Carbon Pultruded Blade Lightning Conductor Bonding Against Arcing
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Solution Overview
Problem
Carbon fiber-reinforced spar caps in wind turbine rotor blades require improved lightning protection due to poor electrical contact between layers, leading to potential electric arcing and mechanical damage.
Innovation Solution
A lightning protection system with independent electrical connections at each end of carbon pultruded layers, connecting them to a lightning conductor, ensuring equitable current distribution and avoiding arcing by maintaining similar electrical voltages across contact points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon pultruded plates are used to produce spar cap layers, then the strength and mechanical performance of the rotor blade is improved, but the electrical contact between layers deteriorates due to the insulating surface layer
Solution Approach 1:
A conductive coating layer is applied to the surface of the carbon pultruded plates to serve as an intermediary that bridges the gap between the insulating surface and the requirement for electrical conductivity. This coating layer maintains the mechanical strength of the original carbon structure while providing the necessary electrical contact between layers.
Solution Approach 2:
The surface properties of the carbon pultruded plates are modified by changing the electrical conductivity parameter through the application of a conductive coating. This alters the surface characteristics from insulating to conductive while preserving the bulk mechanical properties of the carbon structure.
2Manufacturing precision
If the surface of carbon pultruded plates is left with insulating layer, then the manufacturing quality and surface integrity is maintained, but the electrical conductivity between adjacent layers deteriorates
Solution Approach 1:
The surface treatment is applied locally to specific areas of the carbon pultruded plates where electrical contact is needed, such as the bonding surfaces between layers. This allows the bulk of the surface to maintain its original high-quality finish while providing localized conductivity where required for electrical contact.
3Reliability
If traditional lightning protection systems are used with carbon pultruded layers, then basic protection is provided, but electric arcing between layers occurs due to poor electrical contact
Solution Approach 1:
The conductive coating ensures that adjacent carbon pultruded layers are at the same electrical potential by providing continuous electrical contact between them. This eliminates potential differences that would otherwise cause electric arcing during lightning strikes, thereby protecting the blade from this harmful effect.
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 system effectively distributes lightning currents, reducing the risk of arcing and mechanical failure by ensuring uniform electrical contact, while potentially allowing the use of less expensive glass fiber and reducing the number of layers required.
Implementation Method 1
an equipotential bonding element electrically connecting said stack of carbon pultruded layers with said lightning conductor
Implementation Method 2
the surface of the plates contain a thin layer of insulator which avoids a good electrical contact between plates
Data Source
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Figure 2
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AI summary
The invention relates to a lightning protection system for a carbon pultruded blade comprising a stack of carbon pultruded layers having at least a bottom layer (10) and a top layer (30), each layer (10, 30) having a first end (10a, 30a) and a second end (10b, 30b); the stack defining a tip-region (T), a root-region (R), and a mid-region (M); at least one lightning conductor (40) extending along said stack from the tip-region (T) to the root-region (R); and a plurality of electrical connections (50) connecting said stack of layers with said lightning conductor (40), each end (10a, 30a, 10b, 30b) of each layer (10, 30) is electrically connected with the lightning conductor (40) by one of said electrical connections (50); and each electrical connection (50) that connects one of the ends (30a, 30b) of the top layer (30) with the lightning conductor (40) is electrically connected with the bottom layer (10). The invention also relates to a carbon pultruded blade.