An experimental investigation of transient torques

Abstract

A technique is described for measuring and recording the torque generated by a prime mover over the full range of its speed. The prime mover chosen for the investigation is an induction motor in order to demonstrate that the technique can be used even on a motor whose torque over a wide range of speed cannot be readily measured by conventional steady-state methods. A method of measuring the transient motor torque, based on the principle of the reaction torque of a motor, is described. The transducer used in the torque measurement is a strain gauge. A description is given on the bridge and voltage amplifiers. The calibration of the torque output readings is explained. Torque-speed characteristics of the induction motor are obtained, and the accuracy of the measuring system for the starting torque and transient torque is discussed. One by-product of the investigation is the experimental verification of the presence of the switching-transient torque in an induction motor.