Electric actuators are mainly divided into DKJ or DKZ type, integral type, multi-turn type, permanent magnet low-speed synchronous motor type and digital type.
1.DKJ or DKZ electric actuator
DKJ electric actuator is the execution unit of DDZ electric unit combination meter. It receives the control signal of the upper instrument and automatically completes the adjustment task. It is widely used in power station, chemical industry, petroleum, metallurgy, building materials, water treatment and heating. , light industry and other industries. The DKJ electric actuator, coupled with the corresponding electric operator, completes the “manual-automatic” bumpless switching of the adjustment system and remote manual operation.
The DKZ linear actuator is a new technology developed by the "S" electric actuator: a WF-S position transmitter consisting of a precision conductive plastic potentiometer and a national integrated circuit. Therefore, the electric actuator not only greatly improves the reliability, accuracy, load capacity, signal quality coefficient and other performances than the original product, but also broadens the environmental conditions, which is of great significance.
2. Integral electric actuator
The simplest electric actuator consists of only a capacitive phase-separating circuit. There is no preamplifier, and the motor is controlled directly by the action of the switch.
3. Roll-cut motor type electric actuator
A servo motor based on a common asynchronous motor has a high speed and a small torque, so a complicated reducer has to be used in the actuator.
4. Multi-turn electric actuator
Multi-turn electric electric actuator output shaft movement mode is rotary type, and the full stroke exceeds 360 degrees, suitable for controlled objects such as gate valve and globe valve. Multi-turn electric actuator is special, it can be equipped with one-stage reducer. Converted into a quarter-turn electric actuator or a straight-stroke electric actuator, even if it is still multi-rotating, after adding a first-stage deceleration, the output force (moment) increases and the movement speed slows down.
5. Permanent magnet low speed synchronous motor actuator
The actuator consisting of a permanent magnet low-speed synchronous motor takes the domestic ZDAS type stroke actuator as an example, and its output thrust is 400~2500N, the stroke is 10~40mm, and the speed is 0.75~1.25mm/s. The domestic SKZ type actuator is also composed of a permanent magnet low speed synchronous motor.
6. Digital electric actuator
In order to directly cooperate with the computer, a digital electric actuator has recently appeared, the input signal of which is a pulse type, and the servo motor type is a stepping motor driven by a pulse. Although the output angle of the stepping motor has a strict proportional relationship with the number of input pulses, the number of pulses may be wrong due to interference, so the actuator still needs to have a position feedback signal, which is usually sent back in the form of a standard signal of DC 4~20mA. The computer, after A/D conversion, is compared with the set valve position to form a closed loop to ensure that the valve position has the correct opening.