As ever, a full circuit diagram would be invaluable - even if to show that there is nothing much more present than has been stated.
VAC = 220V so Vpeak = 220*1.414 =~ 310V.
180V DC/310 =~ 0.58
This is the sine of thge angle when the rectifiers start (or end ) conducting + 35 degrees.
For 35/90 of the cycle the voltage in is below Vdc so the cap MUST provide the motor current. If you do not have any energy storage in inductors then the cap is seeing a ripple current of in the order of the motor current and peak currents will very likely be higher (depending on transformer and wiring resistsance and more.)
As dissipation will be in the order of proportional to current squared you probably have about 10 x rated dissiation due to excess ripple current.
Nichicon are a well respected brand. Chances are the actual ripple current capacity on a genuine Nichicon meets or exceeds specifications. But it is unlikely to exceed it by enough to save you here IF the circuit is as it seems. It is possible that the cap is a counterfeit. This definitely happens and Nichicon are a well enough known brand that people MAY counterfeit them, although I have no specific knowledge of this happening in this case.
UUCAP I know not.
It is not unusual for little known Asian components to not come close to spec sheet claims.
In this case it appears that they exceed the specs handsomely !!!!
I'd not complain!
But do look at the actual ripple current.
A small sense resistor in the cap ground lead will allow a scope to be used with due care (or in the "hot" side with an isolation device AND if you know what you are doing. Or a Hall clamp / proximity meter or ... .
Note that cap lifetime ~+ Rated hours x 2 ^ [(Trated-Trun) / 10 ]
It is usual to run a cap at WELL below rated temperature.
30C below = 2 ^ (30/10) = 8 x rated lifetime.
So a 2000 hour rated cap would last about 2000 x 8 = 16000 hours ~= 2 years.
The larger margin the better.
Note that an Al electrolytic cap with NO applied voltage, held at high temperature will die faster than when voltage is applied !
I would suspect harmonic distortion of the system voltage due to nonlinear loads. The capacitors are sized to carry current due to the complex impedance of the capacitors at the line frequency. If the actual voltage waveform has significant content of voltages at harmonic frequencies, that increases the capacitor current because the impedance is lower at those frequencies. In addition, harmonic distortion can precipitate a harmonic resonance situation further increasing the capacitor current.
The nonlinear loads can be electronic motor speed controls or other power electronic equipment on the three-phase distribution system or even electronic equipment on single-phase distribution systems that are fed from the three-phase systems.
Many large motors in paper plants are powered through electronic power conversion speed controls.
Best Answer
No, capacitors will charge to any voltage you apply, as long the voltage does not exceed the rating.
Supercapacitors just have lower voltage limits -- meaning how much maximum voltage you can apply across them -- than regular capacitors.