On July 2, a monumental achievement was reached as an 80-ton giant turbine runner was shipped from Harbin Electric Machinery Company Limited (HEC), a subsidiary of Harbin Electric Corporation (HE). This event marked the successful development of the world’s largest-capacity single-unit high-head impulse turbine runner.
This milestone not only showcases China’s historic leap in high-end hydropower equipment, but also positions the nation as the first country in the world to master the full-chain technology of 500 MW-class impulse turbines.
A giant turbine runner weighing 80 tons was developed. [Photo/sasac.gov.cn]
The runner will be installed at the Zhala Hydropower Station in Xizang — a core project of China's west-to-east power transmission program and currently the most technically challenging impulse hydropower project under construction worldwide. The station will house two 500 MW impulse generating units, both the largest and most advanced of their kind globally.
Breakthrough in both size and performance
As the core component of an impulse turbine, the bucket-type runner plays a vital role in converting the kinetic energy of water into mechanical energy, earning its reputation as the “heart” of hydropower units. As a pioneer in impulse turbine development in China, HEC has accumulated decades of experience, having participated in 67 units across 30 domestic and international hydropower stations, including Dongchuan in China and San Gabán in Peru. The company has built a unique system for R&D and manufacturing, with expertise spanning hydraulic design, model testing, structural engineering, and precision manufacturing.
The Zhala runner represents the cutting edge of global impulse turbine technology, with exceptionally demanding requirements for its structural parameters, hydraulic performance, and manufacturing process. It features 21 precision-engineered buckets, an outer diameter of 6.23 meters, a total height of 1.34 meters, and a weight of approximately 80 tons. Its hub forging is the world’s largest martensitic stainless steel forging to date. These record-breaking specifications reflect revolutionary advances in hydraulic efficiency, operational range, and pressure tolerance.
A benchmark of systematic engineering innovation
The development of this turbine runner showcases excellence in systematic engineering. The R&D team prioritized safety and performance, optimizing key elements such as the matching of nozzles and buckets, flow consistency, jet-bucket interaction, interference between adjacent jets, and bucket rigidity.
The project spanned four years and underwent five rounds of expert review. Over 100 design proposals were evaluated, resulting in six observation runners and six performance test models. Final testing on a high-precision impulse rig confirmed world-record levels of peak and weighted average efficiency, providing a strong foundation for safe, stable, and efficient long-term operation.
Technological and manufacturing excellence
To meet the unique challenges of fabricating the 500 MW-class welded and forged structure, HEC coordinated its top resources under a stringent quality assurance framework. It achieved breakthroughs in key areas including structural design, material preparation, welding techniques, and high-precision machining.
A giant turbine runner weighing 80 tons has been developed and will be installed at the Zhala Hydropower Station in Xizang. [Photo/sasac.gov.cn]
A collaborative team adopted a modular and distributed machining approach, streamlining CNC programming from 380,000 to 270,000 lines, and improving turning efficiency by 21 percent and boring efficiency by 27 percent. To mitigate stress issues from oversized components, digital simulation guided the die forging process, while a hybrid welding-forging structure was implemented with strategically placed joints outside the high-stress bucket areas.
Advanced welding techniques were supported by 3D inspection modeling and digital welding control systems, improving weld toughness and fatigue resistance.
By overcoming global challenges across the full technology chain — from hydraulic design and material processing to giant forgings, complex welding, precision machining, and quality assurance — HEC has independently developed the world’s first 500 MW impulse turbine runner. This achievement resolves a longstanding bottleneck in high-head, high-capacity impulse unit technology and injects Chinese technology into the advancement of global energy equipment technology.
(Executive editor: Cui Feng)
