Top 5 Critical Process Controls for GIS Installation & Commissioning Dukkan 5 na Kwallon Kontrollofin Masu Yawancin GIS Installation & Commissioning
Wannan makarantar tafi yawan karamin da muhimmanci na abubuwan da suka samu GIS (Gas-Insulated Switchgear) masana'anta, kuma ya bayyana wasu mafi yawan kontrolun gidadin da kuma hanyoyin kontrolun ingantaccen a lokacin farkon shiga. Yana nuna cewa aikinsu a kan zama'i ba za a iya tabbatar da dukkan gidadin da kuma fahimtatakan aiki na GIS masana'anta. Ba a zama iya tabbas hakan har zuwa da ake kawo shiga kontrolun gidadin mai tsarki a duk lokacin farkon shiga—wanda a nan ake magana da muhimman abubuwa kamar yanayin shiga, tattalin adsorbent, tattalin gas chamber, da kuma tattalin loop resistance testing—zai iya tabbatar da GIS masana'anta ta shiga da kuma ta yi aiki da dalilai.
A halin yadda ake bukata a tattalin kashi, an saukar da muhimmin abubuwa ga tattalin mekaniki da elektrikal na masana'antar birnin kashi. Saboda haka, an fi sani da amfani da masana'antar elektrikal masu ilimi a birnin kashi. Daga cikinsu, Gas-Insulated Metal-Enclosed Switchgear (GIS) ta fi sani da amfani saboda abubuwan da ke da su. Saboda haka, farkon shiga da kuma tattalin GIS ta zama muhimman abu a kan tattalin birnin kashi.
1. Abubuwan Da Suka Samu Masana'antar GIS
Karamin da kafin da ita
Yakin da kusa da darasi masu kyau
Tsunan wadannan da ke da wahala
Farkon shiga da kasa
Zama da kula da kuma tushen da take da kalmomi
2. Muhimman Hanyoyin Kontrolu Ingantaccen da Kuma Hanyoyin Kontrolu a Farkon Shiga GIS
Saboda GIS masana'antar da suka samu karamin da kafin da ita, koyar da abubuwa a lokacin farkon shiga zai iya bazu wahalai da ke da su wanda za su iya haifar da kashin masana'anta ko kuma wahalar da grid. A halin tattalin birnin kashi da suka samu GIS, ya kamata ake kawo shiga kontrolun mai tsarki a nan muhimman abubuwa a lokacin farkon shiga da kuma tattalin shiga.
2.1 Kontrolun Yanayin Shiga
SF₆ gas ana da takamta da ruwa da abubuwan da ba da nasara, don haka, yanayin shiga a lokacin farkon shiga ya kamata ake kawo shiga kontrolu mai tsarki. Idan ake bukata a canza gas chambers, ya kamata a yi aiki a lokaci da ya yi rarrabe da yawa da humidity na biyuwar da 80%. Idan ake bukata a canza chamber, ya kamata a yi vacuum processing daidai don in ba da tsari. Idan ake yi aiki a waje, wind speed ba zai iya da 3 Beaufort scale. Idan ya kamata, ake iya yi local shielding measures a waje da chamber, kuma kuli da abubuwan da ke da nasara a safe zone zai iya kawo shiga kontrolu mai tsarki. Yanayin shiga zai iya da zama da kyau da kuma da kyau.
Malamai ba za a yi babban abokan mutanen da ke da kwayoyi ko gloves. Kaya zai iya da kuma cap, da kuma face masks. A lokacin da ya yi rarrabe, ya kamata a yi cooling measures don in ba da tsari a canza chamber.
2.2 Tattalin Adsorbent a GIS Gas Chambers
Adsorbent da ake amfani a GIS na musamman 4A molecular sieve, wanda ba da dielectric constant da kuma ba da kuli. Yana da takamta da kuma yake da kusa da kuli. Adsorbent zai iya da kula a vacuum drying oven a 200–300°C da 12 hours. Idan ake kula, ya kamata ake kula da kuma a yi shiga a chamber da 15 minutes. Chamber da adsorbent zai iya da kula a vacuum processing daidai don in ba da tsari.
Idan ake shiga, adsorbent zai iya da kula da kuma a yi record. Idan weight zai iya da kula da 25% a lokacin tattalin, yana nuna cewa an ruwa da ita da kuma zai iya da kula da regeneration. Adsorbent daga arc-extinguishing chambers ba zai iya da kula da regeneration.
2.3 Vacuum Processing a Gas Chambers
Vacuum processing zai iya da kula daidai idan ake yi assembly. Check valve zai iya da kula a connecting pipeline, da kuma wanda zai iya da kula da monitoring process. Vacuum pump zai iya da kula daidai, kuma a yi verification don in ba da tsari. Idan ake kula, valves zai iya da kula da kuma a yi off pump.
Idan internal absolute pressure zai iya da kula da 133 Pa, vacuum pump zai iya da kula da 30 minutes, kuma a yi stop da isolation. Absolute pressure (PA) zai iya da kula da 30 minutes. Idan ake kula 5-hour, pressure (PB) zai iya da kula. Chamber zai iya da kula da seal test idan PB – PA < 67 Pa. Idan ake kula, qualified SF₆ gas zai iya da kula a chamber.
A lokacin vacuum processing, ya kamata a ba da tsari idan a nan side of a disk-type insulator yana da rated operating pressure, kuma side na biyu yana da high vacuum, saboda haka zai iya haifar da mechanical damage. Idan ake kamata, ake iya reduce pressure on the pressurized side to below 50% of the rated value.
2.4 Enclosure Grounding
Saboda GIS da suka samu karamin da kafin da ita, electrical clearance between conductors and between conductors and the metal enclosure is very small. Idan ake haifar da internal breakdown, large fault currents zai iya da kula a grounding conductors into the grounding grid. Idan ake kamata, because the GIS enclosure is made of closed-loop metallic material, asymmetric system faults can induce significant voltages on the enclosure due to magnetic induction, potentially damaging equipment or endangering personnel.
Saboda haka, grounding workmanship must meet high standards. Substations using GIS are recommended to use copper grounding grids to minimize total grounding resistance. All connections between the enclosure and the grounding grid must also use copper materials. Due to the presence of disk-type insulators and rubber seals between gas chambers, bonding copper bars must be installed between enclosures. The cross-sectional area of these bonding bars should match that of the main grounding grid.
GIS uses a multi-point grounding scheme. The number and location of grounding points should follow manufacturer and design specifications.
2.5 Main Circuit Resistance Testing
Main circuit resistance testing is crucial in GIS installation. It not only verifies the integrity of contact connections between modules but also confirms the correct phase sequence of the main busbar. For fully enclosed switchgear, correct phasing and reliable connections are especially critical. In practice, rework has occurred due to incorrect phasing or improper conductor connections.
Manufacturers typically provide standard contact resistance values for internal connections. Loop resistance should be tested segment by segment during assembly, allowing early detection and correction of poor contacts. The measured resistance for each section must not exceed the sum of the manufacturer’s specified values for all connections within that section.
After full assembly, a complete loop resistance test should be performed, and the result must not exceed the theoretical calculated value.
Special Note: Loop resistance testing must not be performed on chambers undergoing vacuum processing. Under sub-atmospheric pressure, the dielectric strength inside the chamber is extremely low. Even a few dozen volts can cause surface discharge on disk-type insulators, leaving discharge traces that become weak insulation points and potential fault sources during operation. Therefore, careful checks must be conducted before any resistance measurement to avoid testing on evacuated chambers.
2.6 Withstand Voltage Test
SF₆ gas’s excellent insulation properties enable GIS to achieve compact design. GIS uses grounded aluminum alloy enclosures, and under operating pressure, the gap between internal conductors or between conductors and the grounded enclosure is very small. Due to high factory pre-assembly, critical components are shipped pre-installed. However, component displacement during transport or introduction of tiny impurities during on-site installation can distort internal electric field distribution. Unlike porcelain-insulated equipment, even minor burrs or particles in GIS interrupters can cause abnormal discharge or breakdown.
Therefore, on-site withstand voltage testing serves as the final defense to verify GIS performance and installation quality.
According to acceptance test regulations, the on-site test voltage is 80% of the factory test voltage. For example, for a 110 kV GIS, the main circuit withstand test voltage is 80% of the factory test voltage: 230 kV × 80% = 184 kV, applied for 1 minute. The test should be conducted at least 24 hours after complete gas filling. Surge arresters and voltage transformers should not be included in the test. High-voltage outgoing cables should be tested together after being connected to the GIS. Before the test, insulation resistance should be measured and confirmed satisfactory.
Test Procedure: Increase voltage at a rate of 3 kV/s to the rated operating voltage (63.5 kV), hold for 1–3 minutes to observe equipment status, then raise to 184 kV and maintain for 1 minute. Repeat this procedure for each phase.
GIS that passes the withstand voltage test may be put into service. However, this test cannot detect all potential defects. In service, GIS must withstand not only power-frequency voltage but also lightning and switching overvoltages. The breakdown field strength of SF₆ gas varies with voltage type. For coaxial cylindrical electrode systems, the 50% breakdown voltage of SF₆ can be empirically expressed as:
U₅₀ = (AP + B)μd
Where:
P — Chamber pressure
d — Electrical clearance (mm)
μ — Electric field utilization factor
A, B — Constants dependent on voltage waveform
Thus, breakdown voltage varies with voltage type and polarity. Different internal defects exhibit different sensitivities to various voltage waveforms. Power-frequency AC voltage is sensitive to insulation breakdown caused by moisture, impurities, or metal particles in SF₆, but less sensitive to surface scratches or poor conductor surface conditions.
Therefore, power-frequency withstand tests cannot detect all internal defects. Enhancing process controls during installation and improving overall installation quality remain the most important measures to ensure safe GIS operation.
3. Conclusion
This paper analyzes key process and quality control points in the on-site installation and commissioning of GIS equipment. It demonstrates that on-site withstand voltage testing can only partially reflect the overall quality and workmanship of installed GIS. More importantly, it highlights that only through strict control of every installation process—ensuring full compliance with procedures and work instructions—can GIS equipment be safely and reliably commissioned from the outset.
It is hoped that this summary may serve as a useful reference for colleagues in the power construction industry.
