Magnetic actuators: device and assignment


For what magnetic actuators are used?

The magnetic actuator is intended for remote start-up, the stop and protection of electric units, electric motors. It, as a rule, consists of the constructive and integrated thermal relay and the contactor. Nevertheless in the industry they is issued also without thermal relay. Are intended for work in three-phase network.

Схема устройства магнитного пускателя

Scheme of the device of the magnetic actuator.

Actuators 0-2 sizes can be used also in household (single-phase) network for launch of electric motors of small power. On design features they can be 3-and 4-polar, i.e. 3 or 4 main contacts. As a rule, the fourth contact carries out the role of normally open interlock contact, to its help there is the blocking of the chain management.

The design, namely electromagnet and contact unit, is executed as follows. The electromagnet consists of the Sh-shaped magnetic conductor core consisting of two parts halves, one of which is rigidly installed in the actuator body, and also which are rigidly established and isolated from each other and from the body of the main, upper and lower contacts.

The feeding three-phase cable going from the breaker or the distribution cabinet approaches upper group.

Loading (electric motor) surely via the thermal protective relay is connected to the lower contacts. Here on the lower part the coil is installed. Magnetic actuators can differ in the supply voltage of the coil of 220-380 Century. There is no difference special, but in respect of additional protection of the coil it is 380 V better.

Реверсивная схема управления магнитным пускателем

Reverse scheme of control of the magnetic actuator.

The soulmate of the magnetic conductor mobile also has contacts crossing points which strap the lower contacts. They are designed movably, softly, on springs for readjusting of pressing the main contacts.

In the design of actuators the additional (small) interlock contacts normally open and normally closed which synchronously work with the mobile part of the actuator are installed and are necessary for work in the control circuit. As a rule, them can be one or two couples.

Magnetic actuators are issued from 0-6 sizes, for loadings from 5-140 A for loading over 140 And are used contactors.

Magnetic actuators are issued different models and modifications, but the principle of work at all is identical. In Soviet period the PMA, Party of Peace and Unity, MPA series which proved positively from all directions were issued. They were made of qualitative materials to this day perfectly work.

Схема подключения магнитного пускателя через кнопочный пост

The scheme of connection of the magnetic actuator through the push-button post.

If the actuator is picked correctly up for loading and from time to time is inspected, then they will serve for a long time. As a rule, on audit of time leaves a little. The necessary element of operation of the actuator is the START-UP-FEET button which can be installed in any convenient place proceeding from specifics and technology of the object of assignment.

The normal actuator has two buttons: START-UP (green or black), STOP (red).

Also important element of the actuator is the thermal protective relay selected precisely under the necessary loading. Relays happen two-phase, the manual platoon after switching off and three-phase, self-built. In use quite often one of phases of three-phase power voltage, for example because of burn-out of the safety lock breaks.

Only two phases and current in the stator at the same time are brought to the engine sharply increases that leads to the exit it out of operation because of heating of the winding to high temperature.

Thermal relays of the actuator have to work and disconnect the engine from these currents.

COMMENTS
  1. Name

    Rasklyuchil 0th wire

    To answer
  2. Alexander

    Well пмл to lay out the scheme the request. Thanks.

    To answer
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