Capacitor exploding in a paper plant
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.