Industrial feeder protection

The successful application of protective relays depends upon three factors, namely: initiating action to isolate the faulty part(s) of the electrical power namely: initiating action to isolate the faulty part(s) of the electrical power system; limiting the effects of fault(s) to an acceptable level on the healthy parts of the system; and accomplishing this at an acceptable cost. The authors concentrate upon meeting the foregoing objectives on power system feeders supplying industrial loads. In particular the techniques discussed relate to the necessity to maintain the security of essential loads, where the stability of rotating machinery is a vital consideration. There is an increasing need for higher speed clearance of faults on systems to which electrically-controlled motor drives are connected. Means for the post-fault restoration of supplies to loads which have been disconnected due to faults are also considered. In this respect the advantages of telesignalling via the distribution feeders in order to accelerate the isolation of the faulty section are discussed