Effect of higher supply voltage on electric motors and equipment

Abstract

The effect of applying a higher supply voltage above the rated voltage to electric motors and other domestic equipment is studied in this project. Modem design of motors, in general is based on operation close to the knee of the magnetisation curve. This allows smaller and lighter motors. However, such motors will be effected more on applying a higher supply voltage above standard value. All motors under test were found to operate well below the knee and the above could only be predicted using the behaviour of the tested motors. Practical tests are performed on induction motors and some domestic equipment in order to analyse this effect and hence link the findings with the theoretical research conducted. The steady-state phase currents resulting in a three-phase induction motor are simulated where it is shown that saturation results in induced harmonics and also larger peak currents. This will result in increased losses and depending on the load conditions some derating might be required to keep the motor within the designed thermal conditions.