Directional Ground Relays

This paper deals with the paramount importance of ground protection on transmission systems which has been demonstrated by experience over the past few years. It presents the advantages of ground relays and shows that the disadvantages sometimes attributed to them are not well founded or have been overcome. A number of standard and special applications of relays for directional ground protection are described and illustrated by sketches showing connections. The application of these schemes is discussed and their desirability and feasibility supported by records of operating experience. Attention is called to the point that high-speed relaying will soon be an accomplished fact. High-speed relaying will be needed in both phase and ground protection to take full advantage of high breaker speed. In the testing of relays adequate test facilities are necessary to save time and to insure correct test results. Attention is called to the desirability of making staged tests at system voltage to insure correct relay operation and for their experimental value in developing improved forms of protection.