Applying metal-oxide surge arresters on distribution systems

The primary advantages of a metal-oxide surge arrester over a silicon-carbide surge arrester are identified as the extreme nonlinearity (flatness) of the metal-oxide voltage versus current characteristic and the elimination of the requirement for a series gap and its associated gap sparkover voltage. Without a gap, the metal-oxide valve element must support system voltage continuously, necessitating the consideration of thermal stability. Maximum continuous operating voltage and temporary overvoltage capabilities are the important parameters for selecting a metal-oxide surge arrester for a particular application