An alternative to pilot wire relays for industrial power systems

Abstract

The practical installation and setting of pilot wire relays in the field presents a complex problem that may leave the designer uncertain of the reliability of the pilot wire relaying scheme. There are those designers of protective relaying schemes who would prefer to avoid the use of pilot wire relays altogether. A common concern that is often used to dismiss alternatives, is burden and sensitivity to ground fault currents on low resistance grounded systems. A method by which to determine the applicability of an alternative to pilot wire relays for industrial power systems and the scheme itself is summarized below. The burden issue is considered.