I was controlling pneumatic valve for feed water flow of boiler through UDC 6302 (Honeywell)by using its current output signal (4- 20mA). Now i want to control motorized valve through this controller, can anyone tell how can i do it? What kind of software changes i have to make and which output i have to use for the controlling of MCC of motorized valve.

Its rerally urgent ....

thanking u in anticipation.

 

Farooq, Why would you want to do this for a boiler feedwater control loop? Pneumatic control valves work very fast and arrive at their desired position quickly. If you want to use an electric motor operated valve, it will always be much slower. Inserting the lag of a motor operated valve will make the loop less responsive and may introduce instability to the control loop.

Often motor operated dampers are used on power boilers for air handling. Here the dynamic conditions are different from flow control and the speed of the damper movement is not as critical as in flow control. In damper control, the damper position is often measured and the position controlled with a bidirectional ON/OFF controller. You could do this for the feedwater valve with position feedback. In that case, you would cascade the flow controller output to the setpoint of the ON/OFF controller. But...I would not recommend this.

Dick Caro
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what type of control signal does the new motorized control valve want to see

 

If you must use a motorised valve for this application. Most valve controllers still maintain a 4 to 20mAmp control function.

regards

 

There are 2 types of el. Motor actuators:

1.st type accepts a 4-20 mA signal, so the controller can remain same, but some additional Controller parameters shall be changed (due to slower response of the motorized valve). One of parameters is the time of travel of the valve from closed to fully opened. Check the UDC 6302 manual.

2.nd type accepts 2 contacts

first contact activated - open direction
second contact activated -closed direction
neighter activated - valve stop
both activated -error

This type of controller is a standard as well - check in Honeywell manual

So all depends on what type of valve actuator you will get (with 4-20 mA input or without)

regards,

INENCO doo

H. Zelenka