Kwenzeka nini ukuba i-magnetizing inrush current ivele kwii-transformers?

Iimeko zokungena kwemagnetizing nazo zenzeka rhoqo kakhulu kunee-short circuits, ngoko ke le nto ifanelekile ukuphononongwa.

Cinga ngento eyenzekayo xa uqala ngokunika amandla i-transformer yesigaba esinye. I-magnetic flux engaphakathi ilingana ne-integral ye-excitation voltage.

Ukuba isekethe ivaliwe xa i-voltage idlula kwi-zero kwaye i-flux yokuqala ingu-zero, i-sinusoidal flux iya kucinywa ngokupheleleyo ukusuka kwi-zero. Ixabiso eliphezulu le-flux epheleleyo ye-offset liphindwe kabini kunexabiso eliphezulu le-symmetrical sine wave flux. Ngamanye amazwi, i-peak flux ye-offset wave epheleleyo inokuba phantse kabini kune-peak flux eqhelekileyo, edla ngokwanela ukuqhuba i-core iye kwi-saturation.

Kule ngongoma, into ekuphela kwayo ethintela umsinga wemagnetizing yi-air-core impedance ye-winding, eyimiyalelo yobukhulu obuncinci kune-magnetizing impedance eqhelekileyo.

Ngoko ke, ngexesha lesiqingatha somjikelo wokugcwala kwe-core, umsinga wentsimi mkhulu kakhulu kunomsinga wentsimi oqhelekileyo. Ngexesha lesiqingatha somjikelo ochaseneyo, umsinga awusagcwali kwaye umsinga wentsimi uphantse ulingane nomsinga wentsimi oqhelekileyo.

Imeko imbi ngakumbi xa kukho i-residual flux embindini kwaye icala le-residual flux lifana necala le-offset ye-sinusoidal flux wave. Njengoko kubonisiwe kuMfanekiso 2 ngezantsi. Qaphela ukuba iMifanekiso 1 kunye no-2 zidwetshwe kwiikali ezahlukeneyo zamandla ombane, ngoko ke i-peak current edwetshwe kuMfanekiso 2 inkulu kakhulu kune-peak current edwetshwe kuMfanekiso 1.

02 Ixabiso eliphezulu lokunyuka koxinzelelo

Ukuze ufumane ukuba i-peak surge current inqunyelwe kuphela yi-air-core reactance, kulula ukubala i-inductance ye-winding usebenzisa ii-cgs units:

Apha:

N – inani leejika zekhoyili

I-Amt - Indawo ephakathi kobubanzi obuphakathi bekhoyili, cm2

l – ubude be-axial yekhoyili, cm

L – ukuhanjiswa kwekhoyili, μH

I-flux eveliswa yi-inductor φL ilingana ne-residual flux kunye ne-flux eseleyo izihlandlo ezi-2 xa kuthelekiswa ne-flux eqhelekileyo, kuba i-flux ye-saturation ikwi-iron. Kodwa i-φL inxulumene ne-inductance kunye ne-current:

Ke ngoko, i-peak inrush current ibonakaliswa kwinkqubo yeyunithi ye-cgs ngolu hlobo lulandelayo:

Apha:

Ipeak kwii-amps kunye

φr - intsalela yokujikeleza

φn – utshintsho oluqhelekileyo lwe-magnetic flux

φs – ukujikeleza komthamo

Ukuba bekungekho zi-resistor kwisekethe, incochoyi nganye elandelelanayo ibiya kuba nexabiso elifanayo, kwaye ukungena kwamandla kwangoku bekuya kuqhubeka ngonaphakade. Nangona kunjalo, xa kukho ukuxhathisa kwisekethe, ukwehla kwe-voltage kwi-resistance kuya kuba kukhulu kwaye ukunyuka kwe-flux akufuneki kube phezulu njengomjikelo wangaphambili.

I-integral ye-voltage drop imele ukunciphisa okune-net kwi-magnetic flux efunekayo ukuxhasa i-voltage esetyenzisiweyo. Ekubeni i-i×R voltage drop ihlala ikwicala elinye, umjikelo ngamnye unciphisa i-magnetic flux efunekayo. Xa ixabiso eliphezulu le-magnetic flux liwela ngaphantsi kwexabiso lokugcwala kwe-core, i-inrush current iyanyamalala. I-decay rate ayisiyo-exponential, nangona ifana ne-exponential decay current.

kubalulekile! Ngee-transformers ezinkulu zamandla, umsinga wokungena unokuhlala imizuzwana embalwa ngaphambi kokuba unyamalale ekugqibeleni.

I-Line reactance inefuthe lokunciphisa i-peak inrush current ngokongeza nje i-inductance kwi-inductance ye-air core ye-winding. Kukho ubudlelwane obucacileyo phakathi kwe-inrush current kunye ne-short-circuit current, njengoko zombini zinxulumene ne-inductance ye-air-core ye-winding.

Khumbula ukuba ii-short circuits zivame ukutyhala i-flux iphume embindini.

Umthetho oyintloko! Ngokubanzi, umthetho oyintloko kukuba umsinga we-inrush okwincochoyi ungaphezulu kancinci kwi-90% yomsinga we-short circuit. Nangona kunjalo, amandla emagnethi abangelwa ngumsinga we-inrush okwincochoyi adla ngokuba mancinci kakhulu kunamandla e-short-circuit. Ekubeni isigaba ngasinye sinomjikelo omnye kuphela, akukho magnetic repulsion phakathi kwe-windings.

Ingxaki yonke yokuhlalutya i-magnetizing inrush currents iba nzima ngakumbi xa kubandakanyeka ii-transformers zesigaba sesithathu. Oku kungenxa yokuba ii-engile zesigaba se-voltages zokuvusa zihlukane nge-120°, kukho intsebenziswano yamandla kunye ne-voltage phakathi kwezigaba, kwaye iipali ezintathu zesixhobo sokutshintsha azivalwanga ngaxeshanye.

Nangona kunjalo, kukhuselekile ukutsho ukuba umsinga wokungena ophezulu we-transformer yesigaba sesithathu usondele kwinqanaba lomsinga we-short-circuit.

Enye yezinto ezinomdla kwii-magnetizing inrush currents kukuba kukho inani elikhulu lee-harmonics ezifanayo kuba ii-currents zirhoxisiwe ngokupheleleyo. Nee-harmonics azifumaneki rhoqo kwiisekethe zamandla.

03 Ukuhamba kovelwano

Kukwakho nesiganeko esaziwa ngokuba yi-"sympathetic inrush", apho i-transformer eyayinamandla ngaphambili ibonisa utshintsho olukhawulezileyo kumbane xa i-transformer ekufutshane ivula. Ukunyuka kwe-sympathetic kubangelwa lutshintsho lwe-line voltage olubangelwa yi-inrush current ye-transformer yesibini.