Multi-Layer Insulation for Hydroelectric Generator Coils
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Solution Overview
Problem
Existing insulation systems for hydroelectric generators and motors face challenges such as corona breakdown under high voltage and current conditions, occupying valuable space, and requiring improvements in performance and size reduction to enhance machine efficiency and power rating.
Innovation Solution
A multi-layer insulation system comprising various layers like strand insulation, turn insulation, ground wall insulation, slot corona suppression, voltage grading, and armor insulation, using solventless epoxy resin rich tapes, applied through specific temperature and pressure profiles to form and insulate coils before installation, ensuring resistance to corona breakdown and optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer insulation system is used to reduce corona breakdown and enhance performance, then reliability and resistance to corona breakdown are improved, but device complexity and space occupation increase
Solution Approach 1:
The insulation system is divided into multiple functional layers including ground wall insulation, stress control insulation, and corona suppression insulation. Each layer serves a specific purpose: ground wall insulation provides basic electrical isolation, stress control insulation manages voltage distribution, and corona suppression insulation prevents corona discharge. This segmentation allows each layer to be optimized for its specific function while working together as an integrated system.
Solution Approach 2:
The patent employs composite insulation structures combining different materials with complementary properties. For example, it uses combinations of pressboard, plastic insulation, and resinous materials to create a multi-layer system that leverages the electrical, mechanical, and thermal properties of each material to achieve superior corona resistance and overall performance.
2Reliability
If insulation system thickness is increased to improve corona resistance, then reliability is improved, but volume and space occupation increase
Solution Approach 1:
The insulation system applies different thicknesses and material properties at different locations and layers. The ground wall insulation, stress control insulation, and corona suppression insulation are designed with locally optimized characteristics rather than uniform thickness throughout. This allows adequate corona protection where needed while minimizing overall volume consumption.
Solution Approach 2:
The patent transitions from considering insulation as a single-dimensional thickness parameter to a multi-dimensional layered structure. By organizing insulation into multiple functional layers stacked in series, the system achieves superior corona resistance through the cumulative effect of layered protection rather than relying on increased thickness of a single layer, thereby optimizing volume utilization.
Data Source
AI summary
An insulation system and method are disclosed for insulating formed coils of hydroelectric machines, such as a hydroelectric generator. The system includes strand/turn insulation that may include one or more layers of different materials, depending upon the dielectric requirements. A ground wall insulation is applied over the group of turns. The coil may be sized in a slot cell section. Additional insulation layers are provided, including a slot corona suppression insulation that extends just beyond stator slots, a voltage grading layer, and an armor layer. Time temperature profiles and preheating may be used to cure coil sections via press and heat. The resulting system is suitable for installation in situ, and affords superior resistance to degradation.