I would like to know the basic working of a AC Drive on Slip Ring Motor, as we have on Wound Rotor, we change Frequency and speed is controlled. What happens for Slip Ring, how the speed is varied, if resistance of motor is not changed.The concept of using AC Drive with Slip ring motor?
if you are talking about using a VFD on a slip ring motor instead of your resistor bank and speed contactors, you would have to jumper the windings on the rotor together NOT throught the brushes but rather on the rotor winding it's self. This isn't the best practice because the motors insulation classification is probably not up to standards for VFD's . in the long run you would be better off getting a Drive rated motor
As for vfd's they convert the incoming 3 phase A.C. to D.C. then thru pulse width modulation they change the dc cycle then it gets changed back to an A.C, voltage for output. the speeds can be controled via 0-10 volt pot, 4 to 20 ma signal or by presets programmed into the drive 000, 001, 010,
this is just a quick answer for a better understanding talk to a manufacture repThe concept of using AC Drive with Slip ring motor?
It is fairly common on crane upgrades etc to short out the rings on a wound rotor motor and control it from a variable frequency drive. The wound rotor motor speed is controlled by frequency just the same as an induction motor.
As mentioned, make sure the motor has a recent re-wind for use on vfd (class F minimum)
