Latching relays allow the circuit to be controlled by using a single pulse to the relay control circuit and are used when a relay is required to maintain its position if the power is interrupted. There are three basic types of latching relays:
Magnetic latching relays on ship power system
This relay uses one pulse to move the contacts in one direction. A second pulse from a different input is required to return the contacts. Pulses that are repeated from a single input will not have any effect.
Mechanical latching relays on ship power system
This relay uses a locking mechanism to maintain contacts in the set position, a second coil is normally required to change the state. As the latch does not rely on a magnet it does not degrade with time or weaken during thermal cycling.
Impulse Sequencing relays on ship electrical system
Impulse sequencing relays, also known as impulse relays, move contacts with every pulse without redirecting the pulse or reversing the polarity.
Many impulse relays consist of a magnetic latch relay and a solid-state steering circuit. When power is applied, the steering circuit determines the position of the relay, and the opposite coil is energized, transferring and latching the contacts. When the coil is reenergized the contacts transfer once again.
