This could be used for switching over the output from ac mains to inverter mains during inappropriate voltage conditions.
Changeover relay circuit.
In another type a ratchet relay has a ratchet mechanism that holds the contacts closed after the coil is momentarily energized.
Ups relay changeover circuit.
The next concept makes an attempt to create a simple relay changeover circuit with zero crossing detector which may be used in inverter or ups changeover applications.
The pole of the relay will connect with the ground line which must be common to the changeover circuit and the ic 555 circuit both.
The most common changeover function relays are produced to switch a single feed line usually positive position 30 between two active functions in a circuit the relay is switched manually via a toggle push switch or remotely through the circuit.
The circuit diagram shown here is of a automatic changeover switch using ic ltc4412 from linear technologies.
This circuit can be used for the automatic switchover of a load between a battery and a wall adapter ltc4412 controls an external p channel mosfet to create a near ideal diode function for power switch over and load sharing.
The relay may be less expensive than other types but this is partly offset by the increased costs in the external circuit.