AME85 Danfoss electric actuator

Danfoss AME55 AME85Structural principle:

Taking the integral proportional adjustment type of MD series electric actuators as an example.

Danfoss AME55 AME85The position servo mechanism, driven by an AC servo motor, receives a 4-20mA DC control signal from the adjustment system through the PM-2 control board and compares it with the position feedback signal from the position transmitter. The deviation of the compared signal is amplified to conduct the power stage, and the output component of the motor rotation drive actuator moves in the direction of reducing this deviation (the position transmitter continuously converts the actual position of the output component into an electrical signal - the position interference feedback signal is sent to the position transmitter), until the deviation signal is less than the set value. At this point, the output component of the actuator stabilizes at the position corresponding to the input signal.

Danfoss AME55 AME85Predictive maintenance:

Operators can use the built-in data storage to record the data measured by the torque sensing device during each action of the valve. This data can be used to monitor the operation status of the valve, prompt whether the valve needs maintenance, and diagnose the valve.

The following data can be diagnosed for valves:

1. Friction force of valve sealing or packing

2. Friction torque of valve stem and valve bearing

3. Friction force of valve seat

4. Friction during valve operation

5. The dynamic force acting on the valve core

6. Friction force of valve stem thread

7. Valve stem position

Most of the above data exists for all types of valves, but the emphasis is different. For example, for butterfly valves, the frictional force during valve operation can be ignored, but for plug valves, this force value is very large. Different valves have different torque operating curves. For example, for wedge valves, the opening and closing torques are very large, while during other strokes, only the friction force of the packing and thread is present. When closing, the hydrostatic pressure acts on the gate plate, increasing the friction force of the valve seat. The ultimate wedge effect causes the torque to rapidly increase until it is fully closed. So, based on the changes in the torque curve, it is possible to predict the faults that will occur, which can provide valuable information for predictive maintenance.