Problems with the control circuit of electric control valves
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Want to control the pump outlet pressure: when the pressure is high, the bypass flow increases； When the pressure is low, the bypass is opened partially or closed. I want to use a pressure sensor to measure pressure signals, in order to control the opening degree of the bypass valve. What is the simplest control loop? What components are needed? Can the signal from a pressure sensor directly control the degree to which a valve opens and closes?
This post was last edited by liuei on 2010-4-13 09:46. Simple control can be achieved by installing a safety pressure valve. Many hydraulic pumps use this method to control the outlet pressure!
Using a control valve + valve positioner can achieve this function. Pressure transmission and control of valve opening can be achieved through the DCS system
It is entirely possible to adjust the pressure at the pump outlet. Install control valves on the bypass pipeline, and add pressure measurement points at appropriate locations on the outlet pipeline. A short program written using a PLC or DCS can be used to control the pump outlet pressure. If programming proves difficult, with the outlet pressure point remaining unchanged, an electric or start valve can be installed in bypass, along with a secondary meter (with contact output), and two relays – this will enable meeting the control requirements. The former simply has higher control precision, while the latter is conventional control and is somewhat inferior.
4# Steel flowers are flying; there is no DCS or other control system on site. I just want to implement the function of pressure measurement-----flow control on-site. What are the basic configurations required to implement this function? The simpler, the better.
Now DCS is used everywhere; in the past it was possible to get by without DCS as well – just use block panels to install some field controllers
6# dys-zwy: I don’t know how to use a block disk for installation What control components need to be added inside?
Some relays will do the trick
Just buy a PID controller, an electric control valve, and a pressure transducer – these three components make up a standard single-loop control system
It seems that the signal from a pressure transmitter cannot be connected directly to a control valve; a PID controller or a DCS/PLC system is required for regulation.
The signal from the pressure transmitter is connected directly to the control valve, resulting in a pure proportional control system!