Circuit breaker current calculation method

Choyamba werengani mphamvu yonse P ya zida zonse zamagetsi, powerengera nambala yonse yapano A I=P/U,leakage switchayenera kukhala wamkulu kuposa okwana panopa, payenera kukhala Mphepete mwa zina, kapena mu unsembe wa zipangizo zina zamagetsi sangathe kupirira.Zotsalira kutayikira panopa banja 30MA akhoza.Kusintha kotayikiranthawi zambiri sichimateteza chitetezo, ngati mukufuna kuteteza mzerewu kuti ukhale wophwanyira dera laling'ono, wophwanya dera laling'ono sangathe kusankha wamkulu kwambiri.Kawirikawiri, mtundu C umagwiritsidwa ntchito.

Zowonongeka zazing'onogwiritsani ntchito njira yosavuta yowerengera yomwe ili ndi zolakwika zomwe sizili zazikulu kwambiri ndipo zitha kuvomerezedwa muukadaulo:

(1) kwa 10/0.4kV voteji kalasi yachophwanyika chaching'ono, Tingaone mbali mkulu voteji wa mphamvu yochepa dera ndi wopandamalire (10KV mbali ya mphamvu yochepa dera zambiri 200 ~ 400MVA kapena wamkulu, kotero malinga ndi wopandamalire kuganizira, cholakwa ndi zosakwana 10%).

(2) Gb50054-95 "Low-voltage Power Distribution Design Code" 2.1.2 makonzedwe: "Pamene kuchuluka kwa mphamvu yamagetsi yamoto yolumikizidwa pafupi ndi chigawo chachifupi kupitirira 1% yamagetsi afupikitsa, mphamvu Mawonekedwe amotor apano ayenera kuphatikizidwa.Ngati njira yachidule ndi 30KA, tengani 1% yake, yomwe iyenera kukhala 300A.Mphamvu yonse ya mota ndi pafupifupi 150KW, ndipo ikayambika nthawi yomweyo, mayankho omwe akuphatikizidwa akuyenera kukhala 6.5∑In.

(3) mphamvu ya impedance ya UK ya mini-circuit breaker imayimira mbali yaying'ono (yozungulira), mbali ikafika yomwe idavotera, gawo loyambirira la voteji ndilofunika zana lamagetsi ake ovotera.Choncho, pamene magetsi oyambirira ndi magetsi ovotera, mphamvu yachiwiri ndiyomwe ikuyembekezeredwa kuti ikhale yochepa.

(4) Mbali yaying'ono ya wophwanyira dera yomwe idavotera panopa Ite=Ste/1.732U Ste ndi mphamvu ya chophwanyira chaching'ono (KVA), Ue ndi voteji yaing'ono (no-load voltage), Ue = 0.4kV pamene 10 / 0.4kV, motero, mbali yachiwiri yomwe idavoteledwa pakalipano ya mini-circuit breaker iyenera kuwerengedwa ngati mphamvu ya mini-circuit breaker X1.44 ~ 1.50.

(5) Malinga ndi tanthawuzo la Uk mu (3), mawonekedwe afupipafupi a mbali yothandizira (gawo laling'ono la magawo atatu) ndilo tanthauzo la I (3) la Uk, ndi nthawi yochepa ya mbali yothandizira (gawo laling'ono la magawo atatu) ndi I(3)=Ite/Uk, yomwe ili phindu la AC.

(6) Momwemonsomini-circuit breakermphamvu, ngati pali dera lalifupi pakati pa magawo awiriwa, ndiye I(2)=1.732I(3)/2=0.866I(3)

Mawerengedwe omwe ali pamwambawa ndi mtengo wapano wa kagawo kakang'ono komwe kamatuluka kachidutswa kakang'ono, komwe ndi ngozi yowopsa kwambiri.Ngati pali mtunda wina pakati pa dera lalifupi ndi mini-circuit breaker, ganizirani za impedance ya mzere.