Cage motor decompression start-up mode with a star - delta starter, auto start under reduced pressure, the reactor start. These start-up mode are all level decompression hard start, there are obvious shortcomings, that you start the process of secondary impacts current. Soft-start with the traditional decompression start-up mode with the following differences.

    1.1 no impact on current

    Soft starter when starting the motor, by gradually increasing the thyristor conduction angle, the motor starting current is increased linearly from zero to the set value.

    1.2 Constant Current start

    The soft starter can be introduced current closed-loop control of the motor at constant current during start-up, to ensure the smooth start of the motor.

    1.3 Starting current regulation

    Selected according to the load and relay protection characteristics can be freely stepless adjustment to the best start-up current.

    1.4 soft stop

    The motor is stopped, the traditional control method by momentary power failure, but in many applications, the motor is not allowed instant shutdown. Such as the building of high-rise building water supply pump system, instant shutdown will have a huge "water hammer" effect to make the pipe or pump damaged. To reduce and prevent "water hammer" effect, motor gradually slow stop, soft stop. In the pumping station, the soft starter can meet this requirement, the application soft stop technology to avoid the damage of the pump station "knock on the door, reduce maintenance costs and maintenance work.

    The soft starter soft stop function is gradually reduced from full conduction thyristor stop command. Conduction angle, the process of transition to full closed after a certain time. Stopping time according to actual needs can be adjusted between 0 ~ 120s.

    1.5 light-load energy-saving

    Cage induction motor inductive load current lags the voltage in the run. Such as the operating voltage of the motor constant, in the light load power factor is low; is overloaded, the power factor. The soft start can be realized by lowering the motor terminal voltage at light loads, to improve power factor, to reduce the copper loss of the motor, the iron loss, to achieve the purpose of energy saving light load; automatically increase when the load is heavy, the terminal voltage of the motor to ensure that the motor is normal operation.

    2 soft-start protection function

    The soft-start protection function is much better than traditional hard starter protection function.

    2.1 overload protection

    The soft starter introduction of the current control loop, which can keep track of the changes in position of the detected motor current. Turn-off thyristor through increased overload current settings and inverse-time control mode, overload protection, motor overload, and an alarm signal.

    2.2 lack of protection

    Work, the soft-start at any time to detect changes in the three-phase line current, the event of drying up, the reaction can be made phase protection.

    2.3 overheat protection

    Thyristor heatsink temperature through the soft-start internal thermal relay, once the heat sink temperature exceeds the allowable value automatically turn-off thyristor and an alarm signal.

    2.4 Other Functions

Soft starter combination with other protection components, you can achieve the stall protection function. In addition, by the combination of an electronic circuit, but also in the system to achieve various other interlock protection.