What is the difference between soft start and hard start of motor?

The difference is that the current of hard start is much larger than that of soft start.

Motor soft start:

It means that the motor starts slowly with small current, which has little impact on the power grid, reduces the load margin of transformer and control circuit, and improves the service life of equipment. Generally, when the AC motor is started directly, the starting current is 6~ 10 times of the trial running current, but after adopting soft start technology, the starting current is reduced to 1~3 times.

The soft start of the motor mainly adopts the following methods:

1。 Reduce the power supply voltage to start 2. Reduce the power frequency to start 3. Starting by reducing the excitation current

The starting current of hard starting (direct starting) is 3-7 times the rated current of the motor. When starting directly (hard starting), this situation exceeds the rated current of the motor, which brings many constraints to the manufacturing process and structure of the motor itself.