Frequency converters are power converters that generate a variable alternating voltage for the supply of machinery. The values for the output voltage are oriented toward the demands of the machine to be supplied and its load. Frequency converters may also contain inputs for sensors that acquire operating parameters, such as the speed. In principle, frequency converters consist of a rectifier and an inverter.
If motors are operated without a converter, their speed depends on the supply system frequency. The use of a frequency converter enables a steplessly invariable adjustment of the speed without a drop in torque. As a result, they enable a soft start.
The varied speed can be used specifically for pumps to adjust the output of the pump unit to the desired or occurring pump capacity. As a result, the pump uses only as much energy as required for the current operation. This adjustment has a positive effect on energy efficiency.