785XBXCD-12D

Energy Conservation Relays

In many applications it is important for the customer to conserve electrical energy. One approach to energy conservation in
an electrical system is to use relays that do not require constant power to maintain contact closure.
“Latching relay” is a generic term that is used to describe a relay that maintains its contact position after the control power
has been removed. Latching relays allow a customer to control a circuit by simply providing a single pulse to the relay control
circuit. Latching relays are also desirable when the customer needs to have a relay that maintains its position during an
interruption of power.
There are three main types of Latching relays. Magnetic latching, Mechanical Latching and Impulse Sequencing.

Magnetic Latching Relays

Magnetic Latching relays require one pulse of coil power to move their contacts in one direction, and another, redirected pulse
to move them back. Repeated pulses from the same input have no effect. Magnetic Latching relays are useful in applications
where interrupted power should not be able to transition the contacts.
Magnetic Latching relays can have either single or dual coils. On a single coil device, the relay will operate in one direction
when power is applied with one polarity, and will reset when the polarity is reversed. On a dual coil device, when polarized
voltage is applied to the reset coil the contacts will transition. AC controlled magnetic latch relays have single coils that
employ steering diodes to differentiate between operate and reset commands.