10kV SF6 Ring Main Units: Tukturwa Fasaha da Kwalaye Ƙofar Jiragen Sauran da Kwalitasu Ƙofar Jiragen Sauran

1. Bayanin 10kV SF6 Ring Main Units (RMUs)

Yawan 10kV SF6 ring main unit yana da uku masu muhimmanci: gas compartment (tank), operating mechanism compartment, da cable connection compartment.

• Gas compartment ita ce mafi muhimmanci a RMU. An yi jirgin da shi da gas SF6 kuma an samun abubuwa masu muhimmanci kamar load switch, busbars, da switch shaft. Load switch tana da design na uku—wanda ke gudanar da closing, opening, da grounding functions—da kuma ya faru ne da blade switch da arc extinguishing chamber, wadanda suke amfani da gas SF6 don tabbatar da insulation da arc-quenching performance masu kyau.

• A cikin operating mechanism compartment, operating mechanism tana canzawa ta switch shaft zuwa load switch da earthing switch. Mai karatu suna zama manual operating rod zuwa operating hole don yi closing, opening, da grounding operations. Saboda hakan an ruwaito switch contacts a cikin sealed gas tank kuma ba a iya tabbata ba, an bayyana position indicator wanda ya faru ne da switch shaft a cikin operating mechanism, wanda ke nuna yanayi na zamani na load switch da earthing switch. Mechanical interlocks suna fitowa a bayan load switch, earthing switch, da front cover don ci gaba da "five-prevention" requirements, don tabbatar da operational safety.

• Cable connection compartment tana nan a fagen RMU, wanda ke taimakawa waɗannan cable connection. Connection daga cable zuwa RMU's insulating bushing zai iya amfani da touchable ko non-touchable silicone rubber cable accessories, wanda ke taimakawa waɗannan safety requirements a wurare dabam-dabam.

2. Tabbacin Duka Incidents na Fault

2.1 Fault na Gas Leakage SF6

A ranar 31 ga Maris, 2015 a lokacin da rana 21:47, an samu fault outage a 10kV line. A lokacin da ake yi inspection a kan line, an samu smoke tana haɗa daga Yangmeikeng RMU. Idan an buƙata cabinet door, an samu cewa terminal post na switch #2 tana kasa da gas tank tana leakage. Ba a yi lura elbow connector, an samu cewa double-headed bolt wanda ake amfani da shi don fitowa bushing tana misaligned a kan center na lug hole, wanda ke sa bushing zuwa continuous downward tension daga cable. Wannan tana baka cracking a upper end na bushing base, wanda ke haɗa da gas SF6 leakage. Wannan type na RMU (model: GAK4, manufacturer: Shenzhen Minyuanshun, i.e., Ormazabal) tana samu waɗannan failures duka duka, wanda ke nuna familial design ko manufacturing defect.

Waɗannan faults suna samu duka a cable terminal post. Abubuwa masu muhimmanci sun hada da improper cable installation wanda ke sa mechanical stress zuwa terminal post da kullum, ko inherent manufacturing issues a cikin RMU itself—kamar inadequate sealing a wurare dabam-dabam—kuma kowane tana iya haɗa da gas SF6 leakage.

2.2 Cable Terminal Fault a cikin RMU

A watan Disamba, 2014, a lokacin da ake yi routine patrol, an samu blackening a cabinet door na 10kV RMU, wanda ke nuna electrical discharge. RMU tana da compartments na uku, wanda na biyu ba a yi amfani ba kuma an yi spare. Ba a yi power shutdown da kuma cabinet inspection, an samu signs na discharge a compartments na biyu da uku. A compartment na biyu, phase C tana nuna evidence na discharge daga stress cone zuwa cabinet body.

Stress cone tana yi fitowa mai tsarki, wanda ke entirely positioned below semiconducting layer cut-back point na cable. Lower end tana ba ta overlap da semiconducting cut-back, kuma upper end tana ba ta contact da inner semiconducting layer na elbow connector. Wannan tana haɗa da electric field concentration a upper edge na stress cone, wanda ke haɗa da insulation breakdown da kullum da kuma discharge zuwa cabinet wall. A compartment na uku, phase B's elbow connector tana nuna visible signs na arcing damage.

Ba a yi disassembly, an samu cewa terminal lug wanda ake amfani da shi tana designed for outdoor applications, ba original specified type. Saboda dimensional differences, outdoor-type lug tana da smaller inner diameter, wanda ke sa shi ba ta fully seating zuwa bottom na terminal stud. Don haka, an yi add washer mai yawan da shi a kan lug da bushing conductor, wanda ke haɗa da poor contact, increased resistance, da overheating. Kuma, elbow connector wanda ake amfani a cikin compartment tana oversized da kuma mismatched na stress cone, wanda ke ba ta tightly seal cable termination. Wannan tana haɗa da full insulation integrity na RMU, wanda ke haɗa da moisture zuwa surface na cable insulation da support insulators, wanda ke reduce insulation performance da kuma create tracking paths.

Duk da cewa, quality na cable termination fabrication da connection daga cable zuwa RMU suna da muhimmanci. Saboda compact structure da limited internal space na RMUs, high precision a cable joint workmanship tana da muhimmanci. Improper handling na conductor, shield, ko semiconducting layer—wanda ke haɗa da insufficient creepage distance—zai iya haɗa da insulation failure. Strict quality control a lokacin da ake yi cable termination installation tana da muhimmanci don prevent faults na farkon tushen da kuma reduce likelihood na outages.