A soft starter is any device which controls the acceleration of an electric motor by means of controlling the applied voltage.
In technical terms, a soft starter is any device which reduces the torque applied to the electric motor. It generally consists of solid state devices like thyristors to control the application of supply voltage to the motor. The starter works on the fact that the torque is proportional to the square of the starting current, which in turn is proportional to the applied voltage. Thus the torque and the current can be adjusted by reducing the voltage at the time of starting the motor.
Advantages of Soft Start
- Improved Efficiency:The efficiency of soft starter system using solid state switches is more owing to the low on state voltage.
- Controlled startup: The starting current can be controlled smoothly by easily altering the starting voltage and this ensures smooth starting of the motor without any jerks.
- Controlled acceleration: Motor acceleration is controlled smoothly.
- Low Cost and size: This is ensured with the use of solid state switches.