Winding Insulation System with Low Viscosity Resin
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Solution Overview
Problem
Existing high voltage insulation systems for electric machine windings are limited to voltages up to 22 kV due to difficulties in impregnating sufficient layers of tape for higher voltages, making them inadequate for applications requiring higher field strengths.
Innovation Solution
A multi-layered winding insulation system comprising insulated conductors, a main wall insulation with inner, intermediate, and outer sections, a corona shield tape, a stress grading tape, and a sealing tape, utilizing polyimide mica paper and aramid-backed mica tape in half-lap layers, impregnated with low viscosity resin to achieve effective insulation up to 25 kV.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resin impregnation methods are used with multiple layers of tape, then insulation coverage is improved, but the process becomes ineffective for voltages above 22 kV due to impregnation difficulty
Solution Approach 1:
The patent changes the viscosity parameter of the resin from conventional high viscosity to low viscosity, enabling effective impregnation of multiple tape layers at higher voltages (25 kV and above). This parameter modification allows the resin to penetrate through the complex multi-layer tape structure that would be impermeable to conventional resins, thereby maintaining insulation effectiveness while overcoming the impregnation difficulty.
Solution Approach 2:
The patent employs a composite insulation structure combining multiple tape types (pressboard, mica,Nomex®) with low viscosity resin. This composite material system creates a synergistic effect where the diverse tape layers provide structural integrity and electrical insulation, while the low viscosity resin ensures complete penetration and bonding, achieving reliable insulation at 25 kV that neither component could achieve alone.
2Reliability
If the number of tape layers is increased to achieve higher voltage insulation, then voltage rating is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies different tape materials at different locations within the insulation system: pressboard at the main wall, mica tape at critical stress points, and Nomex® in intermediate layers. This local differentiation optimizes the electrical and mechanical properties at each specific location, achieving 25 kV rating without uniformly increasing the total number of layers throughout the entire insulation structure.
Solution Approach 2:
The insulation system is segmented into distinct functional zones with specific tape compositions: inner layer with pressboard and mica, intermediate layer with Nomex®, and outer layer with additional protection. This segmentation allows each zone to be optimized for its specific electrical stress conditions, achieving high voltage rating while maintaining manageable manufacturing complexity through modular construction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides reliable electrical insulation for medium and high voltage windings, effectively managing high field strengths by using advanced tape combinations and resin impregnation, extending the voltage rating beyond the conventional limit of 22 kV to 25 kV.
Implementation Method 1
utilizing polyimide mica paper and aramid-backed mica tape in half-lap layers, impregnated with low viscosity resin
Data Source
AI summary
A winding insulation system includes a set of insulated conductors, main wall insulation provided around the conductors, corona shield tape provided around the main wall insulation, stress grading tape provided around the corona shield tape, and sealing tape provided around the stress grading tape. The main wall insulation includes inner, intermediate, and outer sections. The inner section includes polyimide mica paper reinforced with any combination of the group consisting of: glass cloth, polyester film, and polyester mat, the inner section being provided in half-lap layer(s). The intermediate section includes mica paper reinforced with any combination of the group consisting of: glass cloth, polyester film, and polyester mat, the intermediate section being provided in half-lap layer(s). The outer section includes mica tape backed with aramid and reinforced with any combination of the group consisting of: glass cloth, polyester film, and polyester mat, the outer section being provided in half-lap layer(s).