Usually by the electric control valve electric actuator servo amplifier. Acting servo amplifier is an input signal from the controller, by the magnetic circuit to control and trigger thyristor switches to control power supply drive actuator servo motor.
When the servo amplifier input is zero, the amplifier output is zero, the servo motor does not rotate the output shaft in the original stable position, the position feedback signal transmitter is also zero. When the servo amplifier has an input ISR, the electric control valve and its polar opposite position feedback signal If to compare the pre-magnetic amplifier, since there is a difference, there is a magnetic force generator. This current generated magnetic potential trigger thyristor, servo motor drive the actuator rotates in the direction of decreasing magnetic potential. When position feedback signal equal to the input signal If another ISR, and magnetic potential is zero. Stabilize the output shaft of the input signal corresponding to the angular position. Relationship between the output shaft rotation angle θ of the input signal ISR is θ = KISR. Usually at the end of the servo motor equipped with an electromagnetic brake, when the motor was switched on, the brake disc and motor shaft from the motor can rotate. When the motor is off, the disc brake locking the motor shaft, the shaft can be stopped with a load in a certain position.