电容培训ppt课件

1、电容物位测量此选择是您的明智决定.电容器基础Each electrical charged material is surrounded by an electrical field.Between different charged materialselectrical field lines from positive to negative are created.Two unequal charged metal plates build a capacitor.电容器的基础The principle of the capacitance level measurement is b

2、ased on the change in capacitance through the change of the level.The capacitance of a capacitor depends on 3 factors: Distance between the electrodes (d) Dimensions of the electrodes (A) Dielectric between the electrodes (er)3e0 : electrical field constant : 8,854*1012 C/(Vm)er : permitivity, diele

3、ctric constantA.er不同介电常数的材料固体 DolomiteFerric oxideGrainBroken glassCoffeeSlaked limeQuick limeCoal lumpsCoal dustFeedFlourNylon granulatesSilica powderRiceSand, dryWashing-powderer 7,8 . 89,32,2 . 3,61,2 . 54,653,34,52,32,3 . 34,51,823,53 . 51,1 . 1,3液体 AlcoholPetrolChloroformDesmophen 5100Desmodur

4、44 VDeuteriumLiquid gas- Chlorine- Air -140C- Butane- PropaneGlycerinFuel oilLatexPetroleumWaterer 32 . 35,52,278,121,31,81,51,21,213,22,1162,181Air = 1.电容器基础In level measurement usually only one part of the capacitor is filled with material.The total capacitance is calculated from the sum of the tw

5、o partial capacitances.The change of capacitance DC depends only on the height h and the dielectric constant er of the material.C = C MAT + C AIR.电容器基础Because of the change in polarity at an alternating voltage, electrical losses will be created. These losses are described by an ohmic resistor XC pa

6、rallel to the capacitance C. CRC : capacitance F : 2f 1/sf : measuring frequency HzXC: capacitive blind resistance.电容器基础Normally, cylindrical tanks are used in the field.Then, the capacitor is formed from the probe and the tank wall.LDderCapacitive rodTank wall.In order to convert the change of capa

7、citance into an electrical signal the capacitor is connected to an AC voltage.测量原理Capacitance changes caused by the level result in a change of the measuring current.AC voltage sourceMeasured currentCapacitive rod-+-+-+-+.KLJA change of the dielectric constant has no influence on the capacitance bec

8、ause the filled part of the vessel wall apparently moves to the probe.The measuring current does not only depend on the dielectric constant, but also on the electrical conductivity of the media.电导率Conducting mediaLow conducting mediaNon conducting mediaThe dielectric constant has to be stable. If it

9、 changes, e.g. by humidity the level cannot be determined reliable anymore.最小探头长度For a limit detection (Nivotester) the minimal change of the capacitance DCmin should be 5 . 10 pF.For continuous measurement (Silometer) the minimal change of the capacitance DCmin should be 10 pF (FEC12).Non conductiv

10、e mediaLmin =DCminCs(er-1)Lmin =DCmin CsConductive mediaer = dielectric constant: oil = 2 chlorine = 1.8Cs = capacity of the probe rod at a distance of 250 mm from vessel: 13 pF/m probe with ground tube: 55 pF/m conductive media: 400 pF/mDCmin= minimal change of capacityLmin.最小探头长度 ( 导电介质, 如：酸 )Lmin

11、 = = = 1,3 cmDCmin Cs 5 pF400 pF/mLmin = = = 2,5 cmDCmin Cs 10 pF400 pF/mLimit detection in acids:Continuous measurement in acids:Lmin.最小探头长度 ( 非导电介质, 如：油 )With ground tube:Without ground tube:Limit detection in oil:Lmin = = = 9 cmDCminCs(er-1) 5 pF55 pF/m(2-1)Lmin = = = 38,5 cmDCminCs(er-1) 5 pF13

12、pF/m(2-1)Lmin.最小探头长度 ( 非导电介质, 如：油 )With ground tube:Without ground tube:Continuous measurement:Lmin = = = 18 cmDCminCs(er-1) 10 pF55 pF/m(2-1)Lmin = = = 77 cmDCminCs(er-1) 10 pF13 pF/m(2-1)minL.Rod and rope probe实际的解决方案Full- or partially insulated probesProbes with ground tube.实际的解决方案Screening (inac

13、tive length)Active build-up compensationTemperature spacer.Advantages of the rope probe:- shipping is simpler - there is usually limited space for installation- mechanical stability of long rod probes can not be guaranteedRod Probes100.4000 mmRope probes420.26.000 mm实际的解决方案杆式和缆式的探头.实际的解决方案温度的考虑及全绝缘和

14、半绝缘探头At high operating temperatures in the vessels the electronic is protected by a temperature spacer.Conductive mediaNon conductivemediaFully insulated probePartially insulated probeFully insulated probePartially / fully insulated probefor aggressive media.- Increase in sensitivity for media with

15、low dielectric constants (factor 5)- Reference potential in non metallic vessels- Increased lateral stability of probes used in tanks with agitators- Linearise level indication in horizontal cylindrical and ball-shaped tanks 实际的解决方案带接地管的探头Advantages of the ground tube:The ground tube builds the seco

16、nd electrode of the probe.实际的解决方案带屏蔽管的探头Advantages of screened probes:These prevent errors caused bythe effect of condensation or material build-up on the vessel wall near the process connection.-Used if a conductive layer covers the probe-Highly critical applications can be solved with the active b

17、uild-up compensation.实际的解决方案带抗粘附的探头Advantages of active build-up compensation:The effects of build-up on theprobe are detected using asecond, separate compensation circuit. This is electrically insulatedfrom the actual measuring loopin the electronic insert.The ideal condition for an calibration is

18、no build-up on the probe which effects the electrical field.对 FTC 260 来说不需要标定！iiM = i不带抗粘附抗粘附AProbe potentialA+ uBA.iiM = iThe capacitance of the probe is changing, because of the different dielectric constant from the media. This results in a change of the current.The electronic recognizes the chan

19、ge in the currentif the probe is completely covered by the media.CMLevel抗粘附不带抗粘附AProbe potentialA+ uBA.iiMCiiMCMiACAThe build-up on the probe causes a permanent change in capacity which influences the current i.i = iM + iALEVELBuild-Up抗粘附不带抗粘附AProbe potentialA+ uBA+ uBA.CGCAiiMCMiA=0iGOnly the curre

20、nt through the probe is measured (i=iM). With the guard probe the effect from build-up is eliminated reliable.The current iG through the guard does not affect the measuring circle.LEVELBuild-UpABProbe potentialGuard potential抗粘附带抗粘附BA+ uBAB.性能High pressureHigh temperatureAggressive mediaBuild-upAbra

21、sive mediaCapacitive level measurement proven at:.测液体探头的选择ApplicationConductive liquidsLiquids with high viscosityLong nozzlesCondensationBuild-up on the vesselNon conductive liquidsUse in agitator vesselsVery corrosive liquidsProbe without ground tubeProbe with screeningDC xx xxx Probe with ground

22、tubeDC 11 xxx, DC 16 xxx, 11500 ZMProbe with fully insulatedscreening and flangecoated with PTFEDC 11 xxx, DC 21 xxxSuitable Probes.ApplicationSuitable Probes测液体探头的选择Probe with active build-upcompensation(only for limit detection)DC xx xxxProbe with gas-tight glandDC xx xxProbe with temperature spac

23、erDC xx xxxCeramic probe11500 Z/ZMHeavy build-up on theprobeLiquefied gas tanksMedia harmful to healthHigh/low temperatureVery high temperaturesHigh pressures.测固体探头的选择ApplicationLong nozzles; Condensation; Build-up on the vessel wallHeavy solidsGrain size 10mmApplications in foodindustryProbe with s

24、creeningFTC 331 Z, 12892, 12656, 21262 /A, 21265 /ARope probe with diameter 10 mmFTC 331 /Z, 21262 /A, 12656Fully insulated probesFTC 131 / FTC 260 / FTC 831FTC 968 + protectorSuitable Probes.测固体探头的选择ApplicationBuild-up on the ropeExtreme temperaturesShort depth of intrusionProbe with active build-u

25、pcompensationFTC 260Ceramic probe12892, 12656Probe with a short fixedlengthFTC 968 /ZSuitable Probes.Modular constructionOnly two versions eachwith fully and partially insulationActive build-up compensation3/4“ and 11/2“process connectionCustomized probe forevery application for example protection a

26、gainst aggressive media with special insulationElimination of measuringerror from condensateand build-upCost savingsFeatureBenefits Multicap - Multicap T - Multicap A/EMulticap 探头Usable worldwide.不同点Multicap .Multicap T.11/2“ process connectionPressure up to 100 barFully-insulated or blank screening

27、3/4“ process connectionPressure up to 40 barBlank screeningSuitable for FEC 12/22FM IS, XPCSA IS, XPCenelec Eexia, EEx dPTB Zone 0WHGVbFCenelec EEx iaMulticap .A.Multicap .E.Multicap 探头Probes with screeningActive build-up compensationElectronic insert Continuous level measurement Limit detectionAcce

28、ssories Temperature spacer Gas-tight glandGround tube for accurate measurements in non-conductive liquidsProbe length Rope version up to 26m Rod version up to 6mApproval PTB zone 0 WHG VbF Cenelec EEx iaHousing Aluminum housing Polyester housing Aluminium housing, coatedCable entries Pg 16, NPT 1/2,

29、 G 1/2, M 20 x1,5 Insulating materials Depending on the medium Rod probes e.g. PTFE, PE, PFA Rope probes e.g. PE, FEP, PFAMaterials Stainless steel 1.4571 Steel ST37 Hasteloy C4 MonelProcess connection Parallel thread G 1 1/2 A Tapered thread NPT 1 1/2“ Sanitary thread Triclamp-coupling Flanges DIN/

30、ANSI/JIS.Multicap A/E 探头Accessories Temperature spacer Gas tight glandGround tube for accurate measurements in non-conductive liquidsActive build-up compensationInsulating materials Depending on the medium e.g. PTFE, PE, PFA, .Compact electronic insert FEC 12 FEC 22Electronic insert Continuous level

31、 measurement Limit detection HART-/INTENSOR-protocolHousing Aluminum Ex d-housing with separate connection compartmentProcess connection Parallel thread from G 1 1/2 A Tapered thread from NPT 1 1/2“ Sanitary thread Triclamp-coupling Flanges DIN/ANSI/JISApprovals FM IS, XP CSA IS, XP Cenelec EEx ia E

32、Ex d PTB zone 0, VbF, WHGProbe length Rope version up to 26m Rod version up to 6mCable entries Pg 16, NPT 3/4, G 1/2, M 20,1,5Material Stainless steel 1.4571Probes with screening.Multicap T 探头Housing PBTP-plastic housing Aluminum housing, coated Aluminum Ex d-housing with separate connection compart

33、ment, coated Stainless steel housingCompact electronic insert FEC 12 FEC 22Electronic insert Continuous level measurement Limit detection HART-/INTENSOR-protocolApprovals FM IS, XP CSA IS, XP Cenelec EEx ia EEx d PTB zone 0, VbF, WHGProbe length Rope version up to 20m Rod version up to 3mProcess con

34、nection Parallel thread G 3/4 A Tapered thread NPT 3/4“ Sanitary thread Triclamp-coupling Flanges DIN/ANSI/JISGround tube for accurate measurements in non-conductive liquidsInsulating materials Depending on the medium e.g. PTFE, PE, PFA, FEPAccessories Temperature spacerProbes with screeningActive b

35、uild-up compensationCable entries Pg 16, NPT 3/4, G 1/2, M 20 x1,5Material Stainless steel 1.4435.Nivocompact 探头Compact limit switches for bulk solids, besides power supply and PLCs or DCSs no other components are necessary.FeatureFTC 131 / Z (Rod Probe) - Insulation PE - Probe length 350 mm - Insta

36、llation from above or lateralCompact instrument - easy installation - low installation costsRobust and stable probes for light and heavy duty applicationsBenefits of Nivocompact probesFTC 331 / Z (Rope Probe) - Insulation PVC - Probe length up to 22 m - maximum pull force up to 8 tFTC 231FTC 331 / Z

37、FTC 131 / ZFTC 231 - Probe length up to 22 m - Maximum pull force up to 3 tEasy calibration - variable switchpoint.Minicap and Nivocompact 探头Compact limit switches for bulk solids, besides power supply and PLCs or DCSs no other components are necessary.FTC 831FTC 260FeatureBenefitsFTC 831 - Probe le

38、ngth up to 20 m - Maximum pull force up to 0,25 tNo moving parts in tank - no wear - maintenance freeRod probe easy to shorten - convenient storage - for different switchesFTC 260 - Probe length up to 160 mm - integrated active build-up compensation - No calibration necessary at FTC 260/831. Indepen

39、dent from material properties.Build-up consistent and high sensitive because of integrated electronics at the probe end.Nivector and TSP 探头TSP 12656TSP 12892Limit switch solutions at extreme conditions (TSP probes) and for simple applications (Nivector FTC 968). TSP 12656 / TSP 12892 - Ceramic rope

40、or rod probe - Temperature up to 450CFTC 968 / Z - Mounting depth max. 73 cm - max. participle size 10 mmTSP probes designed for - high and sudden changes in temperature - insensitive to abrasive bulk materials and condensationQuick and economicalcommissioning at FTC 968/ZNo calibration necessary at

41、 FTC 968 / ZFTC 968 / ZFeatureBenefits.仪表组成Sensor electronic insert level transmitterEC 11, 72, 613- wirePFM- signalFEC 22FEC 12 4.20 mA Smart INTENSOR/HARTCompact electronic insertsfor Multicap A/E and Multicap TEC 17, 37, 47, 16.FEC 12 一体化液位变送器Powerful 4.20 mA Smart electronic insert in highintegr

42、ated structural shape for Multicap T and Multicap AE probes for continuous level measurement.Besides power supply and PLCs or DCSs no other components are necessary.Measurementfrequency500 kHzRemote calibrationwith handhelddeviceCalibration bypush buttonIntegratedlinearisationcurveEEx iaEEx dapprova

43、l.FEC 12 简单的标定Read and WriteRead onlyRESETEmpty calibration 0% 4 mAFull calibration 100% 20 mAPress 5s.FEC 22 一体化的液位开关Microprocessor controlled compact limit switchfor Multicap T - and Multicap AE-probes.The FEC 22 is available as a DC- and an AC-version.Besides power supply and PLCs or DCSs no othe

44、r components are necessary.Because of the integrated build-up compensationa reliable switch point is guaranteed, even withheavy build-up on the probe.Active build-upcompensationAutomatic switchpoint optimisationCalibration bypush buttonMin. / Max.Fail-safeEEx d approval.FEC 22 简单的标定Press 5sPress 2sP

45、ress 2sRESETCalibration when probe uncoveredCalibration when probe coveredSwitchpoint optimization682.FEC 22 功能总结No.1 2 3 4 5 6 78SwitchsettingSymbolAssigning ValuesFunction2pF 4pF 8pF 16pF 32pF 32 pF pF pF pF pFDC DCOFF ON0,5s 1,5s 6s 12s 20sDt0,5s 1,5s 6s 12s 20sDtMIN MAXOFF ONOFF ONDC -4 pF -4 pF

46、 DC -2 pF -2 pF DC -2 pF -2 pF DC -4 pFCalibration coveredService-ModeCalibration uncoveredMinimum/Maximum Failsafe modeSwitching delay when probe uncoveredSwitching delay when probe coveredOptimised SwitchpointON/OFFManual Switchpoint setting.分段总结in solidsin liquidsfor light and heavy bulk solidsfo

47、r explosion endangered areasfor food stufffor abrasive mediafor media with build-upfor media with build-upfor acid and lyesfor high temperaturefor high pressureContinuous measurementand limit detectionLimit detection.在液体中的连续测量with Multicap probesIn small tanks, for example for adjustment in intermed

48、iate- or buffer tanks the Multicap T probes are ideal.DC 11 TxxDC 12 Txxwith FEC 12For process tanks with high pressure, temperature and with corrosive media the best solution are Multicap probes. A 11500 probe should be used in case ofextreme conditions.DC 11 / AE11500with EC xx or FEC 12.在液体中的限位探测

49、with Multicap probesDC 16 / T / AEwith EC 16 or FEC 22DC 11 / T / AEwith EC xx or FEC 22DC 21 / T / AE11500In media, such as sludge mudor glue, a reliable limit detection can be made with an active build-up compensation.The fully insulated probes of the Multicap series areprotected against aggressive acids and lyes. This guarantees a reliable limit detection.In case of extreme conditions the ceramic probe 11500 is