FinalControl-ASSUMPTIONUNIVERSITY最终控制易三仓大学

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1、FinalControl/FinalControlElementsFinalControlThefunctionoffinalcontrolelementistotranslatelow-energycontrolsignalintoalevelofactionFinalControlOperationSignalConversionsThemodificationtothecontrolsignaltoproperlyinterfacewiththeactuatorForexample,theelectricmotoractuatortooperatethevalveCur

2、rent-to-voltageconversionThedevicesthatperformsignalconversionsarecalledtransducersActuatorThetranslationofcontrolsignalintoactiononthecontrolelementForexampleValve(controlelement)Mechanismtoopenorclosethevalvecanbeelectrically(Solenoid,ormotor)pneumaticallyhydraulicallycontrolledHeater(co

3、ntrolelement)RelayswitchControlElementThedevicethatinfluencestheprocessvariablesForexampleFlowValveTemperatureHeaterSignalConversionsSignalconversionistoconvertlow-energycontrolsignaltoahigh-energysignaltodrivetheactuatorThesignalfromcontrollercomesin3formsElectricalcurrent4-20mAPneumati

4、cpressure3to15psiDigitalsignalCommonelementtoperformanalogsignalconversionareRelayAmplifiersCommonelementtoperformdigitalsignalconversionareON/OFFcontrolDACDirectactionPneumaticSignalsInpneumaticsystem,signalsiscarriedinformofgaspressureThepressuregastravelsatspeedof330m/s.Thereare3typesofc

5、onversionAmplificationNozzle/FlappersystemCurrent-to-PressureconvertersAmplificationPneumaticamplifierorboosterraisepressureviaaregulatorAstheinputpressureincreases,thediaphragmmotionwillmovetheplugintotheboosterNozzle/FlapperSystemThepressuresignaliscontrolledbytheflapperI/PConverterConver

6、t4-20mAinto3-to-15psisignalPowerElectronicsThehighpowerelectronicsdevicestoconvertlow-levelenergysignaltohigh-levelenergysignalThedevicesiscategorizedintoSwitchingdevicesControllingdevicesSwitchingDevicesThesolid-statesemicoductordevicesthatcaneitherbeinanofforonstateSCRGTOTRIACSCRSCRorthyr

7、istoristhedevicethatconductscurrentintheforwardbiasdirectionifapositivevoltageisappliedtothegateSCRwillcontinuetoconductunlessthereistheforwardbiasisremovedDuringtheONstate,therewillbevoltagedropacrossSCRcalledRonThepowerdissipatedinSCRisApplicationofSCR