Method and circuit for synchronization of relay operation

摘要

A control circuit synchronizes operation of a latching relay to extend contact life. The relay is switched using an H-bridge drive circuit. The synchronization is done using a two-step delay. The first delay is provided by a phase shifter, which delays the timing signals used by a logic controller relative to a zero crossing. The second delay is provided by an adjustable timer circuit including a potentiometer. The two delays are used so that the latching relay is tripped at a selectable time coinciding with the second zero crossing after a switching command is received.