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Zifundise ukufunda okwengeziwe mayelana nokunikezwa kwamandla e-POE!

Abangane abaningi babuze kaningi ukuthi amandla kagesi wezinkondlo azinzile?Iyiphi ikhebula engcono kakhulu yokunikezwa kwamandla ka-poe?Kungani usebenzise inkinobho ye-poe ukunika amandla ikhamera namanje ingekho isibonisi?nokunye, empeleni, lezi zihlobene nokulahlekelwa kwamandla kagesi we-POE, okulula ukungazinaki kuphrojekthi.
1. Kuyini ukunikezwa kwamandla kwe-POE
I-PoE ibhekisela ekudlulisweni kwedatha kwamanye amatheminali asekelwe ku-IP (njengamafoni e-IP, amaphoyinti okufinyelela e-LAN engenantambo, amakhamera enethiwekhi, njll.) ngaphandle kokwenza izinguquko kungqalasizinda yekhebula ye-Ethernet Cat.5 ekhona.Ngesikhathi esifanayo, ingahlinzeka nobuchwepheshe bokunikezwa kwamandla kagesi we-DC kumadivayisi anjalo.
Ubuchwepheshe be-PoE bungaqinisekisa ukusebenza okuvamile kwenethiwekhi ekhona kuyilapho kuqinisekiswa ukuphepha kwekhebula ehleliwe ekhona, futhi kunciphise izindleko.
Uhlelo oluphelele lwe-PoE luhlanganisa izingxenye ezimbili: okokusebenza kukagesi kanye nemishini yokwamukela amandla.

Izisetshenziswa Zokuhlinzeka Ngamandla (PSE): Amaswishi e-Ethernet, amarutha, amahabhu noma amanye amadivaysi okushintsha inethiwekhi asekela imisebenzi ye-POE.
Idivayisi enikwe amandla (i-PD): Kuhlelo lokuqapha, ikakhulukazi ikhamera yenethiwekhi (IPC).
2. Izinga lokunikezwa kwamandla kwe-POE
Izinga lakamuva lamazwe ngamazwe IEEE802.3bt linezidingo ezimbili:
Uhlobo lokuqala: Olunye lwazo ukuthi amandla okukhipha e-PSE ayadingeka ukuze afinyelele ku-60W, amandla afinyelela idivayisi eyamukela amandla angu-51W (kungabonakala etafuleni elingenhla ukuthi lena idatha ephansi kakhulu), futhi ukulahlekelwa amandla ngu-9W.
Uhlobo lwesibili: i-PSE iyadingeka ukuze kuzuzwe amandla okukhipha angu-90W, amandla afinyelela idivayisi yokwamukela amandla ngu-71W, futhi ukulahlekelwa kwamandla ngu-19W.
Kusukela kule mibandela engenhla, kungaziwa ukuthi ngokwanda kokuphakelwa kukagesi, ukulahleka kukagesi akulingani nokuphakelwa kukagesi, kodwa ukulahlekelwa kuya ngokuya kuba kukhulu, ngakho kungabalwa kanjani ukulahlekelwa kwe-PSE ekusetshenzisweni okungokoqobo?
3. POE ukulahlekelwa amandla
Ngakho-ke ake sibheke ukuthi kubalwa kanjani ukulahleka kwamandla kakhondatha ku-physics yesikole samabanga aphakeme esincane.
I-Joule's Law iyincazelo yobuningi yokuguqulwa kwamandla kagesi abe ukushisa ngokuqhutshwa kwamandla.
Okuqukethwe yilokhu: ukushisa okukhiqizwe i-current edlula ku-conductor kuhambisana nesikwele samanje, ngokulingana nokumelana komqhubi, futhi ngokulingana nesikhathi enikwa ngaso amandla.Okusho ukuthi, ukusetshenziswa kwabasebenzi okukhiqizwa ohlelweni lokubala.
Inkulumo yezibalo yomthetho ka-Joule: Q=I²Rt (isebenza kuwo wonke amasekhethi) lapho u-Q amandla alahlekile, P, mina imanje, R ukumelana, kanye no-t isikhathi.
Ekusetshenzisweni kwangempela, njengoba i-PSE ne-PD zisebenza ngesikhathi esifanayo, ukulahlekelwa akuhlangene nesikhathi.Isiphetho siwukuthi ukulahlekelwa kwamandla ekhebula lenethiwekhi ohlelweni lwe-POE lilingana nesikwele samanje futhi lilingana nobukhulu bokumelana.Kalula nje, ukuze sinciphise ukusetshenziswa kwamandla kwentambo yenethiwekhi, kufanele sizame ukwenza i-current yocingo ibe mncane futhi ukumelana kwekhebula lenethiwekhi kuncane.Phakathi kwazo, ukubaluleka kokunciphisa amandla amanje kubaluleke kakhulu.
Bese sibheka amapharamitha athile wezinga lamazwe ngamazwe:
Esilinganisweni se-IEEE802.3af, ukumelana kwentambo yenethiwekhi kungu-20Ω, i-voltage edingekayo ye-PSE ephumayo ingu-44V, yamanje ngu-0.35A, futhi ukulahlekelwa kwamandla ngu-P=0.35*0.35*20=2.45W.
Ngokufanayo, ku-IEEE802.3at evamile, ukumelana kwentambo yenethiwekhi ngu-12.5Ω, i-voltage edingekayo yi-50V, yamanje ngu-0.6A, futhi ukulahlekelwa kwamandla ngu-P=0.6 * 0.6 * 12.5 = 4.5W.
Womabili amazinga awanayo inkinga ngokusebenzisa le ndlela yokubala.Nokho, lapho izinga le-IEEE802.3bt lifinyelelwa, alikwazi ukubalwa ngale ndlela.Uma i-voltage ingu-50V, amandla we-60W kumele adinge i-current ye-1.2A.Ngalesi sikhathi, ukulahlekelwa kwamandla ngu-P=1.2*1.2*12.5=18W, khipha ukulahlekelwa ukuze ufinyelele i-PD Amandla edivayisi angama-42W kuphela.
4. Izizathu zokulahlekelwa amandla e-POE
Ngakho siyini isizathu?
Uma kuqhathaniswa nemfuneko yangempela ye-51W, kukhona amandla amancane angu-9W.Ngakho-ke yini ngempela ebangela iphutha lokubala.

Ake sibheke ikholomu yokugcina yale grafu yedatha futhi, futhi siqaphele ngokucophelela ukuthi okwamanje kuzinga lokuqala le-IEEE802.3bt kusese ngu-0.6A, bese sibheka amandla amabili asontekile, singabona ukuthi amapheya amane wamandla amabili asontekile. ukunikezwa kusetshenziswa (IEEE802.3af, IEEE802. I-3at inikwa amandla ngamapheya amabili amapheya asontekile) Ngale ndlela, le ndlela ingathathwa njengesekethe ehambisanayo, amandla amanje esekethe yonke ngu-1.2A, kodwa ukulahlekelwa okuphelele kuphindwe kabili. lokho kwamapheya amabili okunikezwa kwamandla okusontekile,
Ngakho-ke, ukulahlekelwa P = 0.6 * 0.6 * 12.5 * 2 = 9W.Uma kuqhathaniswa namapheya angu-2 ezintambo ezisontekile, le ndlela yokunikeza amandla yonga amandla angu-9W, ukuze i-PSE yenze idivayisi ye-PD ithole amandla lapho amandla okukhiphayo engama-60W kuphela.Amandla angafinyelela ku-51W.
Ngakho-ke, lapho sikhetha imishini ye-PSE, kufanele sinake ukwehlisa amandla amanje kanye nokwandisa i-voltage ngangokunokwenzeka, ngaphandle kwalokho kuzoholela kalula ekulahlekeni kwamandla ngokweqile.Amandla emishini ye-PSE yodwa angasetshenziswa, kodwa awatholakali ekusebenzeni.

Idivayisi ye-PD (efana nekhamera) idinga i-12V 12.95W ukuze isetshenziswe.Uma kusetshenziswa i-12V2A PSE, amandla okukhiphayo angu-24W.
Ekusetshenzisweni kwangempela, lapho okwamanje kungu-1A, ukulahlekelwa P=1*1*20=20W.
Uma okwamanje kungu-2A, ukulahlekelwa P=2*2*20=80W,
Ngalesi sikhathi, lapho umsinga umkhulu, ukulahlekelwa okukhulu, futhi amandla amaningi asetshenzisiwe.Ngokusobala, idivayisi ye-PD ayikwazi ukuthola amandla adluliswa yi-PSE, futhi ikhamera izoba namandla anganele futhi ayikwazi ukusebenza ngokujwayelekile.
Le nkinga nayo ijwayelekile ekusebenzeni.Ezimweni eziningi, kubonakala sengathi ukunikezwa kwamandla kukhulu ngokwanele ukuze kusetshenziswe, kodwa ukulahlekelwa akubalwa.Ngenxa yalokho, ikhamera ayikwazi ukusebenza ngokujwayelekile ngenxa yokungatholakali kwamandla okwanele, futhi isizathu asitholakali ngaso sonke isikhathi.
5. Ukumelana nokunikezwa kwamandla kwe-POE
Yiqiniso, okushiwo ngenhla ukumelana kwekhebula lenethiwekhi lapho ibanga lokunikezwa kwamandla lingamamitha angu-100, okungamandla atholakalayo ebangeni eliphezulu lokunikezwa kwamandla, kodwa uma ibanga langempela lokunikezwa kwamandla lincane kakhulu, njenge-10 kuphela. amamitha, khona-ke ukumelana kungu-2Ω kuphela, ngokuhambisanayo Ukulahlekelwa kwamamitha angu-100 kuphela i-10% yokulahlekelwa kwamamitha angu-100, ngakho-ke kubaluleke kakhulu ukucabangela ngokugcwele ukusetshenziswa kwangempela lapho ukhetha imishini ye-PSE.
Ukumelana kwamamitha ayi-100 wezintambo zenethiwekhi zezinto ezahlukahlukene zezinhlobo ezinhlanu zamapheya asontekile:
1. Intambo yensimbi egqoke ithusi: 75-100Ω 2. Intambo ye-aluminiyamu egqoke ithusi: 24-28Ω 3. Intambo yesiliva enethusi: 15Ω
4. Intambo yenethiwekhi yethusi egqoke ithusi: 42Ω 5. Intambo yenethiwekhi yethusi engenawo umoya-mpilo: 9.5Ω
Kungabonakala ukuthi okungcono ikhebula, ukumelana okuncane kakhulu.Ngokwefomula ethi Q=I²Rt, okungukuthi, amandla alahlekile ngesikhathi senqubo yokuphakelwa kwamandla amancane, ngakho-ke yingakho ikhebula kufanele lisetshenziswe kahle.Uphephe.
Njengoba sishilo ngenhla, ifomula yokulahlekelwa amandla, i-Q=I²Rt, ukuze ukunikezwa kwamandla we-poe kube nokulahlekelwa okuncane ukusuka esiphelweni sokuphakela amandla se-PSE kuya kudivayisi yokwamukela amandla ye-PD, ubuncane bamanje kanye nokumelana okuncane kuyadingeka ukuze kuzuzwe. umphumela omuhle kakhulu kuyo yonke inqubo yokuphakelwa kwamandla.


Isikhathi sokuthumela: Mar-17-2022