The effects of broken rotor bars on the transient run up of induction machines

The authors set out to examine the effects of broken bar faults on the transient torque characteristic of squirrel cage rotor induction machines. The torque is monitored using an improved technique based on terminal data measurements. Results showing various starting torque transients of a squirrel cage machine using both normal and faulty rotors are presented, and they demonstrate the effect of broken rotor bars on transient torque production. It is shown that the transient torque of a faulty machine is significantly different to that of a normal one, for both free acceleration, and also when starting under load. The supply switching angle and the initial spatial position of the fault have been fully accounted for in the results through the use of a point on wave switch.