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What does this block diagram mean?

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Presentation on theme: "What does this block diagram mean?"— Presentation transcript:

1 What does this block diagram mean?
Process Control What does this block diagram mean? PID G(s) Controller Plant OP PV SP Error

2 Control Terms - Three Term Control
Proportional Proportional Band Integral Integral Time Constant Derivative Derivative Time Constant Output ( OP ) = K ( 1 + xdt + dx/dt ) ( P I D) PID G(s) Controller Plant OP PV Error SP

3 Loop Response Under Damped Setpoint Critically Damped Over Damped Time
Under Damped--Overshoot gives minimum time to setpoint Critically Damped--No overshoot and stable Over Damped--No overshoot but excessive time to setpoint Under Damped Over Damped Critically Damped Setpoint Time

4 Loop Tuning Setpoint x t osc Time Rule Of Thumb:
Proportional Band--P = 2* Integral Time Constant--I = 1.5* Derivative Time Constant--D = I/5

5 How can I relate this loop response to my process?
Three Term Control How can I relate this loop response to my process? Under Damped Over Damped Critically Damped Setpoint Time

6 Proportional Term Analogy
Speed (mph) Depress gas pedal Ease off gas pedal Proportional Band 50 46 40 0 mph mph 46 mph Time

7 Integral Term Analogy Speed (mph) Time 46 mph 48mph 50mph 50 46 40
Slowly depress gas pedal to reach 50 mph 50 46 40 46 mph 48mph 50mph Time

8 Derivative Term Analogy
Speed (mph) Proportional Band 52 50 48 50 mph mph mph mph mph Time

9 How do they differ from each other in terms of speed of response?
Process Control How many parameters are controlled in my Cast Film or Blown Film process? & How do they differ from each other in terms of speed of response?

10 Cast Film D Drive speed control MP Melt pump
Th S MP Barrel Die G/B D Drive speed control MP Melt pump T Temperature control P Pressure control SC Screen changer S Scanning frame G/B Gravimetrics / Blender Th Thickness control SC T P

11 Blown Film D Barrel G/B SC Die Tr S Th T D Drive speed control
T Temperature control SC Screen changer G/B Gravimetrics / Blender Th Thickness control S Scanning frame AB Air board C Cage B Bubble diameter sensing Tr treater C B

12 Use Of Computer Systems
What benefits can I achieve by using a computer system on my process? & How is my process control equipment connected to a computer system?

13 Computer Supervision - 1
A computer system provides: One window to view all line information The ability to modify line parameters Storage and download of stored recipes Live trending of data

14 Computer Supervision - 2
Additional computer system benefits are: Generation of batch and shift reports Statistical Process Control (SPC) trending and data Historical trend and data information Networking of data to other departments

15 Linking to the Computer - 1
Ideal Industrial Computer Temperature Control Drive Control Thickness Gauge Gravimetric Blending Pressure Control PLC Control Temperature Control Drive Thickness Gauge Gravimetric Blending Pressure PLC Industrial Computer Actual

16 Linking to the Computer - 2
Improved system Industrial Computer Temperature Control Pressure Control Gravimetrics / Blending PLC Drive Control Scanning Frame Industrial Computer OEM system Temperature and Pressure Control Thickness Gauge Drive Control Gravimetric Blending PLC Control

17 Digital Communications
My computer has RS232 and the process equipment has RS232. This is all I need, right? Wrong!

18 RS (EIA) 232, 422 & 485 Analogy EIA-232:
3 - wire connection ( plus enable links ): Tx, Rx, Common Point to point ( one to one ) Short distance transmission ( <50ft / 15m ) EIA-422/485: 5-wire connection (422):Tx+, Tx-, Rx+, Rx-, Common 3-wire connection (485):A (Tx+ & Rx+), B (Tx- & Rx-), Common Multi drop capability: ( 8 for EIA 422 and 32 for EIA 485 ) Long distance transmission ( 4000ft / 1230m ) EIA-232 & EIA-422/485 are analogous to using the air as the transmission medium for us to communicate. They do not tell us how we communicate.

19 EIA-232 / EIA 422 (485) Explained EIA 232 EIA 422 (485) Tx Rx
Input signal Recovered signal Noise pulse EIA 232 Tx Rx + - _ Input signal Recovered signal Noise pulse Signals subtracted EIA 422 (485)

20 Communications Protocol Analogy
Allo! Hola! ' ' Moshi moshi! Pronti! Hullo! Hello!


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