Some problems that should be paid attention to correct selection of pneumatic valve electric device (3)

programming pneumatic valve electric actuator, pneumatic valve, automatic control and remote control device is indispensable, its journey, the torque or the size of the axial thrust to control movement. Because of the characteristic of the pneumatic valve electric device and used depends on the pneumatic valve, pneumatic valve pipe fittings and the specification of the work or equipment in pipe, therefore, correct selection of pneumatic valve electric device, in order to prevent overload, Job site types of transfer torque control torque ratio, higher) Is indispensable. Normally, correct selection of pneumatic valve electric device, based on the following:
operating torque operating torque is to choose the main parameters of pneumatic valve electric actuator, electric actuator output torque should be pneumatic valve operation. To. Times the maximum torque.
the main thrust of pneumatic valve electric device structure, has two kinds: one kind is not configured thrust plate, direct output torque; Another is configuration thrust plate through the thrust plate of pneumatic stem nut can be converted into output torque output thrust.
output shaft speed pneumatic valve electric actuator output shaft speed and the number of nominal diameter of the stem thread pitch, some threads on the first calculated according to (M = H/ZS M for electric devices should satisfy to the total number of rotating, H is height of pneumatic valve opens, S for pneumatic valve stem drive screw pitch, Z for pneumatic valve stem thread) 。
stem diameter level of multi-turn pneumatic valve in the next shot, if allow maximum electric actuator pneumatic valve stem diameter can't through assemble electric pneumatic valve pneumatic valve stem. Therefore, the internal electrical equipment must be greater than stem diameter hollow output shaft pneumatic valve pneumatic valve stem diameter. For rotary pneumatic valve and pneumatic valve multi-turn non-rising stem part of pneumatic valves, although not consider thick stems, but also should give full consideration to supporting, stem diameter and keyway size, enables the assembly work.
output speed pneumatic valve opening and closing speed, if too fast, easy to produce water hammer. Therefore, according to the different situation of use, select the appropriate opening and closing speed.
pneumatic valve electric device have special requirements, must be able to limit torque and axial force. Limited torque coupling usually pneumatic valve actuator. Specification is determined, when electrical equipment, control torque is determined. Generally run at a predetermined time, motor overload. However, if the following conditions may lead to overload: one is the low voltage power supply and does not require the torque, the motor stop running, the second is wrong, it is set torque limit agencies to stop torque is greater than that of continuous production caused by excessive torque, the motor stop running; Third, continuous use, the heat generated by the more than the allowed temperature of the motor more savings; Four, for some reason, the torque limiter circuit fault, the torque is too large; Fifth, the environment temperature is too high, in the motor heat capacity relative decline.
in the past, the method is to use fuse protection motor, overcurrent relay, thermal relay, thermostat, etc. , but these methods have advantages and disadvantages. The change of this kind of equipment of electrical equipment load, absolute protection method is reliable. Therefore, we must take all kinds of combination can be summed up in two aspects: first, to increase or reduce the motor input current judgment; The motor itself, the second heat, to judge the situation. The two, whether the motor heat capacity must consider the given time allowance.
normally, basic overload protection method is: continuous operation of mobile operation or overload protection of motor, and the operation of the thermostat, motor stalling protection, thermal relay; Short circuit, the fuse or over-current purposes the use of electrical appliances.
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