Running a 440V motor on a 380V power supply (at reduced voltage) will bring up a few problems:
- Starting and maximum torque will be low. Thus, a longer acceleration period will be needed and this will result in overheating while starting.
- The current will be higher in order to maintain the same power output. Therefore heating occurs while running.
- Ageing of insulation will be accelerated due to over-heating
The economic loss from premature motor failure is devastating. In most cases, the price of the motor itself is trivial compared to the cost of unscheduled shutdowns of processes. Both high and low voltages can cause premature motor failure, as will voltage imbalance. Here, we’ll look at the effects of low and high voltage on motors and the related performance changes you can expect when you use voltages other than those noted on the nameplate.
Cooling can help?
The one thing you can take into account is cooling. The motor will be specified at a certain ambient free flow air environment. If you can increase the air-flow over the rotor or otherwise extract heat from the core, you can in fact drive the motor harder with little significant effect on the motor other than reduced brush life.