Lightning Current Transfer Assembly for Wind Turbines
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Solution Overview
Problem
Conventional lightning current transfer assemblies in wind turbines experience frequent sparking flashovers due to temporary interruptions in galvanic connections, leading to electromagnetic energy emission, especially when located near radio transmitters, which increases radio frequency interference.
Innovation Solution
A lightning current transfer assembly with a spark gap connected in series to an electric contact arrangement and a spark-gap-bridging resistance, providing two alternative current paths: a lightning current path across the contact arrangement and spark gap, and a permanent-discharge current path across the contact arrangement and through the spark-gap-bridging resistance, reducing sudden current rises and preventing damage from lightning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a galvanic contact arrangement is used to transfer lightning current between rotatable parts, then continuous electrical connection is provided, but frequent sparking flashovers occur due to temporary interruptions in the connection
Solution Approach 1:
A spark gap is introduced as an intermediary protective element in series with the galvanic contact arrangement. The spark gap acts as a mediator that prevents direct harmful sparking at the contact surfaces by providing a controlled discharge path, thereby eliminating the harmful electromagnetic energy emission while maintaining continuous electrical connection through the contact arrangement.
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 reduces electromagnetic energy emission by minimizing sparking flashovers and ensuring the spark-gap-bridging resistance is not damaged by lightning currents, maintaining efficient lightning current transfer while reducing radio frequency interference.
Implementation Method 1
When the rotor blade is struck by lightning, the high lightning voltage will create a discharge over the spark gap
Implementation Method 2
a permanent-discharge current path across the at least one electric contact arrangement and through the spark-gap-bridging resistance
Data Source
AI summary
A lightning current transfer assembly (2) for a wind turbine (1) is arranged to transfer lightning current from a wind-turbine part (8) to another part (8) rotatable relative to it. The assembly comprises at least one electric contact arrangement (11′, 11″) comprising complementary contact members (12a′, 12b′, 12a″, 12b″) which provide electric connection by mechanically contacting each other while being movable relative to each; a spark gap (4) connected in series with the movement-enabling contact arrangement (11′, 11″); and a spark-gap-bridging resistance (6) connected parallel to the spark gap (4). Thereby, the assembly provides at least two alternative current paths: (i) a lightning current path across the at least one electric contact arrangement and the spark gap, and (ii) a permanent-discharge current path across the at least one electric contact arrangement and through the spark-gap-bridging resistance.