Puas yog qhov kev tiv thaiv sab hauv hloov thaum lub fuse hloov los ntawm multimeter?
Multimeters tau siv ntau zaus hauv kev ntsuas hluav taws xob thiab hluav taws xob, thiab nws yog qhov ua rau cov fuses hlawv tawm. Ntau yam ntawm pointer multimeters xws li MF47 yog nruab nrog ib tug 0.5A (φ5 × 20) fuse, thiab nws sab hauv kuj yuav tsum tau them sai sai rau thaum hloov. Vim tias cov chaw tsim khoom multimeter suav nrog qhov tsis kam sab hauv ntawm 0.5A fuse raws li tus nqi me me thaum tsim thiab tsim cov khoom (thawj), piv txwv li, MF30 hom meter tsawg dua {{ 15}}.8Ω, MF47 hom meter tsawg dua 1Ω, thiab MF500 hom (hom kev txhim kho) Cov lus tsawg dua 0.5Ω. Tam sim no, qhov kev tiv thaiv sab hauv ntawm 0.5A fuses muag ntawm lub khw feem ntau yog nyob ib puag ncig 3Ω, thiab tsawg heev yog tsawg dua 0.5Ω.
Yog tias siv lub fuse nrog kev tiv thaiv sab hauv ntawm 3Ω, nws yuav muaj ob qhov kev cuam tshuam tsis zoo ntawm kev ntsuas ntawm multimeter: thawj qhov tsis zoo yog qhov pom tseeb, uas yog, thaum qhov kev tawm tsam ntawm multimeter nyob rau hauv R × 1Ω ntau, Nws yog feem ntau tsis tuaj yeem kho cov ohms mus rau xoom. Zero, muab qhov kev xav tsis tseeb tias 1.5V roj teeb tsis txaus, txawm tias lub roj teeb tshiab hloov lub sijhawm no, nws yuav tsis raug kho rau xoom. Qhov laj thawj yog vim li cas qhov nruab nrab ntawm qhov tsis kam ntawm RX1Ω ntau ntawm MF47 multimeter yog 16.5Ω, thiab lub zog sab hauv ntawm lub fuse txuas nrog nws. Lub roj teeb 1.5V yog nyob rau hauv voltage; Qhov cuam tshuam thib ob tsis tuaj yeem pom ncaj qha, tab sis nws yuav ua rau muaj kev ntsuas qhov yuam kev ntawm multimeter's DC tam sim no ntau. Piv txwv li, thaum hom MF47 nyob rau hauv DC tam sim no ntau ntawm 500mA, lub shunt kuj nyob rau hauv lub multimeter yog 0.6Ω. Thaum qhov kev tiv thaiv sab hauv ntawm lub fuse txuas nrog nyob rau hauv series nrog txog 3Ω, qhov yuam kev nce ntxiv yog xav tau. Txawm hais tias nyob rau hauv 50mA ntau yam, lub shunt kuj nyob rau hauv lub multimeter yog 6Ω, thiab qhov yuam kev nce kuj loj heev.
Vim li cas qhov kev tiv thaiv sab hauv ntawm tib yam 0.5A fuse txawv heev?
Vim tias cov ntaub ntawv fuses rau kev ua fuses tau muab faib ua ob hom: ib qho yog cov khoom siv qis melting uas muaj peev xwm tawg qis, xws li cov hlau lead-tin alloy los yog cov hlau lead, nrog lub zog loj; lwm yam yog ib tug siab melting point cov ntaub ntawv uas muaj siab tawg muaj peev xwm, xws li nyiaj, tooj liab, thiab lwm yam., lub resistivity yog me me, thiab qhov sib txawv ntawm ob yog yuav luag ib tug txiav txim ntawm magnitude. Qhov kev kwv yees yog vim yog kev tsim khoom, xav txog tus nqi ntawm cov ntaub ntawv, nws yog ib qho nyuaj rau yuav ib tug 0.5A fuse nrog ib tug internal resistance ntawm tsawg tshaj li 0.5Q nyob rau hauv lub lag luam. Thaum yuav khoom, ib lub multimeter yuav tsum tau siv los ntsuas nws cov kev tiv thaiv sab hauv kom tsis txhob muaj cov teebmeem saum toj no.
Tsis tas li ntawd, cov multimeter dav dav yog nruab nrog 200mA (φ5 × 20) fuse, yog tias qhov kev tiv thaiv sab hauv loj, nws tseem yuav ua rau muaj qhov yuam kev loj hauv cov ntaub ntawv tam sim no ntawm multimeter. Lub hauv paus ntsiab lus: Piv txwv li, thaum lub DT-830 multimeter nyob rau hauv qhov tam sim no ntau yam ntawm 200mA, lub shunt kuj nyob rau hauv lub 'meter' yog 1Ω, thiab ces lub internal kuj ntawm lub fuse txog 3Ω yog txuas nrog nyob rau hauv series, thiab qhov yuam kev. tshwm sim los ntawm nws tsis yooj yim rau kev xav; Txawm nyob rau hauv 20mA ntau yam, lub shunt kuj nyob rau hauv lub 'meter' Nws yog 10Ω, thiab qhov yuam kev tshwm sim tsis yog me me.
Los ntawm txoj kev, 200mA fuse nrog kev tiv thaiv sab hauv tsawg dua 1Ω kuj tseem nyuaj rau yuav hauv khw, vim tias nws yog nyias dua li 0.5A fuse thiab yog li muaj qhov loj dua sab hauv.
