On May 13, a major milestone was hit at the 220-kilovolt overhead-to-underground conversion project in Zijingang Science and Technology City, western Hangzhou: China's longest single-section 220-kilovolt land cable-stretching 1,715 meters-was successfully laid. Slowly and steadily, the cable was guided from a custom-built reel into a 20-meter-deep underground tunnel.
This isn't just a construction feat-it's a critical energy lifeline for the Zhejiang West Science and Technology Innovation Corridor. Once finished, it will deliver reliable power to innovation powerhouses like Westlake University, Westlake Science and Technology Economic Park, and Yungu Town, fueling their development.
As cities grow, overhead power lines are giving way to underground cables-creating a need for longer, larger-capacity cables. Mao Wei, project manager at State Grid Hangzhou Power Supply Company, pointed out that traditional 500-meter cable sections force countless joints, driving up costs and operational risks.
The project's G1-G6 shaft tunnel was the perfect fit: flat, straight, and 1,760 meters between firewalls (with 30 meters on each end for joints). That's why the 1,715-meter cable was tailor-made for this exact stretch.
Moving the massive cable was no small task. State Grid Hangzhou designed a 7.8-meter-diameter reel, transported the 90-ton unit via a specialized flatbed, and used two cranes in sync for hoisting. For laying, the team developed an automatic cable conveyor with four-wheel-drive induction-solving key issues like load management, braking, speed matching, and angle control on the spot.
