Soft starters PPPM are designed for smooth starting of high-voltage AC motors rated 3, 6, and 10 kV with power from 400 kW to 12.5 MW in electric drives with fan-type load characteristics. The PPPM power circuit is based on a thyristor voltage regulator. The microprocessor-based control system enables asynchronous and quasi-frequency motor starting with limitation of the starting current amplitude. Motor starting must be performed under minimal load conditions and with a load torque not exceeding 0.4 of the rated torque.
During the starting process, the following is ensured:
- limitation of motor starting current to a specified level in the range Istart = (1.5 ... 3.0) In;
- limitation of starting current (torque) during the starting process compared to direct-on-line starting;
- reduction of dynamic torques in the motor–mechanism system compared to direct starting;
- reduction of inrush currents in the starting switching equipment compared to direct starting;
- reduction of stator and rotor winding losses during starting (in quasi-frequency mode) compared to direct starting;
- permissible number of motor starts up to 12 per hour (in quasi-frequency starting mode);
Nominal data:
- Rated voltage: 3, 6, 10 kV;
- Rated current of main circuits: 70, 150, 200, 400, 630, 800 A;
- Number of outgoing load lines is determined by the number of motors being started.