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

1. Regarding GIS, how should the requirement in Clause 14.1.1.4 of the State Grid’s "Eighteen Anti-Accident Measures" (2018 Edition) be understood?14.1.1.4: The neutral point of a transformer shall be connected to two different sides of the main mesh of the grounding grid via two grounding down conductors, and each grounding down conductor shall meet the thermal stability verification requirements. Main equipment and equipment structures shall each have two grounding down conductors connected to

Recently, a ±550 kV DC GIS (Gas-Insulated Switchgear), jointly developed by a Chinese GIS manufacturer and multiple companies, successfully completed a 180-day outdoor long-term energized reliability test at the Xi’an High Voltage Apparatus Research Institute. This marks the first time in the industry that a next-generation ±550 kV DC GIS has passed such a long-term energized evaluation.The ±550 kV DC GIS had already undergone comprehensive performance verification tests at the Xi’an High Voltag

On October 16, a ±800 kV ultra-high-voltage (UHV) transmission project completed all its maintenance tasks and was fully re-energized. During this period, a regional power company successfully conducted the first-ever fully unmanned inspection of the GIS (Gas-Insulated Switchgear) room at a UHV converter station within this power system.As a key component of China’s “West-to-East Power Transmission” strategy, the ±800 kV UHV project has been in operation since 2016 and has delivered nearly 400 b

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

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