)
stated of calling
the BS4343 plugs 'Commando Plugs'.
Or the way 36-positon (printer) or 50-position (SCSI-I) connectors
are referred to as "Centronics" connectors. Before that, when the 50-
position unit saw most of its use in office key telephone systems, it
was often referred to as an "Amphenol" or "Blue Ribbon" connector.
I've never heard the 24-position version of the connector used for
GPIB called "Centronics", however.
Some names just stick, defying any reason.
--Chuck
12:18 p.m.
Or the way 36-positon (printer) or 50-position
(SCSI-I) connectors
are referred to as "Centronics" connectors. ?Before that, when the 50-
position unit saw most of its use in office key telephone systems, it
was often referred to as an "Amphenol" or "Blue Ribbon" connector.
Blue Ribbon was the name of the product line, and covered quite a few
styles of connectors.
--
Will
12:28 p.m.
On 6 Feb 2011 at 19:52, Tony Duell wrote:
And of course the well-known 'fact' that all D connectors are in a size
'B' shell :-)
But I guess it's like the example Philip (I
think) stated of calling
the BS4343 plugs 'Commando Plugs'.
Or the way 36-positon (printer) or 50-position (SCSI-I) connectors
are referred to as "Centronics" connectors. Before that, when the 50- position unit saw most of its use in office key
telephone systems, it
I've seen it called a 'Telco' connctor, even in respectable manuals like
those from HP.
was often referred to as an "Amphenol" or
"Blue Ribbon" connector.
I thought that strictly 'Blue Ribbon' were the larger ones, like the oens
used on Tektornic 1-series and letter-series plug-ins. The
Centronics/SCSI-1/GPIB connectors are 'microribbon'.
I've never heard the 24-position version of the
connector used for
GPIB called "Centronics", however.
I have. At least one catalogue used to list 'Centronics' connectors in
14, 24, 36 and 50 way versions. Another catalogue (from a very well-knwon
electronic compont distributro over here) listed 'IEEE-488' conenctors in
14, 24, 36 nad 50 way versions. Yes, they are what we're talking about...
-tony
12:51 p.m.
On 6 Feb 2011 at 20:28, Tony Duell wrote:
And of course the well-known 'fact' that all D
connectors are in a
size 'B' shell :-)
Aren't PL/SO-239 coax connectors still called "UHF" connectors by
some? That comes from a time when anything above about 30 MHz was
"UHF"--and anything above 300 MHz was "microwave".
--Chuck
6 Feb
6 Feb
12:11 p.m.
On the subject of plugs and receptacles, quite a
number of
professional building contractors around here use 3-prong "twist-
lock" aka "Hubbel" connectors for their corded tools. ?One advantage
is that the plugs won't simply pull out.
Yes, extension cords at construction sites tend to take a tremendous
amount of abuse, getting run over, yanked, chopped, abraded, and
stolen. Twistlocks help.
They were quite common in comptuer data centers, but I
don't know if
that's still true.
Generally, yes. I think there is a move away from the older R&S style
connectors of the big mainframe era. Which is good for us, because the
latter are EXPENSIVE (especially the ones for 400 Hz power).
--
Will
1:01 p.m.
On 2011 Feb 6, at 12:11 PM, William Donzelli wrote:
Generally, yes. I think there is a move away from the older R&S style
connectors of the big mainframe era. Which is good for us, because the
latter are EXPENSIVE (especially the ones for 400 Hz power).
Are these (R&S) the threaded aviation/military connectors?
My HP2116C came with a threaded-and-keyed-housing connector with 3
round pins in a triangle, one being longer than the others.
One of a large family of connectors with various housing diameters and
number of pins, which I've always taken to be primarily an aviation and
military-use family, but never known the name of.
I don't know if it was a special order on the HP2116 or standard (never
seen it on other HP equip), but I replaced it rather than try to find
the mate.
2:53 p.m.
Are these (R&S) the threaded aviation/military
connectors?
No, those threaded things form a diverse family, and go under the
names of AN3100s, MS connectors, and so forth.
The old R&S connectors are the big "pin and sleeve" types, with older
models in metal enclosures. The new ones are plastic, color coded, and
in the UK are called "Commando plugs". They are often seen at marinas,
as they are available in water tight enclosures.
My HP2116C came with a threaded-and-keyed-housing
connector with 3 round
pins in a triangle, one being longer than the others.
One of a large family of connectors with various housing diameters and
number of pins, which I've always taken to be primarily an aviation and
military-use family, but never known the name of.
Originally AN310x, with x signifying straight/angle/chassis/cable
options. The system was formed around 1941 (I think), in order to
standardize the US military's connector situation.
I don't know if it was a special order on the
HP2116 or standard (never seen
it on other HP equip), but I replaced it rather than try to find the mate.
Those three pinners in various sizes are quite common.
--
Will
6:18 p.m.
On 2011 Feb 6, at 2:53 PM, William Donzelli wrote:
Ah-ha, I've found the Amphenol catalog for the MS3100 series and
matched up the part number for the 2116 connector. Can't say I'm ready
to order the plug, but it's nice to know what it is for future ref.
Are these
(R&S) the threaded aviation/military connectors?
No, those threaded things form a diverse family, and go under the
names of AN3100s, MS connectors, and so forth.
The old R&S connectors are the big "pin and sleeve" types, with older
models in metal enclosures. The new ones are plastic, color coded, and
in the UK are called "Commando plugs". They are often seen at marinas,
as they are available in water tight enclosures.
My HP2116C came with a threaded-and-keyed-housing
connector with 3
round
pins in a triangle, one being longer than the others.
One of a large family of connectors with various housing diameters and
number of pins, which I've always taken to be primarily an aviation
and
military-use family, but never known the name of.
Originally AN310x, with x signifying straight/angle/chassis/cable
options. The system was formed around 1941 (I think), in order to
standardize the US military's connector situation.
I don't know if it was a special order on the
HP2116 or standard
(never seen
it on other HP equip), but I replaced it rather than try to find the
mate.
Those three pinners in various sizes are quite common.
5 Feb
5 Feb
12:42 p.m.
On electronic (i.e. personal computer) gear, I wonder
if the role of
the ever-present ground wire isn't more for RF noise than actual
safety protection.
Possibly. Althoguh a lot of computer equipment is metal-cased and
certainly wouldn't meet the requirements for double insulation. One
consern would be the mains filter. With no ground wire the casing would
flaot at half mains voltage due to a capacitive voltage divider formed
from the capacitors from the power-carrying wires to
the case. Yes, the
source impedance would be quite high, but enough to give you a
tingle.
Worse than that, if you connect the machine ta an earthed device and if
the logic ground wire is defective you are most likely to end up zapping
driver and receiver ICs. This was, I am told, a problem with some Acorn
Econet installations...
-tony
1:13 p.m.
On 5 Feb 2011 at 20:42, Tony Duell wrote:
Possibly. Althoguh a lot of computer equipment is
metal-cased and
certainly wouldn't meet the requirements for double insulation. One
consern would be the mains filter.
Those metal-cased line filters are becoming increasingly rare on
power supplies. Progress, I guess.
--Chuck
6 Feb
6 Feb
7:56 a.m.
On 5 Feb 2011 at 20:42, Tony Duell wrote:
And some things only have 2-pin mains conenctors :-(. I wonder how they
comply with the EMC directives....
actually, plenty of my classic machines don't have mains filter modules.
They have spearate capaxcitors and indcutors on the PCB. I prefer that --
easier to repair.
-tony
Possibly. Althoguh a lot of computer equipment is
metal-cased and
certainly wouldn't meet the requirements for double insulation. One
consern would be the mains filter.
Those metal-cased line filters are becoming increasingly rare on
power supplies. Progress, I guess.
5 Feb
5 Feb
1:49 p.m.
On 2011 Feb 5, at 11:06 AM, Chuck Guzis wrote:
On 5 Feb 2011 at 18:27, Pete Turnbull wrote:
Remember old (pre ~1970) power drills? : non-polarised plug,
ungrounded, and *aluminum* housing and handle.
Some might think some of the safety rules these days are overkill, but
when you look at the way a lot of old stuff was built you see the other
side.
Same here (most are DI) but it doesn't stop
them getting wet, or stop
cables getting frayed.
That's always bothered me a bit. I've replaced the 2-wire cord in a
drill with a 3-wire one, attaching the ground wire to the field coil
laminations. While not perfect, it's probably better than nothing.
6 Feb
6 Feb
8:02 a.m.
That's
always bothered me a bit. I've replaced the 2-wire cord in a
drill with a 3-wire one, attaching the ground wire to the field coil
laminations. While not perfect, it's probably better than nothing.
Remember old (pre ~1970) power drills? : non-polarised plug,
ungrounded, and *aluminum* housing and handle.
12:10 p.m.
On 2011 Feb 6, at 8:02 AM, Tony Duell wrote:
No, I rememebr pre-1970 poer tools. Aluminium casing, 3 core cable,
proper ground to a polarised mains plug.
If you wish to point out that's the way it was over there, fine; that's
interesting. It's not the way it was over here.
That's always bothered me a bit. I've
replaced the 2-wire cord in a
drill with a 3-wire one, attaching the ground wire to the field coil
laminations. While not perfect, it's probably better than nothing.
Remember old (pre ~1970) power drills? : non-polarised plug,
ungrounded, and *aluminum* housing and handle.
12:24 p.m.
Remember old (pre ~1970) power drills? : non-polarised
plug,
ungrounded, and *aluminum* housing and handle.
No, I rememebr pre-1970 poer tools. Aluminium casing, 3 core cable,
proper ground to a polarised mains plug.
5 Feb
5 Feb
11:10 a.m.
Many power tools sold in the US have no 3rd wire for grounding at
all, instead, a "double insulated" method of construction is used.
Samve over here. I guess it's safer than having a tool that should be
earthed if the earth wire has fallen off, but I am not sure I trust
double insulation as much as an earthed metal device.
What's curious is that such tools often employ the
"large blade =
neutra, small blade = line" polarized plugs.
All our plugs are polarised, and AFAIK all mains leads have different
colours of insulation on the live and neutral wires whether it matters or
not.
I wonder if the polarisated plugs on some power tools are due to the fct
that they only have single pole mains swtiches (wbich should be wired in
the live wire, of coruse [1]). I prefer doubel-pole switches, but that's
anothe rant...
[1] I once saw an SMPSU unit -- I think for a copy of the Apple ][ (but
certainly not a genuine Apple one)-- which was wired witha fuse in one
wire and a single pole switch in the other. OUCH!
-tony
5 Feb
5 Feb
11:04 a.m.
I think there's something in it, but I agree that
just about any shock will
make muscles do uncontrolled things.
The most "shocking" thing about getting shocked with house current is
not the pain, nor the involuntary muscle movement, but the surprise.
Most people never expect to get shocked, and the weird sensation will
cause a panic, with the brain thinking "pull out!" and the muscles
perhaps not following orders exactly, all with perhaps a little bit of
a flash-bang effect - and then the injury happens (falling off
ladders, etc.). Look at electricians, especially ones that repair old
installations. They get bitten all the time, and they really don't
flinch much at all. They are used to getting shocked. 120 V AC really
does not hurt much at all, and 240 V is only slightly more painful -
and I am not talking about whack your thumb with the hammer pain,
here. A fair number of electricians actually test wires with their
fingers. It is mostly just a very weird sensation. Get used to it,
respect it, and it is not really an issue.
--
Will
6 Feb
6 Feb
9:53 p.m.
On Saturday, February 05, 2011, William Donzelli wrote:
hammer pain, here. A fair number of electricians
actually test wires
with their fingers. It is mostly just a very weird sensation. Get
used to it, respect it, and it is not really an issue.
Indeed. After making sure i'm well insulated, I like to brush the
terminals of the circuit I'm working with the a knuckle, to make sure
it's de-energized. My fingers are very unlikely to fail at telling me
if there's some voltage there...
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
10:56 p.m.
On 7 Feb 2011 at 0:53, Patrick Finnegan wrote:
Indeed. After making sure i'm well insulated, I
like to brush the
terminals of the circuit I'm working with the a knuckle, to make sure
it's de-energized. My fingers are very unlikely to fail at telling me
if there's some voltage there...
That's not even in the "weird" ballpark. I knew a fellow once who
could estimate the voltage with a fair degree of accuracy across the
terminals of a used 9V PP3 "transistor radio" battery by licking the
terminals.
I wonder whatever happened to him.
--Chuck
5 Feb
5 Feb
11:45 a.m.
On 2011 Feb 5, at 2:05 AM, Pete Turnbull wrote:
On 05/02/2011 00:42, Brent Hilpert wrote:
I have heard that argument too, but I'm not at all convinced by it. It
strikes me more as 230V system users trying to justify why it's
'better', or 'not less safe'.
As someone with direct experience working with both voltages (relative
to ground), I'm not fond of being shocked by either level, but I can
tell you quite quickly which level I prefer to work around and 'prefer'
to come in contact with. It varies between individuals and conditions,
but 120V shocks for many are quite tolerable in the sense of it being
enough to warn you without producing damage (or as William was pointing
out, the difference between 'shock' and 'surprise'). IME, I can't say
the same thing about 240.
240 is double 120, by Ohm's law and impedance, lethal currents are more
'likely' or easily produced by the higher voltage.
Yes, one always has to be careful around both levels for both shock
concern and because there is a fair mount of energy behind both
(slipped tools producing big sparks and damage).
I'm not well acquainted with the UK/Euro rules history, but I'll put
forth that the UK/Euro 110/55 building-site requirements are evidence
of the point. It's nice that it actually lowers the V-to-ground to such
a low level, but I expect it exists because the 240V-to-ground is
considered unsafe, while in NA we get by safely enough with the
120V-to-ground on building sites.
The real-world difference between North American
240V and Euro 240V
is the maximum potential relative to ground:
NA: 120 VRMS, 170V peak
Euro: 240 VRMS, 340V peak
Of course, the lower potential to ground is precisely why NA uses the
split-phase 120/240: it is much safer for humans but you still have
240 for heavy loads.
I believe that's debatable.
Now, I expect most of us would agree that voltage below about 70-90V
peak (around 55V RMS) is much safer, on the grounds that while it
might give a person an unpleasant surprise, a shock, even across the
body, is unlikely to be fatal. Hence the SELV rules and our use of
RLV 110V AC centre tapped to ground on building sites, giving a
maximum of 55V RMS. (According to the standards bodies like IET, that
means a maximum around 40V for indirect contact shock protection, well
below the accepted standard safe touch voltage and therefore we don't
need to limit earth loop impedances and worry about RCDs on building
sites.)
Nevertheless, I've often heard it argued that voltages around 230V RMS
are safer than, say, 110V RMS, on the grounds that a casual brush with
a 230V live conductor will cause a very rapid reaction in humans,
often jerking the contact free, whereas voltages around the 100-150V
range don't. I can't remember where I read supporting evidence, but
it's certainly something I've often heard mentioned, and is one reason
we think American voltages are actually more dangerous than ours. All
that said, either can give a potentially fatal shock, as both are
sufficient to overcome initial skin resistance.
7:27 a.m.
The real-world difference between North American 240V
and Euro 240V is=20=
the maximum potential relative to ground:
NA: 120 VRMS, 170V peak
Euro: 240 VRMS, 340V peak
That's one difference. The other difference is that in the States you
have a centre-tap available.
Of course, the lower potential to ground is precisely why NA uses the=20
split-phase 120/240: it is much safer for humans but you still have 240=20=
for heavy loads.
For equipment, in theory, there could be a problem if the insulation=20
rating of some component (e.g. caps) could not handle the higher=20
potential to ground. In practice, it's somewhat unlikely a manufacturer=20=
would build anything such that that would be a problem.
They certianly shouldn't. I don't know what your regulations require, but
over here I belive it has to be able to stand at least twice the mains
voltage between the current-carrying wires and ground. I test everyting
at 1000V (and repair it if there's any leakage I can't justify). Note
that 'everything' includes brand-new stuff too, and yus, I've had the odd
faiulur (in fact classic computing equipment seems to be rahter better
than new stuff in this regard).
-tony
3:05 p.m.
On 2011 Feb 5, at 7:27 AM, Tony Duell wrote:
? The centre-tap is there as an outcome of the design, not innate
intent.
The real-world
difference between North American 240V and Euro 240V
is=20=
the maximum potential relative to ground:
NA: 120 VRMS, 170V peak
Euro: 240 VRMS, 340V peak
That's one difference. The other difference is that in the States you
have a centre-tap available. 
3:32 p.m.
New subject: Mac's and 400K diskettes
Hi,
I'm working on an archive project and for the past 2 days I've gotten a
Powermac 5260/100 back to life, gotten it hooked up to my network via
its CS Slot Ethernet card (make not, the cable must have ALL pins
connected, not just 1,2 & 3,6 - otherwise the cable isn't recognized as
an active link by the Apple CS card...
Got Appletalk protocol and Appleshare setup on my Win 2K3 server, now
I'm connected, all is well in the universe...
Oh, Mac has OS 8.1 installed...
So I pop in a bunch of Corvus Mac diskettes from 84-85 so I'm assuming
they are 400K ... no good, Mac won't read them, has no prob reading 800K
diskettes, but won't read any of the Corvus disks... I am hoping the
disks aren't bad (really hoping since they are next to impossible to
find/replace)
So, question is....
Does anyone know if Powermac's will read older 400K mac diskettes???
curt
3:43 p.m.
New subject: Mac's and 400K diskettes
On 2/5/11 3:32 PM, Curt @ Atari Museum wrote:
Does anyone know if Powermac's will read older
400K mac diskettes???
You can image them, but machines after OS 8 can't read the earlier MFS
disk format.
http://guides.macrumors.com/Mac_OS_%28Classic%29
Mac OS 8
* This was the last system to support reading from the MFS. Creating MFS disks had
been dropped in System 3, when MFS was replaced with HFS.
There is also a problem where early Mac apps get confused with aliases. Forget when that
occured, probably
when aliases were added.
3:47 p.m.
New subject: Mac's and 400K diskettes
On 2/5/2011 3:32 PM, Curt @ Atari Museum wrote:
Hi,
I'm working on an archive project and for the past 2 days I've gotten
a Powermac 5260/100 back to life, gotten it hooked up to my network
via its CS Slot Ethernet card (make not, the cable must have ALL pins
connected, not just 1,2 & 3,6 - otherwise the cable isn't recognized
as an active link by the Apple CS card...
Got Appletalk protocol and Appleshare setup on my Win 2K3 server, now
I'm connected, all is well in the universe...
Oh, Mac has OS 8.1 installed...
So I pop in a bunch of Corvus Mac diskettes from 84-85 so I'm assuming
they are 400K ... no good, Mac won't read them, has no prob reading
800K diskettes, but won't read any of the Corvus disks... I am
hoping the disks aren't bad (really hoping since they are next to
impossible to find/replace)
So, question is....
Does anyone know if Powermac's will read older 400K mac diskettes???
curt
What software are you using to read them? I would not expect that using
the Finder to read these floppies would be successful, since they're
going to use a pre-HFS filesystem that 8.1 is probably not going to
support. I know I used a PowerMac 6100/66 a long time ago to *write*
out 400K Lisa floppies, using "Disk Dup+" and "Disk Copy" but I
don't
recall using that same machine to read 400K floppies. One would hope
that a system that can write 400K disks could also read them back, though...
Josh
3:49 p.m.
New subject: Mac's and 400K diskettes
--- On Sat, 2/5/11, Curt @ Atari Museum <curt at atarimuseum.com> wrote:
Does anyone know if Powermac's will read older 400K mac
diskettes???
The PowerMac will. System 8.1 will not. They dropped support for 400K disks in System 7.6.
So, you'll need to have 7.5 or older installed to read data from them. IIRC, DiskCopy
will still make images of the 400K disks, even though the OS won't read them.
-Ian
4:36 p.m.
New subject: Mac's and 400K diskettes
Sounds like I'll need to install 7.5 and see what happens... Thanks everyone for the
quick answers
Curt
-----Original Message-----
From: cctalk-bounces at classiccmp.org on behalf of Mr Ian Primus
Sent: Sat 2/5/2011 6:49 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Mac's and 400K diskettes
--- On Sat, 2/5/11, Curt @ Atari Museum <curt at atarimuseum.com> wrote:
Does anyone know if Powermac's will read older 400K mac
diskettes???
The PowerMac will. System 8.1 will not. They dropped support for 400K disks in System 7.6.
So, you'll need to have 7.5 or older installed to read data from them. IIRC, DiskCopy
will still make images of the 400K disks, even though the OS won't read them.
-Ian
10:47 p.m.
New subject: Corvus Mac Disks...
Hi,
Just wanted to thank everyone again for the assistance. I installed
System 7.5.3 and viola! I was able to read the diskettes (most)....
One diskette (Corvus User Client) isn't reading for some reason... I
tried Norton Disk Doctor 3.5 and it read the drive label and saw it as
"Corvus User Client" but said it didn't support repair/verify of non-HFS
disks so I got a little closer, but not close enough...
So I'll have to find a disk repair tool that works with older 400k
diskettes so I can run a repair/fix on it and get it fully readable.
Well, the good news is that 4 of the 5 disks were readable, I moved
them over to my server via Appleshare and just posted up a quick page
(I'll clean up the disk images later on, but just posted up the scans of
the disks and then linked them to .ZIP images of the contents of each
diskette (no apple imaging, straight files copy and then zipped up the
directories I had made)
http://www.corvusmuseum.com/software/mac/
If anyone has any Corvus diskettes and wants to contribute to the
archive project, please email me off-list, thanks!
Curt
10:10 a.m.
New subject: Corvus Mac Disks...
Arrrrgggggggg......... okay, you got me, Voila! Though Piano does
sound better ;-)
Christian Corti wrote:
On Sun, 6 Feb 2011, Curt @ Atari Museum wrote:
7.5.3 and viola! I was able to read the
diskettes (most).... One
Why not guitar or piano? ;-)
Christian
7 Feb
7 Feb
12:03 p.m.
New subject: Corvus Mac Disks...
From: Curt @ Atari Museum
Sent: Sunday, February 06, 2011 10:11 AM
Christian Corti wrote:
> On Sun, 6 Feb 2011, Curt @ Atari Museum wrote:
>> 7.5.3 and viola! I was able to read the
diskettes (most).... One
> Why not guitar or piano? ;-)
Arrrrgggggggg......... okay, you got me, Voila!
Though Piano does sound
better ;-)
Softly, now!
Rich Alderson
Vintage Computing Sr. Server Engineer
Vulcan, Inc.
505 5th Avenue S, Suite 900
Seattle, WA 98104
mailto:RichA at vulcan.com
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/
6 Feb
6 Feb
8:07 a.m.
On 2011 Feb 5, at 7:27 AM, Tony Duell wrote:
? The centre-tap is there as an outcome of the design, not innate
intent.
The peak voltage from the power-carryingwires to ground is also an
outcome of the design.
My real point is that no device that requires 220V should care about the
voltage to ground (within reason). I would certainly consider a 220V
device that could not satand 220V between one of the power-carrying wires
to ground ans being unsafe.
But as various people have pointed out, many US 220V appliances do use
110V for something (controller, timer, etc). That's a bigger problem when
running them in Europe
Actualyl, I have amn instrument (I think it's my Tektronix 575 curve
tracer) whic hahs sepprate wiring arrangements for 115V, 230V with the
centre earthed and 230V with one side earthed. No, the last 2 are not a
safety thing. Appranetly by having certain points of the transformer
primary close ot ground you get slightly less noise in the instrument.
-tony
The
real-world difference between North American 240V and Euro 240V
is=20=
the maximum potential relative to ground:
NA: 120 VRMS, 170V peak
Euro: 240 VRMS, 340V peak
That's one difference. The other difference is that in the States you
have a centre-tap available.
12:08 p.m.
On 2011 Feb 6, at 8:07 AM, Tony Duell wrote:
You're obfuscating. The point of your comment remains a mystery other
than being to find something to comment on. At this point, no, I don't
want an explanation.
On 2011 Feb 5, at 7:27 AM, Tony Duell wrote:
? The centre-tap is there as an outcome of the design, not innate
intent.
The peak voltage from the power-carryingwires to ground is also an
outcome of the design. The
real-world difference between North American 240V and Euro 240V
is=20=
the maximum potential relative to ground:
NA: 120 VRMS, 170V peak
Euro: 240 VRMS, 340V peak
That's one difference. The other difference is that in the States you
have a centre-tap available. My real point is that no device that requires 220V
should care about
the
voltage to ground (within reason). I would certainly consider a 220V
device that could not satand 220V between one of the power-carrying
wires
to ground ans being unsafe.
Yes, good design would say that it shouldn't matter and I can't say
that I've run across a device where it did matter. But I'm not about to
tell someone working on a device I'm not acquainted with that they
never will. Hence my use of the word 'unlikely' in the earlier message.
But as various people have pointed out, many US 220V
appliances do use
110V for something (controller, timer, etc). That's a bigger problem
when
running them in Europe
Actualyl, I have amn instrument (I think it's my Tektronix 575 curve
tracer) whic hahs sepprate wiring arrangements for 115V, 230V with the
centre earthed and 230V with one side earthed. No, the last 2 are not a
safety thing. Appranetly by having certain points of the transformer
primary close ot ground you get slightly less noise in the instrument.
12:23 p.m.
? The centre-tap is there as an outcome of the design,
not innate
intent.
The peak voltage from the power-carryingwires to ground is also an
outcome of the design.
1:14 p.m.
On 2011 Feb 6, at 12:23 PM, Tony Duell wrote:
I think we are ageed on the following (and there are plenty of books to
back this up ) :
US 23)V mains is 115-0-115V with the centre tap connected to something
close to local ground. Therefore the peak votlage between any
current-carrying conductor and ground is 115*qrt(2)V
UK 230V minas has one side connected to something close to local
ground.
Therefore the peak voltge between a current-carrying conductor and
ground
is 230*sqrt(2)V.
This may make a difference in some cases, but _I_ feel that the number
of
cases where that matters is vanishingly small.
But also US 230V mains has that centre-tap available, so you can wire
part of your device to run from 115V (centre-tap to one outside wire)
if
you want to. I understnad this is commonly done to power control units,
lamps, timers, etc.
UK mains does not hve an avialable centre tap. if you want 10V you have
to use a step-down (auto)transformer.
Practically, if you want to run a US 230V device in the UK, it is much
more likely you will have to provide 110V as well than that you'll ahve
to worry about something breaking down due to the higher peak voltage
to
ground.
Yes, all of which was covered earlier in the thread.
30 Jan
30 Jan
8:05 p.m.
Hi,
On 31/01/2011, Brian Lanning <brianlanning at gmail.com> wrote:
In the US, two separate 110 legs are delivered to the
house. When we
need 220, the magic of constructive interference is applied, and we
get 220. The 220 is delivered to the appliance as two separate 110
wires, a neutral wire, and sometimes a separate ground wire for
safety.
This doesn't look quite right to me, but it is probably close enough
for most applications.
Because of this arrangement, sometimes appliances (I
believe, maybe
I'm wrong) will pull 110 from one of the legs to power electronics in
the appliance.
But I think european 220 doesn't work this way. Is one 220 leg
delivered to the house? And the electronics work off that 220 leg?
Or are two 110 lines delivered and every outlet gets the sum of those
two 110 lines?
In Europe, a typical property is supplied with a single 230V RMS AC
single phase and neutral supply. If you pay enough money and/or are
small industrial etc, you can get a three phase and neutral supply.
Each phase is 230V RMS AC phase to neutral, 400V RMS AC phase to
phase.
The only way to get 110V RMS AC is through a stepdown transformer.
If it's not two separate legs, I'm thinking
that it will be impossible
to wire an american 220 appliance to work with european 220. Is this
right?
I don't know enough about american 220V applicances.
Many switch mode power supplies will work happliy with both 230V and
110V. The 110/230 switch only ever seemed to switch in a secondary
capacitor after the bridge rectifier for the HV DC supply to the
switching circuitry. I guess it was difficult to get 300VDC+
capacitors for a while. Adding a second capacitor (in series) meant
that each capacitor only ever saw about 1/2 the DC voltage, and hence
kept the smoke in.
Simon
--
------------------------------------------------------------------------
"Well, an engineer is not concerned with the truth; that is left to
philosophers and theologians: the prime concern of an engineer is
the utility of the final product."
Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh
31 Jan
31 Jan
11:15 a.m.
On 31 Jan 2011 at 12:05, Simon Fryer wrote:
It's been 240/120 V in the USA for years. The voltmeter on the
outlet next to my system here says that the line voltage at this
outlet is 122 volts.
Consider the light inside an electric kitchen oven. It's always a
120V item, even though the oven elements themselves run from 240V.
Strictly speaking, a US "crowfoot" outlet used for appliances is not
a grounded one--there should be no continuity between the third
(neutral) leg and the chassis of the appliance. It's a
"grandfathered" situation--a current-carrying supply line should not
also serve the purpose of protection.
Some local codes require that a separate grounding wire be installed
for safety. There are applications where a 3+ground outlet is
required by code, mostly in outdoor applications, such as RV hookups
and generators.
On 31/01/2011, Brian Lanning <brianlanning at
gmail.com> wrote:
In the US, two
separate 110 legs are delivered to the house. When
we need 220, the magic of constructive interference is applied, and
we get 220. The 220 is delivered to the appliance as two separate
110 wires, a neutral wire, and sometimes a separate ground wire for
safety.
This doesn't look quite right to me, but it is probably close enough
for most applications. In Europe, a typical property is supplied with a
single 230V RMS AC
single phase and neutral supply. If you pay enough money and/or are
small industrial etc, you can get a three phase and neutral supply.
Each phase is 230V RMS AC phase to neutral, 400V RMS AC phase to
phase.
In the USA, some locales do not allow 3-phase service to be installed
on a residential property. For 3-phase shop equiment, a rotary
converter (really a 3-phase motor with a large capacitor hooked
between two legs) is often used for the home shop owner who wants to
run his South Bend lathe with a 5HP 3-phase motor.
I'm out in the country, so my service is still single-phase with a
buried 6600V supply drop going to a pad-mounted transformer in my
front yard. I'm sure I could get 3-phase service, but it'd cost a
fortune to install, what with the trenching and all. I was surprised
to see the size of the wire going to my transformer. It must be
something like 3/0 AWG copper--it's heavy. I was told that the same
wire was used for the buried "loop" servicing the neighborhood as
well as all the drops. Seems like a waste of money to me.
If you want to run heavy appliances however, keep in mind the line
frequency issues. While there are lots of appliances that will
accept 50 or 60 Hz line current, it's not universally true.
--Chuck
4:29 p.m.
All,
On 01/02/2011, Chuck Guzis <cclist at sydex.com> wrote:
On 31 Jan 2011 at 12:05, Simon Fryer wrote:
It's been 240/120 V in the USA for years. The voltmeter on the
outlet next to my system here says that the line voltage at this
outlet is 122 volts.
I was assuming you were getting two phases from a three phase system.
Tony seems to indicate that the two legs in the US are from a centre
tapped transformer, so you would be getting 220/240V.
[more scary US distribution wiring]
Simon
--
------------------------------------------------------------------------
"Well, an engineer is not concerned with the truth; that is left to
philosophers and theologians: the prime concern of an engineer is
the utility of the final product."
Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh
On 31/01/2011, Brian Lanning <brianlanning at
gmail.com> wrote:
In the
US, two separate 110 legs are delivered to the house. When
we need 220, the magic of constructive interference is applied, and
we get 220. The 220 is delivered to the appliance as two separate
110 wires, a neutral wire, and sometimes a separate ground wire for
safety.
This doesn't look quite right to me, but it is probably close enough
for most applications. 
5:50 p.m.
Simon Fryer wrote:
I was assuming you were getting two phases from a
three phase system.
Tony seems to indicate that the two legs in the US are from a centre
tapped transformer, so you would be getting 220/240V.
[more scary US distribution wiring]
There's some reasonable text about various AC systems at:
http://en.wikipedia.org/wiki/Split-phase_electric_power
cheers
Jules
12:39 p.m.
Many switch mode power supplies will work happliy with
both 230V and
110V. The 110/230 switch only ever seemed to switch in a secondary
capacitor after the bridge rectifier for the HV DC supply to the
switching circuitry. I guess it was difficult to get 300VDC+
capacitors for a while. Adding a second capacitor (in series) meant
that each capacitor only ever saw about 1/2 the DC voltage, and hence
kept the smoke in.
Not at all!. The adjustable SMPUS are designed so that the chopper
cirucit works correctly with a DC inpout of around 350V. This can be
obtained in 2 ways :
a) By full0-wave rectifiying a 230V mains supply
b) By voltage-doubling a 115V mains supply
The first uses a bridge rectifier (normally) and a smoothing capacitor.
The second uses a pair of diodes and a pair of capacitors. It turns out
you can use 4 diodes (in a normal bridge configuration) and 2 capacitors,
along with a couple of resistors to get the 2 capacitors to charge to
approximatle the same voltage if you want to use the series combination
as a single cacpaitror) to make a cirucit that can aci as either of those
simply by adding a link for (b).
That;s what happens in every dual-voltage SMPUS I've worked on.
-tony
4:21 p.m.
All,
On 01/02/2011, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
I stand corrected. I can say that I have learnt something today.
Many switch
mode power supplies will work happliy with both 230V and
110V. The 110/230 switch only ever seemed to switch in a secondary
capacitor after the bridge rectifier for the HV DC supply to the
switching circuitry. I guess it was difficult to get 300VDC+
capacitors for a while. Adding a second capacitor (in series) meant
that each capacitor only ever saw about 1/2 the DC voltage, and hence
kept the smoke in.
Not at all!. The adjustable SMPUS are designed so that the chopper
cirucit works correctly with a DC inpout of around 350V. This can be
obtained in 2 ways : a) By full0-wave rectifiying a 230V mains supply
b) By voltage-doubling a 115V mains supply
The first uses a bridge rectifier (normally) and a smoothing capacitor.
The second uses a pair of diodes and a pair of capacitors. It turns out
you can use 4 diodes (in a normal bridge configuration) and 2 capacitors,
along with a couple of resistors to get the 2 capacitors to charge to
approximatle the same voltage if you want to use the series combination
as a single cacpaitror) to make a cirucit that can aci as either of those
simply by adding a link for (b).
That;s what happens in every dual-voltage SMPUS I've worked on.
Ahhh. That makes much more sense.
Simon
--
------------------------------------------------------------------------
"Well, an engineer is not concerned with the truth; that is left to
philosophers and theologians: the prime concern of an engineer is
the utility of the final product."
Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh
30 Jan
30 Jan
11:50 p.m.
H,
But I think European 220 doesn't work this way. Is one 220 leg
delivered to the house? And the electronics work off that 220 leg?
Or are two 110 lines delivered and every outlet gets the sum of those
two 110 lines?
Here in the Netherlands, most domestic houses do have a single leg
240V power.
For an additional 'connection fee' you can get 3 phase power delivered.
I have 3 phase power at home, guess why....
Ed
If it's not two separate legs, I'm thinking that it will be impossible
to wire an american 220 appliance to work with european 220. Is this
right?
brian
--
Dit is een HTML vrije email / This is an HTML free email.
31 Jan
31 Jan
1:18 a.m.
-----Oorspronkelijk bericht-----
Van: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
Namens E. Groenenberg
Verzonden: maandag 31 januari 2011 8:50
Aan: General Discussion: On-Topic and Off-Topic Posts
Onderwerp: Re: OT: american vs european 220
H,
But I think European 220 doesn't work this way. Is one 220 leg
delivered to the house? And the electronics work off that 220 leg?
Or are two 110 lines delivered and every outlet gets the sum of those
two 110 lines?
Here in the Netherlands, most domestic houses do have a single leg 240V
power.
For an additional 'connection fee' you can get 3 phase power delivered.
I have 3 phase power at home, guess why....
Ed
If it's not two separate legs, I'm thinking that it will be impossible
to wire an american 220 appliance to work with european 220. Is this
right?
brian
In most western Europe countries the power systems are 3-fase 230V with a
180 degrees phase-shift.
Neutral is earthed at the distribution (10kV ->230V) transformer . So only
the phase(brown) wire has a voltage potential to earth.
The voltage between earth, neutral and the other legs is always 230V AC and
between the 3 phase legs 400V AC.
Most new houses in NL are wired for a 3 phase-system but at the power inlet
just one leg is fused so the owner sees a 1 phase-system, but it easy (for
the power company) to upgrade to a 3 phase-system ( 2 fuses and a new
powermeter).
And yes I do have a 3-phase system with also a separate earth system for
measurement systems.
-Rik
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Dit is een HTML vrije email / This is an HTML free email.
1:08 p.m.
-----Oorspronkelijk bericht-----
Van: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
Namens Pete Turnbull
Verzonden: maandag 31 januari 2011 14:56
Aan: General Discussion: On-Topic and Off-Topic Posts
Onderwerp: Re: OT: american vs european 220
On 31/01/2011 09:18, Rik Bos wrote:
In most western Europe countries the power systems
are 3-fase 230V with
a
180 degrees phase-shift.
120-degree phase difference, not 180 :-)
--
Pete Peter Turnbull
Network Manager
University of York
Yes, sometimes I'm just to quick.....;-)
12:39 p.m.
On 1/31/2011 12:50 AM, E. Groenenberg wrote:
Uhmm, no, it's needed for powering up my pdp-11's
--
Dit is een HTML vrije email / This is an HTML free email.
For an additional 'connection fee' you
can get 3 phase power delivered.
I have 3 phase power at home, guess why....
Ed
Tube audio power supply ... :)
4:34 p.m.
On 1/31/2011 1:39 PM, E. Groenenberg wrote:
Is that for the cpu & memory or just the I/O devices?
Ben.
On 1/31/2011 12:50 AM, E. Groenenberg wrote:
Uhmm, no, it's needed for powering up my pdp-11's
For an additional 'connection fee' you
can get 3 phase power delivered.
I have 3 phase power at home, guess why....
Ed
Tube audio power supply ... :)
1 Feb
1 Feb
12:12 a.m.
On 1/31/2011 1:39 PM, E. Groenenberg wrote:
Is that for the cpu & memory or just the I/O devices?
Ben.
For one large configuration, basically a 11/70 with full memory complement,
and some peripherals (one RM03 drive, 3 RK07 drives, one PC05 paper tape,
one RX02 floppy unit, one TU56 tape drive, 2 TU-80 tape drives and a
Decwriter-III.
Don't need to heath the garage then, this dissipates enough to keep
you warm in the winter ;)
--
Dit is een HTML vrije email / This is an HTML free email.
On 1/31/2011 12:50 AM, E. Groenenberg wrote:
Uhmm, no, it's needed for powering up my pdp-11's
For an additional 'connection fee' you
can get 3 phase power
delivered.
I have 3 phase power at home, guess why....
Ed
Tube audio power supply ... :)
31 Jan
31 Jan
7:28 a.m.
Brian Lanning wrote:
Because of this arrangement, sometimes appliances (I
believe, maybe
I'm wrong) will pull 110 from one of the legs to power electronics in
the appliance.
Our clothes dryer runs the drum motor from one leg and the heaters / timer
from the other - there's not really any
"electronics" (the timer's a simple
switch/cam thing driven by a
small motor) but it seems sensible that other
high-draw appliances might run different parts via different 110V legs, too.
But I think european 220 doesn't work this way.
Is one 220 leg
delivered to the house? And the electronics work off that 220 leg?
Or are two 110 lines delivered and every outlet gets the sum of those
two 110 lines?
In the UK it was typically three 220V [1] phases to the street, I believe -
but only one of those would then make it as far as the house (resulting in
certain faults causing just part of the street to go dead as a phase was lost :-)
[1] or 230V, or 240V... I can never remember exactly. Historically the UK was
on 240V, but they harmonised with the rest of Europe which, IIRC, is 230V.
If it's not two separate legs, I'm thinking
that it will be impossible
to wire an american 220 appliance to work with european 220. Is this
right?
As others said, a step-down would work - but the number of 220V US appliances
are relatively few IME, and those that are may not require the split-power
arrangement to function. One gotcha is that US power is 60Hz and Europe 50Hz,
which might have an effect on anything that relies on line frequency for timing.
cheers
Jules
7:43 a.m.
On 31 January 2011 16:28, Jules Richardson <jules.richardson99 at gmail.com> wrote:
[1] or 230V, or 240V... I can never remember exactly.
Historically the UK
was on 240V, but they harmonised with the rest of Europe which, IIRC, is
230V.
Historically, the Britain was 240V, while mainland Europe was
(predominantly) 220V, as were Ireland and Northern Ireland. EU
regulation harmonised that to 230V. Not that it makes much of a
difference, really.
.tsooJ
9:59 a.m.
On Mon, Jan 31, 2011 at 04:43:38PM +0100, Joost van de Griek wrote:
On 31 January 2011 16:28, Jules Richardson
<jules.richardson99 at gmail.com> wrote:
IIRC the trick was that the "harmonized standard" defined 230 V as the
standard voltage with the tolerances large enough to cover pretty much all
the voltages (220 ... 240 V) that were mostly in use at that time.a
Kind regards,
Alex.
--
"Opportunity is missed by most people because it is dressed in overalls and
looks like work." -- Thomas A. Edison
[1] or 230V, or 240V... I can never remember
exactly. Historically the UK
was on 240V, but they harmonised with the rest of Europe which, IIRC, is
230V.
Historically, the Britain was 240V, while mainland Europe was
(predominantly) 220V, as were Ireland and Northern Ireland. EU
regulation harmonised that to 230V. Not that it makes much of a
difference, really.
10:32 a.m.
On 31/01/2011 17:59, Alexander Schreiber wrote:
IIRC the trick was that the "harmonized
standard" defined 230 V as the
standard voltage with the tolerances large enough to cover pretty much all
the voltages (220 ... 240 V) that were mostly in use at that time.a
Correct, in the UK it's officially 230V +10%/-6% instead of 240V +/-6%,
but in practice it's generally close to 240V. At least it is for the
"average" consumer; someone close to the supply transformer might
actually get up to 253V and someone further down the line where the
voltage has dropped might only get 216V, and still both would be within
the limits. Something similar is true in other parts of Europe, of
course. It makes calculations and specifications of power in water
heaters and the like rather interesting: P=V^2/R so for a resistive
heater the difference can be quite large.
Likewise, people here often refer to 3-phase as 415V, but the standard
says 400V plus/minus something.
--
Pete Peter Turnbull
Network Manager
University of York
2:22 p.m.
Obviously, european penises are 220cm long and american penises are
220in long, clearly making us superior. America loves to do things big.
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://legalizeadulthood.wordpress.com/the-direct3d-graphics-pipeline/>
Legalize Adulthood! <http://legalizeadulthood.wordpress.com>
1 Feb
1 Feb
3:53 p.m.
On Monday, January 31, 2011, Richard wrote:
Obviously, european penises are 220cm long and
american penises are
220in long, clearly making us superior. America loves to do things
big.
You mean 230cm and 240in.
Geeze, get it right.
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
7:58 p.m.
You mean 230cm and 240in.
Geeze, get it right.
Does it matter what colour the plug is?
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
-- Anything that can be put into a nutshell belongs there. -- F. G. Brauer ----
31 Jan
31 Jan
12:43 p.m.
On 31 January 2011 16:28, Jules Richardson <jules.richardson99 at gmail.com>
wrote:
IIRC, the oigianl spec was that mainland Euriope was 220V +/-
something-or-orhter, and the UK was 240V +/-somethingelse. The
'harmonisation; was to call mainland Europena mans '230V +alitle/-alot'
and UK mains '230V+alt/-alittle'. In other words they fiddled with the
tolerances and didn't actually change the voltages :-)..
-tony
[1] or 230V, or 240V... I can never remember
exactly. Historically the UK
was on 240V, but they harmonised with the rest of Europe which, IIRC, is
230V.
Historically, the Britain was 240V, while mainland Europe was
(predominantly) 220V, as were Ireland and Northern Ireland. EU
regulation harmonised that to 230V. Not that it makes much of a
difference, really.
12:14 p.m.
In the US, two separate 110 legs are delivered to the house. When we
need 220, the magic of constructive interference is applied, and we
get 220. The 220 is delivered to the appliance as two separate 110
wires, a neutral wire, and sometimes a separate ground wire for
safety.
I was under the impression that the US mains was in fact 220V (or 230V,
234V, depending on which reference you believe), centre-tapped. The
centre-tap is the 'neutral' wire and is connected to earth ground at one
point. The outside 2 ieres are this 110V with respect to neutral, but as
they're in antipahse there's 220V between them. Most devices are 110V and
run between one live/phase wire and neutral, high-power stuff (cooking
ovens, tumble driers, etc) run their heating elements between the 2
outside wires so as to reduce the current they draw.
Because of this arrangement, sometimes appliances (I
believe, maybe
I'm wrong) will pull 110 from one of the legs to power electronics in
the appliance.
I beleive you are corrrect. IIRC the timer of a cooker or tumble drier,
possibly the motor of the latter is run from 110V -- between one phase
wire and neutral.
But I think european 220 doesn't work this way. Is one 220 leg
delivered to the house? And the electronics work off that 220 leg?
Yes, exactly. The domestic mains is nomianlly 230V now. We get a single
phase wire and a neurtal, the latter being close to ground. Everything is
designed to run off that 230V supply. There is no 'centre tap'. So our
cookers, say, have 230V elements and a timer that runs off 230V mains.
Actually, the European mains is 3 phase. The final transformer secondary
is start (wye?) connected with the star point being th eneautral. Houses
get a single phase supply consisting of that neurral wire and one of the
phase wires -- to balance the load, neighbouring hosues in a road get
different phases [1]. Of coruse industral places get the full 2 phase
mains to run larger motors, etc. It's very difficult to convince the
electricity companies to run 3 phase mains into a normal house, though,
which is a problem for people who ant to run large disk drives ;-)
[1] In the cases of blocks of flats, student halls of residence, etc,
it's not unheard-of for each floor to be wired to wired to a different
phase. This has led to studend running extension leads to the rooms above
and below theres so as to get a 3 phase supply...
Or are two 110 lines delivered and every outlet gets
the sum of those
two 110 lines?
No, if we ant 110V, we have to provide our own step-down transfoemr
If it's not two separate legs, I'm thinking that it will be impossible
to wire an american 220 appliance to work with european 220. Is this
right?
It depends on what yuou are trying to do. Certainly a US appliance that
needs 110V for any function is not going to work on European mains
without modifications. That may be as simple as providing a small
step-down transofrmer for the control unit supply.
Waht are you trying to do?
-tony
1:43 p.m.
Tony Duell wrote:
Yes, I think that's the basic setup, but as Chuck noted the voltage of one
half is around 120V, not 110V (I got 122.8V on a nearby outlet just now)
I'd always assumed US cooker timers to be 240V/60Hz, but as Chuck pointed out
the bulbs are still 120V and so need a split supply - so they probably just
use commodity 120V timer motors, too...
In the US, two
separate 110 legs are delivered to the house. When we
need 220, the magic of constructive interference is applied, and we
get 220. The 220 is delivered to the appliance as two separate 110
wires, a neutral wire, and sometimes a separate ground wire for
safety.
I was under the impression that the US mains was in fact 220V (or 230V,
234V, depending on which reference you believe), centre-tapped. The
centre-tap is the 'neutral' wire and is connected to earth ground at one
point. The outside 2 ieres are this 110V with respect to neutral, but as
they're in antipahse there's 220V between them. Most devices are 110V and
run between one live/phase wire and neutral, high-power stuff (cooking
ovens, tumble driers, etc) run their heating elements between the 2
outside wires so as to reduce the current they draw.
As mentioned though, our elderly dryer just runs the elements and the timer
from one 'hot' wire and the motor from the
other - perhaps that's
unconventional, though. It does have an interesting
effect in that our dryer's
hooked to a load-control setup, but when the power company send a signal to
shut the power to load-controlled devices off (which they do during periods of
peak demand) the dryer stops producing heat and the timer stops advancing, but
the drum motor continues to turn. (it took me a while to diagnose that - I
wasted a few hours looking for a non-existent intermittent dryer fault :-)
Because of
this arrangement, sometimes appliances (I believe, maybe
I'm wrong) will pull 110 from one of the legs to power electronics in
the appliance.
I beleive you are corrrect. IIRC the timer of a cooker or tumble drier,
possibly the motor of the latter is run from 110V -- between one phase
wire and neutral. [1] In the cases of blocks of flats, student halls of
residence, etc,
it's not unheard-of for each floor to be wired to wired to a different
phase. This has led to studend running extension leads to the rooms above
and below theres so as to get a 3 phase supply...
ISTR people doing that in student halls because each room had its own breaker
with a ridiculously-low capacity, so running extensions from other rooms -
sometimes on different floors - was not unheard of.
No, if we ant 110V, we have to provide our own
step-down transfoemr
Y'know, I think I remember seeing shaver sockets in UK bathrooms with 120V
outputs (possibly in conjunction with 240V ones; long time since I've seen on
at all). Presumably those had a small step-down inside.
cheers
Jules
1 Feb
1 Feb
11:03 a.m.
I was under
the impression that the US mains was in fact 220V (or 230V,
234V, depending on which reference you believe), centre-tapped. The
centre-tap is the 'neutral' wire and is connected to earth ground at one
point. The outside 2 ieres are this 110V with respect to neutral, but as
they're in antipahse there's 220V between them.
Yes, I think that's the basic setup, but as Chuck noted the voltage of one
half is around 120V, not 110V (I got 122.8V on a nearby outlet just now) Most devices are 110V and
run between one live/phase wire and neutral, high-power stuff (cooking
ovens, tumble driers, etc) run their heating elements between the 2
outside wires so as to reduce the current they draw.
As mentioned though, our elderly dryer just runs the elements and the timer
from one 'hot' wire and the motor from the other - perhaps that's
unconventional, though. It does have an interesting effect in that our dryer's
hooked to a load-control setup, but when the power company send a signal to
shut the power to load-controlled devices off (which they do during periods of
peak demand) the dryer stops producing heat and the timer stops advancing, but [1] In the
cases of blocks of flats, student halls of residence, etc,
it's not unheard-of for each floor to be wired to wired to a different
phase. This has led to studend running extension leads to the rooms above
and below theres so as to get a 3 phase supply...
ISTR people doing that in student halls because each room had its own breaker
with a ridiculously-low capacity, so running extensions from other rooms -
sometimes on different floors - was not unheard of. No, if we ant 110V, we have to provide our own
step-down transfoemr
Y'know, I think I remember seeing shaver sockets in UK bathrooms with 120V
outputs (possibly in conjunction with 240V ones; long time since I've seen on
at all). Presumably those had a small step-down inside. from an isolating transformer. Most of thse sockets
have a tapped
secondary winding on the transofemr, and do, indeed, provide 110V as
well.
The trnasofemrs are typically about 20VA, and have many other uses. I
rememebr when a local 'pound shop/ had a load of such sockets, presumbly
bankrupt stock from sowewhere. Yes, I bought quite a few for the
isolating transformers.
-tony
1:16 p.m.
On 1 Feb 2011 at 19:03, Tony Duell wrote:
I think the voltage will depend on various things. I've heard it
quoted as 117V/234V [1] but that was some time ago, so it may well
have changed...
It's been variously quoted as 110/220, 115/230, 117/234 and today,
120/240. The "standard" has crept up over the years. Japan, I
believe, is still 100V, although it can be either 50 or 60 Hz.
I was under the impression that the US mains was in
fact 220V (or
230V, 234V, depending on which reference you believe),
centre-tapped. The centre-tap is the 'neutral' wire and is
connected to earth ground at one point. The outside 2 ieres are
this 110V with respect to neutral, but as they're in antipahse
there's 220V between them.
Yes, I think that's the basic setup, but as Chuck noted the voltage
of one half is around 120V, not 110V (I got 122.8V on a nearby
outlet just now) [1] Anyone else remember valves like the 117Z which
was (IIRC) a
double diode recrtifier with a 117V (!) filament. I think there wsa a
half-wave rectifer/ooutput pentode with a 117V filament too, used in
cheap record players.
117L7/M7GT if memory serves. Another combination was a 70L7 beam
power tube with a 35Z5 rectifier and a 12SK7 (or other 12.6V pentode
or triode).
Weren't there also some European countries (or parts thereof) that
used various DC voltages for lighting and small appliances? (Belgium
or Italy?).
Another artifact of earlier days in US industrial applications is
55/110/220/440V 25 Hz distribution. The power transformers are huge
and the "hum" is more of a "rattle".
--Chuck
1:48 p.m.
[1] Anyone
else remember valves like the 117Z which was (IIRC) a
double diode recrtifier with a 117V (!) filament. I think there wsa a
half-wave rectifer/ooutput pentode with a 117V filament too, used in
cheap record players.
117L7/M7GT if memory serves. Another combination was a 70L7 beam power tube with a 35Z5 rectifier and a 12SK7 (or other
12.6V pentode
or triode).
Right...
Weren't there also some European countries (or parts thereof) that
used various DC voltages for lighting and small appliances? (Belgium
or Italy?).
We had DC mains in England into the 1950s in some areas. A lot of radios
and TVs weew 'AC/DC',not just to save the cost of the mains transformer.
I rememebr working on TVs (long after the 1950s, of coruse) with
different voltage selector settings for AC and DC mains (possibly due to
fact that the smoothing capacitor would charge to the peak and not the
RMS votlage of AC mains). One of the Mullard books of audio amplfiier
cirucits (including things like the 5-10 and 5-20) includes a circuit
for an amplifier (4 valves, something like UF86, 2 * UCL82, UY85) for
AC/DC mains. Of coruse it was hot-chassis which is a right pain...
DC mains was somethign of a pain too. It was not smooth DC. It came from
commutator-type generators and had a lot of relatively high frequency
(audo band) ripple/noise on it. Non-triival to keep out of audio amplifiers!
Even if the mains was AC, it wasn't necessarily 50Hz. I think all sorts
of other frequencies were used in some areas at some times. Certainly
Lynmouth (north Bevon) had 100Hz mains until the hydro-electric power
station was destroed in the floods of 1952.
-tony
2:29 p.m.
On 1 Feb 2011 at 21:48, Tony Duell wrote:
Cheap record playes over here tended to use the
turntable motor widing
and an autotransformre to run the valve heaters (series string
totalling around 100V) and get the HT (B+) by half-0wave rectifying
the mains.
> power tube with a 35Z5 rectifier and a 12SK7 (or other 12.6V pentode
> or triode).
There was a brief time when AC/DC/battery radios were offered that
could be switched between line and battery operation. A 117Z3 or
similar rectifier was used to power both the filaments and as a plate
supply for the low-voltage tubes in the receiver section. Later
versions used a selenium rectifier instead of the 117Z3.
--Chuck
2 Feb
2 Feb
10:38 a.m.
There was a brief time when AC/DC/battery radios were
offered that
could be switched between line and battery operation. A 117Z3 or
similar rectifier was used to power both the filaments and as a plate
supply for the low-voltage tubes in the receiver section. Later
versions used a selenium rectifier instead of the 117Z3.
Yes, we had those over here too...
The battery-only radios would use 4 valves. The later series (25mA
filaments) were DK96 (pentagrid frequency changer), DF96 (IF amplifier
pentode), DAF96 (detecotr diopde and audio pentode) and DL96 (output
pentode). The last had a pair of filaments that could be wired in series
or parallel. Theser were directly heated valves, 1.4V per filament.
In battery-only sets. all 5 filament secions were wiredf in parallel
normally. The LT (A) supply was a 1.5V battery with 2 or 4 cells in
parallel. The HT (B+) supply was a 90V (noemally) layer battery.
The filaments had to be run off DC of course. So the mains/DC models put
all the filaments in series for a total of 7.5V, and put baalsat
resistor around bits fo the chain to compensate for the fact that in a
directly heated valve the anode currnet passes through the filament (and
with such low filament currents it did matter). For abttery operation,
the LT supply was a 7.5V dry battery. For mains operation, the filament
string was run throug ha dropping resistor from the HT+ line, and the
latter was nomrally supplied from the mains via a dropping resistor and
selenium rectifier.
There were exceptions. I have an old Vidor battey/mains portable that
does much the smae thing with the filaments (in series, run off the HT+
line in mains mode), but the HT comes from a trnasofemr and valve (EZ40
IIRC) rectifier. Tht at leat means it's not live-chassis.
-tony
1 Feb
1 Feb
1:49 p.m.
It's been variously quoted as 110/220, 115/230,
117/234 and today,
120/240. ?The "standard" has crept up over the years. ?Japan, I
believe, is still 100V, although it can be either 50 or 60 Hz.
It has been 120/240 for a very long time.
Another artifact of earlier days in US industrial
applications is
55/110/220/440V 25 Hz distribution. ?The power transformers are huge
and the "hum" is more of a "rattle".
I think this is all finally gone, apart from the NorthEast Corridor.
The only reason the NEC is still 25 Hz is due to railroad
ultra-conservative engineering.
--
Will
2:25 p.m.
On 1 Feb 2011 at 16:49, William Donzelli wrote:
I think this is all finally gone, apart from the
NorthEast Corridor.
The only reason the NEC is still 25 Hz is due to railroad
ultra-conservative engineering.
In my younger days, I worked at Inland Steel in various plants and
departments. There were three power distribution frequencies in use;
DC, 25Hz and 60 Hz. The 25Hz was generated locally from waste heat;
the 60 Hz was purchased and the DC could come from either source (via
large rotary converters).
The DC made sense as it was used for the overhead cranes (and
electromagnets), traction motors as one might find on an ingot buggy,
welding and for the large motors that powered the rolling mills.
Since the 25Hz was the cheapest power source, it was used for
lighting, ventilation, running various control instruments and as
general utility. A side effect of this was that new equipment was
being ordered at a significant premium to make use of 25Hz.
My tenure occurred when the plants began shifting from incandescent
to mercury vapor lighting. While the incandescent lighting had a
distinct pulse to it on 25Hz, the mercury vapor flicker was probably
sufficient to induce a seizure.
--Chuck
1:36 p.m.
On 01/02/2011 19:03, Tony Duell wrote:
The UKL regulations prohibit any socket outlets in
bathrooms (defined as
a 'room containing a fixed bath or shower') apart from shaver sockets run
from an isolating transformer.
In typical cases, effectively they do, but that's oversimplifying a bit
because there are places where it is allowed (depends on distances and
barriers). It just doesn't happen in a typical sized house!
--
Pete Peter Turnbull
Network Manager
University of York
3:14 a.m.
On Mon, 31 Jan 2011, Tony Duell wrote:
is start (wye?) connected with the star point being th
eneautral. Houses
get a single phase supply consisting of that neurral wire and one of the
phase wires -- to balance the load, neighbouring hosues in a road get
different phases [1]. Of coruse industral places get the full 2 phase
mains to run larger motors, etc. It's very difficult to convince the
electricity companies to run 3 phase mains into a normal house, though,
Maybe in the UK, but in Germany it's very usual to have three phases. For
example, our house gets three phases (fused at 63A each) which are then
distributed to the individual rooms (one phase here, another phase there,
and so on). The kitchen for example has in addition to the single phase
for the light and outlets a three-phase line for the stove. And it's not
unusual to have a red CEE outlet in some cases (we had one in the cellar
until we needed this additional three-phase line for the separate oven).
In France you can get three phases to your house (three-wire cable coming
into the house), it depends on your choice whether you actually have three
or only one phase available, e.g. you can have 1x60A (called "monophas?")
or 3x20A ("triphas?"), the price is the same.
Christian
5066
days inactive
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