The method of adjusting motor speed - cascade speed regulation method
Cascade speed regulation refers to the adjustable additional electric potential in the rotor loop of wound motor to change the slip of motor and achieve the purpose of speed regulation. Most of the slip power is absorbed by the additional potential of the series, and then the additional device is used to return the absorbed slip power to the power grid or to make use of the conversion energy. According to the mode of slip power absorption and utilization, cascade speed regulation can be divided into motor cascade speed regulation, mechanical cascade speed regulation and thyristor cascade speed regulation, most of which are thyristor cascade speed regulation. This method is suitable for fan, water pump, rolling mill, mine hoist and extruder.
The characteristics are as follows.
1, The slip loss in the speed regulation process can be fed back to the power grid or production machinery, and the efficiency is high.
2, The device capacity is proportional to the speed regulation range, the investment is low, and it is suitable for the speed regulation range in the rated speed 70% ≤ 90% production machinery. 3, The speed regulation device can be switched to full speed operation to avoid shutdown when the speed regulation device fails.
4, The thyristor cascade speed regulation power factor is low and the harmonics have great influence.