Direct On Line (DOL) starting

Protection with thermal relay

Operating mode: By pressing Start push button the Q1 contactor coil is energized, the motor will start run and maintains itself after the button Start release, by means of auxiliary Q1 contact, the Stop button and and thermal relay 97-98 normal close contact. When overload occur thermal relay 97-98 normal close contact opens, so the motor is stopped.

Thermal relay and contactor calculation

The values for Q1, TF1 must be chosen according to the rated power of your motor, base on the data found on motor plate. Fuse F1 must have current value of 5-7 times higher than rated motor current. Fuses F2, F3 for the control circuit may be up to 10 A.

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