It would be cool if somebody could help me out with the following:

I wanted to know the essential characteristics and chief differences between PID Control & Dual PID Control function in micro processor based temperature Controllers

Cheers!

 

Actually this topic is interest me also, i hope there some one could help me ... thx

 

I'm guessing that a dual PID controller can handle two loops simultaneously. It must have two sets of analogue inputs for PV and SP, two sets of outputs for CO, and two sets of registers for tuning parameters. If you have a particular brand of controller in mind you might consult their literature. The phrase "dual PID controller" sounds to me to be something "coined" by a particular manufacturer. Please correct me if I'm wrong ;-)

 

"Dual PID Controller" is a standard PID controller mode not "joined" to a particular manufacturer. A Dual controller is usually used to control Heat-Cool processes, where the "Zero" output position corresponds to 12 mA (50% Controller Output).

In a Proportional 4-20 mA output controller and means that no heat or cool is needed. 4-12 mA (0-49 % Controller Output) inputs COOL to the process. and 12-20 mA (51-100 % Controller Output) inputs HEAT to the process, or vice versa. These controllers need especial control valves/field instruments. Normally the controller provides an automatic method to switch tuning constant sets for Heat/Cool applications.

 

It depends on how the device is marketed.

I have seen the term or a similar term used for either application described above, either
- dual PID loops in one box (Dual AI, dual output, dual PID) or
- heat/cool control
* with split range, dual output; (relay/current; relay/relay) or
* with a single current output, as described above.

There are also single loop controllers that offer two sets of PID settings. The choice of which set to use is selected by various logic schemes.

Caveat Emptor

 

There are many details to the proper installation and configuration of a split-range control scheme.

I have written a short book called "Mastering Split-Range Control". The book covers all aspects of the use of split-range control. Starting with the basics, the book discusses when to use split-range and when not to, costs and benefits, how to configure the control strategy, how to calibrate the valves, how to tune the loops, and even how to train operators and troubleshoot problems. Color pictures illustrate the key concepts.

It is available via Amazon's CreateSpace service at:
https://www.createspace.com/3395995

-George Buckbee, P.E.