Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

1. IntroductionSF₆ is widely used in electric power transmission and distribution systems, such as gas-insulated switchgear (GIS), circuit breakers (CB), and medium-voltage (MV) load switches. It possesses unique electrical insulation and arc-quenching capabilities. However, SF₆ is also a potent greenhouse gas, with a global warming potential of approximately 23,500 over a 100-year time horizon, and therefore its use is regulated and subject to ongoing discussions regarding restrictions. Consequ

1.IntroductionIn response to climate change, extensive research and development efforts have been undertaken globally to develop various types of SF₆-free gas-insulated switchgear as alternatives to conventional SF₆-based equipment. On the other hand, SF₆-free gas-insulated switchgear has been in service since the late 1960s. By integrally molding live components of the switchgear using solid insulation materials—such as epoxy resin—with dielectric strength significantly higher than that of SF₆,

Recently, Chinese GIS manufacturers announced exciting news: the first ZF11C-252(L) mixed-gas double-break GIS product developed by a Chinese GIS manufacturer successfully passed its on-site power frequency withstand voltage test on the first attempt at a project site. This achievement marks another milestone for Chinese GIS manufacturers in advancing green and high-quality development of power grids.The ZF11C-252(L) mixed-gas double-break GIS that passed the test represents the culmination of t

GIS (Gas-Insulated Switchgear) offers advantages such as compact structure, flexible operation, reliable interlocking, long service life, maintenance-free operation, and small footprint. It also possesses many irreplaceable advantages in insulation performance, environmental friendliness, and energy saving, and is increasingly applied in industrial and mining enterprises, airports, railways, subways, wind power stations, and other fields.A certain enterprise’s 35 kV indoor substation was origina

1.Description of the Fault PhenomenonThe disconnector fault in a 550 kV GIS equipment occurred at 13:25 on August 15, 2024, while the equipment was operating under full load with a load current of 2500 A. At the moment of failure, the associated protection devices acted promptly, tripping the corresponding circuit breaker and isolating the faulty line. System operating parameters changed significantly: the line current dropped abruptly from 2500 A to 0 A, and the bus voltage instantly decreased

Impact of GIS Disconnector Operations on Secondary Equipment and Mitigation Measures1.Impacts of GIS Disconnector Operations on Secondary Equipment 1.1Transient Overvoltage Effects During opening/closing operations of Gas-Insulated Switchgear (GIS) disconnectors, repeated arc reignition and extinction between contacts cause energy exchange between system inductance and capacitance, generating switching overvoltages with magnitudes 2–4 times the rated phase voltage and durations ranging from tens

High-voltage switchgear refers to electrical equipment operating within a voltage range of 3.6 kV to 550 kV, used in power generation, transmission, distribution, energy conversion, and consumption systems for switching, control, or protection purposes. It primarily includes high-voltage circuit breakers, high-voltage disconnectors and earthing switches, high-voltage load switches, high-voltage auto-reclosers and sectionalizers, high-voltage operating mechanisms, high-voltage explosion-proof swi

Hitachi Energy recently announced it will supply State Grid Corporation of China’s Central China Branch with the world’s first 550 kV SF₆-free GIS. This groundbreaking innovation marks a significant milestone in grid decarbonization and contributes to China’s commitment to achieving carbon neutrality by 2060.State Grid Corporation of China is the world’s largest power grid operator, serving 88% of China’s territory and over 1.1 billion people. As a leader in the energy sector, State Grid activel

On November 9, a new type of circuit breaker for gas-insulated metal-enclosed switchgear—designated ZF27-800(L)/Y6300-80—successfully passed a national-level technical appraisal organized by the Chinese Society for Electrical Engineering (CSEE) in Beijing. Developed jointly by a leading Chinese manufacturer of gas-insulated metal-enclosed switchgear and multiple partner institutions, this world-first 800 kV, 80 kA circuit breaker, featuring full independent intellectual property rights, has achi

IEEE Std C37.20.9™ defines the design, testing, and installation requirements for metal-enclosed gas-insulated switchgear (MEGIS) using gas at pressures above ambient as the primary insulation medium for alternating current systems rated from 1 kV to 52 kV. This includes, but is not limited to, circuit breakers, switches, bushings, busbars, instrument transformers, cable terminations, meters, and control/protection relays. In these switchgear assemblies, vertical compartments—some or all of the