Help to replace blown capacitors on UPS

davenn

hi

Sydney, Australia

the surges are usually/mainly caused by lightning strikes in the area. Australia has a pretty active storm season stretching mainly from September through to March
The last 2 companies I worked for had me spending a lot of time repairing or replacing equip blown apart by lightning induced power surges.
Our mains power in Australia is pretty respectable as well. The majority of power cuts would again be caused by lightning strikes.

Dave

es1

Interesting. Thanks!

jim hardy

you said you were running from a generator when this happened?

it is a trait of alternators that disconnecting a large load from them will cause output voltage to rise (briefly) until voltage regulator can catch up. How much? difficult to guess, shouldn't be drastic but if your MOV's were sized close they might have died a noble death trying to contain the transient. What's insignificant to a big generator could be darn significant to a little UPS.

If this happened when you disconnected a large load like a cooktop or large string of lights, be aware of this generator trait and maybe adjust your operating procedure so UPS is last on, first off... A minimum load for generator might help it avoid using the surge protection you plan to add, perhaps a substantial incandescent lamp that's left always on .

just a thought. (I assume you ordered a few extra MOV's for UPS....)

old jim

westom

Maybe view the datasheet for that varistor. To have that particular catastrophic damage means a voltage well exceeding 900 volts. That should get your attention. Because no protector adjacent to an appliance will stop or absorb that kind of surge. A protector adjacent to the appliance can only block that current or absorb that energy. Best protection at the appliance is already inside the appliance.

Your concern is to avert that destructive current at its source. Then superior protection inside an appliance would not be damaged. Many spend a little more for a Honda (or equivalent) generator. The solution starts with how a generator is designed. Not with 'add on' boxes.