In the textile industry, Eddy Current couplings have been very popular for rewind applications where adjustable tension control is required, although simple in operation they are costly to maintain and parts are becoming impossible to find in some cases.
An Eddy current consist of three principle parts, an induction motor prime mover running at constant speed, a DC coil surrounding a separate rotor and reduction gearbox. An adjustable output speed is obtained through the control of the DC excitation voltage, the unit can then run in speed or torque control, a tacho generator is built in to regulate the speed.
Mitsubishi A800 inverters have superb open loop torque control functionality and perfect to replace the older eddy current couplings.
Newton Tesla has successfully delivered this solution, both within textile applications but also fan and pump applications.