In the most simple terms an automotive relay is an electronically operated switch. The type most commonly used in the automotive industry is an electro-mechanically operated switch. They are found in all types of vehicles - cars, trucks, vans, trailers and boats.
They employ an electromagnet device to mechanically manoeuvre a switch to make or break an electrical circuit. The type of relay most frequently used in the automotive industry is the small cube shaped unit known as a standard relay or a mini relay.
Latching relays are 'bi-stable,' meaning they have two relaxed states. (These are also known as 'stay' relays.) When an electrical flow is turned off, the latching relay remains in the last state it was in. Latching relay is really a generic term that is used to describe the type of relay that maintains its position after the power is removed. The reason latching relays are used is because they allow control of a circuit by providing a single pulse to a relay control circuit. They are also used when it is necessary to have a relay that will maintain its contact position during power interruptions, when power must be conserved.
There are many uses in today's electric devices for latching relays. These include industrial or commercial machines, such as car wash equipment that utilizes dryers and pumps. HVAC and refrigeration, anti-condensation equipment, industrial cleaning equipment are all excellent examples of equipment that utilizes latching relays. Commercial coffee machines and commercial cooking equipment also use latching relays.