17 Jun
2004
17 Jun
'04
1:56 p.m.
Hi
Most know about motor rotation but he was
talking about delta versus Y. This can be quite
different.
Dwight
From: "Antonio Carlini"
<arcarlini(a)iee.org>
I can't think of a specific incident like
that, but I do know
that our University uses a non-standard order of phases, and
that all the electrical contractors who come on site get a
lecture about it, for obvious reasons!
What's a "standard order of phases"? I know if you inadvertently
swap any two you potentially end up spinning the other way. For
some things this matters and for other it doesn't.
I can only assume I'm missing something obvious ...
Antonio
--
---------------
Antonio Carlini arcarlini(a)iee.org
17 Jun
17 Jun
4:44 p.m.
Most know about motor rotation but he was talking
about delta versus
Y. This can be quite different.
What _is_ the difference between delta and Y? A while ago we had a
discussion that ended up revolving around what point is grounded
("neutral"). As far as I can see, delta and Y are basically
equivalent, provided you don't try to refer anything to ground (or
anything else beyond the three phases), and provided you don't overload
anything.
Am I missing something?
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5:43 p.m.
New subject: A case for downgrading to PCs (was: WARNING: RANTING COMPUTERNUT...
What _is_ the difference between delta and Y? A while
ago we had a
discussion that ended up revolving around what point is grounded
("neutral"). As far as I can see, delta and Y are basically
equivalent, provided you don't try to refer anything to ground (or
anything else beyond the three phases), and provided you don't overload
anything.
Am I missing something?
Smoke and sparks, for a start.
William Donzelli
aw288(a)osfn.org
5:56 p.m.
At 09:44 PM 6/17/04 -0400, you wrote:
There's a BIG difference. In delta the windings are arranged like a
triangle with the power lines connected at the apexs so there isn't a
neutral leg and the hot legs all work against each other. In Y, the
windings are arranged like a Y with the neutral at the junction and the
power lines at the ends of the legs therefore neutral is connected to one
end of each of the three windings. There's also a significant difference in
the voltages between the hot legs. IIRC the hot leg of a Y is 240 VAC WRT
to neutral and about 300 VAC between the legs (it's the sum of the voltages
on each leg times the SINE of their phase angles). In Delta there doesn't
need to be a neutral but if there is it's isolated from the hot legs so
there's no voltage difference. Also the voltage between the hot legs is
fixed at 220VAC. Delta only needs three lines to work effectively, Y needs
four (three for power plus neutral). Ideally the neutral in Y connection
should be at 0 VAC WRT to ground but if you get a heavy power draw on one
leg of a Y then it can shift the neutral away from 0 volts.
The point is that there's a big difference in the voltages between the
legs and also from the legs to neutral or ground in the two systems. I may
not be exactly right about the exact voltages but it doesn't matter since
they vary from country to country and region to region but you get the idea.
Joe
A while ago we had a
Most know about motor rotation but he was talking
about delta versus
Y. This can be quite different.
What _is_ the difference between delta and Y? discussion that ended up revolving around what point is
grounded
("neutral"). As far as I can see, delta and Y are basically
equivalent, provided you don't try to refer anything to ground (or
anything else beyond the three phases), and provided you don't overload
anything.
Am I missing something?
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6:33 p.m.
New subject: E-Mail (Spam) filtering....
Alas, I have yet to find anything that "really" works for me.
I run a software consulting firm. On a fairly regular basis, I will get
either a forward or an attachment of a spam (or virally infected) message
from a legitimate client (potental, current or past)
who will ask "How do I
get rid of these...."
Of course the person does not realize that they are being an idiot doing
this, but if I lose the message, I lose business......
The best I have come up with so far:
1) Auto file (NOT delete) all suspicious messages in a specific folder [I
use Outlook 2003]
2) Run my mail client from within a virtual machine [VMWare] with regular
backups and undoable disks.
Again my situation does NOT match that of most people.....
David
18 Jun
18 Jun
12:43 p.m.
New subject: A case for downgrading to PCs (was: WARNING: RANTING COMPUTERNUT...
I can only assume that the star (Y) system was a four wire system. The star
system can be either 3 or 4 wire it appears, whereas delta is always 3 wire.
It was 1970 when I did this , so if anyone wants to put me right -feel free.
It does seem a logical explanation though.
Geoff.
----- Original Message -----
From: "der Mouse" <mouse(a)rodents.montreal.qc.ca>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk(a)classiccmp.org>
Sent: Friday, June 18, 2004 2:44 AM
Subject: Re: A case for downgrading to PCs (was: WARNING: RANTING
COMPUTERNUT...
Most know
about motor rotation but he was talking about delta versus
Y. This can be quite different.
What _is_ the difference between delta and Y? A while ago we had a
discussion that ended up revolving around what point is grounded
("neutral"). As far as I can see, delta and Y are basically
equivalent, provided you don't try to refer anything to ground (or
anything else beyond the three phases), and provided you don't overload
anything.
Am I missing something?
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\ / Ribbon Campaign
X Against HTML mouse(a)rodents.montreal.qc.ca
/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
7374
days inactive
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5 comments
6 participants
participants (6)
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aw288＠osfn.org -
dvcorbin＠optonline.net -
dwight.elvey＠amd.com -
geoffreythomas＠onetel.net.uk -
mouse＠Rodents.Montreal.QC.CA -
rigdonj＠cfl.rr.com