Answer / carl_ellis

Gain, ti and td are PID proportional control tuning terms/constants. PID controllers use PID tuning constants to calculate an output based on the error signal; final control elements (valves) do not do a PID calculation so valves are not involved with gain, ti and td. The controller is typically in the control room, the valve is somewhere out in the process.

A PID controller calculates the expected valve/damper position from the error signal and the tuning constants, the result of which is an output control signal ranging from 0-100%.

A valve positioner or valve I/P receives that control signal from a controller (4-20mA, Profibus) and supplies air or electric power to the actuator to achieve the correct position demanded by the control signal.

Ti is the term for reset or integration. It is used when the process itself is not an integrating process. Level, pressure, and pH are usually integrating processes. Sometimes temperature is an integrating process, sometimes not. When the process is non-self regulating/integrating process, the ti term is not used in the PID calculation.

Flow and temperature processes typically use the ti term for PID calculation.

An exception to the rule of PID being done in a separate controller is Foundation Fieldbus (FF), which allows function block PID execution in FF devices. In a case where PID control is executed in an FF valve positioner, then a valve would use the PID tuning constants.

why is not useing in boiler skin thermocople

1 Answers   KNPC,

---

can i get model question papers of mahagenco exam?

11 Answers   MahaGenco, MSGEN,

---

please send the drdo exam paper

0 Answers   DRDO,

---

need instrumentation job completed 1 year trainee ship in mnc pesticide company. now in search of job

0 Answers  

---

Hi i m B.E. In elect. & comm. I m workin in bio mass plant from 6 mnths as inst. Engg. but now i m in dept. Of operation as shift engg...which is best operation or inst. 4 me? M confusd..plz help and reply me..

2 Answers  

---

how to make a calibration for differential pressure

2 Answers  

---

What is Difference between Bench Set & Operating Range of Control Valve?

1 Answers   AB Sugar,

---

what is the full form of psig.

8 Answers  

---

what is meaning of static pressure

4 Answers   Ambuja,

---

i saw in my company drawing seat cable size as mensioned like this 12p*15 sqmm,12t*1.5sqmm, 9c*1.5sqmm. now what my que is what is mean by p , t , c.

3 Answers  

---

PT RTD Range: -200 to 500 degree celsius If I configured in DCS Lower range and Upper range . In face plate it shows red colour due to overa range how was the characteristics look If the temperature is more than operating range. how was the characteristics look . whether its in Resistance vs Temperature curve is Linear or Non linear

0 Answers   MSL, SRAAC,

---

There is a problem with our HART475 it is not communicating with smart devices error becomes "NO DEVICE FOUND"we have insert 250ohm resistance as per requirement but invain plz tell me the solution?

1 Answers  

---