Dab tsi yog cov ntsiab lus tseem ceeb ntawm cov dej noo hauv qhov txias txias uas ua rau muaj kev txhaum hauv av hauv PFA rhaub ntawm 480 VAC?

Hauv PFA lub rhaub dej, qhov hluav taws xob txiav tawm ntawm cov tub ntxhais hlau nrog lub hwj chim cable yog nyob rau hauv qhov chaw txias saum cov kua kab. Nyob rau tib lub sij hawm noo noo yuav tsim nyob rau hauv lub txias cheeb tsam no los ntawm kev nkag mus, condensation los yog tsis seals. Ntawm qhov tseem ceeb ntawm cov dej noo nws tsim txoj hauv kev los ntawm qhov hluav taws xob siab (480 VAC) mus rau hauv av thiab boom, koj muaj qhov txhaum hauv av. Cov ntsiab lus tseem ceeb ntawm cov dej noo yog 0.5 - 1.0 g ntawm dej dawb nyob rau hauv ib qho chaw txias txias (ntim 100 - 300} cm3). Qhov no sib haum mus rau ib tug txheeb ze humidity ze rau 100% thiab pom condensation. Cov xau tam sim no los ntawm cov yeeb yaj kiab ya raws ntawm 480 VAC yog 5-30 mA, txaus los mus rau GFCI lossis ua rau muaj kev ceeb toom hauv av. Cov dej noo tsis tas yuav tsum tau ua kom tiav npog ntawm cov terminals, ib zaj duab xis ntawm 0.1-0.5 hli bridging lub davhlau ya nyob twg insulator yog txaus. Desiccants los tiv thaiv lossis tshem tawm cov dej noo yog qhov tseem ceeb rau kev ntseeg siab ntawm lub tshuab hluav taws xob siab.

Kev sib raug zoo ntawm noo noo tsub zuj zuj thiab to tam sim no
Cov dej ntws tam sim no I_leak=V / R, qhov twg R yog qhov tsis kam ntawm cov dej noo. Qhov dav dav dav dav dav dav ntawm 10 hli muab cov yeeb yaj kiab dej tiv thaiv nyob ntawm qhov zoo ntawm cov dej. Cov dej condensed los ntawm huab cua huab cua muaj qhov ua tau zoo ntawm 10-100 µS / cm (resistivity 0.01-0.1 MΩ cm). Hais 0.1 hli tuab, 10 hli x 5 hli cheeb tsam. R=ρL / A=0.05 MΩ•cm x 1 cm / 0.5 cm2=0.1 MΩ . I_leak=480/100,{23}} mA @ 480 VAC, qis dua qhov nruab nrab 30 mA GFCI mus ncig, tab sis kuaj tau . Yog tias cov dej khaws cov ionic impurities (cov ntsev los ntawm cov khoom siv hluav taws xob, cov khoom siv corrosion), kev ua haujlwm nce mus txog 1000-10000 µS/cm (resistivity 0.0001-0.001 MΩ*cm), ua rau I_leak=480 / {{31.} A tuag Dab tsi yog qhov tseem ceeb hauv qhov tseem ceeb ntawm cov dej noo tsis yog qhov dej ntau, tab sis nws cov purity ionic.

The "critical moisture content" is defined as the quantity of water which, mixed with typical ionic contamination (5–50 µg of chlorides, sulphates, or salt) decreases resistance below 1 MΩ (leakage >0.5 mA ntawm 480 VAC). Qhov no tshwm sim ntawm li 0.5 g ntawm dej dawb nyob rau hauv ib tug 200 cm3 txias seem txaus los tsim ib tug nruam txheej ntawm lub davhlau ya nyob twg thaiv.

Critical Moisture Content by Voltage and Contamination Level Voltage (VAC) Insulation Resistance Trip Threshold (MΩ) Leakage Current at Trip (mA) Critical Free Water (g) in 200 cm³ Required Water Conductivity (µS/cm) Contamination Level (ppm NaCl equivalent) 120 1.0 120 2.0 >500 >300 240 1.0 240 1.5 >300 >200 480 1.0 480 1.0 >200 >100 480 (GFCI 30 mA) 16 30 0.3 >1,000 >500 480 (GFCI 5 mA) 96 5 0.1 >3,000 >1,500 480 (equipment protection) 10 48 0.5 >500 >300 690 1.0 690 0.8 >150 >80 1,000 1.0 1,0
Rau ib tug raug 480 VAC system nrog ib tug 30 mA GFCI qhov yuav tsum tau noo noo cov ntsiab lus yog 0.3-0.5 g ntawm dej dawb nrog me me paug (300-500 ppm NaCl sib npaug). Yog tias qib qis dua 0.3 g, GFCI yuav tsis mus. Yog hais tias nws yog tshaj 0.5 g, qhov teeb meem tsis txaus ntseeg tuaj yeem tshwm sim.

Qhov chaw ntawm Moisture hauv Cold Section
Muaj peb txoj hauv kev rau kev nkag mus rau hauv qhov txias txias:

Permeation los ntawm PFA: Qhov txias yog tsis nquag rhuab ntawm 480 VAC (nws yog saum cov kua kab). Nws ua haujlwm ntawm 40-80℃. Dej vapor flux los ntawm phab ntsa PFA 0.1-0.5 g/m2·hnub. Rau qhov chaw txias ntawm 0.05 m 2 qhov no yog 0.005-0.025 g hnub -1 . Tshaj li 1 xyoo (365 hnub) noo noo ntawm 2-9 g tuaj yeem tsim-txog-ntau tshaj qhov kev txwv.

Condensation los ntawm huab cua nyob ib puag ncig: Yog tias qhov txias txias txias mus rau qhov dej lwg (xws li nres thaum hmo ntuj), huab cua ntub dej condenses sab hauv. Ib qho kev tshwm sim condensation tuaj yeem tso ntawm 0.5 mus rau 2 g dej.

Cov ntsaws ruaj ruaj: Ua tsis tiav O-rings lossis gaskets ua rau cov dej nkag mus ntau. Kev xau ntawm 1 poob ib teev (0.05 g / h) pab txhawb 1.2 g / hnub

Kev Tshawb Fawb & Kev Tiv Thaiv
Cov av noo sensor lossis conductance sojntsuam tuaj yeem muab tso rau hauv qhov chaw txias kom paub cov ntsiab lus tseem ceeb ntawm cov dej noo ua ntej yuav muaj qhov txhaum hauv av. Tus txheeb ze av noo siab tshaj 80% los yog ib tug conductivity siab tshaj 10 µS / cm ntawm ob tus pins cais activates lub tswb los ntawm cov txij nkawm yuav ua tau ua ntej lub GFCI mus ncig ua si.

Cov tswv yim tiv thaiv:

Desiccant pob: Muab ib qho molecular sieve (zeolite) hauv qhov txias txias. Hloov txhua 6-12 lub hlis. Ib pob 10 g yuav tsum tau 2-3 g dej kom txaus.

Nitrogen ntxuav: nruam ntws ntawm qhuav N 2 los ntawm qhov txias txias ntawm 0.1 bar. RH <10% Khaws thiab tshem tawm cov vapors nkag mus.

Hermetic foob. Siv lub khob-rau-hlau lossis ceramic-rau-hlau foob rau lub davhlau ya nyob twg feedthrough, tshem tawm cov polymer to.

Txias seem cua sov Khaws seem txias ntawm 50-60 degree, saum toj no dew point, nrog me me cua sov (5-10 W) los tiv thaiv condensation.

Piv txwv teb
Lub 480 VAC PFA rhaub nyob rau hauv ib qho av plating kab (80% RH ambient) tripped txhua lub limtiam ntawm teeb meem GFCI tom qab 6 lub hlis ua haujlwm. Kev tshuaj xyuas pom 0.8 g dej dawb hauv cheeb tsam txias (los ntawm qhov hnyav). Dej conductivity yog 800 µS / cm (los ntawm absorbed acid mists). Lub tshuab cua sov tau qhuav tawm thiab siv lub pob desiccant. Cov kev mus ncig tau nres rau 8 lub hlis thiab rov qab los. Cov chaw tau muab tshem tawm tas li nrog N 2 ntawm 0.5 L / min. Tsis muaj kev mus ncig ntxiv rau 3 xyoos.

Cov ntsiab lus: Av txhaum Vim 0.3-0.5 g Dej Dawb ntawm 480 VAC
Rau lub tshuab cua sov PFA, qhov xav tau cov dej noo nyob rau hauv qhov chaw txias rau hauv av txhaum ntawm 480 VAC yog 0.3-0.5 g ntawm dej dawb nrog cov kab mob ionic (300-500 ppm ntsev sib npaug). Cov dej noo tsim cov txheej txheem ntawm lub davhlau ya nyob twg thaiv, txo cov rwb thaiv tsev tiv thaiv kom tsawg dua 1 MΩ thiab tsim kom muaj qhov xau tam sim no ntau dua 5-30 mA, tripping GFCI.Is lossis lub tswb txhaum hauv av. Moisture ingress tshwm sim los ntawm permeation (2-9 g / xyoo), condensation (0.5-2 g / qhov tshwm sim) los yog foob xau. Txhim kho cov pob khoom desiccant, tshem tawm nitrogen los yog ntxiv cov cua sov kom tsis txhob muaj qhov ua txhaum hauv av. Saib cov av noo los yog conductance rau ya raws ua ntej nws mus rau theem tseem ceeb. Ob peb tee dej ntawm 480 VAC tuaj yeem tua koj cov txheej txheem. Tsis txhob ntub qhov txias txias - lossis lwm yam. Kev ntsuas dej noo, kev zam tsis raug Qhov txias yog qhov tsis zoo. Saib xyuas nws.