AC contactor wiring diagram

- Aug 02, 2019-

In order to enable the motor to turn and reverse, two contactors KM1, KM2 replacement motor three-phase power supply phase sequence, but the two contactors can not absorb, if the simultaneous suction will cause a short-circuit accident of the power supply, in order to prevent such an accident, in the circuit should take a reliable interlocking, The image above is a control circuit that uses a button and contactor double interlock for the motor to operate in both positive and reverse directions. The route analysis is as follows:

First, forward start:

1, close the air switch QS turn on the three-phase power supply

2, press the forward start button SB3, KM1 power-absorbing merge self-locking, the main contact closed to connect the motor, the motor at this time the phase sequence is L1, L2, L3, that is, forward operation.

Second, reverse start:

1, close the air switch QS turn on the three-phase power supply

2, press the reverse start button SB2, KM2 power-suction merge through the auxiliary contact self-locking, often open the main contact closed and replaced the motor three-phase power phase sequence, when the phase sequence of the motor is L3, L2, L1, that is, reverse operation.

Third, interlocking link: with a prohibited function in the line to play a security protection role

1, contactor interlock: KM1 coil circuit into KM2's normal closed auxiliary contacts, KM2 coil circuit string into KM1's normal closed contacts. When the forward contactor KM1 coil power action, KM1's auxiliary normally closed contact disconnectkm2 coil circuit, if KM1 is electro-absorbed, you must first make KM2 power release, its auxiliary often closed contact reset, which preventkm1, KM2 at the same time suction caused by a short-circuit between phases, this line link called interlocking link.

2, button interlock: in the circuit using the control button operation of the forward and back transmission control circuit, button SB2, SB3 have a pair of normally open contacts, a pair of normally closed contacts, these two contacts are connected with KM1, KM2 coil circuit. For example, the normally open contact of button SB2 is in series with the contactor KM2 coil, while the normally closed contact is in series with the contactor KM1 coil circuit. The normally open contact of button SB3 is in series with the contactor KM1 coil, while the normally closed contact press KM2 coil circuit in series. So when you press SB2 can only have contactor KM2 coil can be powered on and KM1 power off, when sb3 can only have contactor KM1 coil can be powered on and KM2 power off, if you press SB2 and SB3 at the same time, two contactor coils can not be energized. This acts as an interlocking role.

Fourthly . After the motor is forward (or reverse) started to run, the motor does not have to be stopped by pressing the stop button, and can directly press the reverse (or forward) start button to make the motor run in the opposite direction.

Fifth, the overload protection of the motor is completed by the thermal relay FR. Motor reversible operation control wiring diagram

1, check the main circuit road wiring is correct, in order to ensure that the two contactors can reliably change the phase sequence of the motor, wiring should make the contactor's upper port wiring consistent, in the contactor's lower mouth phase.

2, check the wiring is correct, power test, power test in order to prevent accidents, should first disconnect the motor wiring.

Fault phenomenon pre-treatment;

1, do not start; one of the reasons, check the control insurance FU is open, hot relay FR contact is used incorrectly or bad contact, SB1 button's normal closed contact is not good.

Reason two is the new interlock wiring is wrong.

2, when the contactor "boo" does not suck, this is because the contactor's often closed contact interlock wiring is wrong, the interlock point into their own lock, starting often close is the contactor coil of the electric suction, contactor suction after the often closed contact point, contactor coil and power release, Release the normal closed contact point and turn on the contactor and suction, the contact point is disconnected, so there will be a "boo" contactor does not suck the phenomenon.

3, can not self-lock a lift hand contactor disconnect, this is because the self-locking contact wiring is wrong.

Using the answer method

One: General three-phase contactors have a total of 8 points, three inputs, three outputs, and two control points. The output and input are corresponding and are easy to see.If you are to add a self-locking, you also need to connect the line from one terminal at the output point to the control point.

Two: First of all, you should know the principle of AC contactors. He uses external power to add to the coil, creating electromagnetic fields. Power-up absorbs and the contact point disconnects after power is off. Once you know the principle, you should figure out the contact points of the additional power supply, that is, the two contacts of the coil, usually in the lower part of the contactor, and on one side. Several other inputs and outputs are generally in the upper part, as you know at a glance. Also note the voltage of the additional supply (220V or 380V), which is generally marked. And note whether the contact point is normally closed or open. If there is self-locking control, according to the principle of the line on it.