Starting current of the asynchronous motors might be 4-6 times of the nominal current. Starting resistors are used to limit these high currents.
Crane control is a quite common application for braking resistors. During descent the load, especially if heavy, may cause the motor to generate power as if it were lifting. Resistors are thus used to avoid unwanted and uncontrolled acceleration.
Disexcitation of large capacitors and inductors must be carried out with care to avoid impulsive currents that could
damage them permanently.
Discharge resistors limit the peak current and protect the capacitive / inductive device.
General application areas;
- Steel industry
- Cement factories