1. Operating torque
Operating torque is the most important parameter for selecting the valve electric device. The output torque of the electric device should be 1.2 to 1.5 times the maximum torque of the valve operation.
The main structure of the valve electric device has two types: one is to directly output torque without a thrust disk; the other is to configure a thrust disk, and the output torque is converted to output thrust through the valve stem nut in the thrust disk.
3.Number of rotations of output shaft
The number of rotations of the output shaft of the valve electric device is related to the nominal diameter of the valve, the pitch of the valve stem, and the number of screw heads. Opening height, s is the thread pitch of the stem transmission thread, z is the number of stem thread heads).
For multi-turn type bright stem valves, if the maximum valve rod diameter allowed by the electric device cannot pass through the valve stem of the valve, the electric valve cannot be assembled. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the stem of the bright stem valve. For the part of the rotary valve and the multi-turn valve of the dark-stem valve, although the passage of the stem diameter need not be taken into consideration, the diameter of the stem and the size of the keyway should be fully taken into consideration when matching, so that it can work normally after assembly.
If the opening and closing speed of the valve is too fast, water hammer may easily occur. Therefore, the appropriate opening and closing speed should be selected according to different use conditions. Valve electric devices have special requirements, that is, they must be able to limit torque or axial force. Valve electric devices usually use couplings that limit torque. When the size of the electric device is determined, its control torque is also determined.
The motor is generally operated within a predetermined time, and the motor will not be overloaded. However, the following conditions may cause overload: First, the power supply voltage is low, the required torque cannot be obtained, and the motor stops rotating; second, the torque limit mechanism is incorrectly adjusted to make it larger than the stopped torque, Causes continuous excessive torque to stop the motor. Third, intermittent use, the heat generated exceeds the allowable temperature rise of the motor; fourth, the torque limiter circuit malfunctions for some reason, causing the torque to be excessive. Large; Fifth, the use of ambient temperature is too high, which relatively reduces the motor's thermal capacity.