Anzake ambiri afunsapo nthawi zambiri ngati mphamvu ya poe ndi yokhazikika?Kodi chingwe chabwino kwambiri cha poe power supply ndi chiyani?Chifukwa chiyani mumagwiritsa ntchito kusintha kwa ndakatulo kuti mugwiritse ntchito kamera popanda chiwonetsero?ndi zina zotero, makamaka, izi zikugwirizana ndi kutaya mphamvu kwa magetsi a POE, omwe ndi osavuta kunyalanyaza mu polojekitiyi.
1. Kodi magetsi a POE ndi chiyani
PoE imatanthawuza kutumiza kwa deta kwa ma terminals ena a IP (monga mafoni a IP, opanda waya LAN access point APs, makamera a network, etc.) popanda kupanga kusintha kulikonse kwa Ethernet Cat.5 cabling infrastructure.Nthawi yomweyo, imathanso kupereka ukadaulo wamagetsi wa DC pazida zotere.
Ukadaulo wa PoE utha kuwonetsetsa kuti maukonde omwe alipo akugwira ntchito pomwe akuwonetsetsa chitetezo cha ma cabling omwe alipo, ndikuchepetsa mtengo wake.
Dongosolo lathunthu la PoE limaphatikizapo magawo awiri: zida zamagetsi ndi zida zolandirira mphamvu.

Zida Zopangira Mphamvu (PSE): Ma switch a Ethernet, ma routers, ma hubs kapena zida zina zosinthira maukonde zomwe zimathandizira ntchito za POE.
Chipangizo choyendetsedwa ndi mphamvu (PD): Mu dongosolo loyang'anira, makamaka ndi kamera ya netiweki (IPC).
2. Mulingo wamagetsi wa POE
Muyezo waposachedwa wapadziko lonse wa IEEE802.3bt uli ndi zofunikira ziwiri:
Mtundu woyamba: Mmodzi wa iwo ndikuti mphamvu yotulutsa ya PSE ikufunika kuti ifike ku 60W, mphamvu yofikira pa chipangizo cholandirira mphamvu ndi 51W (itha kuwoneka kuchokera patebulo pamwambapa kuti iyi ndi data yotsika kwambiri), ndipo kutaya mphamvu ndi 9W.
Mtundu wachiwiri: PSE ikufunika kuti ikwaniritse mphamvu yotulutsa 90W, mphamvu yomwe ikufika pa chipangizo cholandirira mphamvu ndi 71W, ndipo kutaya mphamvu ndi 19W.
Kuchokera pazomwe zili pamwambazi, zikhoza kudziwika kuti ndi kuwonjezeka kwa magetsi, kutayika kwa magetsi sikufanana ndi magetsi, koma kutayika kukukulirakulira, kotero kutayika kwa PSE mu ntchito yothandiza kungawerengedwe bwanji?
3. POE kutaya mphamvu
Chifukwa chake tiyeni tiwone momwe kutayika kwa mphamvu za conductor mu junior sekondale physics kumawerengedwera.
Lamulo la Joule ndi kufotokozera kwachulukidwe kwa kutembenuka kwa mphamvu yamagetsi kukhala kutentha ndi conduction current.
Zomwe zili ndi izi: kutentha komwe kumapangidwa ndi magetsi omwe akudutsa pa kondakitala kumayenderana ndi malo amakono, molingana ndi kukana kwa conductor, komanso nthawi yomwe amapatsidwa mphamvu.Ndiko kuti, kugwiritsidwa ntchito kwa ogwira ntchito komwe kumapangidwa powerengera.
Kafotokozedwe ka masamu a lamulo la Joule: Q=I²Rt (yomwe imagwira ntchito pamabwalo onse) pomwe Q ndi mphamvu yotayika, P, ine ndipano, R ndi kukana, ndipo t ndi nthawi.
Pogwiritsidwa ntchito kwenikweni, popeza PSE ndi PD zimagwira ntchito nthawi imodzi, kutayika sikukugwirizana ndi nthawi.Mapeto ake ndikuti kutayika kwa mphamvu kwa chingwe cha netiweki mu dongosolo la POE kuli kofanana ndi lalikulu lapano komanso molingana ndi kukula kwa kukana.Mwachidule, kuti tichepetse mphamvu yogwiritsira ntchito chingwe cha intaneti, tiyenera kuyesetsa kuti mawaya ang'onoang'ono akhale ochepa komanso kukana kwa chingwe cha intaneti kukhala kochepa.Pakati pawo, kufunikira kochepetsa mphamvu yamagetsi ndikofunikira kwambiri.
Kenako tiyeni tiwone magawo enieni a muyezo wapadziko lonse lapansi:
Muyeso wa IEEE802.3af, kukana kwa chingwe cha netiweki ndi 20Ω, voteji yofunikira ya PSE ndi 44V, yapano ndi 0.35A, ndipo kutayika kwa mphamvu ndi P = 0.35 * 0.35 * 20 = 2.45W.
Momwemonso, mu IEEE802.3at muyezo, kukana kwa chingwe cha netiweki ndi 12.5Ω, voliyumu yofunikira ndi 50V, pano ndi 0.6A, ndipo kutayika kwa mphamvu ndi P = 0.6 * 0.6 * 12.5 = 4.5W.
Miyezo yonseyi ilibe vuto kugwiritsa ntchito njira yowerengera iyi.Komabe, pamene muyezo wa IEEE802.3bt wafika, sungathe kuwerengedwa motere.Ngati voteji ndi 50V, mphamvu ya 60W iyenera kukhala ndi 1.2A.Panthawiyi, kutaya mphamvu ndi P = 1.2 * 1.2 * 12.5 = 18W, kuchotseratu kutayika kufika ku PD Mphamvu ya chipangizocho ndi 42W yokha.
4. Zifukwa za POE kutaya mphamvu
Ndiye chifukwa chake ndi chiyani?
Poyerekeza ndi zofunikira zenizeni za 51W, pali mphamvu zochepa za 9W.Ndiye ndi chiyani chomwe chikuyambitsa cholakwika chowerengera.
Tiyeni tiyang'anenso gawo lomaliza la graph iyi ya data, ndikuwonetsetsa kuti zomwe zilipo mu IEEE802.3bt yoyambirira ikadali 0.6A, kenako yang'anani pamagetsi opotoka, titha kuwona kuti mawiri awiri amagetsi opotoka. kuperekedwa kumagwiritsidwa ntchito (IEEE802.3af, IEEE802. 3at imayendetsedwa ndi awiriawiri opotoka) Mwa njira iyi, njirayi ikhoza kuonedwa ngati dera lofananira, panopa la dera lonse ndi 1.2A, koma kutayika kwathunthu ndi kawiri. ya mapeyala awiri amagetsi opotoka,
Choncho, kutaya P = 0.6 * 0.6 * 12.5 * 2 = 9W.Poyerekeza ndi ma 2 awiriawiri a zingwe zopotoka, njira yoperekera mphamvuyi imapulumutsa mphamvu 9W, kotero kuti PSE ikhoza kupanga chipangizo cha PD kulandira mphamvu pamene mphamvu yotulutsa imakhala 60W yokha.Mphamvu imatha kufika 51W.
Chifukwa chake, tikasankha zida za PSE, tiyenera kulabadira kuchepetsa komwe kulipo komanso kukulitsa voteji momwe tingathere, apo ayi zingayambitse kutaya mphamvu kwambiri.Mphamvu ya zida za PSE zokha zitha kugwiritsidwa ntchito, koma sizipezeka muzochita.
Chipangizo cha PD (monga kamera) chimafunika 12V 12.95W kuti chigwiritsidwe ntchito.Ngati 12V2A PSE ikugwiritsidwa ntchito, mphamvu yotulutsa ndi 24W.
Pogwiritsira ntchito kwenikweni, pamene panopa ndi 1A, kutaya P = 1 * 1 * 20 = 20W.
Pamene panopa ndi 2A, kutaya P=2*2*20=80W,
Panthawiyi, mphamvu yamagetsi ikuluikulu, kutayika kwakukulu, ndipo mphamvu zambiri zatha.Mwachiwonekere, chipangizo cha PD sichingalandire mphamvu yotumizidwa ndi PSE, ndipo kamera idzakhala ndi mphamvu zosakwanira ndipo sizingagwire ntchito bwino.
Vutoli ndilofalanso pochita.Nthawi zambiri, zikuwoneka kuti magetsi ndi aakulu mokwanira kuti agwiritsidwe ntchito, koma kutayika sikuwerengedwa.Chotsatira chake, kamera sichikhoza kugwira ntchito bwino chifukwa cha mphamvu zopanda mphamvu, ndipo chifukwa chake sichipezeka nthawi zonse.
5. POE mphamvu yamagetsi kukana
Zoonadi, zomwe tatchulazi ndi kukana kwa chingwe chaukonde pamene mtunda wamagetsi ndi mamita 100, yomwe ndi mphamvu yomwe ilipo pamtunda wamagetsi, koma ngati mtunda weniweni wamagetsi ndi ochepa, monga 10 okha. mamita, ndiye kukana ndi 2Ω kokha, mofananamo Kutayika kwa mamita 100 ndi 10% yokha ya kutayika kwa mamita 100, kotero ndikofunikanso kuganizira mokwanira ntchito yeniyeni posankha zipangizo za PSE.
Kukaniza kwa 100 metres zingwe zama netiweki zamitundu yosiyanasiyana yamitundu isanu yopindika:
1. Waya wachitsulo wovala mkuwa: 75-100Ω 2. Waya wa aluminiyamu wovala mkuwa: 24-28Ω 3. Waya wasiliva wovala zamkuwa: 15Ω
4. Chingwe cha netiweki chamkuwa: 42Ω 5. Chingwe cha netiweki chamkuwa wopanda okosijeni: 9.5Ω
Zitha kuwoneka kuti bwino chingwe, kukana kochepa kwambiri.Malinga ndi formula Q=I²Rt, ndiye kuti, mphamvu yomwe idatayika panthawi yamagetsi ndiyocheperako, ndiye chifukwa chake chingwechi chiyenera kugwiritsidwa ntchito bwino.Khalani otetezeka.
Monga tafotokozera pamwambapa, njira yochepetsera mphamvu, Q=I²Rt, kuti mphamvu ya poe ikhale ndi kutayika pang'ono kuchokera kumapeto kwa magetsi a PSE kupita ku chipangizo cholandirira magetsi cha PD, kukana kocheperako komanso kukana kochepa kumafunikira kuti mukwaniritse. zotsatira zabwino mu njira yonse yoperekera mphamvu.
Nthawi yotumiza: Mar-17-2022