Immersing lub tshuab hluav taws xob siv hluav taws xob rau hauv cov kua hluav taws xob zoo li cov kua qaub lossis ntsev xav tau kev cais hluav taws xob kiag li. Txhua qhov xau tam sim no tuaj yeem ua rau plating tsis xws luag, stray tam sim no corrosion, lossis cov neeg ua haujlwm poob siab. PTFE cov khoom tshwj xeeb hluav taws xob rwb thaiv tsev muab qhov tseem ceeb thaiv qhov no. Yog tsis muaj kev ntseeg siab insulating sheath, lub immersion rhaub nws tus kheej dhau los ua qhov chaw ntawm cov txheej txheem sib kis thiab kev nyab xeeb. Kev nkag siabPTFE hluav taws xob rwb thaiv tsev immersion rhaubkev ua tau zoo pib nrog cov cuab yeej tseem ceeb: lub zog dielectric.
Dielectric zog yog dab tsi thiab vim li cas nws tseem ceeb?
Lub zog dielectric yog qhov siab tshaj plaws hluav taws xob uas cov khoom siv tuaj yeem tiv taus yam tsis muaj kev tawg thiab ua cov khoom siv hluav taws xob. Nws feem ntau qhia hauv kilovolts ib millimeter (kV / mm). Thaum cov hluav taws xob hluav taws xob hla ib qho insulator tshaj nws lub zog dielectric, electrons raug yuam los ntawm cov khoom, tsim ib txoj hauv kev conductive. Qhov kev puas tsuaj no tuaj yeem ua rau muaj kev puas tsuaj sai sai.
Rau PTFE, luv luv - lub sij hawm dielectric zog yogTsawg kawg yog 15 kV / mm. Tus nqi no deb tshaj qhov kev khiav hauj lwm voltages rau immersion heaters, uas nyob ntawm 110 V rau 480 V AC. Txawm tias ntawm 480 V, qhov yuav tsum tau rwb thaiv tsev thickness los tiv thaiv kev tawg yog tsawg dua 0.05 hli, piv txwv li cov khoom zoo meej. Hauv kev xyaum, PTFE sheaths yog tsim nrog thicknesses ntawm 1-3 hli, muab ib tug loj kev nyab xeeb margin.
Nws yog ib qho tseem ceeb kom nco ntsoov tias 15 kV / mm daim duab siv rau luv luv -lub sij hawm, DC, los yog luv heev AC raug. Rau qhov kev pabcuam AC txuas ntxiv ntawm lub zog zaus (50/60 Hz), lub sijhawm ntev - lub zog dielectric qis dua vim muaj qhov tso tawm ib nrab thiab kev laus. Txawm li cas los xij, txawm tias kev kwv yees qhov chaw ua haujlwm tsis tu ncua ntawm PTFE lub zog ntawm 4-6 kV / mm, tseem ntau tshaj qhov tsim nyog rau cov qauv ntsuas hluav taws xob.
Yuav ua li cas PTFE tiv thaiv tam sim no leakage nyob rau hauv Conductive Baths
Ntau daim ntawv thov tso rau hauv lub rhaub dej suav nrog cov kua ua kua: cov tshuaj electroplating (piv txwv li, npib tsib xee, tooj liab, chromium), da dej anodizing (sulfuric lossis phosphoric acid), thiab cov kev daws teeb meem (hydrochloric lossis nitric acid). Cov kua dej no muaj kev tiv thaiv tsawg li ob peb ohm-cm. Ib qho kev ua txhaum cai ntawm lub tshuab hluav taws xob rwb thaiv tsev tsim hluav taws xob ncaj qha los ntawm cov xaim hluav taws xob sab hauv mus rau hauv da dej.
A PTFE hluav taws xob rwb thaiv tsev immersion rhaubtso siab rau peb lub zog hluav taws xob tseem ceeb los tiv thaiv xws li to:
High dielectric zog- Tiv thaiv kom tsis txhob muaj hluav taws xob tawg los ntawm cov sheath thickness.
Siab ntim resistivity- Tiv thaiv tam sim no ntws los ntawm cov khoom siv ntau.
High nto resistivity- Tiv thaiv kev taug qab tam sim no nyob rau sab nrauv, tshwj xeeb tshaj yog nyob rau hauv cov dej ntub dej lossis cov kab mob sib kis.
PTFE nthuav tawm qhov ntim tiv thaiv ntau dua 10¹⁸ ohm-cm, yog ib qho txiaj ntsig zoo tshaj plaws ntawm cov khoom siv insulating. Rau kev sib piv, cov insulators zoo ib yam li nylon muaj ntim resistivity nyob ib ncig ntawm 10¹²–10¹⁴ ohm-cm. Qhov tsis tshua muaj siab tiv thaiv ntawm PTFE txhais tau hais tias txawm tias nyias nyias, zoo li PTFE txheej nthuav tawm yuav luag tsis muaj qhov tsis txaus ntseeg rau tam sim no ntws.
Lub txim ntawm rwb thaiv tsev tawg
Cov kev paub dhau los qhia tau hais tias thaum PTFE rwb thaiv tsev tsis ua haujlwm, cov txiaj ntsig tsis tshua muaj kev hloov maj mam. Pinholes, kab nrib pleb, los yog nyias me ntsis nyob rau hauv lub sheath cia tam sim no mus rau hauv lub da dej. Nyob ntawm daim ntawv thov, ntau yam teeb meem tshwm sim:
Plating tsis xws luag- Hauv electroplating tso tsheb hlau luam, stray tam sim no los ntawm lub rhaub hloov pauv tam sim no ntawm cov khoom ua haujlwm. Qhov tshwm sim tuaj yeem yog qhov tsis sib xws ntawm cov nyiaj tso nyiaj tsis sib xws, qhov kev loj hlob nodular, lossis cov nyiaj kub kub.
Fais fab tam sim no corrosion- Cov dej ntws tam sim no pom nws txoj hauv kev mus rau hauv av los ntawm lwm cov khoom siv hlau hauv lub tank -cov khoom siv hluav taws xob, cov phab ntsa tank, lossis cov khib nyiab. Qhov no accelerates corrosion ntawm cov ntsiab lus tawm tam sim no.
Cov neeg ua haujlwm poob siab- Yog hais tias lub da dej yog grounded (raws li muaj nyob rau hauv ntau txoj kab plating), ib tug to tam sim no tsim ib tug voltage gradient nyob rau hauv cov kua. Tus neeg teb xov tooj kov lub da dej thiab cov khoom hauv av tuaj yeem tau txais kev poob siab.
Lub tshuab ua kom sov ua ntej pib ua tsis tiav- Cov dej ntws tam sim no feem ntau ua rau cov cua sov hauv cheeb tsam ntawm qhov hluav taws xob tawg, uas ntxiv degrades PTFE thiab nws thiaj li ua rau qhib Circuit Court lossis hauv av txhaum.
Hauv kev xyaum, cov cim ceeb toom ntxov tshaj plaws ntawm kev cuam tshuam kev cuam tshuam feem ntau yog txheej txheem - cuam tshuam es tsis yog lub tshuab cua sov - ntsig txog. Cov neeg ua haujlwm plating tuaj yeem pom qhov tsis zoo ntawm cov nyiaj tso cia ntev ua ntej cov khoom siv tiv thaiv hluav taws xob mus ncig.
Kev sib piv ntawm PTFE rwb thaiv tsev nrog lwm cov ntaub ntawv
PTFE tsis yog tsuas yog fluoropolymer siv rau immersion rhaub rwb thaiv tsev. PFA (perfluoroalkoxy) thiab FEP (fluorinated ethylene propylene) muaj cov khoom siv tshuaj thiab hluav taws xob zoo sib xws. Txawm li cas los xij, PTFE tseem ceeb tshaj plaws tau teev tseg vim nws qhov sib npaug ntawm kev ua haujlwm hluav taws xob, nqi, thiab muaj. Cov lus hauv qab no sib piv dielectric zog thiab ntim resistivity rau cov ntaub ntawv insulating uas siv nyob rau hauv immersion heaters.
| Insulating khoom | Dielectric zog (kV/mm, luv-term) | Volume Resistivity (ohm{0}}cm) | Qhov siab tshaj plaws Kev Pabcuam Nruam Kub (degree) |
|---|---|---|---|
| PTFE | 15 – 20 | > 10¹⁸ | 260 |
| PFA | 15 – 20 | > 10¹⁸ | 260 |
| FEP | 15 – 20 | > 10¹⁸ | 200 |
| ETFE | 15 – 18 | 10¹⁶ – 10¹⁷ | 150 |
| Polypropylene | 18-22 (tab sis degrades chemically) | 10¹⁵ – 10¹⁷ | 80 (hauv dej) |
| Silicone roj hmab | 14 – 20 | 10¹⁴ – 10¹⁵ | 180 |
Nco tseg: Dielectric zog qhov tseem ceeb yog rau cov qauv huv, qhuav nyob rau hauv lub chaw kuaj mob. Tiag -Kev ua haujlwm hauv ntiaj teb nyob ntawm qhov kub, av noo, thiab tshuaj lom neeg raug.
Nws yog ib qho tsim nyog sau cia tias thaum polypropylene thiab ETFE muaj qhov sib piv lossis ntau dua dielectric zog nyob rau hauv qhuav qhuav, lawv tsis muaj PTFE cov tshuaj tiv thaiv thiab siab - kub stability. Hauv cov tshuaj lom neeg da dej ntawm qhov kub siab, PTFE thiab nws cov fluoropolymer kwv tij PFA thiab FEP yog tib txoj kev xaiv.
Yog vim li cas High Dielectric zog ib leeg tsis txaus
Txawm hais tias PTFE lub zog dielectric ntawm ntau dua lossis sib npaug ntawm 15 kV / mm yog qhov tshwj xeeb, kev cia siab rau cov cuab yeej no rau kev nyab xeeb hluav taws xob yuav ua tsis tiav. Ob peb lub tswv yim zoo txo qhov kev ua tau zoo ntawm rwb thaiv tsev:
Kub- Dielectric zog ntawm PTFE txo nrog nce kub. Ntawm 200 degree, nws yuav poob mus rau kwv yees li 50-60% ntawm chav tsev-tus nqi kub.
Kev nqus dej noo- PTFE yog hydrophobic thiab absorbs zoo tsis muaj dej. Txawm li cas los xij, yog tias muaj kev sib kis los yog cov kab nrib pleb tshwm sim, cov dej noo tuaj yeem tsim txoj hauv kev uas hla cov rwb thaiv tsev ntau.
Kev puas tsuaj- Kos, puas, lossis khoov tsis zoo tuaj yeem txo qis hauv zos, ua rau muaj kev ntxhov siab hauv hluav taws xob.
Kev laus thiab kev tso tawm ib nrab- Ntau xyoo ntawm kev ua haujlwm AC, ib nrab tso tawm hauv cov voids microscopic maj mam erodes PTFE, txo nws cov dielectric zog.
Cov kev paub dhau los qhia tau hais tias feem ntau cov rwb thaiv tsev tsis ua haujlwm hauv PTFE immersion heaters tsis tshwm sim los ntawm qhov hluav taws xob tawg los ntawm cov khoom tsis zoo. Hloov chaw, lawv tshwm sim los ntawm kev puas tsuaj, tshuaj tua kab mob ntawm kev sib tsoo, lossis thermal degradation. Lub siab dielectric zog ntawm PTFE muab ib tug dav dav kev nyab xeeb margin, tab sis nws tsis tshem tawm qhov yuav tsum tau rau kom zoo tuav, installation, thiab txij nkawm.
Lub luag haujlwm ntawm Kev Tsim Qauv: Kev Siv Hauv av thiab GFCI Kev Tiv Thaiv
Txawm nrog qhov zoo tshaj plawsPTFE hluav taws xob rwb thaiv tsev immersion rhaubtsim, kev txhaum tseem tuaj yeem tshwm sim. Yog li, kev tsim qauv tsim nyog yuav tsum suav nrog cov kev tiv thaiv theem nrab:
Cov khoom siv hauv av- Lub tshuab cua sov cov khoom siv hlau sab nraud (flange, mounting bracket, lossis av xaim) yuav tsum tau txuas nrog rau qhov chaw hauv av. Qhov no ua kom ntseeg tau tias txhua qhov ntws tawm tam sim no muaj qhov tsawg -impedance txoj kev rov qab mus rau qhov chaw, tripping overcurrent devices.
Ground fault circuit interrupter (GFCI) lossis kev tiv thaiv hauv av- GFCI cov cuab yeej kuaj pom qhov tsis sib xws ntawm kab thiab nruab nrab tam sim no tsawg li 5-30 mA. Hauv qhov chaw ntub dej xws li plating tank, kev tiv thaiv hauv av yog qhov tseem ceeb rau kev nyab xeeb ntawm cov neeg ua haujlwm.
Periodic rwb thaiv tsev kuj kuaj – A megohmmeter applied between the heater leads and ground (with the heater dry and de-energized) can detect degrading insulation before a failure occurs. Typical acceptable values are >1 megohm rau low-voltage heaters, ho tshiab PTFE heaters feem ntau ntsuas nyob rau hauv lub gigaohm ntau.
Nws yog ib qho tseem ceeb kom nco ntsoov tias tsis muaj rwb thaiv tsev zoo tag nrho, thiab tag nrho cov ntaub ntawv nws thiaj li degrade. Kev tiv thaiv hauv av thiab GFCI muab cov txheej txheem thib ob ntawm kev tiv thaiv uas tseem muaj txiaj ntsig txawm tias tom qab PTFE rwb thaiv tsev tau raug cuam tshuam.
Cov txiaj ntsig zoo rau kev xaiv lub rhaub thiab ua haujlwm
Thaum qhia txog lub rhaub dej kub rau lub da dej conductive, hluav taws xob rwb thaiv tsev ntawm PTFE ncaj qha cuam tshuam rau ntau qhov kev txiav txim siab tsim:
Sheath thickness- Thicker sheaths muab ntau dua dielectric zog thiab ntau dua txhua yam robustness tab sis txo tshav kub hloov. Qhov sib npaug yuav tsum raug ntaus raws li kev khiav hauj lwm voltage thiab tshuaj ib puag ncig.
Kev ntsuas hluav taws xob- Rau tib lub tshuab rhaub hluav taws xob, qhov hluav taws xob ntau dua txo qhov tam sim no, uas tuaj yeem txo qhov kev poob qis hauv kev coj. Txawm li cas los xij, qhov hluav taws xob ntau dua ua rau lub zog hluav taws xob muaj kev ntxhov siab ntawm cov rwb thaiv tsev. Feem ntau PTFE immersion rhaub yog ntsuas rau 240 V lossis 480 V AC, nrog 480 V yuav tsum tau ua tib zoo saib xyuas cov ntaub qhwv zoo.
Kev tshuaj xyuas thiab hloov lub sijhawm- Cov chav da dej nrog cov khoom siv hluav taws xob siab thiab cov tshuaj lom neeg muaj zog tiv thaiv kev ntsuas hluav taws xob ntau zaus. Ib qho kev poob qis ntawm cov rwb thaiv tsev tsis zoo qhia tau tias yuav tsum tau teem caij hloov lub rhaub.
Hauv kev xyaum, ntau tus neeg ua haujlwm lub tank xav tias PTFE- lub tshuab hluav taws xob sheathed yog hluav taws xob "tsis pom" rau da dej. Qhov no yog qhov tseeb tsuas yog ntev li ntev raws li qhov rwb thaiv tsev tseem nyob ruaj khov thiab qhuav. Ib qho kev ua txhaum cai -txawm tias ib lub tshuab ntsuas me me- tam sim ntawd txuas lub tshuab hluav taws xob hluav taws xob rau hauv da dej.
Xaus
PTFE's superior hluav taws xob rwb thaiv tsev zog-nrog rau lub zog dielectric tsawg kawg yog 15 kV / mm thiab ntim resistivity ntau tshaj 10¹⁸ ohm-cm-yog qhov tseem ceeb rau kev nyab xeeb thiab tsis muaj paug- tso cua sov dawb. Cov khoom no tiv thaiv cov xaim tam sim no los ntawm cov xaim hluav taws xob sab hauv mus rau hauv cov khoom siv tshuaj da dej, tsis txhob plating qhov tsis xws luag, stray tam sim no corrosion, thiab kev poob siab.
Txawm li cas los xij, cov khoom siv zoo heev ib leeg tsis tuaj yeem lav kev nyab xeeb. CovPTFE hluav taws xob rwb thaiv tsev immersion rhaubtso siab rau cov ntaub qhwv kom zoo, ua tib zoo tsim kom tsis txhob muaj pinholes, thiab txhim kho kom raug los tiv thaiv kev puas tsuaj. Tsis tas li ntawd, txawm tias qhov rwb thaiv tsev zoo tshaj plaws tuaj yeem ua rau tsis zoo, ua rau hauv av thiab kev tiv thaiv hauv av uas tseem ceeb ntawm txhua qhov kev tso cua sov.
Kev nyab xeeb hluav taws xob hauv qhov chaw ntub dej yuav tsum muaj cov ntaub ntawv zoo heev thiab tsim kom zoo. PTFE muab thawj kab ntawm kev tiv thaiv-ib qho kev tiv thaiv hluav taws xob tshwj xeeb. Cov cuab yeej tiv thaiv thib ob muab qhov thib ob. Ua ke, lawv ua kom cov cua sov tso rau hauv lub tshuab ua kom muaj kev ntseeg siab rau ntau xyoo hauv qee qhov nyuaj tshaj plaws tshuaj thiab hluav taws xob ib puag ncig pom hauv kev lag luam.
