A one slip cycle out-of-step relay equipment

WHEN the out-of-step condition develops on a power system, the resulting disturbance may result in a major loss of load. It is, therefore, desirable to be able to recognize such a condition promptly and to take corrective measures to minimize the disturbance. This article describes a new relay equipment which is capable of recognizing an out-of-step condition before the completion of the first slip cycle, whereas earlier forms of out-of-step relays did not usually give an indication until after the third slip cycle.