Electronic relays [india] manufactures short circuit protection relays that operate on the principle of sensing current flowing through the heat load. The ssr is very sensitive to sharp spikes of currents [transients] so load selection should be carefully done so that the transient current do not switch off the ssr. The load currents may be set to any value by tuning the potentiometer to the appropriate position as referred by the marking on the potentiometer. The short circuit protection relay goes off in case of any sudden increase of load and the removal of the load sets it again to the normal position. The ssr has 2.5 kvrms high isolation between input and output terminals by optical isolators and up to 1.5 kv between heat sink and output terminals for operator protection from shock. The reliability of the short circuit protection relay could be achieved by a proper heat sink and loading within operating areas of derating curves. The short circuit protection relays are available with leds for indicating normal and fault operations. Green led indication shows normal function whereas red/green both on indicates fault. The short circuit protection relays have an auto reset function for scanning the output every 6 sec and if over load or short circuit does not exists the relay resumes to its normal operation. These short circuit protection relays require two supply voltages for operation between +32 v control voltages and single supply for 1 and 3 control voltage for 10-18 v dc voltages.
