Deionized (DI) dej muaj hluav taws xob conductivity tsawg heev -feem ntau 0.1–10 µS/cm, piv rau 500–1,000 µS/cm rau kais dej. Hauv qhov xwm txheej hauv av uas PFA sheath tau ua txhaum cai thiab cov khoom cua sov tiv tauj DI dej, qhov ntws tawm tam sim no qis dua hauv cov dej kais dej vim yog qhov muaj zog ntawm DI dej. Tus qauv 30 mA GFCI (hauv av txhaum Circuit Court cuam tshuam) yuav tsis tawm mus vim tias cov dej ntws tawm los ntawm DI dej tsuas yog 5-15 mA -tsis txaus mus txog 30 mA qhov pib. Lub tshuab hluav taws xob txuas ntxiv ua haujlwm nrog qhov ua txhaum latent, thiab cov tub ntxhais hlau corrodes maj mam dhau lub lis piam lossis hli. Thaum kawg, cov khoom siv corrosion tuaj yeem tsim txoj hauv kev, lossis cov tub ntxhais yuav tsis qhib, tab sis qhov ncua sij hawm tso cai rau da dej paug. Rau DI dej systems, GFCI mus ncig ua si pib yuav tsum yog 5-10 mA, tsis yog 30 mA. Qee qhov chaw tso cai tso cai 5 mA rau kev tiv thaiv cov cuab yeej hauv siab - cov kua dej tsis haum.

Conductivity thiab Leakage Current hauv DI Dej

Cov xau tam sim no los ntawm cov khoom cua sov (120 VAC) mus rau hauv av los ntawm DI dej yog I=V / R, qhov twg R yog qhov tsis kam ntawm txoj kev dej. Resistance R=ρ × L / A, qhov twg ρ yog resistivity (Ω·cm), L yog txoj kab ntev (cm), A yog hla -sectional cheeb tsam (cm²). Rau DI dej nrog ρ=1 MΩ·cm (1,000,000 Ω·cm), L=10 cm, A=1 cm², R=1,000,000 × 10 / 1=10,000,000 Ω. Cov dej ntws tam sim no I=120 / 10,000,000=0.012 mA- deb tshaj qhov pib. Txawm li cas los xij, yog tias thaj chaw raug loj dua (A{26}} cm²) thiab txoj kev luv dua (L{27}} cm), R=1,000,000 × 1 / 100=10,000 Ω, I=120 / 10, 000=12 mA. Qhov no yog siab dua 5 mA tab sis qis dua 30 mA. A 30 mA GFCI yuav tsis mus; 5 mA GFCI yuav tawm hauv 200-300 ms.

Raws li lub rhaub tub ntxhais corrodes, hlau ions (nickel, hlau, chromium) yaj mus rau hauv dej DI, nce conductivity. Ib qho txhaum me me uas pib ntawm 12 mA tuaj yeem loj hlob mus rau 30 mA dhau 24-48 teev. Thaum lub sij hawm ntawd, lub rhaub dej txuas ntxiv ua haujlwm, thiab cov hlau ions paug cov dej DI. Hauv semiconductor lossis kws tshuaj DI systems, txawm tias ppb qib ntawm cov hlau ions tuaj yeem ua rau cov khoom puas. A 5 mA GFCI mus ncig ua si thaum qhov txhaum tseem me me, txo qis kev sib kis.

GFCI Trip Threshold Comparison rau DI Dej

Kev txiav txim siab tshwj xeeb rau Ultra-Pure DI

Hauv ultra- dej ntshiab DI (18 MΩ·cm, siv hauv cov khoom siv hluav taws xob semiconductor), cov dej ntws tawm los ntawm lub tshuab cua sov feem ntau qis dua 1 mA. Tsis yog 30 mA lossis 5 mA GFCIs yuav mus. Rau cov tshuab zoo li no, lub rhaub dej yuav tsum tau tsim nrog ntau yam teeb meem (piv txwv li, ob chav PFA sheaths) los yog siv cov cua kub sib txawv (xws li, hauv - kab quartz rhaub). Qee qhov chaw siv tshuaj tiv thaiv kev tiv thaiv kev tiv thaiv hluav taws xob (IRM) tsis yog GFCI: lub kaw lus txuas ntxiv ntsuas kev tiv thaiv ntawm cov cua sov thiab hauv av. Thaum qhov kev tawm tsam poob qis dua qhov pib (piv txwv li, 10 MΩ rau ultra-pure DI), lub tswb nrov. IRM tuaj yeem kuaj xyuas qhov tsis raug uas yuav tsis mus rau GFCI vim tias cov dej ntws tawm tsawg dhau (0.5 mA ntawm 120 V txog 240 kΩ? Tos: I=120/10e6=0.012 mA). Qhov tseeb, 10 MΩ muab 0.012 mA, uas tuaj yeem pom los ntawm IRM rhiab tab sis tsis yog los ntawm GFCI. IRM qhov pib ntawm 1-10 MΩ yog ​​siv.

Rau feem ntau DI dej systems (tsis yog-semiconductor), resistivity yog 0.5–5 MΩ·cm, thiab 5–10 mA GFCIs yog zoo. Rau semiconductor ultra- ntshiab DI, siv IRM (alarm ntawm 1–10 MΩ) ntxiv rau ob - thaiv kev tsim kho.

Code thiab Jurisdictional Considerations

NEC (NFPA 70) Tshooj 426 yuav tsum muaj kev tiv thaiv hauv av rau cov khoom siv hluav taws xob ruaj khov. Rau cov cua sov submersible, qhov siab tshaj plaws mus txawv tebchaws yog 30 mA rau cov neeg ua haujlwm tiv thaiv. Txawm li cas los xij, Tshooj 427 tso cai rau qis dua (tsawg li 5 mA) rau kev tiv thaiv cov cuab yeej siv uas cov neeg ua haujlwm tiv thaiv tsis yog qhov kev txhawj xeeb tseem ceeb (xws li, lub tshuab cua sov hauv qhov siv tau tab sis tsis yog - neeg siv - thaj chaw sib cuag). Rau DI dej tshuab, qhia "cov cuab yeej tiv thaiv GFCI" nrog 5-10 mA mus ncig ua si pib. Hauv qee qhov kev txiav txim siab, 5 mA GFCI yuav tsum muaj rau txhua lub rhaub dej hauv cov dej uas muaj cov khoom siv qis dua 100 µS / cm. Tshawb xyuas cov lej hauv zos.

Rau retrofitting DI dej tso tsheb hlau luam uas twb muaj lawm nrog 30 mA GFCIs, hloov nrog 5 mA GFCIs. Cov chav nyob sib pauv tau (tib yam qauv) thiab raug nqi $ 50-100, tsawg dua tus nqi ntawm ib qho kev sib kis.

Piv txwv teb

Lub semiconductor fab's DI dej polishing voj siv PFA rhaub nrog 30 mA GFCIs. Tshaj li 2 xyoos, peb lub tshuab cua sov tau tsim cov av me me (tam sim no 10-20 mA) uas tsis tau mus rau 30 mA GFCIs. Cov neeg ua haujlwm pom tsis muaj lub tswb. Hlau ions (hlau, npib tsib xee) leached rau hauv DI dej, spiking resistivity ntawm 18 MΩ·cm mus rau 2 MΩ·cm thiab paug ib pawg ntawm wafers. Lub fab hloov mus rau 5 mA GFCIs. Tom qab lub cua sov faults tripped tam sim ntawd ntawm 5 mA, txwv tsis pub kis mus rau negligible theem. Lub fab kuj ntxiv IRM nrog 10 MΩ lub tswb pib rau ultra{16}}pure loops.

Xaus: Siv 5-10 mA GFCI rau DI Dej

Deionized water's low conductivity limits ground fault currents to 5–20 mA for typical breach sizes. A standard 30 mA GFCI may not trip, leaving the heater operating with a latent fault, corroding the core, and contaminating the bath. For DI water systems (0.5–5 MΩ·cm resistivity), specify a GFCI with 5–10 mA trip threshold. For ultra-pure DI water (>10 MΩ·cm), siv rwb thaiv tsev tiv thaiv kev saib xyuas tsis yog GFCI. Tus nqi ntawm 5 mA GFCI yog qhov tsawg tshaj plaws piv rau cov nqi sib kis. Tsis txhob xa lub tshuab rhaub PFA rau DI dej kev pabcuam nrog 30 mA GFCI. Qhia qis. Taug kev ntxov, mus ncig ntau zaus. Tiv thaiv da dej, tiv thaiv cov khoom.