Power outages can be extremely damaging to critical facilities such as hospitals, prisons, and data centers. Backup generators are invaluable to such facilities and are usually switched in automatically after the loss of utility power. Consideration must be given to the transition between utility and generator power when PFCCs are in the system.
A capacitor is an energy storage device. The energy stored in a capacitor when power is disrupted will remain until dissipated by the load or by discharge resistors. This takes a few minutes. Problems can occur when power is disrupted and the capacitor is re-energized before the stored energy has time to dissipate. In this case, the applied voltage can be over twice the rated voltage. This extreme voltage and associated excessive current and heat results in capacitor cell damage and premature failure.
The solution is to provide for a two- to five-minute time delay prior to re-energizing the capacitor after power loss. This time delay is a function of the controller on our automatic systems (Autocapacibank™
). For fixed systems, the time delay can be accomplished by the addition of an auxiliary contactor and timer circuit. This option is available in the Calmount®
, and Capacitrap®