Rated voltage:
Usually 3-phase AC 380V (50Hz) or AC 480V/600V (60Hz), which is the most common industrial voltage level. There are also cabinets suitable for other voltage levels (such as 220V, 690V).
Rated current:
This is the most critical parameter, which determines how much power the soft start cabinet can drive. The range is very wide, ranging from tens of amperes to thousands of amperes (for example, 30A, 75A, 160A, 250A, 400A, 630A, 800A, 1200A, etc.).
Selection basis: It must be greater than or equal to the full-load rated current of the controlled motor, and leave a certain margin (usually selected as 1.1 - 1.3 times the rated current of the motor).
Motor power:
Calculated based on rated voltage and rated current, it is an intuitive indicator for cabinet selection (e.g. 15kW, 30kW, 55kW, 90kW, 160kW, 250kW, 400kW, 630kW, etc.). The power corresponding to the same current is different under different voltages.
Starting method:
Voltage ramp start: The most common. The output voltage starts from the set initial voltage (e.g. 40%-70% rated voltage) and rises linearly to full voltage according to the set time.
Current limit start: Control the starting current not to exceed the set limit value (e.g. 2-5 times the rated current), and the voltage is automatically adjusted to meet the current limit.
Torque control start: Provides a smoother mechanical start, especially suitable for starting with load (such as crushers, compressors).
Pulse jump start: Apply a short high voltage pulse at the moment of starting, and turn to normal ramp start after overcoming static friction.
Intelligent/Adaptive Start: Automatically detect load characteristics and optimize the start curve.
Stop mode:
Free stop: Directly cut off the power supply and the motor stops by inertia.
Soft stop: The output voltage drops linearly to zero according to the set time, so that the motor decelerates and stops smoothly, reducing the "water hammer" effect (pump load) and mechanical shock.
Brake stop: Some soft starters can achieve energy braking or DC braking with a brake unit.
Start time:
Refers to the time required from the start to full pressure. The adjustable range is usually 1 - 60 seconds or wider. It needs to be set according to load inertia and requirements.
Stop time (soft stop):
Refers to the time required for the output voltage to drop from full pressure to zero. The adjustable range is usually 1 - 60 seconds or wider.
Initial starting voltage/torque:
Set the output voltage percentage or torque level at the beginning of the start to overcome static friction.
Current limit value:
Under the current limit starting mode, the maximum allowable starting current multiple (relative to the rated current of the motor) is set.
Control power supply:
Usually AC 220V or AC/DC 24V, used to power the soft starter's own control circuit, the control circuit in the cabinet, indicator lights, relays, etc.

Smooth start, reduced starting current:
Significantly reduce the motor starting current (usually limited to 2-4.5 times the rated current, while direct start can reach 6-8 times or even higher), reduce the impact on the power grid, and avoid voltage sag.
Reduce mechanical shock:
By controlling the smooth rise of torque, reduce the impact stress on the transmission system (gears, belts, couplings) and driven equipment (pumps, fans, compressors, conveyor belts), and extend the life of the equipment.
Soft stop function:
Especially suitable for water pump loads, can effectively eliminate the "water hammer" phenomenon; also suitable for occasions such as conveyor belts and elevators that require smooth stopping.
Complete protection function:
Integrate a variety of motor and line protection to improve system safety and reliability.
Energy saving:
Energy saving during the starting process (compared with star-delta and other starting methods); bypass contactor conduction during operation eliminates thyristor conduction loss.
Multiple optional starting modes:
The most suitable starting mode can be selected according to the load characteristics (fan pump, light load, heavy load) to optimize the starting effect.
Compact structure, easy installation and debugging:
Supplied as a complete set, the internal wiring is complete, and only the power line and motor line need to be connected on site, and the control line can be connected.
Relatively simple maintenance:
The soft starter is bypassed during operation, reducing the loss of core components; the layout of components in the cabinet is clear and easy to repair.
Improved intelligence:
With a communication interface, it is easy to integrate into the automation system to achieve remote monitoring and parameter management.