ABB Jokab Safety Relays
ATC / DIVERSIFIED Timing Relays
EATON /CUTLER HAMMER Relays
DOLD Safety Relays
ELOBAU Safety Relays
EUCHNER Safety Relays
SCHLEICHER Safety/TIming Relays
SCHMERSAL Safety Relays
SSAC TIming Relays
SYMCOM TIming Relays
A control relay is a locally or remotely controlled electromagnetic switch that is widely used in all forms of equipment due to its ability to switch higher currents than would otherwise be impossible without it. Control relays, which may be controlled manually or automatically by logic circuits, also electrically isolate the output voltages from the control voltages. The control relay is an electromechanical device that relies on the force of an electromagnetic field. When the relay coil is energized by driving an electrical current above the holding current, the relay contacts move to the second of two positions. For instance, when the relay contact is open, energizing the relay coil will close the contact and vice versa.
The normal position of a relay contact is the default de-energized position of the relay. It is either normally open or closed. Using the normally open position is common for applications that power up a load. A normally closed position is usually used for applications that shut down the load. In this case, energizing the relay coil opens the relay contacts.
Switches are commonly used in electrical controls. When the load currents require bigger contacts for the switch, manually closing the switch becomes inconvenient and impractical. For instance, switching a fraction of an ampere is fine with simple switches. When bigger currents should be switched, the arching on the switch contacts will damage the switch too soon, more so with motors which are inductive loads. A relay is added to the circuit to build durable high-power switches.
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