Both relays and also contactors room electromagnetic switching devices, relays are switching devices that work in the control loop, and contactors are switching tools that work-related in the main loop.

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The relay is an automatic electric appliance, i m sorry is an ideal for remotely connecting and breaking AC and also DC small-capacity manage circuits, and provides control, protection and also signal conversion features in the electric drive system. The input quantity of the control relay is usually the electric quantity such as current and voltage, and it can likewise be non-electric quantity such together temperature, pressure, speed, etc. The output amount is the electric signal sent by the contact or the parameter readjust of the calculation circuit.

1. When the relay is represented by a single letter, use K.

2. When the relay is represented by double letters, over there are:

KA - Instantaneous call relay, Instantaneous through or without relay, AC contactor.

KL - Latching call relay, Bistable relay.

KM - Contactor.

KP - Polarized Relay.

KR - Reed relay, Countercurrent relay.

KT - hold-up with or there is no relay, Time relay.


Contactors are split into AC contactors (voltage AC) and also DC contactors (voltage DC), i beg your pardon are used in electrical power, power distribution and also electricity applications. In a wide sense, a contactor describes an electric appliance that supplies a coil to flow present to generate a magnetic field and also close the call to regulate the load.

The graphic symbol of the contactor is displayed in the figure below, and also the text symbol is KM.


Wiring technique of contactor





The difference in between relay and contactor

1.Different functions:

The primary function of a relay is signal detection, transmission, conversion, or disposal. That is on-off circuit present is typically small, and also it is normally used in control circuits to control weak signals.

The primary function of the contactor is to connect or disconnect the main circuit. Generally, the current through the key circuit is bigger than that of the control circuit.

Contactors with large capacity normally have arc extinguishing covers. The call capacity that the relay usually does no exceed 5A, the contact capacity the the little relay generally only needs 1A or 2A, and the call capacity that the contactor is at the very least 9A; the contactor the the contactor typically has 3 pairs of main contacts (the key contacts are all that is a usually open contact), there are also several bag of assistant contacts.

The contact of the relay typically do not have to distinguish between main contacts and also auxiliary contacts. The contact of the relay are sometimes arranged in pairs, that is, the normally open contacts and also the normally closed contacts room combined, and also the contactors room not i ordered it in pairs. early to specific needs, relays will certainly be merged with various other equipment and also planned right into time relays, counters, press relays, etc., i m sorry have added functions, if contactors usually do not.

2.The call opening and also closing are not the same:

The contactor is provided to affix or disconnect the pack with higher power. It is used in the key circuit. The main contact can have interlocking contact to suggest the opening and closing the the key contact. Relays are normally used in electrical regulate circuits to increase the call capacity the miniature or small relays come drive bigger loads.

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3.Whether it has an arc extinguishing device:

The most necessary difference in between contactors and also relays is that contactors have actually arc extinguishing devices, yet relays execute not.