Silicone Elastomer Putty for Stator Bar End Thermal Management
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Solution Overview
Problem
Existing high voltage electric generator stator bar end arrangements face challenges in managing increased thermal losses due to higher current density, as traditional thermal conductivity materials like epoxy resin with quartz filler have low thermal conductivity, leading to potential debonding and reduced heat transfer efficiency.
Innovation Solution
A composite cap filled with a silicone elastomer putty containing high thermal conductivity fillers such as boron nitride or alumina, ensuring improved adhesion and thermal conductivity exceeding 1.1 W/mK, while maintaining mechanical strength and preventing debonding during thermal cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional epoxy resin with quartz filler is used as putty, then the cap provides good electrical insulation, but the thermal conductivity is low (typically 0.25 W/mK) leading to poor heat transport
Solution Approach 1:
The patent changes the thermal conductivity parameter of the putty by replacing traditional epoxy resin with silicone elastomer and adding high thermal conductivity fillers (boron nitride or alumina), increasing thermal conductivity from 0.25 W/mK to greater than 1.1 W/mK
Solution Approach 2:
The patent creates a composite material system consisting of silicone elastomer base material combined with boron nitride or alumina fillers, achieving both high thermal conductivity and good adhesion properties that cannot be obtained with single materials
2Power
If increased current density is used to increase generator capability, then power output increases, but thermal losses increase requiring better heat transport
Solution Approach 1:
The patent converts the harmful effect of increased thermal losses (caused by higher current density) into a manageable condition by using the heat-conductive putty to efficiently channel and transport the excess heat away from the lugs, allowing the generator to operate at higher power levels
3Ease of manufacture
If traditional putty materials are used, then manufacturing is simple, but debonding occurs at the putty-copper interface during thermal cycling, creating crevasses with poor thermal conductivity
Solution Approach 1:
The patent uses silicone elastomer putty that can be easily applied and cured, providing a reliable bond that prevents debonding during thermal cycling, avoiding the need for complex bonding processes or additional reinforcement structures
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 effectively enhances heat diffusion and maintains mechanical integrity, ensuring stator bar end components operate within safe temperature limits even at increased current density, outperforming traditional arrangements by maintaining thermal conductivity and adhesion under thermal stress.
Implementation Method 1
The thermal conductivity of the putty is greater than 1.1 W/mK... the heat transport through cups and putty has to be increased
Implementation Method 2
provide a good adhesion between the putty and the copper of the lugs as well as the putty and the cap under thermal cycling
Data Source
Figure 1
AI summary
The arrangement comprises conducting bar ends connected together and a cap (6) covering them filled with a putty (7). The cap (6) comprises a resin containing a high thermal conductivity filler. The putty (7) is a silicone elastomere containing a high thermal conductivity filler.