Development of a static distance relay with conic characteristics for the protection of long transmission lines

The paper reports the development of a static distance relay with conic characteristics. The instantaneous comparison of three inputs in a hybrid comparator is a technique now applied with a new mode of relay circuitry. The output circuit utilizes IC operational amplifier and tntegrator. The circuit details are shown and discribed. In addition a comprehensive theoretical basis for the conic characteristics is presented in appendix. Static and dynamic test results are also furnished.