Cov transformers ua lub luag haujlwm tseem ceeb hauv cov kab ke faib hluav taws xob, nce lossis nqis voltage kom tau raws li qhov xav tau ntawm ntau yam kev siv. Txhawm rau kom ntseeg tau tias kev ua haujlwm zoo thiab txhim khu kev qha ntawm cov transformers, National Electrical Code (NEC) tsim cov kev cai tshwj xeeb rau lawv txoj kev tiv thaiv, kev txiav tawm, kev sib txuas hauv av, kev ua pa, thiab kev cim. Tsab xov xwm no yuav muab cov lus qhia dav dav ntawm NEC cov kev cai ntsig txog kev tiv thaiv transformer, suav nrog kev tiv thaiv overcurrent, kev txiav tawm txhais tau tias, kev sib txuas hauv av, kev ua pa, thiab cov cim npe.

Kev Tiv Thaiv Overcurrent rau Transformers (NEC 450.3)

Kev tiv thaiv overcurrent thawj zaug

Yuav tsum muaj kev tiv thaiv overcurrent thawj zaug rau cov transformers uas muaj lub zog hluav taws xob thawj zaug ntawm 1,000 volts lossis tsawg dua, tshwj tsis yog tias lub transformer ua tau raws li ib qho ntawm cov kev zam uas teev nyob rau hauv NEC 450.3 (A). Lub cuab yeej tiv thaiv overcurrent thawj zaug (OCPD) yuav tsum tau ntsuas lossis teeb tsa tsis pub ntau tshaj 125% ntawm lub transformer qhov ntsuas tam sim no thawj zaug. Rau cov transformers uas muaj ntau lub windings thawj zaug, txhua lub winding yuav tsum muaj nws tus kheej OCPD.

Kev tiv thaiv theem ob overcurrent

Yuav tsum muaj kev tiv thaiv overcurrent thib ob rau cov transformers uas muaj qhov hluav taws xob thib ob ntawm 1,000 volts lossis tsawg dua, tshwj tsis yog tias lub transformer ua tau raws li ib qho ntawm cov kev zam uas teev nyob rau hauv NEC 450.3 (B). Lub OCPD thib ob yuav tsum tau ntsuas lossis teeb tsa tsis pub ntau tshaj 125% ntawm lub transformer qhov ntsuas tam sim no thib ob. Hauv cov xwm txheej uas qhov ntsuas tam sim no thib ob tsawg dua 9 amperes, OCPD tuaj yeem ntsuas lossis teeb tsa tsis pub ntau tshaj 167% ntawm lub transformer qhov ntsuas tam sim no thib ob.

Cov kev zam thiab cov xwm txheej tshwj xeeb

NEC 450.3 muab ntau qhov kev zam rau qhov yuav tsum tau tiv thaiv thawj thiab thib ob overcurrent. Cov kev zam no siv rau qee qhov kev teeb tsa transformer, xws li autotransformers, thiab rau transformers nrog cov yam ntxwv tshwj xeeb, xws li cov uas muaj impedance siab lossis cov uas siv hauv cov voj voog tswj lub cev muaj zog. Nws yog ib qho tseem ceeb uas yuav tsum tau saib xyuas NEC 450.3 (A) thiab (B) kom txiav txim siab seb lub transformer puas ua tau raws li ib qho ntawm cov kev zam.

Cov Txhais Tau Tias Transformer Disconnecting (NEC 450.14)

Qhov chaw ntawm kev txiav cov cuab yeej

Cov cuab yeej txiav hluav taws xob rau lub transformer yuav tsum nyob rau hauv qhov pom ntawm lub transformer lossis nyob rau hauv qhov chaw nyob deb. Yog tias nyob rau hauv qhov chaw nyob deb, cov cuab yeej txiav hluav taws xob yuav tsum xauv tau raws li NEC 110.25.

Cov kev cai nkag mus tau yooj yim

Cov cuab yeej txiav transformer yuav tsum yooj yim nkag mus tau thiab yuav tsum tsis txhob nyob deb tshaj 6.5 feet (2.0 m) saum pem teb lossis lub platform ua haujlwm, tshwj tsis yog ua tau raws li ib qho ntawm cov kev zam uas teev nyob rau hauv NEC 450.14 (A).

Cov cim tas mus li

Cov cuab yeej txiav transformer yuav tsum muaj cim tas mus li los qhia tias lub transformer uas lawv tswj hwm. Cov cim yuav tsum pom tseeb thiab yuav tsum muaj cov ntaub ntawv hauv qab no:

• Kev txheeb xyuas Transformer (piv txwv li, "Transformer T1")
• Transformer voltage thiab tam sim no ratings
• Qhov chaw ntawm lub transformer (yog tias tsis pom qhov kev txiav tawm)

Kev Tiv Thaiv Transformer (NEC 450.10)

Kev sib txuas ntawm cov transformer enclosures

Cov thawv transformer yuav tsum tau grounded raws li NEC 250.4, uas tsim cov kev cai dav dav rau grounding thiab bonding. Tus neeg xyuas av yuav tsum tau loj raws li NEC 250.66 thiab yuav tsum tau txuas nrog lub thawv transformer siv lub grounding terminal lossis bus uas teev tseg.

Kev sib txuas ntawm cov hluav taws xob theem nrab ntawm transformer

Cov transformer secondary circuits yuav tsum tau grounded raws li NEC 250.20 thiab 250.30. Txoj kev grounding nyob ntawm lub transformer lub secondary voltage thiab hom hluav taws xob (piv txwv li, cais derived system lossis tsis cais derived system). Feem ntau, tus conductor grounding yuav tsum tau loj raws li NEC 250.66 thiab yuav tsum tau txuas nrog lub secondary circuit siv lub grounding terminal lossis bus uas teev tseg.

Kev Ua Pa thiab Txias ntawm Transformer (NEC 450.9)

Cov kev cai ntawm qhov cua rau cov transformer vaults

Cov qhov cua nkag ntawm lub transformer yuav tsum muaj qhov qhib kom cua sov tawm ntawm cov transformers. Cov qhov cua nkag yuav tsum tau ua raws li NEC 450.45 thiab yuav tsum tau muab tso rau hauv qhov chaw kom muaj cua nkag hla lub qhov cua nkag. Qee zaum, yuav tsum tau siv tshuab cua nkag kom tswj tau qhov kub thiab txias hauv lub qhov cua nkag.

Cov kev cai txias rau cov transformers uas muaj kua dej

Cov transformers uas muaj kua yuav tsum tau muab cua txias txaus kom tiv thaiv kev kub dhau thiab xyuas kom ua haujlwm zoo. Txoj kev txias nyob ntawm qhov loj ntawm lub transformer thiab hom kua siv rau kev rwb thaiv tsev thiab txias (piv txwv li, roj av, kua silicone, lossis kua uas tsis yooj yim hlawv). Cov transformers uas muaj kua yuav raug txias los ntawm kev sib hloov cua sov ntuj, kev txias cua, lossis cov khoom hloov cua sov ua kua. Lub kaw lus txias yuav tsum tau tsim raws li cov lus qhia ntawm cov chaw tsim khoom transformer thiab yuav tsum muaj peev xwm tswj tau qhov kub ntawm kua kom nyob hauv qhov txwv uas tau txais.

Cov Cim Npe Transformer (NEC 450.11)

Cov ntaub ntawv sau npe uas yuav tsum muaj

Cov ntawv cim transformer yuav tsum muaj cov ntaub ntawv hauv qab no:

• Lub npe ntawm lub chaw tsim khoom transformer
• Transformer ntsuas kilovolt-amperes (kVA)
• Zaus
• Lub zog hluav taws xob theem pib thiab theem nrab
• Impedance (yog tias 25 kVA lossis loj dua)
• Qhov chaw uas yuav tsum tau muaj rau qhov cua nkag
• Tus nqi thiab hom kua rwb thaiv tsev (rau cov transformers uas muaj kua)
• BIL qib ntawm cov hluav taws xob siab (rau cov transformers nrog cov hluav taws xob siab tshaj 1,000 volts)

Kev ruaj khov ntawm cov ntawv sau npe

Cov ntawv cim npe ntawm lub transformer yuav tsum ua los ntawm cov khoom siv ruaj khov uas tuaj yeem tiv taus qhov chaw ib puag ncig uas lub transformer tau teeb tsa. Lub npe ntawv yuav tsum tau txuas ruaj khov rau lub transformer thiab yuav tsum nyeem tau thoob plaws lub neej ntawm lub transformer.