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Process Control What does this block diagram mean?

Process Control What does this block diagram mean?. Plant. Controller. SP. Error. OP. PID. G(s). PV. Control Terms - Three Term Control. P roportional ---- Proportional Band I ntegral ---- Integral Time Constant D erivative ---- Derivative Time Constant

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Process Control What does this block diagram mean?

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

  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) Plant Controller SP Error OP PID G(s) PV

  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

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

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

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

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

  8. Derivative Term Analogy Speed (mph) 52 50 Proportional Band 48 Time 50 mph 49 mph 50 mph 51 mph 50 mph

  9. 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 G/B Th SC Barrel MP Die S P D D D D D D T 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

  11. Blown Film 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 Tr G/B B B SC Die S Barrel Th D D D D D T

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

  16. OEM system Industrial Computer Temperature Control Pressure Control Gravimetrics / Blending PLC Drive Control Scanning Frame Linking to the Computer - 2 Improved system Industrial Computer 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 Noise pulse Tx Rx Input signal Recovered signal EIA 422 (485) Noise pulse + + + Tx Rx Input signal Recovered signal - _ Signals subtracted Noise pulse EIA-232 / EIA 422 (485) Explained

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

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