Contactors in general for HV Motor.....

Dear Sir,

HV Motors are used for important applications in Industries.It is necessary to run the motors as per process requirements.If we use AC control voltage for coil of Ac contactors to close , it may work as long as healthy Ac supply is available.If Ac supply fails we canot give AC power to the contactor coil for closing of contactor for running of AC motors required as per industrial process needs.

Similarly shunt trip coil is used for remote trip of Ac contactor.This will work fine as said earlier solong healthy AC power ie AC control Voltage is available.If Ac control supply fails due to nonavailability of AC supply ,then tripping of contactor will not take place when it is necessary to trip the motor for trip conditions which may lead to catastrophy.

Hence in both above cases if Dc supply is used from Battery system for energisation of Ac contactor coil for closing and shunt tripping coil , it will work smmothly since it is not dependent on availability of Ac supply but depends only on healthy battery which give desired Dc voltage at all time.

Mechanical latching is some times used in the closing position of contactor ,that even power supply fails the contactor stays in ON position as additional safety.

Regards

V.Ambarani

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