Classification

Driving time from relay power requirements (driving line package working voltage) to points, general relay AC relay DC relay points, respectively, for AC circuit and DC circuit, in addition, based on its working voltage level, there are 6,9, 12,24,36,110,220,380 different operating voltages, for use in different control circuits. Another distinction between the time the relay contact point is it (turn on or off the implementation of controlled circuit switching), respectively, normally open, normally closed, the difference between the conversion, plus the difference between the number of contacts, you can control how much Operating voltage and current (ie contacts allowed to control the power of) the difference between different uses for selection; in addition there are special contacts with self-locking (after the action even if the control voltage disappears, the contacts themselves losing control hold state when) with pull delay or time-release function types, for use in special cases.

To distinguish appearance from the relay, sealing, small, micro and other differences. Sometimes, for example, a control circuit starts from the button control to the last control the load time relay intermediate, also used other relays, because the relays only play the role of other control relay, the contacts do not need to load large, used in these parts of the relay, often called an intermediate relay. For example, using the three buttons and relays (AC contactor) protection and thermal control can be composed of three-phase motor positive inversion and stop circuit. The washing machine, the relay in the microcomputer control, engagement, disconnect the motor to control Washing positive, reverse, etc., are the tasks of the relay, because the output of the microcomputer can not directly drive the washing machine motor work, so the "relay." Various sensors detecting circuit for detecting temperature, pressure, time, etc. Different physical quantity detected output connected to the relay, the relay on the composition of the so-called voltage respectively, and so the pressure relay. Such relay, including relay actually contains an electronic device, not independent relays.

Special Category

Step relay: In the past the use of automatic telephone switchboard lot relay itself can automatically move the movable contact to the appropriate location according to the number of pulses input control coil, such as pulse input 6, the movable contact on the fixed contact is turned on the 6th point, enter 9 pulses, we received 9 contacts so. Automatically transferred to the phone line according to the needs of dial pulse digits.

Resonant Relay: The relay itself has a number of different length, thickness, such as reed movable contact, the contacts themselves and rational distribution of different resonant frequencies, when the input relay coil current frequency coincides with a reed contact the resonant frequency is the same, due to the resonance of the reed produces a great earthquake, so that the corresponding fixed contact is closed, when the input signal frequency to another, you can make another contact action, which is equivalent to translate signals of different frequencies to correspond the operation of the circuit connection, which is now completely different electronic decoding is achieved through mechanical principles.

Proportional Relay: able to distinguish between packet input line drive pulse signal duty cycle relay and automatically adjust the output (ON different contacts); and so on. Now using a switching circuit composed of thyristors, independent encapsulate said solid state relay (non-contact relay), in the use of partially replace traditional relay, but also has its shortcomings. So ordinary relays are also a large number of applications.