Cov nram qab no peb yam tseem ceeb ntawm cov twj paj nruag yuav tsum tau teeb liab grounding (functional grounding) yuav tsum tau ua nyob rau hauv -site, raws li "single-point grounding ntawm teeb liab loops" lub hauv paus ntsiab lus, los tiv thaiv kev tsim ntawm av loops uas yuav qhia tau cuam tshuam.
Cov cuab yeej uas xav tau cov teeb liab grounding ntawm qhov chaw teeb tsa
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Hom |
Yog vim li cas vim li cas Field Signals yuav tsum tau Grounded |
Lub hauv paus tseem ceeb |
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Hauv av -hom thermocouple |
Nws ntsuas qhov kawg (kub kawg) txuas ncaj qha rau cov txheej txheem cov cuab yeej (uas feem ntau yog hauv av) ntawm lub tes tsho hlau tiv thaiv, thiab lub teeb liab qhov chaw nws tus kheej ua lub hauv paus taw tes. Yog tias muaj kev sib txuas hauv av ntxiv rau ntawm chav tswj sab, yuav tsim ob lub -point grounding loop. |
HG/T 20513-2014, Clause 5.1.3 (Explanatory Notes): "Cov cuab yeej xws li grounded thermocouples, pH meters, thiab electromagnetic flowmeters yuav tsum tsuas yog grounded on-site." |
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Kev ntsuas pH (acidity meter) |
Cov khoom siv hluav taws xob txuas nrog rau hauv av los ntawm cov tshuaj electrolyte raug kuaj, thiab cov teeb liab qhov chaw (electrode) nws tus kheej twb yog grounded. |
HG/T 20513-2014, Clause 5.1.3 (Explanatory Notes): "Cov cuab yeej xws li grounded thermocouples, pH meters, thiab electromagnetic flowmeters yuav tsum tsuas yog grounded on-site." |
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Electromagnetic flowmeter |
Lub hauv paus ntsiab lus ntawm kev ntsuas yuav tsum tau ntsuas lub sensor, qhov nruab nrab conductive ntsuas, thiab cov txheej txheem piping nyob twj ywm ntawm tib lub peev xwm, yog li tsim kom muaj qhov ruaj khov, huv si siv xoom taw tes rau qhov tsis muaj zog induced electromotive quab yuam (hauv millivolt ntau). Qhov kev sib txuas ntawm qhov sib npaug no yuav tsum ua kom tiav ntawm qhov chaw teeb tsa sensor (hauv thaj chaw). |
HG/T 20513-2014, Clause 5.1.3 (Explanatory Notes): "Cov cuab yeej xws li grounded thermocouples, pH meters, thiab electromagnetic flowmeters yuav tsum tsuas yog grounded on-site." |
Kev piav qhia
Tib -Point Grounding Principple. Rau peb hom twj paj nruag uas tau hais los saum no, qhov taw qhia hauv av ntawm lub teeb liab voj yog tsau ntawm qhov chaw nyob. Yog hais tias ob qho tib si lub teeb liab qhov chaw (tseem ntsuas) thiab qhov kawg tau txais (tswj chav tsev) yog grounded, muaj peev xwm sib txawv ntawm ob qhov chaw, yog li tsim ib tug "av voj voog" nyob rau hauv lub shielding txheej los yog teeb liab kab. Qhov tam sim no yuav superimpose rau qhov kev ntsuas qhov tseem ceeb, ua rau muaj kev cuam tshuam loj heev thiab ua rau tsis ruaj khov, hloov pauv, lossis qhov ntsuas tsis raug. Rau cov cim tsis muaj zog ntawm electromagnetic flowmeters, xws li los ntawm ob peb microvolts mus rau ob peb millivolts, xws li cuam tshuam yog kev puas tsuaj. Cov Lus Cim Tshwj Xeeb: Cov txheej thaiv thaiv ntawm cov teeb liab cables rau cov cuab yeej no yuav tsum tau muab tso rau hauv qhov chaw tswj hwm sab (ua haujlwm hauv av); Txawm li cas los xij, txij li lub teeb liab Circuit Court nws tus kheej (xws li qhov tsis zoo ntawm lub thermocouple lossis kab teeb liab ntawm lub flowmeter) twb tau cog rau ntawm qhov chaw, qhov chaw tswj yuav tsum nyob twj ywm insulated, thiab ntxiv grounding yog nruj me ntsis txwv tsis pub.
Lub hauv paus ntsiab lus ntawm "tsuas yog ib qho kev taw qhia hauv av ib lub voj voog": 1) HG/T 20513-2014, Clause 5.1.2, Cov Lus Qhia Piav Qhia: Txhua lub ntsuas ntsuas lub voj yuav tsum muaj qhov taw qhia hauv av nkaus xwb. 2) GB 50093-2013, Nqe Lus 10.2.8 tsuas muaj ib qho kev taw qhia Circuit Court. Cov lus piav qhia: Cov nqe lus no yog tsim los tiv thaiv cov teeb liab cuam tshuam los ntawm qhov muaj peev xwm sib txawv . 3) SH/T 3551-2024, Clause 10.4.2: Grounding ntawm cov teeb liab circuits yuav tsum tau txais ib txoj hauv kev hauv av.
GB 50093-2013 Code rau Kev Tsim Kho thiab Kev Txais Kev Ua Haujlwm Zoo ntawm Automation Instrumentation Engineering, Clause 10.2.9: Thaum siv cov thermocouples hauv av thiab cov twj paj nruag uas twb muaj cov ntsiab lus hauv av, yuav tsum tsis muaj av ntxiv rau ntawm cov khoom ntsuas sab.
Electromagnetic flowmeters yuav tsum tau ua hauv av los xyuas kom meej tias lub raj ntsuas, cov kua dej, thiab cov electrodes nyob ntawm tib lub peev xwm, yog li muab cov teeb liab ruaj khov siv thiab txo cov kev cuam tshuam ntau tshaj - hom. Txij li thaum electromagnetic flowmeters yog qhov tshaj tawm- cov cuab yeej siv raws li electromagnetic induction, lawv cov electrodes ntes cov hluav taws xob hluav taws xob tsim tawm thaum cov kua txiav los ntawm cov kab sib nqus. Yog tias cov kua dej muaj peev xwm hloov tau, qhov kev kuaj pom yuav tsis ruaj khov. Yog li ntawd, lub ntsiab lus equipotential no yuav tsum raug yuam kom tsim los ntawm - qhov chaw siv lub voj hauv av, hauv av electrode, lossis txuas cov yeeb nkab. Kev tsim nyog hauv av ntawm electromagnetic flowmeter yog qhov tsim nyog ua ntej rau kev ntsuas kom raug.
Yog hais tias qhov system tsim yuav tsum tau lub teeb liab yuav tsum tau grounded nyob rau hauv qhov chaw thaum lub sij hawm txais cov cuab yeej yuav tsum tau grounded nyob rau hauv lub tswj chav tsev (xws li, vim hais tias ntawm tej yam system architecture yuav tsum), tsuas yog grounding ob xaus tsis txaus. Yuav tsum tau siv "kev cais hluav taws xob" (xws li kev tiv thaiv kev nyab xeeb lossis lub teeb liab cais tawm) yuav tsum tau siv.
