4 May
2017
4 May
'17
9:10 a.m.
On May 4, 2017, at 8:59 AM, Jon Elson <elson at
pico-systems.com> wrote:
On 05/04/2017 10:36 AM, Guy Sotomayor Jr via cctalk wrote:
OK, that?s not helping. Here?s what I have (from IBM site planning docs GC22-7064-10 and
GC22-7069-2):
3340-A2 DASD: 2.2 kVA 3-phase
3340-B2 DASD: 1.7 kVA 3-phase (powered from 3340-A2)
3803 Tape Control unit: 1.8 kVA 3-phase
3420 Tape drive: 2.9 kVA 3-phase (powered from 3803) (x2)
2821 control unit: 1.4 kVA 3-phase
1403N1 Printer: 1.5 kVA 3-phase (powered from 2821)
2540 card reader/punch: 1.2 kVA 3-phase (powered from 2821)
So I have 3 potential power feeds:
DASD: 3.9 kVA
Tape: 10.5 kVA
I/O: 4.1 kVA
For a total of 18.5 kVA
So the several $1000 question is how do the kVA?s map into 208v 3-phase amps? 18.5
KVA /208 = 88.94
88.94 / 1.732 = 51 A
Since this is given as KVA, it should include the power factor.
Thanks.
So if I want to run it off of one converter, that needs to be able to supply 51A. If I
split it, then I would end up with:
Tape: 30A
DASD: 11A
I/O: 12A
So at this point it comes down to cost. If I can find one that can supply 60A that?s
reasonable that would work. Otherwise I?d likely get either 2 30A converters or 1 30A and
2 15A (if they come in those sizes). ;-) I?ll just have to figure out what makes the
most sense cost wise.
Thanks.
TTFN - Guy
Depending upon how that works out I need to
figure out if 2/3 converters make sense or just one big one.
My simple minded conversion is to take the 18.5kVA, multiply by 1000 and divide by 208.
That gives me just shy of 90A. Do I then divide by 3 to get A/phase? If so, then it?s
30A per phase which seems reasonable. But I don?t know if that?s the correct formulation.
It isn't. See above. A lot of this is circulating current, so the real power
draw from the mains will be less. Still, most likely over 10 real-power KW from your 240
V single-phase mains.