China's first ±550 kV DC GIS completes long-term energized test.

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 Voltage Apparatus Research Institute in 2022, meeting all expected performance requirements. Due to the absence of established product standards and any existing operational track record for similar equipment, the project team adopted industry-accepted practices by conducting an extended energized operation to verify the product’s reliability. 

Drawing on extensive domestic and international literature, the team designed a scientifically rigorous validation protocol. During the test, the equipment operated at 1.2 times its rated voltage for more than half of the duration while carrying DC current, simulating real-world operating conditions. Conducted outdoors, the test subjected the GIS to extreme environmental stresses—including intense sunlight, heavy rain, sandstorms, high temperatures, and heavy snow—providing the most severe possible assessment of its performance under climatic variations. The successful completion of this test confirms the product’s reliable operation under both outdoor and indoor normal service conditions.

The successful passing of this long-term energized test signifies that China has independently mastered the full-chain R&D capability for ±550 kV DC GIS and thoroughly validated its readiness for practical engineering applications. The large-scale deployment of this ±550 kV DC GIS will significantly support the development of offshore wind power and renewable energy bases in desert, Gobi, and barren regions (“Sha Ge Huang”), positioning it as another major national asset in the construction of China’s new power system.