Two-Part Down Conductor Layout for Lightning-Protected PV Roofs
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Solution Overview
Problem
Existing lightning protection systems for large-area building structures with metal roofs and photovoltaic panels face inefficiencies in ionization and energy loss, and the length of down conductors required for earthing increases the risk of spark flashes and fires, while being costly due to the need for high-voltage insulation.
Innovation Solution
A compact system using a PDA-type lightning rod with a two-part down conductor, where the first part is a high-voltage insulated cable and the second part is an uninsulated conductor embedded in reinforced concrete columns, connected through a control connector to the earthing, reducing the length of down conductors and minimizing energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a long down conductor is used for earthing the lightning rod, then the lightning protection coverage is improved, but the risk of spark flashes and fires increases and the cost increases due to high-voltage insulation requirements
Solution Approach 1:
The down conductor is divided into two separate parts: an upper insulated part connecting the lightning rod to the roof structure, and a lower uninsulated part embedded in the concrete column. This segmentation eliminates the need for continuous high-voltage insulation along the entire conductor length, reducing cost and fire risk while maintaining protection effectiveness.
Solution Approach 2:
The roof structure and concrete column act as intermediary elements that provide natural insulation and physical separation between the lightning rod and the earthing electrode. The concrete column serves as both a structural support and an insulating medium, eliminating the need for artificial insulation on the lower conductor section.
2Reliability
If a long down conductor with high-voltage insulation is used for earthing, then the lightning current can be safely conducted to ground, but the system cost increases due to expensive insulated cables
Solution Approach 1:
The down conductor path is segmented into zones with different insulation requirements. Only the upper portion exposed to the air requires high-voltage insulation, while the lower portion embedded in concrete uses simple uninsulated conductor. This reduces material costs significantly while maintaining safety.
Solution Approach 2:
The concrete column itself provides the insulation function for the lower conductor section, eliminating the need for expensive insulated cables in that region. The structural element serves a dual purpose: mechanical support and electrical insulation.
3Use of energy by moving object
If the lightning rod blade has a large equivalent surface area, then more electric charge is induced from the thundercloud, but the wind force on the blade increases and aesthetic considerations are compromised
Solution Approach 1:
The lightning rod uses an active emission mechanism (PDA system) that changes the operational parameter from passive charge induction to active electron emission. This allows effective lightning protection with a smaller, more aerodynamic blade structure that experiences less wind force and better aesthetics.
Solution Approach 2:
The passive mechanical charge induction system is replaced with an active electronic emission system. Instead of relying on large surface area to induce charge, the PDA system uses electrical fields and electron emission to create the lightning leader, allowing for a smaller blade structure.
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
This solution enhances the efficiency of lightning protection by reducing energy loss and minimizing the risk of spark flashes and fires, while being more cost-effective by shortening the length of down conductors and improving the reliability of the earthing system.
Implementation Method 1
accelerated ionization of the air around its blade
Implementation Method 2
inductive module consisting of a coil and a spark gap
Implementation Method 3
down conductor for a lightning current, taken over by this head, to the ground
Implementation Method 4
first part of which being electrically connected to this head by means of an insulated cable, while the second part of this down conductor is made of an uninsulated conductor embedded in this reinforced concrete column
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The subject of the invention is the lightning protection of large-area building structures, especially with roofs equipped with photovoltaic panels, which is characterized in that it consists of at least one two-part down conductor to the ground for the lightning current taken over by a head (8) of a lightning rod (7), the first part of this down conductor being a cable (19) with a metal core with a cross-section of 10 mm2 up to 70 mm2 covered with highvoltage polyethylene insulation, the lower end of which is electrically and mechanically connected to the upper end of the second part of this two-part down conductor, which is an uninsulated conductor (27) with a cross-section of 50 mm2 up to 120 mm2, embedded inside the reinforced concrete column (6) and inseparably connected with its steel reinforcement (22), the lower end of the uninsulated conductor (27) being connected through the control connector (29) to the conductor (27') connected to the earthing (28).