Capacitor for Power Electronic

Your UPS exploded? What part?

If your UPS manufacturer wants to replace a part of their equipment with s "suitable" replacement, then I would make sure I would get a warranty statement for their field change.

It's very hard to determine the correct value for your output caps (PFC?) without having the full specs/requirements.

Each phase of the UPS is "single phase" when connected across the capacitor...therefore the cap is single phase. Three caps...three phases...one cap per phase.

Do you have a schematic, one line, or web site with the info for your UPS?

Your capacitor failure was probably more likely due to harmonic current. There really is no advantage to trying to correct the power factor on the output side of a UPS. The reason people usually use a UPS is to provide power in the event there is a problem with power from the utility (or generator?).

Harmonic currents come from devices that change the frequency of the UPS output from its normal frequency to anything else, including DC. Most electronic devices you would connect to a UPS will take that AC power and convert it to DC. If the power supplies are not well designed, they will gulp current right at the peak voltage. This causes harmonic distortion.

Harmonic currents fed back into power correction capacitors cause higher than normal voltages to be present. Depending on how much harmonic current is present, it is possible to exceed the rated voltage of the capacitors. When that happens, short circuits begin to occur in the layers of the capacitor and that is followed closely by smoke and fire and sometimes a boom!

To deal with the harmonic distortion, line reactors can be used to limit the effects but to really get rid of them you need special equipment. Eaton is one of the manufacturers that makes such devices. I am sure there are others.

So, to answer your question, if the previous capacitors was rated for your voltage and the new capacitors are also rated for the same voltage, then you should expect them to fail as well. The real question is do you really need them at all?