[Beowulf] Re: Re: UPS & power supply instability (Robert G. Brown)
James.P.Lux at jpl.nasa.gov
Wed Sep 28 18:33:27 EDT 2005
At 12:19 PM 9/28/2005, Maurice Hilarius wrote:
>Robert G. Brown wrote:
> >If you discover that -- surprise -- the "PFC" supplies aren't, you can
>Or, the proper answer, which is :
>d) Contact Dell, have them pick up their machines.
>Then buy hardware from a reputable vendor who deliver what they quoted,
>and who do not try to sneak substandard parts on orders to you.
>Discuss with your organizations purchasing and acquisitions department
>about their contract regulations and the associated penalties for fraud.
Ahhh.. but then you might get into a discussion of what PFC corrected
really means, and odds are, that's where the problem is. You might think
it's one thing and they might think it's another.
The other problem is that it's possible the onus of determining the correct
model number might have been on the buyer.. i.e. they ordered a model
abc123, relying on some fuzzy statement by a sales rep that "sure they're
PFC", without an actual contractual requirement defining what that meant.
The Dell PowerEdge 1850 datasheet says nothing about PFC.. just 550W power
supply. Digging a bit gets the following list of regulatory certifications:
FCC (U.S. only) Class A
ICES (Canada) Class A
CE Mark (EN 55022 Class A, EN55024, EN61000-3-2, EN61000-3-3)
VCCI (Japan) Class A
BSMI (Taiwan) Class A
C-Tick (Australia/New Zealand) Class A
SABS (South Africa) Class A
CCC (China) Class A
MIC (Korea) Class A
CAN/CSA C22.2 No. 60950
I think that EN61000-3-2 is the relevant one, since it specifies harmonic
This document has a summary:
For loads less than or equal to 600W.. (probably figured at 240VAC, though)
3.4 mA/Watt for the third harmonic (but no more than 2.3A)
1.9 mA/Watt for the fifth harmminc (but no more than 1.14A)
3.4 mA*600W = 2.04Amps That's a pretty large harmonic current for a load
that's drawing only 3A or so.
(For what it's worth, the PF would be about 0.83 at this level.. and the
peak line current is 2 times the rms current, vs the usual 1.4 for a clean
Hence.. these puppies aren't really PFC in the strictest sense of the word
Searching Dell's website.. very few of their products even mentions power
factor correction (the 7250, for instance: The power supply modules are
Server System Infrastructure (SSI) compliant, universal AC input with Power
Factor Correction (PFC) Distributed Power Supplies (DPS). The power supply
modules are rated at 1200 W over an input range of 180-264 VAC, and at 700
W over an input range of 90-132 VAC.)
No numerical specs given.
James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
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