Technical Publications & Webinars

Comparison of New and Old High Voltage Diamond Coil Electrical Insulation Performance for Hydroelectric Generators

A comparison of high-voltage diamond coils removed from hydroelectric generators after 38 years of service with newly manufactured resin-rich replacement coils. The original coils come from the US Army Corps of Engineers' renovation of the Chief Joseph Dam in Washington State, where 16 generator units (92,920 kVA, 13,800 V) are being rewound with new coils supplied by Preformed Windings. With the average US hydroelectric station approaching 50 years of age, the paper sets out the insulation-performance gains achievable by rewinding the fleet using coils made with modern techniques.