The difference between soft start and traditional decompression start mode

Update:16 Nov 2018
Summary:

Conventional decompression starting methods for cage mo […]

Conventional decompression starting methods for cage motors include Y-q starting, auto-decompression starting, and reactor starting. These starting methods are all graded decompression starting, and there are obvious disadvantages, that is, secondary inrush current occurs during starting. The difference between soft start and traditional decompression start mode is:

(1) No inrush current. When the soft starter starts the motor, the motor starting current is linearly increased from zero to the set value by gradually increasing the conduction angle of the thyristor.

(2) Constant current starting. The soft starter can introduce current closed-loop control to keep the motor constant during the starting process to ensure smooth start of the motor.

(3) According to the load situation and the choice of grid relay protection characteristics, it can be freely and steplessly adjusted to the optimal starting current.