- The motor runs 20% faster,
- The starting torque is reduced,
- For blowers and centrifugal pumps the load increases drastically for a slight increase in speed and the value of the current will rise,
- The motor overheats,
- Ageing of insulation will be accelerated due to over-heating and current value,
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 frequency can cause premature motor failure and installation damage.
Here, we’ll look at the effects of low and high frequency on motors and the related performance changes you can expect when you use frequencies other than those noted on the nameplate.
Use frequency converters or…
Can cooling help?
The other 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.