Presentation on theme: "What does this block diagram mean?"— Presentation transcript:
1 What does this block diagram mean? Process ControlWhat does this block diagram mean?PIDG(s)ControllerPlantOPPVSPError
2 Control 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
3 Loop 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
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 ControlHow can I relate this loop response to my process?Under DampedOver DampedCritically DampedSetpointTime
6 Proportional Term Analogy Speed(mph)Depress gas pedalEase off gas pedalProportional Band5046400 mph mph 46 mphTime
7 Integral Term Analogy Speed (mph) Time 46 mph 48mph 50mph 50 46 40 Slowly depress gas pedal to reach 50 mph50464046 mph 48mph 50mphTime
9 How 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?
10 Cast 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
11 Blown 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
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 informationThe ability to modify line parametersStorage and download of stored recipesLive trending of data
14 Computer 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
15 Linking to the Computer - 1 IdealIndustrialComputerTemperatureControlDriveControlThicknessGaugeGravimetricBlendingPressureControlPLCControlTemperatureControlDriveThicknessGaugeGravimetricBlendingPressurePLCIndustrialComputerActual
16 Linking to the Computer - 2 Improved systemIndustrialComputerTemperature ControlPressure ControlGravimetrics / BlendingPLCDriveControlScanningFrameIndustrialComputerOEM systemTemperature and Pressure ControlThicknessGaugeDriveControlGravimetricBlendingPLCControl
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, 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.