Modular Blade Joint Conductive Elastomer for Lightning Current Bypass
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Solution Overview
Problem
Lightning strikes on wind turbine blades made of carbon fibre pose a challenge due to the high potential difference induced between conductive elements, as the carbon fibre is separated from metal inserts by a thin layer of non-conductive adhesive, leading to potential damage and inefficient lightning transmission.
Innovation Solution
A conductive elastomer or metallic spark gap with a toroidal shape is inserted between the carbon fibre laminates and metal joints to provide an alternative conductive path, preventing damage to the adhesive and ensuring efficient lightning transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon fibre laminates are used in the blade, then the blade strength and conductivity are improved, but the risk of adhesive breakdown and uncontrolled current passage increases
Solution Approach 1:
A conductive element is introduced as an intermediary between the carbon fibre laminate and the metal insert. This conductive element provides a controlled electrical pathway that intercepts lightning current before it can pass through the adhesive, thereby protecting the adhesive from thermal damage while maintaining the structural integrity and conductivity of the carbon fibre blade.
2Manufacturing precision
If a thin layer of adhesive is used to bond carbon fibre to metal inserts, then the manufacturing precision is improved, but the electrical insulation reliability deteriorates during lightning strikes
Solution Approach 1:
The conductive element serves as a mediator that provides a preferred electrical pathway between the carbon fibre and metal insert. During lightning strikes, the high current density preferentially flows through this conductive element rather than through the adhesive layer, protecting the adhesive from breakdown while maintaining the precise bonding achieved during manufacturing.
Solution Approach 2:
The invention changes the electrical conductivity parameter at the interface between carbon fibre and metal insert by introducing a conductive element. This creates a controlled low-resistance electrical pathway that redirects lightning current away from the adhesive, effectively changing the electrical behavior of the joint without affecting the mechanical bonding properties.
3Reliability
If multiple connection points between carbon fibre and down conductor are provided, then the lightning transmission reliability is improved, but the complexity of the device increases
Solution Approach 1:
The conductive element merges multiple functions into a single component: it provides structural support for the metal insert, creates an electrical connection between the carbon fibre and metal insert, and serves as a lightning current pathway. This consolidation reduces the number of separate connection points needed while maintaining reliable lightning transmission.
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 directs lightning current away from the adhesive, maintaining the integrity of the joint and ensuring reliable lightning protection during assembly and operation.
Implementation Method 1
a device that conducts the small percentage of the current transmitted by the conductive laminates of the blade that is not diverted to the cable during the high intensity peaks
Implementation Method 2
the claimed device is an elastic element with greater electrical conductivity than that of the adhesive used to glue the inserts to the carbon fibre
Data Source
AI summary
A lightning-protection device in a modular blade that connects the outboard module, where the lightning strikes, to the inboard module through which the lightning is conducted to the hub, and includes the lightning down conductor cable. The device is an elastic element with greater electrical conductivity than the adhesive used to affix the inserts in holes previously drilled inside the carbon fiber and that make up the metal joint of the modular blade. The device is an elastomer with a preferably toroidal shape thar surrounds each and every one of the metal elements that make up the joint of the blade and covers the gap formed between the carbon fiber of the cap and the aforementioned metal elements. The use of other shapes and other conductive materials that allow its geometry to be elastic is an option.