Kwenzeka nini ukuthi i-magnetizing inrush current ibe khona kuma-transformer?

Izimo zokungena kwegesi ezisebenzisa ugesi ziyenzeka futhi ngesivinini esiphezulu kakhulu kunezijikelezo ezimfushane, ngakho-ke lesi simo kufanelekile ukusihlola.

Cabanga ngalokho okwenzekayo lapho uqala ngokunika amandla i-transformer yesigaba esisodwa. I-magnetic flux enkabeni ilingana ne-integral ye-voltage yokuvuselela.

Uma isekethe ivaliwe lapho i-voltage idlula ku-zero futhi i-flux yokuqala ingu-zero, i-sinusoidal flux izosuswa ngokuphelele kusuka ku-zero. Inani eliphakeme kakhulu le-full offset flux liphindwe kabili kunenani eliphakeme kakhulu le-symmetrical sine wave flux. Ngamanye amazwi, i-peak flux ye-full offset wave ingaba cishe kabili kune-peak flux evamile, okuvame ukwanele ukushayela i-core iye ekugcwalisweni.

Kuleli qophelo, okuwukuphela kwento ekhawulela ugesi odonsayo yi-air-core impedance ye-winding, okuyi-oda elincane kakhulu kune-magnetizing impedance evamile.

Ngakho-ke, ngesikhathi somjikelezo wesigamu sokugcwala kwe-core, i-field current inkulu kakhulu kune-field current evamile. Ngesikhathi somjikelezo wesigamu ohlukile, i-core ayisagcwali futhi i-field current cishe ilingana ne-field current evamile.

Isimo sibi kakhulu uma kukhona i-residual flux enkabeni futhi isiqondiso se-residual flux sifana nesiqondiso se-offset ye-sinusoidal flux wave. Njengoba kuboniswe kuMfanekiso 2 ngezansi. Qaphela ukuthi Izibalo 1 no-2 zidwetshwe ngezikali ezahlukene zamandla kagesi, ngakho-ke amandla kagesi aphezulu adwetshwe kuMfanekiso 2 empeleni makhulu kakhulu kunomandla kagesi aphezulu adwetshwe kuMfanekiso 1.

02 Inani eliphakeme lokunyuka komfutho wokuvuselela

Ukuze uthole ukuthi i-peak surge current inqunyelwe kuphela yi-air-core reactance, kulula ukubala i-inductance ye-winding usebenzisa amayunithi e-cgs:

lapha:

N – inani lokujika kwekhoyili

I-Amt – Indawo engaphakathi kobubanzi obuphakathi bekhoyili, cm2

l – ubude be-axial bekhoyili, cm

L – ukukhishwa kwekhoyili, μH

Ukugeleza okukhiqizwa yi-inductor φL kulingana nokugeleza okusele kanye nokuphindwe kabili kokushintsha kokugeleza okujwayelekile ngaphandle kokugeleza kokugcwala, njengoba ukugeleza kokugcwala kusensimbini. Kodwa i-φL ihlobene nokugeleza kanye nogesi:

Ngakho-ke, i-peak inrush current ivezwa ohlelweni lweyunithi ye-cgs kanje:

lapha:

Ipeak kuma-amps kanye

φr – ukugeleza okusele

φn – ushintsho olujwayelekile lwe-magnetic flux

φs – ukuguquguquka kokugcwala

Uma bekungekho ama-resistor kusekethe, isiqongo ngasinye esilandelanayo besizoba nenani elifanayo, futhi ukungena kwamanje bekuzoqhubeka unomphela. Kodwa-ke, uma kukhona ukumelana kusekethe, ukwehla kwamandla kagesi kusekethe kuzoba kukhulu futhi ukwanda kokuguquguquka akudingeki kube phezulu njengomjikelezo wangaphambilini.

I-integral ye-voltage drop imelela ukwehla kwe-net ku-magnetic flux edingekayo ukusekela i-voltage esetshenzisiwe. Njengoba ukwehla kwe-voltage ye-i×R kuhlala kusendaweni efanayo, umjikelezo ngamunye wehlisa i-magnetic flux edingekayo. Lapho inani eliphakeme le-magnetic flux liwela ngaphansi kwenani lokugcwala kwe-core, i-inrush current iyanyamalala. Izinga lokubola alilona i-exponential, yize lifana ne-exponential decay current.

kubalulekile! Ngama-transformer amakhulu kagesi, ugesi ogeleza ungahlala imizuzwana embalwa ngaphambi kokuba unyamalale ekugcineni.

Ukusabela komugqa kunomphumela wokunciphisa ugesi ogeleza phezulu ngokumane wengeze ugesi ogeleza emoyeni ogeleza ngaphakathi komoya. Kukhona ubudlelwano obuqondile phakathi kogesi ogeleza ngaphakathi kanye nogesi ojikelezayo omfushane, njengoba kokubili kuhlobene nogesi ogeleza ngaphakathi komoya ogeleza ngaphakathi komoya.

Khumbula ukuthi ama-short circuits avame ukusunduza i-flux iphume enkabeni.

Umthetho wesithupha! Ngokuvamile, umthetho wesithupha uwukuthi ugesi we-inrush ophakeme kakhulu ungaphezu kancane kuka-90% wogesi we-short circuit. Kodwa-ke, amandla kazibuthe abangelwa ugesi we-inrush ophakeme kakhulu ngokuvamile mancane kakhulu kunogesi we-short-circuit. Njengoba isigaba ngasinye siqukethe ukugoqa okukodwa kuphela, akukho ukujikijela kukazibuthe phakathi kokujikijela.

Inkinga yonke yokuhlaziya ama-inrush currents adonsa amandla iba nzima kakhulu uma kuhileleke ama-transformer esigaba sesithathu. Lokhu kungenxa yokuthi ama-engeli esigaba sama-voltage okuvusa ahlukene ngama-120°, kukhona ukuxhumana kwamanje kanye ne-voltage phakathi kwezigaba, futhi izigxobo ezintathu zedivayisi yokushintsha azivaliwe ngesikhathi esisodwa.

Kodwa-ke, kuphephile ukusho ukuthi ugesi ophakeme kakhulu we-transformer yesigaba sesithathu useduze nezinga logesi omfushane.

Esinye sezici ezithakazelisayo zokusebenzisa ama-inrush currents adonsa amandla ukuthi kunengxenye enkulu yama-harmonics ngisho ngoba ama-currents akhanseliwe ngokuphelele. Ngisho nama-harmonics nawo awatholakali kakhulu kuma-power circuits.

03 Ukugeleza kozwelo

Kukhona futhi into eyaziwa ngokuthi "ukungena ngomsindo", lapho i-transformer eyayinamandla ngaphambili ibonisa ushintsho oluzumayo kumandla kagesi lapho i-transformer eseduze ivula. Ukwanda ngomsindo kubangelwa ushintsho lwe-line voltage olubangelwa ukujikeleza ngomsindo kagesi kwe-transformer yesibili.