Surge arresters for shunt capacitor banks

In general it is possible to obtain an efficient protection of even relatively large shunt capacitor banks with commonly-used arresters. Only at lower voltage levels, the need for multiple column arresters exists. This is because the energy demand is approximately a linear function of capacitor MVAr rating independent of system voltage.

It is important to consider the installation. Arresters across capacitor or between phases give a superior protection compared with arresters phase-ground.

In case of arresters between phases or phase-neutral, the insulation phase-ground may be protected by an extra set of arresters or existing phase-ground arresters in the station if found necessary due to the exposure to lightning surges.

The aim of this brochure is to give guidance for selection of surge arresters for capacitor banks, when such protection is considered to be needed. The protection afforded by different arrester protection levels and positioning - such as phase-ground, phase-phase and phase-neutral - against switching overvoltages is dealt with. Arrester energies related to different protection levels and capacitor MVAr ratings are given and the guidance is summarized in a set of diagrams.

Please refer to our technical publication Guidelines for selection of surge arresters for shunt capacitor banks

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