Low speed motor directly drives the drive drum of vertical roller mill, which is a kind of drive mode with speed regulation function. It is generally used in vertical roller mill with speed regulation function and single motor power greater than 1000kW.

Advantages: excellent soft starting performance, linear controllable speed curve when starting, linear controllable speed curve when stopping, good electric braking performance, stepless speed change, excellent controllable performance, closed-loop control, no reducer, high reliability.

Disadvantages: the price is very expensive, the silicon controlled rectifier system is complex, the electric control equipment covers a large area, the power factor is low, the motor has slip ring, the brush is worn heavily, and the maintenance workload is large. At present, there is no explosion-proof type of high power, so it can not be used in coal mines.