Presentation on theme: "What does this block diagram mean?"— Presentation transcript:
1What does this block diagram mean? Process ControlWhat does this block diagram mean?PIDG(s)ControllerPlantOPPVSPError
2Control Terms - Three Term Control Proportional Proportional BandIntegral Integral Time ConstantDerivative Derivative Time ConstantOutput ( OP ) = K ( 1 + xdt + dx/dt )( P I D)PIDG(s)ControllerPlantOPPVErrorSP
3Loop Response Under Damped Setpoint Critically Damped Over Damped Time Under Damped--Overshoot gives minimum time to setpointCritically Damped--No overshoot and stableOver Damped--No overshoot but excessive time to setpointUnder DampedOver DampedCritically DampedSetpointTime
4Loop 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
5How can I relate this loop response to my process? Three Term ControlHow can I relate this loop response to my process?Under DampedOver DampedCritically DampedSetpointTime
6Proportional Term Analogy Speed(mph)Depress gas pedalEase off gas pedalProportional Band5046400 mph mph 46 mphTime
7Integral Term Analogy Speed (mph) Time 46 mph 48mph 50mph 50 46 40 Slowly depress gas pedal to reach 50 mph50464046 mph 48mph 50mphTime
8Derivative Term Analogy Speed(mph)Proportional Band52504850 mph mph mph mph mphTime
9How do they differ from each other in terms of speed of response? Process ControlHow 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?
10Cast Film D Drive speed control MP Melt pump ThSMPBarrelDieG/BD Drive speed control MP Melt pumpT Temperature control P Pressure controlSC Screen changer S Scanning frameG/B Gravimetrics / Blender Th Thickness controlSCTP
11Blown Film D Barrel G/B SC Die Tr S Th T D Drive speed control T Temperature controlSC Screen changerG/B Gravimetrics / BlenderTh Thickness controlS Scanning frameAB Air boardC CageB Bubble diameter sensingTr treaterCB
12Use 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?
13Computer Supervision - 1 A computer system provides:One window to view all line informationThe ability to modify line parametersStorage and download of stored recipesLive trending of data
14Computer Supervision - 2 Additional computer system benefits are:Generation of batch and shift reportsStatistical Process Control (SPC) trending and dataHistorical trend and data informationNetworking of data to other departments
15Linking to the Computer - 1 IdealIndustrialComputerTemperatureControlDriveControlThicknessGaugeGravimetricBlendingPressureControlPLCControlTemperatureControlDriveThicknessGaugeGravimetricBlendingPressurePLCIndustrialComputerActual
16Linking to the Computer - 2 Improved systemIndustrialComputerTemperature ControlPressure ControlGravimetrics / BlendingPLCDriveControlScanningFrameIndustrialComputerOEM systemTemperature and Pressure ControlThicknessGaugeDriveControlGravimetricBlendingPLCControl
17Digital Communications My computer has RS232 and the process equipment has RS232. This is all I need, right?Wrong!
18RS (EIA) 232, 422 & 485 Analogy EIA-232: 3 - wire connection ( plus enable links ): Tx, Rx, CommonPoint to point ( one to one )Short distance transmission ( <50ft / 15m )EIA-422/485:5-wire connection (422):Tx+, Tx-, Rx+, Rx-, Common3-wire connection (485):A (Tx+ & Rx+), B (Tx- & Rx-), CommonMulti 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.