Geoffreye
2012-07-06, 12:00 PM
I have seen one new 80 kw, 740 rpm, rotaryjoint rotary joints (http://www.electricslipring.com/through-bore-slip-rings-rotaryjoint-rotary-joints.html) motor to rotate with 60 % full load speed though the rotor is disconnected from the controller and kept open .
If the motor is a wound rotor induction motor and the rotor is disconnected from the external resistors, I can't see how the motor can function as an induction motor. With no current path, the rotor current would have to be zero. However, the motor could possibly operate as a reluctance motor, a hysteresis motor or even a permanent magnet synchronous motor. Not much torque would be produced. It probably would not operate with much load connected and might not be self starting. There is also a possibility of current paths in the rotor iron and structural parts. That current might be sufficient to allow the motor to produce some torque as an induction motor.
If the motor is a synchronous motor, there would be amortisseur circuits that would allow the motor to operate as an induction motor in the absence of current in the rotor field winding.
slipring (http://www.electricslipring.com/)
revolving joints (http://www.electricslipring.com/revolving-joints.html)
If the motor is a wound rotor induction motor and the rotor is disconnected from the external resistors, I can't see how the motor can function as an induction motor. With no current path, the rotor current would have to be zero. However, the motor could possibly operate as a reluctance motor, a hysteresis motor or even a permanent magnet synchronous motor. Not much torque would be produced. It probably would not operate with much load connected and might not be self starting. There is also a possibility of current paths in the rotor iron and structural parts. That current might be sufficient to allow the motor to produce some torque as an induction motor.
If the motor is a synchronous motor, there would be amortisseur circuits that would allow the motor to operate as an induction motor in the absence of current in the rotor field winding.
slipring (http://www.electricslipring.com/)
revolving joints (http://www.electricslipring.com/revolving-joints.html)