The Contactor
A contactor is an electrically controlled switch used for switching an electrical power circuit, similar to a relay except with higher current ratings. A contactor is controlled by a circuit which has a much lower power level than the switched circuit. A contactor is composed on two parts: Power and control part. |  |
The power part is composed of contacts (3 / 4) with high Interruption capacity. All contact are closing or Opening at the same time. They are moved by the coil of the control circuit. When this one is supplied, it attracts the moving part and the power contacts are closing. In contrary, when the coil is not powered, a spring move back the moving part and the power contacts are opening. A contactor is a switch controlled by a coil.
The power part can have 1, 2, 3 or 4 contacts. They can be Normally Open or Normally Closed. The rating depends on the load current.
The control is divided in two parts: The coil, which can be supplied in ac or dc and several voltages and the auxiliary contact moving at the same time of the power contacts.
If it is require, auxiliary contact can be added on the contactor's front or side.
Method : 6.1. Contactor choice
Note : Categories
The IEC 947-4 Standard characterises the various category of use of the device control. For the motor feeder in ac, the mains categories are:
Definition : 6.3. Symbols
