Applying the directional neutral, 67N, function in microprocessor multifunction relays

This paper is a case study of the application of the 67N function in a digital multifunction relay. The directional neutral current relay, function number 67N, is often found to be critical to the proper operation of a protective scheme. Furthermore, a false trip of a 67N will usually be devastating. The 67N is a complex function that always required more wiring than almost any other relay. The 67N is now available as one of many functions in digital multi-function relays. However, in the digital relay the 67N may be even more difficult to set and test than it was as a single function in an old electromechanical relay.