Huilai Power Plant's 5th and 6th units (2x1000MW ultra-supercritical) entered commercial operation in February 2026, adding 88.4 billion kWh of annual generation capacity to the grid. The project offers useful reference points for how disconnect switches, lightning arresters, and drop-out fuse cutouts are specified in large thermal power plants, particularly those in coastal environments.
Disconnect switches at this site are specified for high humidity and salt fog. The switchyard uses motor-operated centre-break disconnect switches with silver-plated main contacts, sealed bearings, and 50°C-rated motors. Earlier projects at similar coastal sites experienced contact overheating with tin-plated switches within three years of operation. Motor ratings also required adjustment-40°C-rated motors tripped frequently during summer months due to internal cubicle temperatures reaching 58°C. All insulators are silicone rubber rather than porcelain. In coastal conditions, salt fog creates a conductive layer on porcelain surfaces, while silicone rubber maintains hydrophobic properties. For desert installations, silicone rubber similarly outperforms porcelain as moisture-absorbing sand can create tracking paths.
Lightning arresters use enhanced creepage and silicone rubber housings. Metal-oxide gapless arresters are installed at all line entrances and transformer bays. Creepage distance is specified at 31mm/kV, exceeding IEC heavy pollution recommendations. This follows experience with standard creepage arresters on adjacent lines, which developed surface tracking and housing carbonization after four years. Energy rating is 5kJ/kV rather than the conventional 3kJ/kV, accounting for long incoming transmission lines and high local lightning flash density. Silicone rubber housings were selected after porcelain units showed visible surface discharge activity in night inspections. For projects in Southeast Asia with overhead lines crossing open terrain, these specifications reduce the risk of premature arrester failure.
Drop-out fuse cutouts use polymer housings for durability. The plant's auxiliary distribution system employs hundreds of drop-out fuse cutouts protecting distribution transformers. All are polymer-housed. Porcelain units previously used elsewhere shattered on operation, creating recurring replacement costs. Polymer housings withstand impact and reduce weight for hot-stick handling. Operating mechanisms were verified during commissioning for smooth engagement-critical in sandy environments where poorly designed mechanisms can jam. Fuse links are sized to individual transformer ratings and coordinated with upstream protection devices. Initial coordination issues causing upstream breaker tripping were resolved by adjusting fuse curves rather than using uniform ratings across all transformers.
Key specifications for similar environments
Disconnect switches: silver-plated contacts, 50°C motor rating minimum, silicone rubber insulators. Coastal and desert installations require these specifications regardless of voltage class.
Lightning arresters: creepage distance 31mm/kV or higher for polluted environments, silicone rubber housings, energy rating with minimum 20% margin above calculated requirements based on line length and lightning activity.
Drop-out fuse cutouts: polymer housings, operating mechanism compatible with standard hot-stick tools, fuse links selected by transformer rating and coordinated with upstream protection curves.
Huilai's experience confirms that component specifications tailored to local conditions prevent operational issues that typically emerge within three to five years of commissioning. For buyers in Southeast Asia and the Middle East, these parameters provide a practical baseline for equipment selection.