Power system protection based on personal computer

This investigation centres on the practical advantages of microcomputer based replacements for parts of the conventional electromechanical and static protective relays used in power system protection. Incremental instantaneous protection, in which a trip decision is made on the basis of the rate of change of current, has only become a practical proposition with the advent of fast microcomputers. With the correct choice of current transformer ratio, and preset values in the software, a 12 bit analog-to-digital system is shown to be adequate. Software is also developed to implement the inverse definite minimum time trip function, with satisfactory results.<>