Calibration of electric valves equipped with multi-turn electric actuators

Thread Content

Multi-turn electric actuators are powered by AC380V three-phase alternating current (or AC220V single-phase alternating current); a three-phase (or single-phase) motor is used to drive gears or worm gears, which in turn move the valve stem to open or close the valve. Most multi-turn electric actuators are equipped with stop valves, gate valves, etc. The actuator contains travel switches and torque switches; when the travel distance or safe torque limit is exceeded, the power supply to the motor is cut off to prevent damage to the valve. This article shares the methods and steps for calibrating electric valves equipped with multi-turn electric actuators. http://yunrun.com.cn/upload/201712/24/201712241851077956.png yunrun.com.cn/tech/1677.html 1. Adjustment of the torque control mechanism for multi-turn electric actuators: ① Follow the torque characteristic curve provided with the multi-turn electric actuator, starting from a low torque value and gradually increasing the torque in the closing direction until the valve is fully closed. ②The opening torque is adjusted according to the operating characteristics of the electric valve equipped with a multi-turn electric actuator; generally, the opening torque is greater than the closing torque. ③Both the open-direction torque adjustment and the close-direction torque adjustment are carried out under conditions of no load and no medium present. When there is pressure or temperature due to the presence of a medium, it is necessary to check whether the multi-turn electric actuated valve can close properly; if it cannot close tightly, the torque value for the close direction of the multi-turn electric actuator should be increased appropriately to ensure that it can close and open properly. 2. Adjustment of the travel control mechanism for multi-turn electric actuators ① Adjustment of the closing travel for multi-turn electric actuators: Manually close the electric valve equipped with a multi-turn electric actuator completely, turn it half a turn, then release the travel switch and adjustment lock device that controls the valve’s closing direction. Rotate the cam in the direction indicated by the arrows until the valve is fully closed; at that point, the closing travel switch should activate. Secure the travel switch and adjustment lock device. Open the electric valve equipped with the multi-turn electric actuator a few turns before attempting to close it again, and check whether the activation of the closing travel switch occurs at the exact moment when the valve reaches its fully closed position. If it does not meet the requirements, it can be adjusted again following the above procedure. ②Adjustment of the opening stroke for electric actuators with multiple rotations: After adjusting the closing stroke, open the electric valve equipped with such an actuator to its full open position, turn it half a turn, release the stroke switch and its locking mechanism. Rotate the cam in the direction indicated by the arrows until the opening stroke switch activates properly; then tighten the stroke switch and its locking mechanism. Close the electric valve equipped with the actuator several times before attempting to open it again, and check whether the activation of the opening stroke switch corresponds to the valve being fully opened. If it does not meet the requirements, it can be adjusted again following the above procedure. 3. Live commissioning of electric valves equipped with multi-turn electric actuators ① For the commissioning of split-type electric valves, perform a test operation before enabling electric operation; first supply only the control power to check whether the control circuit is reliable. Reconnect the power to the main circuit and check the phase sequence in jog mode to confirm that the operation of the electric valve switch matches the actual direction in which the valve opens and closes. ②Phase sequence checking must also be performed on integral multi-turn electric actuator electric valves that do not have a phase detection function, or those that have such a function but are unable to perform automatic phase detection. ③For integrated intelligent valves, the relevant parameters are set according to actual needs. It specifies the rotation direction (clockwise or counterclockwise) for closing the electric valve driven by a multi-turn electric actuator, the method of stopping the stroke (at the end of the stroke or when a certain torque is reached), the value of the switching torque, as well as the selection of the output functions and states of each relay contact (normally closed or normally open). This enables confirmation that the switching stroke has reached the desired position based on the actual opening and closing position of the electric valve driven by the multi-turn electric actuator. 4. Joint commissioning test of electric valves equipped with multi-turn electric actuators: ① Operate the valve under maintenance via the CRT screen in the control room; the valve’s movement direction should be consistent with the commanded direction, and the feedback should be accurate. In the event of a malfunction, go to the on-site electric valve and distribution box to inspect and address it. ②For electric valves equipped with multi-turn electric actuators that have special requirements, such as interlocked opening or interlocked closing, when the interlock conditions are not met, the relevant departments should cooperate with the operators to set the conditions within the DCS, and then carry out tests for interlocked opening and interlocked closing until the electric valve operates accurately. 5. After the adjustment of electric valves is completed, clean up the site and restore the system: ① For electric valves equipped with multi-turn electric actuators, the area around the valves, as well as the equipment inside the distribution box and intermediate cabinets, should be cleaned thoroughly so that the equipment shows its original color; any paint that has worn off should be repainted. The labels on the equipment at the site must be clear and correct. ②The wiring label numbers on the measurement circuit are clear and complete; the wiring is proper and neat, and there is no looseness when the wires are gently pulled. The inlet and outlet connections have been sealed off. ③The original power supply circuit has been restored; the power switch on the Heshan panel is in operation, and the valve status displayed in the DCS matches the actual condition.