A dynamometer for the accurate, automatic determination of induction motor torque-speed characteristics has been developed as part of an investigation into induction motor losses. The speed range of interest is scanned at constant acceleration so as to simplify corrections for inertia torque, the speed being measured by a highly accurate tachogenerator. The torque is measured by a magnetostrictive torque meter mounted between the dynamometer and the machine under test, the linearity and reproducibility being better than ±0.5% of the rated torque. A 12 KW 3-phase power unit, which may be operated in either the constant voltage or constant current mode, has been constructed to supply the induction motor. The equipment has been successfully employed in the determination of stray loss at large slips but deficiencies have become apparent when the measurement of loss at small slips is attempted. This will require an improvement in the speed of response of the 3-phase power supply and a method for the continuous determination of the machine input impedance. Methods for accomplishing this are suggested.

Barton, T. (Supervisor)