May I ask if one AO signal can control 2 electric valves? Thank you all
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In the plant’s HVAC system, the design called for only one electric valve per air duct; however, due to the long length of the air ducts, there are now two electric valves on each side of the equipment. This may result in a shortage of control points in the system (for the ECS700). These valves do not require automatic control and are used for manual operation. Is it possible to have one AO channel controlling two actuators? Indicate the opening degree on the screen; when both valves operate simultaneously, will the output be consistent? Thank you all
Two solenoid valves can be controlled using a relay.
It depends on the total impedance of your external circuit. I remember that with a 700 AO, if the external impedance exceeds 750 ohms, it won’t be able to drive it.
First, make sure your idea is feasible – adding a two-part safety barrier (P+F/MTL) will do the trick. But we have seen this method used before. Normally, it is a one-to-one channel relationship. It doesn’t seem to meet the standards. It's just my personal opinion.
It’s not a solenoid valve, but an electric valve controlled by 4-20mA
Normally, 1 point is spent on AI features; I’ve never used AO either
Could the moderator provide information on the relationship between impedance and circuit control? I’m not very familiar with this area
It should be able to drive two electric valves; the power for these valves does not come from the 4-20mA signal, as they have their own power supply, with 4-20mA serving merely as a control signal.
Using a 1-in-2-out safety barrier is the best method
Check the coil specifications of the electric valve on site; under normal circumstances, one digital signal can control two cut-off valve devices that perform the same function. That’s exactly what I do