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Capacitor and filter bank protection

Shunt capacitor banks, also called filter banks, are widely used in transmission and distribution networks to produce reactive power support.

ABB's capacitor bank protection is used to protect against faults that are due to imposed external or internal conditions in the shunt capacitor banks. Internal faults are caused by failures of capacitor elements composing the capacitor units, and units composing the capacitor bank. Other faults inside the bank can be a flashover within the rack (short circuit over a single or multiple series groups of units of the same phase) and rack phase-to-phase and phase-to-earth faults.

External power system conditions, such as overload, cause stress to capacitor banks. For example, overvoltage caused from the combined effect of sustained overvoltage and increased levels of harmonics create an overload situation. The purpose of the protection scheme is to limit the effect of overload to a safe and acceptable level, and to prevent the abnormal system conditions from damaging the shunt capacitor bank by disconnecting it in case of a loss-of supply condition.


  • Protection against faults that are due to imposed external or internal conditions in the shunt capacitor banks

Product benefits

  • Protection, control, measurement and supervision of capacitor banks
  • Protection of harmonic filter circuits

Product features

  • Protection unit for H-bridge, double Y or single Y connected capacitor banks and the feeder cable
  • Extensive range of protection and control functionality, can also be used with harmonic filter circuits
  • IEC 61850 communication, including redundant Ethernet, GOOSE, and process bus for voltages (in Relion 615 series)

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