MPR is a phase failure relay operating on negative sequence voltage sensing principle. It offers protection against.
MPR is an auxiliary relay and it should be used along with the motor starter only. The effective working of MPR will depend on efficient working of electromagnetic motor starter. Before installing MPR check whether the motor starter is operating perfectly by starting the motor with "START" push button and switching it off by "OFF" push button. If motor does not "START" or "STOP" on respective operations, the starter needs to be serviced. Do not install MPR with faulty motor starter.
Trip Setting: Relay can be set to trip the starter for any unbalance voltage between 30 V to 70 V + 9V between any two phases.
Time Delay: MPR offers sufficient Trip time delay of 3 - 4 Sec. for all, Phase Sequence, Phase Loss and Phase unbalance conditions, to prevent nuisance tripping and hence protects motor.
Reset: The relay can be set in Auto reset or manual & remote reset mode by removing or putting a short link between terminal 11 & 12. Relay can be remotely reset by extending the remote reset push button provided on terminal 10 & 11 (Use continuous cable at max. distance of 100 meters) Relay will reset if unbalance voltage is reduced to less than 20 V between all three phases.