Pneumatic valve electric actuator selection method

usually, correct selection of the basis of a pneumatic valve electric actuator are as follows:
. Operating torque operating torque is to select the main parameters of the pneumatic valve electric actuator, electric actuator output torque should be maximum torque of pneumatic valve operation. ~。 Times.
　　. Operating thrust host structure of the pneumatic valve electric device has two kinds: one kind is not configured thrust plate, direct output torque; The other is a configuration thrust plate, the output torque by thrust plate pneumatic stem nut into output thrust.
　　. Output shaft rotate laps pneumatic valve electric device output shaft circle the number of how many and the nominal size of the pneumatic valve, pneumatic valve stem thread pitch, thread, according to M = H/ZS computing ( M for electric devices should satisfy the total number of rotating ring, H is height of pneumatic valve opens, S for pneumatic valve stem drive screw pitch, Z for pneumatic valve stem thread) 。
　　. Pneumatic valve stem diameter for multi-turn type pneumatic valve stem, if electric device allows the largest pneumatic valve stem diameter can't through the pneumatic valve pneumatic valve stem, cannot assemble into electric pneumatic valve. As a result, the inner diameter of the hollow output shaft electric actuator pneumatic valve pneumatic valve lever must be greater than stem diameter. For part of rotary pneumatic valve and multi-turn non-rising stem of the pneumatic valve pneumatic valve, pneumatic valve stem diameter is not considered through the problem, but also should fully consider when selecting pneumatic valve stem diameter and the size of the keyway, after assembly to work properly.
　　. If output rotation speed of pneumatic valve opening and closing speed too fast, easy to produce water hammer. Therefore, should be used according to different conditions, choosing the proper opening and closing speed.
　　. Pneumatic valve electric actuator has its special requirements, which must be able to limit torque and axial force. Pneumatic valve electric device adopts usually limiting torque shafts. When the electric actuator specifications was determined, the control torque is determined. Generally run in a predetermined time, the motor will not overload. But as the following conditions may lead to overload: one is the low voltage power supply and can not get the required torque, the motor stop running; 2 it is wrong to set torque limit, make its torque is greater than the stop, cause continuously produce too large torque, the motor stop running; 3 it is intermittent use, the heat generated by the savings, more than the allowed temperature of the motor to appreciate; Four is a torque limit institutions circuit for some reason fails, the torque is too large; Five is the use of the environment temperature is too high, the relatively decreased motor heat capacity.
in the past for motor protection method is to use a fuse, overcurrent relay, thermal relay, thermostat, etc. , but these methods all have advantages and disadvantages. For this kind of variable load equipment, electric device is not absolutely reliable measures for the protection of. So we must take various combinations, induces has two kinds: one is the increase or decrease of the motor input current judgment; The second is the motor itself heating situations. These two approaches, both the heat capacity of the given time allowance to consider motor.
usually, on the basis of the overload protection method is:
. Continuous operation of motor or inching operation over load protection, using a thermostat;
　　 . The protection of motor blocked, the thermal relay;
　　 . For short circuit accident, adopt the fuse or over-current relay.
pneumatic valve electric actuator is the realization of program-controlled pneumatic valve, automatic control and remote control of the indispensable equipment, its movement process can by travel, torque, or to control the size of the axial thrust. Correct selection of pneumatic valve electric device, to prevent overload phenomenon, Work torque is higher than the control torque) Is of crucial importance.