PID two-way direction and without Integral Function

Hello,

In a HVAC I need to order 2 analog valves, hot and cold water. I only need the P function from 1 only Compact_PID. But when I put the "r_Ctrl_Ti" to “0” then the output is never going higher (the manual says the with Ti tto “0” the “I” function is disabled but it seems not correct..) .

Also is it possible to work with only 1 Controller with an output 0-50-100%. I mean wenn PV=SP the output is 50%. When the PV goes down, then also the output from goes 50 to 0%. Wenn the PV goes up then the output from 50 to 100%.

Thanks and best regards

Tomske

Hello,

In a HVAC I need to order 2 analog valves, hot and cold water. I only need the P function from 1 only Compact_PID. But when I put the "r_Ctrl_Ti" to “0” then the output is never going higher (the manual says the with Ti tto “0” the “I” function is disabled but it seems not correct..) .

Also is it possible to work with only 1 Controller with an output 0-50-100%. I mean wenn PV=SP the output is 50%. When the PV goes down, then also the output from goes 50 to 0%. Wenn the PV goes up then the output from 50 to 100%.

Thanks and best regards

Thanks Hamid !

I’m now using two PI controllers: one for the hot water valve with normal output direction and another PI-Controller for the cold water valve with inverted output. Then I make two comparators and some additions. When both PI-Controllers are zero (=0% for the warm water and then 100% for the cold water) that’s make then 50%. It is working but I have a conjecture that it is not so nice…

Kind regards and best wishes.

Tomske

Thanks Hamid !

I’m now using two PI controllers: one for the hot water valve with normal output direction and another PI-Controller for the cold water valve with inverted output. Then I make two comparators and some additions. When both PI-Controllers are zero (=0% for the warm water and then 100% for the cold water) that’s make then 50%. It is working but I have a conjecture that it is not so nice…

Kind regards and best wishes.

hdhosseini

2- Link mentioned by FreakOnALeash is suitable for On-OFF
actuators.For analog output on positioner and your requirement
you should use comparators to limit output signal.

Tomske

Hello FreakOnALeash

In the manual I do not see many explications about that analog Output_PER.
The 2 digital outputs brings the valve to closed or opening. But by the analog output and wenn the PV=SP,is the Output_PER than 50% and goes down to 0% with a digital Output_DN and goes up to 100% wenn digital Output_UP ?

Best wishes

Thanks Marco,
It is a proportional system with an analog 4-20mA input. The thing is that on normal or closed position the system needs 50% (normal state=12mA).
The analog output from the PID-regulator must been 50% when the PV is the same to the SP.

Like described above I'm now using two PI-Controller and some additions (one for regulation between 0-50%, and another regulator for between 50-100%. But it seems me not so nice.
Best regards.