Relay is a quarantine function of automatic switching elements, are widely used in remote control, telemetry, communications, automation, Mechatronics and electrical and electronic equipment, is one of the most important control elements.
Following electrical General are has can reflect must entered variable (as current, and voltage, and power, and impedance, and frequency, and temperature, and pressure, and speed, and light,) of induction institutions (entered part); has can on was control circuit achieved "pass", and "broken" control of implementation institutions (output part); in following electrical of entered part and output part Zhijian, also has on entered volume for coupled isolation, function processing and on output part for drive of middle institutions (drive part).
1) expand the scope of control. For instance, the contact relay control signal reaches a certain value, according to the different forms of contact group, and change, breaking through the road circuit.
2) amplification. For example, sensitive relays, relay, use a very small amount of control, you can control a high power circuit.
3) signal. For example, when more than one control signal at the input in the form of relay windings provided, through a more integrated, achieve the intended effect.
4) automatic, remote control and monitoring. For example, the automatic device of relays and other equipment, and can form a control line, in order to achieve automated operation.