Control valve
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Everyone, take a look – is this control valve two-wire or four-wire? The DCS output is a passive AI signal
I understand; it’s two lines. The DCS output wasn’t specified, so it should be powered by the circuit. Also, if this is an explosion-proof device, a cable for the valve leading into the explosion-proof enclosure should be added.
It’s all AO and AI along the way; the feedback signals require power from the DCS
This is a pneumatic control valve with a positioner that provides feedback.
This is a pneumatic valve equipped with a positioner. The positioner receives a 4-20MA current signal from the DCS, and its valve position feedback is provided as a 2-wire 4-20MA signal; therefore, an external power supply is required.
The AO signal requires a DCS to supply 24V DC
https://bbs.hcbbs.com/data/attachment/forum/201809/05/102029vtgstepnngza7m1g.jpg The AO signal from DCS is located in the upper left corner; it is a signal sent by the controllers in DCS； In the lower left is the AI signal sent to the DCS, which is the valve position signal ； In the upper right is the DI signal sent to the DCS, which is the high-limit switch signal for the valve position ； In the lower right is the DI signal sent to the DCS, which is the valve position low-limit switch signal.
It’s all sensible people; they agree with what was said above
Everyone answered very clearly; just passing by
DCS provides AI points; is external power supply required?