Answer / krishna

proportion control function is to maintain constant offset
between set point and process variable .but it cannot remove
the offset. it makes the p.v to oscillate between high and
low limits.

There are two things required for calibrating control valve
1)pneumatic tester ( signal :0.2 to 1kg /cm2
)
2) air supply source according to design of valve.
initial for 0.2 kg.cm2 valve should be (open or close )
according to ATO ATC) )
THEN CHECK POSITION AT 25 50 75 100 % OF VALVE ACCORKING TO
SIGNAL TUNE WITH POSITIONER

Answer / www.islamqa.com

Actually we can make it simple:

# P:
it's a controller gain which modify the controller o/p
proportional to the error.

# I:
it's a controller gain which modify the controller o/p
proportional to the integral of the error.

# D:
it's a controller gain which modify the controller o/p
proportional to error rate of change.



We have 4 parameters in our control loop to focus on:
1 - the rise time: the period of time during which the pv
get 90% of the desired sp value
2 - max overshoot
3 - settling time: the period of time during which the pv
get the desired sp value and saturate.
4 - error/offset

we can get it clear from this pic:
http://controls.ame.nd.edu/ame437/S2003/hw1/specifications.j
pg

Now we will take a look about the effect of each controller
gain on these parameters:

# P gain:
decrease rise time
increase max.overshoot
increase settling time
decrease error (but not eliminate)


# I gain:

decrease rise time
increase max.overshoot
increase settling time
eliminate error.


# D gain:

no effect on rise time
decrease max.overshoot
decrease settling time
decrease error.

the previous is guidelines to be in background while
dealing with PID,but they are not sharp limits.

Regards,

Ahmed Sabry
Control and Instrumentation Engineer
GPC - General Petroleum Company
ahmedsabry.online@gmail.com
CELL.: 00 2 0121367310

Answer / prashant

proportional function is take place an action to maintain
the pv proportionaly to error in p.v . but an offset error
is sustained , that will be reduced by integral funtional.


calbration of control valve :::
1. check the pneumatic pressure of regulator
2. give the 4-20 ma to check the strock of c/v
3. if storck is not achieving then adjusted by zero
& span adjustement

what is difference between differial pressure & delta pressure?

3 Answers  

---

how to calculate static pressure in a pipe line,when we know the DP(differential pressure) in the line, area of the pipe? please any one tell me the relation between them..?

2 Answers  

---

in my company organisation in plan to take new PLC system for replacing old relay system , for that what I/P needsd to submit to the system house of PLC supplier?

1 Answers  

---

What is re-latch the manual trigger in solenoid valve

0 Answers   Valvitalia Systems Division,

---

what is temperature compensation?

1 Answers  

---

what is PID n give me brief info. about P&I&D.

2 Answers  

---

I am manjunath having exp in maintenance of chemical plants,know i want to do a design course INTOOLS,after doing design course can we get jobs in design field.sinve i dont have design exp..

0 Answers  

---

Transducer Input 0 to 230 v ac Output-0 to 10vdc Receiver Input 0 to 10 vdc and Output 4 to 20 ma How?

1 Answers  

---

i want all model questions paper for robert bosch

1 Answers   Bosch, Patni,

---

how to measured k type thermocouple temp.

3 Answers   NTPC,

---

HOw To Use 24V DC in Instrument?

2 Answers  

---

How I identify to solonied coil which is 24v or 230v In our lab.because there is no tag.

1 Answers   MRPL Mangalore Refinery and Petrochemicals Limited,

---