T diamond in SAMA diagram ?

[ozmongoose]

Hi all,

Need your explanation about the T (Transfer) in the diamond in SAMA diagram. What is the physical meaning ? Why is it always placed in between PID controller output and actuator ?

Thanks a lot

Mongoose

 

[itsmoked]

It usually means a transfer between two control curves or two modes like automatic and manual.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[JLSeagull]

I have not seen SAMA diagrams in a very long time. However the Transfer is normally depicted for the auto/manual and perhaps other modes such as cascade.

A PID algorithm includes an automatic/manual selector in almost all applications. The rare exceptions might include compressor surge control, etc.

 

[ozmongoose]

Thank you all,

But it is still unclear to me since the description in the SAMA standard says that this is the symbol of a automatic/manual transfer switch. Could some one explain more in details? What is the difference and what happens when we put a T in rectangle (means automatically executed) instead of the T in the diamond, in an example SAMA diagram with 1 PID connected to an actuator (control valve).

Thank you

 

[rajant2001]

T within the Dimond is Manual Transfer Switch. Normally it can receive to INput (Analog) Signals, one may be from a PID Controller and other may be from an another controller or a computing relay or Manual loader. The output shall be connected to final control element or yet another control componet. The transfer shall be done manually depending on the processs requirement.

R.Thiyagarajan.

 

[ScottyUK]

This site might be of interest. I have skimmed some of the documents in the past. We use a lot of SAMA symbology in the paper representation of our turbine control logic.


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Sometimes I only open my mouth to swap feet...

 

[itsmoked]

The invisible site.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ScottyUK]

Dammit!

http://www.measure.org/ReferenceDocs.htm