Re: AS/400 - UPS (Uninterruptible Power Supply) Question

Chuck,

there is a small but relevant possibility that two UPS'es "in a chain" can
interfere with each other.
Think of it as a noise that is not filtered good enough to keep the
power line "clean",  there is a noise of high frequent parts from the
switching circuit that does the charging and/or controls the transformation
of power itself.
This is especially true, if the UPS has to recharge (high load for that circuit)
or to compensate for abnormal utility power.
The "clicking" may have been the switch of the internal UPS when noticing
an "abnormal" power situation and the taking over for a short period.
Normally it is *not* recommend to have two UPS-units after each other.
In short: if you have an external device for your server room, take care
that you don't have servers with internal UPS-units.

HTH, regards from Germany, Philipp Rusch


Chuck Lewis schrieb:

> Get ready for this; life has been fun around here <BG>.
>
>
>
> We got a new 810 in that will eventually replace our 620. In the Computer
> Room we have 2 UPS's; one for the AS/400 and assorted devices and one for
> all the networking stuff and some management PC's, etc.
>
>
>
> Well last week we had an electrical contractor come out to put in a new 220
> circuit for the 810's expansion rack. The 620 is on the UPS and he goes to
> work and BAM ! the 620 is down. He had gotten the WRONG wire in the panel.
> Well the existing panel did not have enough  room, so he was installing a
> new one. Middle of the day but we told him to go ahead and do that. About an
> hour latter we are back up and all is good. So I was wondering what the heck
> happened with the UPS not keeping the 620 up. I called our local service rep
> for the UPS's and he comes out and starts checking things out. He pauses and
> says "Chuck, you aren't going to believe this. Your 620 and 810 are on
> utility/dirty power. The guy took you off the UPS."  So we discussed what to
> do and he said he could fix the mess and that we should get a UPS bypass
> switch too. I agreed and last night they showed up to do that work. It was
> long but all went pretty well. Then I try to power up the 620 and it starts,
> and goes right back to 01 B N. I called support and they had us unplug it
> from the outlet (something I had tried but I did not wait long enough.) and
> after about a minute, plug it back in and try powering up. And "wallah" up
> we came, eventually, after some dumps :-)
>
>
>
> Then about 20 minutes latter we hear this "clicking" sound coming from the
> 620 and I see messages on QSYSOPR that utility power had failed and then
> been restored. This would go on and on. It didn't look like a big deal and I
> figured it could wait until this morning. That was about 10:30. I came in
> this morning and it was still doing it. I called IBM and they thought it
> might be the UPS in the AS/400 (*** Note: we have no signal cable in J14 to
> the external UPS !). He had our CE call me and we discussed what to do. He
> was going to round up some parts, etc. and come over. And then it STOPS - no
> messages, no clicking, nothing.
>
>
>
> So our CE was wondering if maybe the External UPS had to charge up its'
> batteries (recently, 2 months ago, replaced) before it would send a strong
> enough feed to the 620. I've got a call into the UPS folks too but was
> wondering if this sounds plausible to you power gurus on the list ? Sounds
> possible to me.
>
>
>
> Thanks !
>
>
>
> Chuck
>
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