Restriking-voltage characteristics under various fault conditions at typical points on the network of a large city supply authority

This report deals with the rates of rise of voltage at the clearance of different types of fault at given points on a network, with the relation between the power-frequency parameters of the various plant units concerned and those effective during the occurrence of the transients of restriking voltage, and with the range of values of rates of rise to be expected at different types of busbar location. Rates of rise of voltage under different types of fault condition are first expressed in general terms. These are shown to agree with the values measured under different conditions in particular situations on the network of the Birmingham Corporation, by means of the restriking-voltage indicator. The application of the method of symmetrical components to the calculation of transients of restriking voltage on the clearance of all types of fault is discussed, with particular reference to generators. Rates of rise of voltage in concrete instances on an 11-kV system are given, the values ranging from approximately 200 to 7 000 volts per microsecond: it is considered that the latter figure may well represent an upper limit in British practice at this voltage.