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What is the difference between the motor soft starter and the traditional step-down method

The traditional decompression starting methods of squirrel-cage asynchronous motors include Y-0 starting, auto-decompression starting, and reactor starting. These starting methods all belong to step-by-step decompression starting, and the disadvantage is obvious, that is, a secondary inrush current occurs during the starting process. These traditional decompression starting methods are relatively backward in technology, and the state has clearly ordered them to be phased out.

The difference between soft start and traditional decompression start is:

One, no inrush current. When the soft starter starts the motor, by gradually increasing the conduction angle of the thyristor, the starting current of the motor increases linearly from zero to the set value. There is no impact on the motor, which improves the reliability of power supply, starts smoothly, reduces the impact torque on the load machinery, and prolongs the service life of the machine. This is the soft start function of the soft starter.

Second, the soft starter not only has the function of soft start, but also has the function of soft stop, that is, smooth deceleration and gradual shutdown. It can overcome the disadvantages of instantaneous power failure and shutdown, reduce the impact on heavy-duty machinery, and avoid the failure of the elevation water supply system. Water hammer effect, reduce equipment damage.

Third, the starting parameters are adjustable, which can be selected according to the load conditions and the characteristics of the power grid relay protection, and can be freely and steplessly adjusted to the best starting current.

Fourth, the soft starter also adds phase loss protection, overload protection, overvoltage protection, overtemperature protection, undervoltage protection, etc., to protect the motor more comprehensively.