Abahlobo abaninzi baye babuza amaxesha amaninzi ukuba amandla ombane azinzile?Yeyiphi eyona ntambo yombane yombane?Kutheni usebenzisa i poe switsha ukunika amandla ikhamera nangoku akukho umboniso?kwaye njalo, ngokwenene, ezi zihambelana nokulahlekelwa kwamandla ombane we-POE, ekulula ukuyihoxisa kwiprojekthi.
1. Yintoni unikezelo lwamandla lwe-POE
I-PoE ibhekisela ekuhanjisweni kwedatha kwezinye ii-terminals ezisekelwe kwi-IP (ezifana neefowuni ze-IP, i-wireless LAN access point APs, iikhamera zenethiwekhi, njl.) ngaphandle kokwenza naluphi na utshintsho kwi-cabling ekhoyo ye-Ethernet Cat.5.Kwangaxeshanye, inokubonelela ngeteknoloji yonikezelo lwamandla eDC kwizixhobo ezinjalo.
Itekhnoloji ye-PoE inokuqinisekisa ukusebenza okuqhelekileyo kwenethiwekhi ekhoyo ngelixa iqinisekisa ukhuseleko lwe-cabling ekhoyo emiselweyo, kunye nokunciphisa iindleko.
Inkqubo ye-PoE epheleleyo ibandakanya iinxalenye ezimbini: izixhobo zokubonelela ngombane kunye nezixhobo zokufumana amandla.

Izixhobo zokubonelela ngombane (PSE): Ukutshintsha kwe-Ethernet, ii-routers, ii-hubs okanye ezinye izixhobo zokutshintsha inethiwekhi ezixhasa imisebenzi ye-POE.
Isixhobo esinamandla (PD): Kwinkqubo yokubeka iliso, ikakhulu ikhamera yenethiwekhi (IPC).
2. Umgangatho wonikezelo lwamandla we-POE
Umgangatho wamva nje wehlabathi IEEE802.3bt uneemfuno ezimbini:
Uhlobo lokuqala: Enye yazo kukuba amandla emveliso ye-PSE afuneka ukuba afikelele kwi-60W, amandla afikelela kwisixhobo sokufumana amandla yi-51W (inokubonwa kwitheyibhile engasentla ukuba le yeyona datha isezantsi), kwaye ilahleko yamandla yi-9W.
Uhlobo lwesibini: i-PSE iyadingeka ukufezekisa amandla okuphuma kwe-90W, amandla afikelela kwisixhobo sokufumana amandla yi-71W, kunye nokulahlekelwa kwamandla yi-19W.
Ukususela kule migaqo ingentla, kuyaziwa ukuba ngokunyuka kokunikezelwa kwamandla, ilahleko yamandla ayilingani nokunikezelwa kwamandla, kodwa ilahleko iya ikhula kwaye ibe nkulu, ngoko ingaba ilahleko ye-PSE kwisicelo esisebenzayo ingabalwa njani?
3. Ukulahlekelwa kwamandla e-POE
Ke makhe sijonge indlela ilahleko yamandla omqhubi kwifiziksi yesikolo samabanga aphakamileyo kubalwa ngayo.
UMthetho kaJoule yinkcazo yobungakanani bokuguqulwa kwamandla ombane abe bubushushu ngokuqhuba ngoku.
Umxholo ngulo: ubushushu obuveliswa ngumbane odlulayo kwi-conductor bulingana nesikwere sangoku, ngokulingana nokumelana nomqhubi, kunye nokulinganisa ixesha elinikwe amandla.Oko kukuthi, ukusetyenziswa kwabasebenzi okwenziwe kwinkqubo yokubala.
Inkcazo yezibalo yomthetho kaJoule: Q=I²Rt (isebenza kuzo zonke iisekethe) apho i-Q ingamandla alahlekileyo, P, ndim ngoku, R luxhathiso, kunye no-t lixesha.
Ekusetyenzisweni okwenyani, ekubeni i-PSE kunye nePD zisebenza ngexesha elinye, ilahleko ayinanto yakwenza nexesha.Isiphetho kukuba ukulahlekelwa kwamandla kwentambo yenethiwekhi kwinkqubo ye-POE ilingana nesikwere sangoku kunye nokulingana nobukhulu bokumelana.Ukubeka nje, ukuze kuncitshiswe ukusetyenziswa kwamandla kwentambo yenethiwekhi, kufuneka sizame ukwenza i-current ye-wire encinci kunye nokuchasana kwentambo yenethiwekhi encinci.Phakathi kwabo, ukubaluleka kokunciphisa umsinga kubaluleke kakhulu.
Emva koko makhe sijonge iiparamitha ezithile zomgangatho wamazwe ngamazwe:
Kwinqanaba le-IEEE802.3af, ukuchasana kwentambo yenethiwekhi yi-20Ω, i-voltage efunekayo ye-PSE ye-voltage yi-44V, okwangoku yi-0.35A, kunye nokulahlekelwa kwamandla ngu-P = 0.35 * 0.35 * 20 = 2.45W.
Ngokufanayo, kumgangatho we-IEEE802.3, ukuchasana kwentambo yenethiwekhi yi-12.5Ω, i-voltage efunekayo yi-50V, okwangoku yi-0.6A, kunye nokulahlekelwa kwamandla P = 0.6 * 0.6 * 12.5 = 4.5W.
Yomibini imigangatho ayinangxaki ekusebenziseni le ndlela yokubala.Nangona kunjalo, xa umgangatho we-IEEE802.3bt ufikeleleke, awukwazi ukubalwa ngale ndlela.Ukuba i-voltage i-50V, amandla e-60W kufuneka afune i-current ye-1.2A.Ngeli xesha, ukulahlekelwa kwamandla yi-P = 1.2 * 1.2 * 12.5 = 18W, thabatha ilahleko ukufikelela kwi-PD Amandla esixhobo yi-42W kuphela.
4. Izizathu zokulahleka kwamandla e-POE
Ngoko yintoni isizathu?
Xa kuthelekiswa nemfuneko yokwenyani ye-51W, kukho amandla angaphantsi kwe-9W.Ke yintoni kanye kanye ebangela impazamo yokubala.
Makhe sijonge kwikholamu yokugqibela yale grafu yedatha kwakhona, kwaye siqaphele ngononophelo ukuba okwangoku kwinqanaba lokuqala le-IEEE802.3bt kuseyi-0.6A, kwaye emva koko sijonge unikezelo lombane olujijekileyo, siyabona ukuba izibini ezine zamandla amabini ajijekileyo. unikezelo lusetyenziswa (IEEE802.3af, IEEE802. I-3at inikwe amandla ngamabini amabini aphikisiweyo) Ngaloo ndlela, le ndlela inokuthathwa njengesekethe ehambelanayo, i-current of the whole circuit yi-1.2A, kodwa ilahleko iyonke iphindwe kabini. ukuba izibini ezimbini ezijijekileyo zobonelelo lwamandla,
Ngoko ke, ilahleko P = 0.6 * 0.6 * 12.5 * 2 = 9W.Xa kuthelekiswa nezibini ezi-2 zeentambo eziphothiweyo, le ndlela yokunikezelwa kwamandla igcina i-9W yamandla, ukwenzela ukuba i-PSE inokwenza isixhobo sePD sifumane amandla xa amandla aphumayo angama-60W kuphela.Amandla anokufikelela kwi-51W.
Ke ngoko, xa sikhetha izixhobo ze-PSE, kufuneka sinikele ingqalelo ekunciphiseni okukhoyo kunye nokunyusa amandla ombane kangangoko kunokwenzeka, kungenjalo kuya kukhokelela ngokulula ekulahlekeni kwamandla agqithisileyo.Amandla ezixhobo ze-PSE zodwa anokusetyenziswa, kodwa akafumaneki ekusebenzeni.
Isixhobo sePD (esifana nekhamera) sidinga i-12V 12.95W ukuba isetyenziswe.Ukuba i-12V2A PSE isetyenzisiwe, amandla aphumayo angama-24W.
Ekusetyenzisweni kwangempela, xa okwangoku i-1A, ilahleko P = 1 * 1 * 20 = 20W.
Xa okwangoku yi-2A, ilahleko P=2*2*20=80W,
Ngeli xesha, i-current enkulu, ilahleko enkulu, kwaye uninzi lwamandla lusetyenzisiwe.Ngokucacileyo, isixhobo sePD asikwazi ukufumana amandla ahanjiswa yi-PSE, kwaye ikhamera iya kuba nombane ongonelanga kwaye ayikwazi ukusebenza ngokuqhelekileyo.
Le ngxaki ikwaxhaphakile ekusebenzeni.Kwiimeko ezininzi, kubonakala ngathi ukunikezelwa kwamandla kukhulu ngokwaneleyo ukuba kusetyenziswe, kodwa ilahleko ayibalwa.Ngenxa yoko, ikhamera ayikwazi ukusebenza ngokuqhelekileyo ngenxa yombane ongonelanga, kwaye isizathu asikwazi ukufunyanwa rhoqo.
5. Ukuxhatshazwa kombane we-POE
Kakade ke, oko kukhankanywe ngasentla kukuchasana kwentambo yothungelwano xa umgama wonikezelo lombane uziimitha ezili-100, nto leyo ekhoyo amandla akhoyo kumgama wonikezelo lwamandla aphezulu, kodwa ukuba umgama wobonelelo lwamandla lokwenene uncinci, njenge-10 kuphela. iimitha, ke ukuxhathisa yi-2Ω kuphela, ngokuhambelanayo Ukulahlekelwa kweemitha ezili-100 kuphela i-10% yokulahlekelwa kweemitha ezili-100, ngoko ke kubaluleke kakhulu ukuqwalasela ngokupheleleyo ukusetyenziswa kwangempela xa ukhetha izixhobo ze-PSE.
Ukumelana neemitha ezili-100 zeentambo zenethiwekhi zezinto ezahlukeneyo zeentlobo ezintlanu ezijijekileyo:
1. I-Copper-clad steel wire: 75-100Ω 2. I-Copper-clad i-aluminium yocingo: 24-28Ω 3. Ucingo lwesilivere olufakwe ubhedu: 15Ω
4. Intambo yenethiwekhi yobhedu efakwe ubhedu: 42Ω 5. Intambo yenethiwekhi yobhedu engena-oksijeni: 9.5Ω
Ingabonwa ukuba ngcono ikhebula, ukuchasana okuncinci.Ngokwefomula Q=I²Rt, oko kukuthi, amandla alahlekileyo ngexesha lenkqubo yonikezelo lwamandla ngawona mancinci, yiyo loo nto intambo kufuneka isetyenziswe kakuhle.Khuseleka.
Njengoko sele sikhankanyile ngasentla, ifomula yokulahleka kwamandla, Q=I²Rt, ukuze unikezelo lwamandla embongi lube nelahleko encinci ukusuka kwisiphelo sobonelelo lwamandla e-PSE ukuya kwisixhobo sokufumana amandla ePD, ubuncinci bangoku kunye nokuchasana okuncinci kuyafuneka ukuze kuphunyezwe. esona siphumo silungileyo kuyo yonke inkqubo yonikezelo lwamandla.
Ixesha lokuposa: Mar-17-2022