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 multifunction relays. However, the digital 67N may be even more difficult to set and test than it was as a single function in an old electromechanical relay.