Inverters for Electric Motors
Benefits of using Inverters with Electric Motors
The key benefit of 3 phase output inverters is that they allow you to vary the frequency of the 3 phase power output in increments. Grid power is fixed at 60Hz in most regions. But with an inverter, you can set the output frequency to 50Hz, 40Hz, 30Hz, or even lower.
- Why Use a Lower Frequency?
The speed of an AC induction motor is dependent on the applied frequency. By reducing the inverter output frequency from 60Hz to 30Hz, the motor speed is cut in half. This allows the motor to be operated at partial load efficiently. Lower speed operation significantly reduces the power consumption of electric motors.
Affinity laws show that halving the speed reduces the power by a factor of eight!
- Energy Savings in Action (Example senario)
Consider a 100 kW fan motor operating 12 hours per day. At full 60Hz speed it consumes around 75 kWh of electricity. But by reducing the inverter frequency to 30Hz, it now only consumes around 9 kWh while still providing adequate airflow.
Over the course of a year, the energy savings could be over 200,000 kWh! At £0.29 per kWh, that equates to £58,000 in annual savings - enough to pay for the inverter system in a short period of time.
- In summary
Using a 3 phase output inverter allows the frequency and speed of motors to be reduced to match the load requirements. This enables huge energy savings while maintaining production. Its a simple yet highly effective way to cut electricity costs in any facility using electric motors.