In article ,
DLR wrote:
Ink Maker wrote:
Somewhere close to your facility is using a lot of power
intermittently. Whenever they turn on or off a big piece of equipment,
they send the surge to every other users nearby. Since your building
will be torn down soon, a good UPS may be the best bet.

Back in the 80s with low end mini-computers we saw these issues a lot. Many times we'd find things like coffee makers on timers on the same circuit breaker. Or a welder next door but sharing the same transformer. Other times if we could establish the WHEN we'd have the folks spread out for a few days to see what might be going on. The most interesting one was a trash compactor across the street that was run at about 3:45 PM each day which is when the systems would act up. Turned out they were pulling down too much power and affecting the entire block.

David


A lifetime ago, I was hired to run a shiny new datacenter with the
biggest new computer made by Digital Equipment Corp (R.I.P.). That was
in the winter and it was in a first-class large building in Manhattan.
We didn't have a UPS and we knew there were other large computers in
the building in the same state. (I wasn't part of teh planning
process).

Everything was fine until May 1st. At about 7:15 the system crashed
and rebooted with a "power fail" message. OK. Sh*t happens but it
proceeded to happen every day at about the same time.

We escalated the problem, step by step until I finally had a meeting
with the "account rep" for Con Edison, (the utility company for
non-New Yorkers.) Who knew that the power company had sales engineers?

He checked a few things and then declared that we were getting normal
commercial-grade power. The deal was that in the summer they switched
in capacitors to compensate for the power factor for the air
conditioners that people would begin to use. This had been standard
practive for decades and the solution was our problem.

We wound up getting a ferroresonant constant voltage transformer so
large it had to be moved in with a forklift.

Why did the "other mainframes" not have problems?

Becuase they were IBM systems and all of them had motor-generator
units included in the price. they were even better than CVTs and not a
customer third-party option like all the other computer vedors.









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