Misali na abubuwa da ke iya haifar da kisan karkashin ƙaramin birnin a cikin gidajen GIS?

Gas - insulated switchgear (GIS) , da ake kira “SF₆ combined electrical apparatus”, ana amfani da shi a cikin masu tattalin karamin kashi saboda kyakkyawan da ke gane, fadin kasa na tsari, kadan kashi da kafuwarsa. Ana kula wasu abubuwa masu karamin kashi kamar circuit breakers, fast grounding switches, current transformers, da busbars a kasa mai sarrafa da SF₆ gas. Kullum ana zaune a gas chambers daban-daban da suka dace. CT terminal block yana kawo gas chambers, ya kawo ingantaccen abubuwa, kuma ya yi karfin ziyartar karkashin adadin.

1 Muhimmiyar Bayanin da Tabbacin Terminal Block
1.1 Muhimmiyar Bayani

An saki shi a ranar 2017-06-23, akwai gas leakage a ranar 2021-11-06, kuma an samu tabbacin a ranar 2021-11-08. Yanzu mai kyau shi ne CT-side, mai goma shi ne non-CT-side, da 12 outer threaded holes. CT-side tana da tsohon mazaifai masu kuli mai sarrafa (1, 8, 15 per circle from inside); non-CT-side tana da 15 posts (A1-A5, B1-B5, C1-C5 counterclockwise), tana daidaita da CT-side a circles masu tsakiya.

1.2 Tabbacin Gaba-Gaba

An samu tabba mai tsari mai yawa (~30cm) a kusa mai goma, a hanyar raised edge, ta kusa da duwatsu: long crack mai yawa (A1-B1) da short crack mai yawa (C5-A1, ba a iya nuna ba). An yi penetrant testing don neman tabbata da sauran.

1.3 Penetrant Testing

An yi penetrant testing a duk banga terminal block:

• Kusa mai goma: An samu biyu tabbaci, tana daidaita da tabbacin gaba-gaba a tsari da yawa (240mm and 60mm). Short crack ta nuna ba a baya penetrant testing, kuma ba a samu wani tabba ba.

• Kusa mai kyau: An samu biyu tabbaci da yawa daban (approximately 20mm and 8mm) a inner sealing ring. Ba su fi tsakiya ba, da end-to-end distance of about 20mm.

1.4 Tabbacin Fracture Surface

Wadanda aka koyar a A4 sun nuna penetrative cracks a non-CT-side da non-penetrative ones a CT-side. Square conductive sheets da hexagonal nuts ta da structural abrupt changes, with penetrant back-seepage (gaps between metal inserts and epoxy resin). Fine cracks (30° to the terminal block axis) and uneven, spotted contact surfaces (with 45°-angled cracks) sun nuna.

1.5 Force Calculation

Daga 25Nm bolt torque na manufacturer, using T = kFd ((k = 0.15), single-bolt vertical preload tana da 13.9kN. Simulating max preload (M12 bolt, 50cm torque wrench) tana da 220Nm torque (44Nm via a 10cm-arm wrench), tana kafa preload to 24.4kN (1.76× standard). 30°-angled, 31.78mm-long fracture tana da 10.78mm discontinuous joint (resin stress increase). Excessive preload and stress concentration tana jan ta crack initiation and propagation in resin.

2 Sabon Tabbacinta

Excessive bending stress a discontinuous seat structure (edge bolt hole-terminal post) tana jan penetrative cracks. Improper tools/over-tightening tana jan excessive bolt preload. CT-side gas pressure

tana kara bending stress. Poor metal-resin bonding (gaps) tana kuce da bearing cross-section and tana jan stress concentration. Combined, these cracked the terminal block, leaking gas.

3 Hukumar Inganta

Amfani da torque wrenches kamar da manufacturer specs don inganta over-tightening. Follow gas-filling processes don inganta pressure differences. Optimize terminal block design/casting don inganta stress-causing gaps/sharp inserts. Strengthen quality checks don inganta faulty products.

4 Nema

Cracking a CT terminal block a SF₆ apparatus tana jan improper bolt-tightening (excessive preload). The proposed measures guide other power users.