[BC] UPS hell

[Larry Wood]

For months we were plagued by audio dropouts of several seconds on our main signal. I put an AES monitor on our air chain and followed it through to the TX starting at the console. Sometimes it would be a week or more without a dropout. Finally I installed it on the AES input to the exciter, but still perfect AES audio according to the test equipment I was using. While I was standing by the transmitter scratching my head and wondering what the problem could be, the UPS on the exciter went CLICK CLICK and all became clear. The RF part of the exciter was not affected, but the AES card had to re-sync. New UPS, no more dropouts.
100 other UPS problems and stories will be saved for another day.

Larry Wood, CPBE
KQED-FM

-----Original Message-----
  From: Craig Healy

>>> A week ago Sunday one of my clients called me with a radio station
>>> off the air. The problem turned out to be a UPS that was stone
>>> cold dead.
>>
>> I've had the same problem before.  What I did was build a relay and
>> switch box.  The relay is engaged when the UPS is supplying power.
>
> ... and use a spare set of contacts on the relay to trigger an alarm, so 
> you
> know when you've lost the protection of the UPS.

The switch I use has a light on it which I wired to the relay coil.  When 
the light is out, so's the UPS.

It was simple to build.  The relay is a 20a SPDT with a 120vac coil. 
Grainger p/n is 1EHC4 relay and 1EGP6 socket.  Switch, outlet, box, cables 
and cover are all Home Depot parts.  Internal wiring by 12 gauge stranded 
wire.

Turning the switch off pulls the UPS offline and connects AC directly. 
Built a number of them and have had no problems since.  I do make sure that 
both sides are plugged in to the same outlet.  While it probably wouldn't be 
an issue, I want to be sure that the two AC voltages are in phase. 
Theoretically they could be plugged to different circuits so if a breaker 
tripped, there would be a backup for that.

One thing I had happen years ago was a server that dropped off almost every 
morning around 5am.  Turned out the UPS caused it.  Only a momentary dropout 
and I had to be there to see and hear the UPS problem.

Craig Healy
Providence, RI