How to achieve reduced voltage starting with soft starter
Soft starters achieve reduced voltage starting by controlling the starting current and starting torque of the motor, thereby avoiding the excessive current shock during traditional direct starting and protecting the motor and power grid equipment. The reduced voltage starting principle of soft starters mainly includes the following aspects:
Phase voltage control: The soft starter gradually adjusts the motor phase voltage to reduce the voltage when the motor starts. Traditional direct starting connects the motor directly to the power grid, at which time the current and torque will be very large. Soft starters usually use semiconductor devices (such as silicon-controlled rectifiers SCR) to control the voltage. The motor is started at a lower voltage at first, and then the voltage is gradually increased as the motor speed increases until the motor reaches the rated speed.
Gradual start: The soft starter realizes a smooth rise in voltage instead of instantaneously applying full voltage. This gradual start can not only reduce the starting current, but also avoid excessive mechanical shock and reduce the wear of the motor and drive system.
Control the starting torque: By controlling the voltage, the soft starter also controls the starting torque of the motor and reduces the mechanical shock during starting. This is especially important for motors with heavy loads.
Regulation method:
Linear boost: The voltage increases gradually in a linear manner within a certain period of time.
Ramp boost: The voltage increases gradually at a preset slope.
Constant time boost: The voltage gradually increases to the rated value within a set time.
The advantages of soft starters include reducing the current impact of the power grid, increasing the service life of motors and equipment, reducing the loss of electrical equipment, and generating less impact on the mechanical structure during the startup process.