Ups keeps tripping the CB

Thanduxolo · Apr 27, 2020

1KVA online ups keeps on short circuiting and it has blown the mov..what could be the cause?

WHONOES · Apr 27, 2020

Could you expand on your description, it quite brief and doesn't tell us much.

Thanduxolo · Apr 27, 2020

WHONOES said:

Could you expand on your description, it quite brief and doesn't tell us much.
Click to expand...

When I plug in the ups inverter on 230vac it trips on the circuit breaker from the power supply... I've opened it up and the mov and the ac fuse are blown

Harald Kapp · Apr 27, 2020

Remove the MOV, replace the fuse. Does it work now or still blow the fuse?
If it works, replace the MOV by a new one (for testing it is o.k. to use the ups without MOV, but not for continuous operation).
If the fuse still blows, you'll have to inspect the circuit board for other possible causes of a short circuit.

hevans1944 · Apr 27, 2020

I am gonna guess it's an AOG (Act Of God) that proved your UPS really isn't.

Was there any lightning activity near the power line coming into this UPS? Nearby cloud-to-ground strikes can induce severe spikes on the power line, enough to cause the MOV to short-circuit and blow the fuse. That is why @Harald Kapp has suggested that you first remove the now defunct MOV (which may be permanently shorted), replace the fuse, then see if UPS functionality has been restored. If the UPS then works, you can replace the MOV (which died, along with the fuse, to save your UPS) and your problem is solved!

Do not operate the UPS, except for the functionality test, until the MOV is replaced.

If the steps @Harald Kapp offered you do not restore operation, extensive troubleshooting is required. Are you up for it?

Thanduxolo · Apr 29, 2020

Harald Kapp said:

Remove the MOV, replace the fuse. Does it work now or still blow the fuse?
If it works, replace the MOV by a new one (for testing it is o.k. to use the ups without MOV, but not for continuous operation).
If the fuse still blows, you'll have to inspect the circuit board for other possible causes of a short circuit.
Click to expand...

Thanks Harald..its working fine and I will replace the MOV

Ups keeps tripping the CB

Thanduxolo

WHONOES

Thanduxolo

Harald Kapp Moderator Moderator

hevans1944 Hop - AC8NS

Thanduxolo

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