Gradient Insulating Cap for High-Voltage End Windings

The insulating cap incorporates a gradient layer with spatially varying dielectric properties, where the material composition changes continuously from the high-voltage interior to the earthed exterior. This local variation in material quality allows the cap to simultaneously handle high-voltage insulation internally while providing an earthed surface externally, eliminating partial discharge paths without compromising insulation reliability.

The gradient layer changes the dielectric constant parameter continuously through its thickness, transitioning from high dielectric constant material near the high-voltage connection to low dielectric constant material at the external surface. This parameter gradient enables the cap to dissipate electrical field strength gradually, allowing external earthing while maintaining internal insulation integrity and preventing partial discharges.

The solution extends the gradient concept from a one-dimensional internal layer to a through-thickness gradient spanning the entire cap structure. The dielectric constant varies continuously in the radial dimension from interior to exterior, enabling the cap to provide both field control internally and external earthing capability by creating an effective electrical gradient across the full thickness of the insulating structure.

The insulating cap is constructed as a composite structure with a gradient layer comprising multiple materials or material compositions with different dielectric properties. This composite gradient structure combines materials with high dielectric constant for internal field control and materials with low dielectric constant for external earthing, creating a unified component that achieves both electrical field management and external ground connection capability.