Replace the pneumatic control valve with an electric control valve
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In the workshop, there is one that has been converted from a pneumatic control valve to an electric one; a motor is installed inside the pneumatic positioner. Please see the figure below. Now, 4-20 ma signals are available, and they are normal. The one on the far right is 4-20ma, with a voltage of 5-10v. Are those the three wires coming from the motor in the second picture? I hope the teachers can give me some guidance!
Are the three wires inside these the output wires of the motor? :lol
This is the circuit board inside; I hope fellow board enthusiasts can give me some advice!
You mean changing it from pneumatic to electric/pneumatic, installing a motor?
This one must have been a pneumatic positioner before, and it has been changed to an electric positioner. The locator also doesn’t have a motor; instead, it has coils. It is also used in conjunction with a pilot valve.
This locator has feedback, right? That component inside is probably the feedback sensor.
I thought this was a motor; I didn’t know. Then a member below said it was a coil.
There is feedback; I’m not sure right now whether it’s from the sensor or the coil, but based on the hints given, it seems that coils combined with pilot valves are more common. Do you know the principle? Bro
The problem now is that 4-20ma is available, but the corresponding voltage is 5-10v. I don’t understand this – why isn’t it 0-10V? Another issue is that the signal sent from the DCS now doesn’t cause the valve to move at all. I would like to ask the experts here!
The wiring isn’t connected correctly, is it? Why are 3 wires connected? Logically, 2 wires are needed for the 4-20mA input, and 2 wires for feedback if feedback is required.
I removed that wire to measure the current. The wire is fine; it worked before