Damping reactors are designed to be installed in series with a shunt connected capacitor bank. Their function is to limit inrush currents occurring during switching, to limit outrush currents due to close-in faults, and to control the resonant frequency of the system due to the addition of capacitor banks. During normal operation, the capacitor rated current flows through the damping reactor. The maximum permissible (overload) current of the damping reactor is equal to the corresponding value of the capacitor bank, which, according to IEC Publication 70 is 1.3 times the current obtained with rated sinusoidal voltage across the capacitor.

With regard to installation, these devices may be identified as:

• Single phase or three phase
• Cast resin dry type, conventional dry type or oil immersed
• With or without magnetic shield
• For indoor or outdoor installation
• With or without enclosure
• With fixed or variable reactance