Laboratory Model to Teach Relay Coordination in Radial and Mesh System

Nowadays, the demand for electricity is rapidly growing at faster rate in the economically emerging countries. There are a large number of buses and transmission lines involved in the transmission of power in this network. With the increasing size of the transmission network, the frequency of occurrence of the fault also increases. So relays and circuit breakers play an essential part in the protection of these networks. So each transmission line that connects each bus is fitted with a relay and a circuit breaker for protection. When a fault current flows through the transmission line, the circuit breaker acts as an open switch on the relay’s trip signal. In relay coordination, each relay plays a dual role of acting as either the primary protection or the backup protection at a time. This paper describes about the laboratory model which was developed to teach the relay coordination in radial and mesh system. The relay settings are calculated and tested in ETAP. Later, the numerical relay is developed as per the set value and tested in real time for radial and mesh system. The developed model will support the teaching of power system to under graduate students.