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Slip Ring Motors With Vfd


MSBALA

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WE HAVE SLIP RING MOTOR WITH 2.2KW ANALOG DRIVE WITH PERMANENT ROTOR RESISTORS CONNECTED FOR CRANE TROLLEY MOTOR.DUE TO ANALOG FREQUENT CONTROL CARD PROBLEM

NOW WE HAVE CONNECTED SLIP RING MOTOR WITH VFD WITH SAME ROTOR RESISTORS CONNECTED PERMANENTLY.BUT WHEN RUNNING IN VFD MOTOR TAKES HIGH CURRENT .SHOULD WE TAKE OUT THE ROTOR RESISTORS AND TO SHORT THE ROTOR RESISTOR TERMINALS AT THE MOTOR END TO REDUCE THE CURRENT.

ANY ONE CAN GIVE THE SOLUTION

BYE

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Hello MSBALA

 

The connection of rotor resistors when using a ship ring motor with a VSD should not increase the current flowing, rather, it will increase the slip for a given shaft torque.

If you short out the resistors, the current should remain the same, but the motor should run closer to the speed of the VFD.

 

The higher current would usually be the result of an incorrect setting, particularly, the output voltage is higher than it should be for that motor.

 

In the VFD setup, there should be a parameter for the motor frequency and the motor voltage. If these do not match the motor ratings, there will be an incorrect output voltage and this will increase the output current.

 

Best regards,

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WE HAVE SLIP RING MOTOR WITH 2.2KW ANALOG DRIVE WITH PERMANENT ROTOR RESISTORS CONNECTED FOR CRANE TROLLEY MOTOR.DUE TO ANALOG FREQUENT CONTROL CARD PROBLEM

NOW WE HAVE CONNECTED SLIP RING MOTOR WITH VFD WITH SAME ROTOR RESISTORS CONNECTED PERMANENTLY.BUT WHEN RUNNING IN VFD MOTOR TAKES HIGH CURRENT .SHOULD WE TAKE OUT THE ROTOR RESISTORS AND TO SHORT THE ROTOR RESISTOR TERMINALS AT THE MOTOR END TO REDUCE THE CURRENT.

ANY ONE CAN GIVE THE SOLUTION

BYE

Dear MSBALA,

 

Please always post your question in small fonts which is easy to read in a short time.

"Don't assume any thing, always check/ask and clear yourself".

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NOW WE HAVE CONNECTED SLIP RING MOTOR WITH VFD WITH SAME ROTOR RESISTORS CONNECTED PERMANENTLY.BUT WHEN RUNNING IN VFD MOTOR TAKES HIGH CURRENT .SHOULD WE TAKE OUT THE ROTOR RESISTORS AND TO SHORT THE ROTOR RESISTOR TERMINALS AT THE MOTOR END TO REDUCE THE CURRENT.

 

What was the running current before using the VFD ? What is the mains voltage ? Is the motor connected for that voltage ?

 

Advise,

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