Effect due to different types of load on contact of magnetic contactor.

The initial current varies for load to load also the switching off current varies due to some transient effect of load types.

The rating of making and breaking current is very important for the magnetic contactor contact. As the operation movement of contacts happens only for to break or make that is to do switching. Also the low voltage has some adverse effect on contacts.

Non-inductive or slightly inductive loads, resistance furnaces.

The operation is easier with this type of load. The initial current or starting current is equal to the rated current. And the opening or breaking voltage is same as rated voltage.

Slip-ring motors. Starting, switching off.

The voltage at closing and opening is same. But the current of closing & opening is 2.5 times of rated current.

Cage motors. Starting, switching off running motors.

At closing or making the contact, initial current is 6 to 8 times higher than rated current. At breaking or opening, the current is same as rated current but voltage is reduced to 17%.

Effect of loads on contacts of  magnetic contactor.
Effect of loads on contacts of magnetic contactor.

[alva]

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