Distance Relays Automatic Tester

Electromagnetic, static and microprocessor relays must operate rapidly for any disturbance occured on the power system. To check whether the relays operate correctly , it is necessary to test the relays under various conditions before buying and also after each period of time.In the past,traditional relay testers were used in which resistances,inductance ete as sources,Iines and loadQ. These analog testers have various problems such as long time required for testing and impossibility of generating travelling wave high frequencies.In this paper design and onstruction of a computerised relay tester is described. To simulate fault condition for power system,computer software is used.Modelling of steady state and transient conditions are made with the software.An interface hardware including currents and voltages amplifiers are designed and constructed to produce hardware parameters for relay tester.The tester has many advantages compared with traditional ones.Some of them is given belows: a) Automatic testing and storing the result b) Capability of transient signals generation c) High accuracy d) Reduction of test time The relay tester developed is called CART( Computerise d Aided Relay Tester The tester easily can test different types of distance relays( static,electromagnetic and digital ) for both steady state and transient conditions. The software used for simulation of power system condition is EMTS.