What does PT1,PT2,PT3 in Control loop means?

Thread Starter

TarikElec

Joined Oct 17, 2019
76
Hello ,
I always hear Germansengineer use the term PT1,PT2 and PT3 to describe a controller (alternative to PID). I am trying to find their names in English so I can study them.
is there any document in English that explain them?
Thanks
 

MisterBill2

Joined Jan 23, 2018
11,579
It seems like PT1, PT2, are lazy abbreviations for Parameter term #1, and Parameter Term #2.
In PID controller system that could be as simple as Proportional gain, derivative gain, and Integral gain.
In many cases those very experienced folks use obscure names to hide what they are doing, or because they are simpler to write or speak. It may also be that for setting up a particular brand of PID controller the variable terms are numbered on the setup screen. I came across that in one German brand PID controller that I had to service. The result was that I never recommend that brand to any client asking for recommendations.
 

ericgibbs

Joined Jan 29, 2010
15,338
It seems like PT1, PT2, are lazy abbreviations for Parameter term #1, and Parameter Term #2.
In PID controller system that could be as simple as Proportional gain, derivative gain, and Integral gain.
Hi,
They are NOT lazy abbreviations, they are recognized symbols used by engineers designing Control Systems, read the PDF post #3.

E
EG 1259.png
 

LvW

Joined Jun 13, 2013
1,428
Short anwer:
* P means "proportional"
* T1, T2 and T3 is a symbol for a "time constant" of 1st, 2nd and 3rd order, respectively.
* Simple examples: Passive RC lowpass ladder structure of 1st, 2nd or 3rd order.
 

MisterBill2

Joined Jan 23, 2018
11,579
In the many servo systems that I have adjusted at various jobs, the terms were called proportional, derivative, and integral. Then when the servo control systems were all software, the nomenclature became a bit more confusing because of the random scale factors. Proportional gain became a variable around one for some companies, while it was around 100 for others. Then we had first and second derivative terms, with time and gain on what equated to the integral term.
But there was always an explanation provided.
 
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