Troubleshooting the 18 KVA UPS

One of our clients has or rather had, a BEST FERUPS 18 KVA UPS. It has stopped working and I was given the following report:

Radio guy: The power went out, the generator started, then I heard a bang.

Myself: You heard a bang?

RG: Yeah, a big BANG!

Myself: You heard a big bang.

And so he did:

Best FERUPS 18 KVA control board.
Best FERUPS 18 KVA control board.
Best FE18KVA control board, MOV destruction
Best FE18KVA control board, MOV destruction

The primary damage is around two MOV’s mounted on the other side of the board. This is the power sense (voltage sample) input to the board. We have attempted to repair it, but alas, it is not repairable. A replacement board runs over $1,400.00 from Eaton Powerware. Since this unit also needs a new set of batteries, it is likely best to replace the entire unit.

9 thoughts on “Troubleshooting the 18 KVA UPS”

  1. Don’t you love it when the protective devices cause more damage by being there and “doing their job” than if they weren’t? And how many circuit breakers tripped?

    So, if you have a theory as to the chain of events that caused this outage, you can call it . . .

    (wait for it . . .)

    (keep waiting . . .)

    The Big Bang Theory!

    Sorry, I couldn’t resist. Too much Sheldon.

  2. I would check what that generator is throwing out before repairing and putting that back in service.

    I have many UPS/Generator combos that love to do battle. Very finicky, yet necessary, devices.

  3. Oh wait, now I read the last line (missed that) and it isn’t repairable. Those things cost as much as a car to replace.

  4. Eaton really doesn’t want repeat business. With a couple of just out of warranty BEST units we had they wanted more to fix them than buying new.

  5. The board was damaged by a generator over voltage (way over voltage). What is not visible in those photos are the small copper threads that run away from the arc zone to other parts of the board. And yes, Eaton would rather sell a new unit than repair an old UPS that was not theirs to begin with.

  6. Make sure the new board is upgraded to prevent this.
    If not, clean the board up and repair it.
    Hope you have a schematic.

  7. Take note that the FerrUPS units have *ferroresonant* voltage stablization in them; if the rest of the plant expects power that clean, a lower-grade UPS may not make the cut — in particular, *continuous* UPSs are nearly impossible to find these days, and switchovers do piss off some gear, still…

  8. Kent’s Law! A $1400 PC board will fry to protect a $.99 fuse. Yes, Paul, file that PC board under things that go FUBAR or Flambe.

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