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.