| 摘要 |
A valve system includes a valve and a controller that controls the valve. The valve includes a valve body, and a motor configured to deliver a torque to the valve body to cause the valve body to move between an open position and a closed position. The controller is configured to drive the motor by applying a current to the motor. The controller is configured to measure the torque delivered by the motor to the valve body, compare the calculated torque with a threshold value, and diagnose a need by the valve system for preventive maintenance when the calculated torque is substantially equal to the threshold value. The threshold value represents substantially the maximum amount of torque available from the stepper motor.
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