UPS Critical Alarm - "DC Over Voltage"

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Vestre

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Hello Everyone,

I just joined this forum yesterday and would like to ask for your help and support...

I encountered something that maybe some of you already had this experience about UPS [3PH, 440V/200-100V, 500KVA]. After it was energized and on-line for 2 months, the unit experienced a critical alarm due to DC Over Voltage. It transferred to Bypass when the alarm happened. When it was reset, the UPS went back to normal. The findings of UPS vendor is due to the CPU board. It was replaced with a new one to further investigate what really happened to the CPU board. It was retested at the UPS factory and simulated various tests (i.e. visual check, noise test, control power voltage test, etc.). After all tests, the UPS vendor concluded that the main root cause of alarm is the CPU board internal memory. I am worried that this may happen again in the future.

I am just hoping someone experienced the above and any comments/suggestions would be much appreciated.

Thanks
Vestre
 
It was either a design error or PC board failure. If the new board fixed the problem, the UPS attempted to overcharge the batteries.

If the replacement board didn't fix the problem (which I realize it did), then you would consider other issues like impedance problems with batteries or their connections.
 
"Stuff" happens...

Typically if there is an infancy problem with a board, it's a component failure and that happens sometimes. If it were a serious design flaw, a reputable company making UPS systems would be out of business in short order.

That now doesn't hold true for a lot of copy-cat Chinese companies that spring up over night, make something cheap and sell off the inventory on eBay, then quickly disappear. But that would be very unusual for something as involved as a 500kVA UPS system.
 
Earlier in the thread he said they said it was a memory failure. A module can fail.
But I still think he should ask the manufacturer to tell him what the failure rate is. Not the salesman; an engineer at the manufacturer.
 
With any luck, your UPS failed over to bypass "nicely" without the load even noticing.

If that is the case, I'm not sure what you are worried about. The odds of the utility failing at the same time as a UPS failure are pretty low.

If you have quality equipment, and you are still worried about it failing, most UPS's have an option to place 2 or more in parallel.
 
Thanks everyone for your help and input regarding this UPS "once in a blue moon" incident that you may encounter in the future.

After performing all the tests with the CPU board of UPS and identified that the main caused was the memory program, no more further investigation is needed.

So far, no alarms being experience after two months of continuous operation.
 
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