Qualification of Switchable Metal-Oxide Arresters for a Protective Level of 1.6 P.U. on Hydro-Québec´s 735-kV System

This paper presents the results of a series of tests performed at IREQ on 39 sections of metal-oxide surge arresters from six manufacturers. Ranging from 85 kV to 160 kV in rated voltage, these sections were similar to those to constitute the devices to be installed on Hydro-Québec´s 735-kV power transmission system. The purpose of the qualification tests was to assess the merits of this type of arrester as a solution to the overvoltage problem encountered on the James Bay part of the power grid following load-shedding operations. The test program was therefore oriented in terms of demonstrating that the surge arresters will produce the following three features: . they may fail by short circuit in a totally safe manner i.e. without explosion or fracture from thermal shock to their housing; . they will produce a switching surge protective level of 1.6 p.u. of crest system voltage (960 kV) at 5 kA crest; they will withstand a 60-Hz voltage of 1.2 p.u. (510 kV) for the maximum period of 30 s during which they may be switched onto the power system.