Cannot get output from my Eurotherm controller
Cannot get output from my Eurotherm controller
(OP)
I am using a Eurotherm 3504 controller to controll a valve based on input pressure.
See details:
PV – Pressure transmitter input (0-5 bar), 4-20mA (i/p to controller)
Module 1 – Remote setpoint (0-5 bar), 4-20mA (i/p to controller)
Module 2 – Analogue output of valve actuators position to control room (0-100%), 4-20mA (o/p from controller)
Module 3- Analogue output to valve actuators (0-100%), 4-20mA (o/p from controller).
---Proportional action with gain of 40%/bar
(I interprete this to mean ...a 1 bar change in pressure results in 40% valve movement when proportional acts on its own. This gives a gain of 2 and PB of 50% I believe).
---Integral action time – 300 secs
---No derivate
Problem: I do not get any response in the output. Modules 2&3 are both reading their lowest vales – 4mA as output, which corresponds to 0% open in the actuators.
I am using a set point of 2.5 bar (midway of the 0-5bar pressure transmitter scale). When I vary the i/p current I am using to simulate the PV, (4-20mA), I do not get get any output in the valves.
Have I got my interpretation of the PB wrong?
I wish I could post screen captures here.
See details:
PV – Pressure transmitter input (0-5 bar), 4-20mA (i/p to controller)
Module 1 – Remote setpoint (0-5 bar), 4-20mA (i/p to controller)
Module 2 – Analogue output of valve actuators position to control room (0-100%), 4-20mA (o/p from controller)
Module 3- Analogue output to valve actuators (0-100%), 4-20mA (o/p from controller).
---Proportional action with gain of 40%/bar
(I interprete this to mean ...a 1 bar change in pressure results in 40% valve movement when proportional acts on its own. This gives a gain of 2 and PB of 50% I believe).
---Integral action time – 300 secs
---No derivate
Problem: I do not get any response in the output. Modules 2&3 are both reading their lowest vales – 4mA as output, which corresponds to 0% open in the actuators.
I am using a set point of 2.5 bar (midway of the 0-5bar pressure transmitter scale). When I vary the i/p current I am using to simulate the PV, (4-20mA), I do not get get any output in the valves.
Have I got my interpretation of the PB wrong?
I wish I could post screen captures here.





RE: Cannot get output from my Eurotherm controller
You can; the button below does that
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
[IMG http://tinyurl.com/7ofakss]
Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers
Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com: http://www.engineering.com/AskForum/aff/32.aspx
RE: Cannot get output from my Eurotherm controller
Is the existing control action reverse or direct? Have you tried changing to the opposite control action?
RE: Cannot get output from my Eurotherm controller
Hello,
I have been able to get the valves to move, thanks to the explanation below
-----------------------------------------------------------------------------------------------------------
Proportional Band: The amount of change in the controlled variable, expressed in engineering units, required to move the actuator from one end of its stroke to the other.
%PB: Percent proportional band is the proportional band expressed as a percentage of the sensor span.
-----------------------------------------------------------------------------------------------------------
I had previously set the PB as 2.5%, instead of 2.5 eng units.
All is fine now.
Thanks a lot.