No Ouput From My Eurotherm Controller

> PV - Pressure transmitter input (0-5 bar), 4-20mA (i/p to controller)

The controller has an electronic analog input for its PV.

An I/P has a pneumatic output signal.

How does the controller read a pneumatic signal?

On applications that require accurate valve position feedback there is either an on-board valve position monitor included internal to the valve positioner or there is an external valve positioner monitor assembly (optional) that mounts directly on the valve body that has an arm which moves with the valve stem to provide feedback. This device must be physically calibrated to match the valve position to the feedback signal level and polarity.

The only other way to report/display valve position without direct mounted monitoring feedback is to set up a table in the PLC or controller that plots/uses output signal level values in proportional to the valve position from 0 to 100% open. This would be a calculated valve position value which in no way can be accurate due to system dynamics but will work in applications where accuracy is not required. This type of control is often used on domestic heating furnaces which also require fail-safe protective equipment on the burner controls such as timed a flame detector monitor and CO sensors so that valve failure does not violate the integrity and safety of the system.

I was simulating the signals in the lab. I used current injectors to simulate PV and remote setpoint and multimeters to read the 4-20mA outputs. I wired up all these to the controller terminals.

Thanks a lot for helping out. I find you guys very helpful.

Please advise the forum what the outcome of the telephone call to Eurotherm was. What were the recommendations forthcoming from that discussion, and what was the result of trying them all?

Are you able to manually vary the output (to check the functionality of the module)?

Yeah, it worked in the end. See my general response.

Thanks a lot.

Earth to divine; Earth to divine; come in, please!

Hello All and please forgive me for not updating you early enough.

I have taken time to read through the replies and I have learnt a lot from them.

So the problem was with the gain/proportional band setting.

The gain is 40%/bar. This corresponds to 2.5 PB in Engineering units or 50% PB. The controller only has functionality to set the gain in PB and I had incorrectly set it as 2.5 %, instead of 2.5 enginering units.

The response is fine now. I see that it takes roughly 5 minutes (same value as IAT) for the values to go from fully shut to fully open.

Learning point: It is worth checking each controller to see how each defines their parameters. While one uses gain, another might use PB in Engineering Units or as a percentage.

Thanks once again guys.

I got the email. Thanks a lot. You guys are very good here.

Sorry for my late response. The issue appears to have been resolved. Next is to do the the real testing suring SAT.