What is a contractor?
The electrical contractor is a device capable of allowing or blocking the passage of current, through the opening or closing of its contacts, this device has the possibility of being activated according to its type of classification, Contactors can be classified by different systems either by their constitution, by their type of contacts, by current, etc. Below we will leave you some of the types of classifications.
-Electromagnetic contactors. Its operation is carried out through an electromagnet.
-Electromechanical contactors. They are actuated by the action of a servomotor that loads a spring.
-Pneumatic contactors. They are actuated by the pressure of a gas.
-Hydraulic contactors. They are actuated by the pressure of a liquid.
Classification by arrangement of your contacts
-Contactors to the air. The opening of the contacts occurs in the air.
-Vacuum contactors. The opening of the contacts occurs in a vacuum.
-Oil contactors. The opening of the contacts occurs in an oil bath.
Classification by current class
-Contactors for alternating current.
– Contactors for direct current.
Classification by voltage level
– Low voltage contactors: Up to 1000 V.
– High voltage contactors: More than 1000 V.
Classification by load characteristic
– Power contactors: Used to connect power circuits. It is identified by the letter K
– Auxiliary contactors: Used for connecting auxiliary circuits.
There are some important criteria to consider when selecting a contractor.
– Coil supply voltage: This can be continuous or alternating, the latter being the most common, and with voltages of 12 V, 24 V or 220 V.
– Number of times that the electromagnetic circuit will open and close. We may need a Contactor that closes once or twice a day, or perhaps another that is continually opening and closing their contacts. It is necessary to take into account the electric arc that occurs each time this occurs and the consequent deterioration.
– Current consumed permanently by the motor (service current).
Therefore, it is convenient to use manufacturers’ catalogs in which the different characteristics of the Contactors are indicated depending on the model.
Parts of a contactor
1 (L1), 2 (T1), 3 (L2), 4 (T2), 5 (L3), 6 (T3). They are intended to open or close the circuit of force or power.
13-14 (NO) They are used in the command or maneuver circuit. For this reason, they will withstand less intensity than the main ones. The contactor in the figure only has one that is normally open.
– Electromagnetic circuit:
It consists of three parts.
1.- The nucleus, in the form of E. Fixed part.
2.- The coil: A1-A2.
3.- The armor. Mobile part.