New IEC Arrester Standard Printed This Season

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A brand new idea of arrester classification and withstand tests are introduced: the road discharge classification is changed with a classification according to repetitive charge transfer rating Qrs, thermal energy rating Withzz and thermal charge transfer rating Qth, correspondingly. The brand new concept clearly differentiates between impulse and thermal energy handling capacity, that is reflected within the test methods and minimum pass criteria.

The Definitions of those ratings are listed below:

Thermal Energy Rating, Wth: The power, succumbed kJ/kV of Ur, which can be dissipated by an arrester or arrester section inside a thermal recovery test without creating a thermal runaway.

Repetitive Charge Transfer Rating, Qrs: The charge, succumbed coulombs (C) by means of just one event that may be moved a minimum of 20 occasions ( sometimes times that provide cooling to ambient temperature ) with an arrester without causing mechanical failure or unacceptable electrical degradation towards the MO resistors.

Thermal Charge Transfer Rating, Qth: The charge, succumbed coulombs (C) which may be moved with an arrester or arrester section inside a thermal recovery test without creating a thermal runaway.

As proven within the table below, Station Class arresters have a Qrs and Wth rating. Distribution arresters have a Qrs and Qth rating.

Surge Arrester Distribution Table