Structural principle of the contactor

Structural principle of the contactor

Contactor is under external input signal can automatically turn on or off the main circuit with load automatic control appliances, in addition to control motor, can also be used to control lighting, heating, welder, capacitor load, suitable for frequent operation, remote control strong current circuit, and has reliable work, long life, small size, low pressure release of protection function, is one of the most important and commonly used components in relay-contactor control system.

Reversible contactor is a kind of used to control higher power motor positive and reverse mechanical reversible ac contactor, consists of two standard contactors and a mechanical interlock unit, concentrated the advantages of ac contactor and reverse switch, simple operation, safe and reliable, low cost, mainly used for motor positive and reverse operation, reverse braking, constant operation and point operation.

Contactors can turn on and disconnect the load current, but they can not cut off the short-circuit current, so they are often used with fuses and thermal relays.

classify

There are many kinds of contactors, and there are generally four classification methods, including the first one.

① is divided into AC contactor and DC contactor according to the current type of the circuit connected by the main contact.

② is divided into monopole, bipolar, 3,4, and 5 poles according to the number of poles of the main contacts.

③ is divided into normally open type and normally closed type according to the main contact excitation coil.

④ is divided into no arc extinguishing device and no arc extinguishing device according to the arc extinguishing mode.

Structure principle

The main components of the contactor are; electromagnetic system, contact, arc extinguishing system, auxiliary contacts, bracket and housing, etc.When the button is pressed, the coil is energized, the static core is magnetized, and the moving core is sucked up to drive the shaft to make the contact system split and close the operation, so as to connect or disconnect the loop.When the button is released, the procedure is opposite to the above.

Main technical parameters

① rated working voltage: generally refers to the rated voltage of the main contact, including AC: 380V, 660V, 1140V, DC: 220V, 440V, 660V, etc.

② Rated working current: generally refers to the rated current of the main contact, including 6A, 9A, 12A, 16A, 25A, 40A, 100A, 160A, 250A, 400A, 600A, 1000A, etc.

③ turn-on and break ability: refers to the current value that the contactor can turn on and break the electric receiving device.

④ agreed heating current: in the test under the specified conditions, the current works at 8h, and the maximum current carried when the temperature rise of each part does not exceed the limit value.

⑤ operation frequency: refers to the number of operations allowed per hour.

⑥ Mechanical life and electrical life: refers to the average number of operations before the mechanical failure of the main pole without load.Mechanical life is related to the operation frequency.Electrical life is the average number of carrying operations on the main pole without maintenance.Electrical life is related to the type of use, rated working current, and rated operating voltage.