FIELD: electrical engineering.
SUBSTANCE: pushing START button energizes the coil, contactor operates and closes interlocking contact for self-latching. Load is connected to supply mains by means of three contacts of contactor. Current relay checks phase currents of load. Current relay contacts form series-connected combinations of three pairs, each including two parallel-connected contacts of relays inserted in different phases. Since load neutral is connected to supply mains neutral, load is still operating in the event of failure of one phase, and its disconnection takes place only in case of failure of two or more phases.
EFFECT: enhanced reliability.
1 cl, 1 dwg
