Hauv kev ntsuas hluav taws xob thiab kev saib xyuas, lub zog ntsuas hluav taws xob xav tau cov hloov hluav taws xob sab nraud (CTs) yog ubiquitous; lawv yog peb "qhov muag" kom paub qhov tseeb ntawm cov dej ntws loj. Txawm li cas los xij, nyob rau hauv cov txheej txheem sophisticated no yog ib txoj cai tseem ceeb uas yuav tsum tau ua raws li ib txwm: sab thib ob ntawm lub tshuab hloov tam sim no yuav tsum tsis txhob ua haujlwm nyob rau hauv qhov qhib - Circuit Court. Kab lus no yuav qhia txog cov hauv paus ntsiab lus thiab kev phom sij tom qab txoj cai no.
Lub hauv paus ntsiab lus ntawm kev ua haujlwm ib txwm muaj ntawm transformer tam sim no
Tam sim no transformer (CT) yog ib hom tshwj xeeb ntawm transformer uas ua haujlwm raws li lub hauv paus ntsiab lus ntawm electromagnetic induction. Nws cov qauv tsim yog tsom rau "txo tam sim no" thiab "kev cais tawm."
1. Cov qauv: Nws feem ntau muaj cov tub ntxhais hlau kaw, thawj winding nrog tsawg lem (txuas nyob rau hauv series nrog lub ntsiab Circuit Court), thiab ib tug thib ob winding nrog ntau lem (txuas mus rau lub zog ntsuas).
2. Ideal State: Hauv ib txwm kaw Circuit Court, CT ua haujlwm nyob rau hauv kwv yees li "luv-circuit" lub xeev. Raws li Ampere txoj cai circuital thiab txoj cai ntawm electromagnetic induction, thawj tam sim no I1 generates ib alternating magnetic flux Φ nyob rau hauv lub hlau core, uas nyob rau hauv lem induces ib tug tam sim no I2 nyob rau hauv lub thib ob sab. Kev sib raug zoo ntawm lawv yog:
I1 × N1=I2 × N2 + Im × N1
qhov twg N1 thiab N2 yog tus naj npawb ntawm cov lem ntawm thawj thiab theem nrab windings, thiab kuv yog qhov excitation tam sim no. Vim qhov loj excitation impedance nyob rau hauv tus tsim, Im yog heev me me, yog li nyob rau hauv cov ntaub ntawv zoo tagnrho, nws yuav yooj yim rau:
Ntawm no, Kn yog qhov ntsuas kev hloov pauv, piv txwv li, 1000/5A. Nyob rau lub sijhawm no, qhov tam sim no loj ntawm thawj sab yog qhov raug thiab hloov pauv hloov pauv mus rau qhov tam sim no me me ntawm sab thib ob (feem ntau yog tus qauv tus nqi ntawm 5A lossis 1A) rau kev ntsuas kev nyab xeeb los ntawm qhov ntsuas. Nyob rau tib lub sijhawm, lub peev xwm ntawm CT's Secondary Circuit Court yog tsawg heev (feem ntau tsuas yog ob peb volts), uas yog nyob rau hauv qhov chaw nyab xeeb.
Cov ntsiab lus tsom xam thaum sab thib ob qhib -circuited
Thaum qhov thib ob Circuit Court qhib vim xoob terminals, cov xov hlau tawg, los yog kev sib tsoo thaum lub sij hawm sim, nws lub xeev kev khiav hauj lwm tau hloov pauv tsis zoo.
| Kev Ua Haujlwm | Nquag kaw | Secondary Qhib Circuit |
|---|---|---|
| Secondary Tam sim no I₂ |
Tam sim no, proportional rau I₁ | I₂ = 0 |
| Core Sib Nqus Flux Φ |
Lub demagnetizing flux uas ua los ntawm I₂ zoo suppresses cov tub ntxhais flux, tswj cov qib qis. | Kev tsuj poob; flux sai saturates mus rau theem siab heev |
| Secondary Voltage U₂ |
Tsawg heev (ob peb volts) | Induced high voltage nyob rau hauv ntau yam ntawm ob peb kilovolts mus txog kaum ntawm kilovolts |
| Lub cev yam | Kev sib txuas muaj zog, sib sib zog nqus tawm tswv yim: I₂ tawm tsam kev hloov pauv hauv Φ | Kev tawm tswv yim cuam tshuam, lub zog tsub zuj zuj: tag nrho cov thawj ampere- tig (I₁N₁) yog siv rau magnetization |
Cov txheej txheem tseem ceeb ntawm lub cev yog raws li hauv qab no👇:
1. Disappearance ntawm demagnetizing tawm tswv yim:Thaum lub sijhawm ua haujlwm ib txwm muaj, qhov sib nqus flux tsim los ntawm theem nrab tam sim no I2 ib txwm rov qab mus rau qhov sib nqus flux tsim los ntawm thawj qhov tam sim no I1, tsim kom muaj zog "demagnetizing" nyhuv uas txwv qhov tshwm sim sib nqus flux hauv cov tub ntxhais hlau mus rau theem qis. Tom qab qhib lub Circuit Court, kuv 2=0, thiab cov nyhuv demagnetizing tam sim poob rau xoom.
2. Ceev saturation ntawm magnetic flux:Qhov tsis sib npaug ntawm thawj ampere - tig I1N1 tag nrho hloov mus rau ampere zoo siab - tig. Txij li cov tub ntxhais hlau hla- ntu ntu yog tsim los rau qhov sib nqus flux ntom ntom, cov tub ntxhais hlau nkag mus rau hauv lub xeev ntawm kev sib sib zog nqus saturation.
Raws li Faraday txoj cai ntawm electromagnetic induction, alternating magnetic flux induces electromotive force hla lub windings. Nrog rau qhov nce ceev hauv cov hlau nplaum sib nqus, qhov hluav taws xob tsis tshua muaj siab U2 yuav raug ntxias hla cov cua ntsawj ntshab thib ob.
3. Generation ntawm high voltage:Nyob rau hauv lub hwj chim zaus tej yam kev mob, rau ib tug thawj tam sim no ntawm ntau pua amperes, qhov induced voltage ntawm lub qhib -circuited theem ob yuav tau yooj yim mus txog ob peb txhiab volts, thiab nyob rau hauv heev mob, nws muaj peev xwm tshaj 10 kilovolts.
Qhov txaus ntshai ntawm qhov qhib Circuit Court nyob rau theem nrab ntawm lub transformer tam sim no.
Qhov hluav taws xob siab thiab cov xwm txheej tshwm sim tshwm sim los ntawm qhov qhib thib ob -circuit tuaj yeem ua rau muaj ntau cov saw hlau - kev phom sij txaus ntshai.
1. Kev pheej hmoo ntawm hluav taws xob poob siab rau cov neeg ua haujlwm
Ntau txhiab volts ntawm qhov hluav taws xob siab muaj nyob rau ntawm cov kab hluav taws xob thib ob, ncaj qha tsim kev pheej hmoo hluav taws xob hnyav. Cov neeg saib xyuas thiab tshuaj xyuas cov neeg ua haujlwm yuav raug hluav taws xob poob siab yog tias lawv yuam kev kov cov terminals yam tsis muaj kev tiv thaiv zoo.
2. Cov khoom puas tsuaj
● Rwb thaiv tsev tawg: Cov hluav taws xob siab yuav ua ntej sau cov rwb thaiv tsev ntawm cov cua ntsawj ntshab thib ob, nruab nrab ntawm cov khaubncaws sab nraud povtseg, lossis cov rwb thaiv tsev ntawm cov khoom siv hluav taws xob thiab hauv av, ua rau kev puas tsuaj mus tas li ntawm CT.
● Overheating thiab hlawv: Tom qab cov tub ntxhais ua tau zoo heev, nws tsim cov eddy tam sim no loj heev thiab hysteresis poob, ua rau cov tub ntxhais kub dhau. Qhov no tuaj yeem hlawv lub rwb thaiv tsev winding thiab txawm ua rau hluav taws.
● Arc thiab tawg: Qhib- cov ntsiab lus hauv Circuit Court (xws li cov terminals xoob) yuav tsim cov arcs nyob rau hauv high voltage. Qhov kub ntawm cov arcs tuaj yeem ua rau cov khoom puas tsuaj, ua rau cov khoom siv hluav taws xob nyob ib puag ncig, thiab cov pa roj kub kub hauv cov khoom kaw yuav ua rau muaj hluav taws xob tawg.
3. Muaj kev phom sij rau kev ua haujlwm
Kev ntsuas poob thiab tsis ua haujlwm: Rau CT- hom hluav taws xob ntsuas hluav taws xob, cov khoom siv tam sim no dhau los ua xoom, ua rau lawv ntsuas tsis tau hluav taws xob. Qhov no ua rau poob ntawm cov hluav taws xob ntsuas hluav taws xob thiab tuaj yeem ua rau muaj kev tsis sib haum xeeb ntawm kev lag luam daws teeb meem.
Kev phom sij siab -Voltage Sparks: Cov no tsis yog tsuas yog ua raws li qhov hluav taws xob hluav taws xob xwb, tab sis cov hluav taws xob hluav taws xob hnyav uas lawv tsim tuaj yeem cuam tshuam nrog cov khoom siv hluav taws xob nyob ze.
Xaus
Ib qho qhib Circuit Court nyob rau theem nrab ntawm lub tam sim no transformer (CT) ua rau muaj kev kub ntxhov ntawm electromagnetic zog, uas yog thaum kawg tso tawm nyob rau hauv daim ntawv ntawm high voltage, muaj zog arcs, thiab overheating - ib tug kev puas tsuaj rau lub cev. Yog li ntawd, nyob rau hauv tag nrho cov hauj lwm uas muaj xws li CT circuits, "tiv thaiv qhib circuits" yuav tsum tau ua raws li cov txheej txheem nruj me ntsis.
Nyob rau tib lub sij hawm, lub thib ob sab ntawm lub tam sim no transformer txuas nrog lub zog ntsuas yuav tsum tau grounded. Qhov no, nrog rau "thov txwv tsis pub qhib circuits nyob rau sab thib ob," yog ob txoj cai hlau thaiv kev rau CT kev ua haujlwm thiab kev saib xyuas. Grounding tso cai rau qhov hluav taws xob siab kom tawm sai sai rau hauv av los ntawm cov xaim hauv av, tiv thaiv kom tsis txhob muaj kev nce ntxiv hauv cov peev txheej thib ob uas tuaj yeem ua rau cov khoom puas tsuaj lossis hluav taws xob poob.