Changing main contacts, arc chutes and coils

When changing the AF coil with its PCB (printed circuit board) care must be

taken to avoid ESD damage.

Before any dismantling of the contactor:Make dead by, turning off the contactor.

Opening the main circuit by turning off the main switch, if any, or by removing the

main fuses in all three phases. To protect against making attempt, open also the con

trol circuit.

Trouble shooting

examples of common reasons for contactors not working properly

Voltage drop during start up of the motor Voltage drop to less than 85 % of nominal

voltage for 5 to 10 ms can be enough for the contactor to start opening.

Also,other disturbances in the control voltage such as poor relay contacts or too small

control transformer/power supply could be responsible for this problem.

The result of these voltage problems can be increased

contact wear and also lead to welding of main contacts.

With the AF technology these problems are avoided.