LW12-500 Dead tank Circuit Breakers Defect Analysis and Processing Cihazê LW12-500 Dead tank Circuit Breakers Defect Analysis û Process bikin

Pêşnûmak

LW12 - 500 tank - type SF₆ circuit breaker yek parastîna hêza bi hêjî ye. Di dema ku dêmên karbikirina werin derdewam dike, çend pêşkêşkirina serbixweyî û operasyonê pir tiştên guhertinê yên serbixweyî ve hatîne hate bêtir kirin, li ser karkirina bêsik û stabîl a şebêkê ên elektrikî, têkiliya bêrpaşkirina berzaniyê vêyîne û ji bo salan re mafeyên nûçavkirina parastîna we hatine girêdan. Li ser rastiyên komûn û çend pêşkêşkirina serbixweyî ya LW12 - 500 tank - type SF₆ circuit breaker, belgeya ku niha jêrîne piştgirî û rêzikarên peyvên dikare were cih hatine sêkin, bi tenê ku malpera xerabekirinê yên agahî hatine paqankirin û çalakîya şebêkê ên elektrikî bêtir bike.

Taybetmendîya Malpera

LW12 - 500 tank - type SF₆ circuit breaker gasa SF₆ bikar dike ji bo insulasyon û lêserkirina arkê. Sisteman operasyonê bi preseya hydraulîk pur e, û pêşvekên serbixweyî ya sisteman hydraulîk hatine ji Hitachi were hatine wergerandin. Parastîna we dike dikare bi destpêkê duyem de, da ku kapasitordan paralel hatine saz kirin ji du tarafê destpêka serbixweyî. Kapasitoran paralel hatine ji kompaniya Murata ya Japoniyan were hatine wergerandin.

Şertên Karbikirina Malpera

Hêjî malperên LW12 - 500 tank - type SF₆ circuit breaker ûn di sisteman Şirketê Bêrparastî Elektrikê de hene. Bi kerîna salan 2014, 33 malper ewleman di Jibei Company de hatine wergerandin, ji wan 14 malper ewleman bi rezistanên serkerdışan hatine saz kirin, û dema karbikirina wê ≥10 sal.

Veguhestinên Malpera

• Di sala 2002 de, di navbera 9-an, veguheztina phase B ya LW12 - 500 tank - type SF₆ circuit breaker bi phase B û breakers 5031 û 5032 di substationek din de hatine werin. Phase B ya breaker 5032 bi serkerdış hatine serkeftin, lê phase B ya breaker 5031 serkerdış nekirin. Ji bo kontrol, bistin ku biguherîninê ya adjusting nut riya pressure switch, value ya closing lock pressure hatine guhertin, ku hatine were parastîna we serkerdış nekirin.

• Di navbera April û June 2004 de, di navmalên normal a malpera û testên pêşîn de, LW12 - 500 tank - type SF₆ circuit breakers 5053, 5043 û 5012 di substationek din de hatine were veguheztin da ku serkerdış nekirin. Ji bo kontrol, bistin ku veguheztina hatine werin ji bo guhertinê ya hydraulic oil û tevahî û hatine were serkeftin da ku valve body serkeftin nekirin.

• Di June 2004 de, di navmalan de, phase C ya LW12 - 500 tank - type SF₆ circuit breaker 5052 di substationek din de hatine veguheztin da ku discharge internal û tank hatine werin ji bo peeling off û silver-plating layer ya pressure cylinder û arc extinguish chamber.

• Di June 2005 de, ji bo navmalên normal a power-off opening operation di LW12 - 500 tank - type SF₆ circuit breaker 5043 de, rotating shaft pin û opening trip latch û phase B operating mechanism hatine were qazan, ku hatine were phase B ya breaker separate nekirin. Lîsas, series resistance û opening circuit hatine were damaged û desoldered. Ji bo kontrol, ji bo replace the damaged latch, opening coil û opening series resistance, malpera were were hatine wergerandin.

• Di June 2005 de, ji bo navmalên powering on û 2# busbar di substationek din de, phase C ya LW12 - 500 tank - type SF₆ circuit breaker 5053 hatine tripped immediately after closing. Ji bo kontrol, bistin ku deformation of the striker rod hatine were first-stage opening valve reset nekirin, û circuit breaker continuous tripping. Ji bo replace the striker rod, malpera were were hatine serkeftin.

• Di May 2006 de, ji bo continuous tripping faults û line ek din, closing coil û phase B ya LW12 - 500 tank - type SF₆ circuit breaker 5012 hatine were burned out. Ji bo kontrol, bistin ku veguheztina hatine werin ji bo jamming of the closing latch û phase B, ku hatine were closing coil charged for a long time û caused the burnout.

• Di July 2007 de, veguheztina internal discharge û tank û phase B ya LW12 - 500 tank - type SF₆ circuit breaker 5031 di substationek din de hatine werin. Ji bo kontrol, bistin ku veguheztina hatine werin ji bo poor painting process (manual brushing) û conductive rod û bushing. Ji bo uneven brushing, foreign matters û brush bristles adhered to the conductive rod, û brush bristles fell off on the shield, causing the shield to discharge to the inner wall of the tank.

• Di November 2007 de, ji bo veguheztina Substation 3#, LW12-500 tank-type SF₆ circuit breaker 5013 hatine experienced multiple opening and closing failures, leading to the escalation of the accident.

• Di February 2009 de, ji bo protection actuation test û power outage maintenance di LW12-500 tank-type SF₆ circuit breaker 5012 de, phase C failed to close. Ji bo kontrol, bistin ku shaft connecting the closing latch û buckle in the mechanism inflexible, preventing the latch û buckle from releasing û causing the phase failure to close.

• Di June 2009 de, internal flashover û phase A ya LW12-500 tank-type SF₆ circuit breaker 5021 di power transmission after major maintenance de hatine werin. Ji bo kontrol, bistin ku veguheztina hatine werin ji bo sharp corners û shield assembly û unclean interior of the tank.

• Di March 2012 de, after opening, phase A ya LW12-500 tank-type SF₆ circuit breaker 5053 first experienced interrupter breakdown, which then developed into a ground fault. Ji bo kontrol, bistin ku degradation of parallel capacitor plates between the interrupters caused the capacitor to burst after breakdown, triggering discharge between the shield and the tank.

• Di January 2013 de, after opening, phase B ya LW12-500 tank-type SF₆ circuit breaker 5043 again experienced interrupter breakdown, followed by a ground fault; the 12-second arc between the interrupters in phase A was cleared by the bus differential protection before developing into a ground fault. The fault was similarly caused by degradation of parallel capacitor plates between the interrupters, with capacitor breakdown and bursting triggering shield-to-tank discharge.

Rastiyên Serbixweyî

• Malperên early-production hatine poor insulation paint application û conductive rod inside the bushing (manual brushing process), leaving hidden hazards of internal insulation discharge due to adhering brush bristles, delamination, û peeling of the paint.

• The internal surface of the tank had poor insulation paint workmanship, prone to delamination and peeling, causing internal insulation discharge risks; the grading shield inside the tank had poor machining and assembly, with sharp corners and protrusions.

• The silver-plated layer on the inner surface of the arc extinguish chamber's pressure cylinder was prone to delamination and peeling.

• Poor alignment of moving and stationary contacts or low-quality contact springs caused fragmentation and shedding of arc contact fingers and nozzles.

• Degradation of parallel capacitor plates between interrupters posed risks of insulation breakdown.

• Unreasonable design of mechanism heating and sealing systems caused ultra-high oil pressure alarms in multiple circuit breakers during seasonal transitions.

• Frequent hydraulic mechanism failures, particularly high damage rates of seals and pressure accumulators, reduced mechanism reliability:

• Multiple occurrences of "immediate reclosure after opening" or "continuous tripping" due to poor machining of the hydraulic mechanism's primary valve;

• Severe degradation of hydraulic oil, leading to frequent pressurization and oil leakage;

• Insufficient strength and prone-to-fracture/deformation of some metal parts (e.g., latches) in the operating mechanism due to poor material or machining quality;

• Quality issues with pressure accumulators, causing pre-charged pressure drops in multiple units that failed to meet operational requirements after prolonged operation.

Retrofit Measures

The implemented maintenance measures for LW12-500 circuit breakers include:

• Replacing the conductive rod inside the bushing with a new type featuring advanced insulation coating technology.

• Thorough internal inspection and maintenance of the tank: focusing on checking the internal paint layer, closing resistor assembly, silver-plated layer of the pressure cylinder (replaced if delaminated/peeled), and alignment adjustment of moving/stationary contacts.

• Inspection and maintenance of the operating mechanism: including valve systems, pressure accumulators, working cylinders, hydraulic pumps, and complete replacement of hydraulic oil.

• Replacing interrupter parallel capacitor plates with improved-process components provided by Japan's Murata Corporation.

Suggested Improvement Measures

• To ensure power grid safety and stability, timely maintenance of LW12-type circuit breakers is crucial. However, challenges in spare parts supply and technical services—compounded by the breaker's long-term discontinuation and poor spare parts availability—have made maintenance difficult, with high single-unit overhaul costs approaching those of purchasing new breakers. Considering safety, economy, and technological advancement, overall replacement of LW12-500 tank-type SF₆ circuit breakers is recommended.

• Before retirement, strengthen operational condition monitoring and maintenance of LW12-type breakers. Use advanced technologies such as ultrasonic partial discharge detection and SF₆ gas chromatographic analysis to regularly assess internal insulation status under operating voltage, shorten detection cycles, and timely track insulation degradation trends. This enables targeted measures to prevent sudden internal insulation failures during operation.