How to control the accuracy of electric actuator

Electric actuator is a kind of control equipment widely used by people nowadays. It has three types: straight stroke, angular stroke and multi rotation. The angle stroke electric actuator takes the motor as the power component, and converts the input DC current signal into the corresponding angular displacement (0-90 degrees). This actuator is suitable for operating rotary control valves such as butterfly valves and baffles.

 

After receiving the input DC current signal, the straight stroke actuator makes the motor rotate, and then decelerates by the reducer and converts it into linear displacement output to operate various control valves such as single seat, double seat, tee and other linear control mechanisms. Multi turn electric actuator is mainly used to open and close gate valve, globe valve and other multi rotary valves.

 

Because of its large motor power, the larger one is dozens of kilowatts, which is usually used for local control and remote control. These three types of actuators are position servo mechanisms driven by two-phase AC motor. The electrical principle of the three types of actuators is identical, but the reducer is different.

 

Matters needing attention when controlling the precision of electric actuator:

 

1. Firstly, find out the vibration source. For the oscillation induced by the outside, keep the control valve away from the vibration source; eliminate or weaken the oscillation intensity of the vibration source; and use the method of increasing fulcrum to weaken the vibration of the control valve when it is considered appropriate. For the oscillation caused by the inner medium flow, the resistance of the control valve should be reduced as much as possible.

A bypass pipe can be added in case of adjustment of things permitted by experience. For rapid response control system, special logarithmic valve spool can be selected. The butterfly valve shall try its best to work in the range of 10 ~ 70 ° to avoid the effective force alternating point of the medium to the valve body.

 

2. The electric actuator brake does not work. The brake is used to eliminate the influence of inertia idling of rotor and output shaft after power failure of electric actuator and the influence of load reaction force torque, so that the output shaft can stop at the corresponding position correctly. If the brake does not work, the control precision of the electric actuator will be reduced. Because this should do the following.

 

(1) Adjust the braking torque according to the load volume;

 

(2) The gap between brake wheel and brake disc should be adjusted properly;

 

(3) Sufficient friction coefficient shall be ensured for brake shoe, and it is forbidden to drip oil (when adding lubricating oil, do not exceed the larger limit position of oil mark).

 

3. The output of electric actuator is backward. The main backward link lies in the connection between the output shaft of the angular stroke electric actuator and the regulating mechanism. Because of this, all connecting rods and levers should not have looseness or clearance during installation. Try to use special coupling to replace linkage. The pressure control system of coke oven collector in our plant is considered appropriate and a special coupling is used, and the effect is satisfactory.