THE OPTIMUM ADJUSTMENT OF MOTOR PROTECTION RELAYS IN AN INDUSTRIAL-COMPLEX

In this paper a distribution network is considered supplying electrici ty to a number of factories belonging to one industrial complex. The c osts of interruption may vary more than one order of magnitude from on e factory to another. The problem studied in this paper is how to adju st the time lags of the undervoltage protection relays in each factory in order to obtain a minimum in the total costs of interruptions of a ll factories together. By properly adjusting the time lags of the rela ys it may be provoked that factories with low interruption costs are d isconnected from the network rather fast after the occurrence of a sho rt circuit through which action the chance that a factory with high in terruption cost is switched off is decreased.