Rectified DC can exceed an AC rating because a capacitor charges near the waveform peak. Use load and ripple needs to size it while allowing for inrush and voltage.

Bulk capacitance may not stop fast switching overshoot and ringing. A correctly placed snubber controls the transient when its values and pulse ratings fit the circuit.

Unsure whether an HVDC scheme needs DC filters? Assess converter harmonics, route configuration, resonance, interference risk and lifecycle maintenance needs.

A humming or slow ceiling fan may have a failing capacitor. Rule out mechanical drag, then match the original microfarad value, VAC rating, wiring and case size.