Corrosion-Protected Raceway for Power Transmission Lines
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Solution Overview
Problem
Improper laying and filling of raceway components in electrical power transmission lines can lead to air gaps, causing water evaporation and condensation, resulting in electrochemical potential differences that trigger corrosion of the raceway cover, which is not effectively addressed by existing shielding methods.
Innovation Solution
A basic passivating material is applied to the inner surface of the raceway cover, forming a protective layer that prevents corrosion by maintaining a basic pH and creating a barrier against electrochemical potential differences, using a combination of cement mortar, alkaline sand, and water-swellable materials to ensure contact with the filling material and prevent air gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-pieced raceway with wet filling material is used to house electrical cables, then the magnetic field is shielded and heat is dissipated, but air gaps may form between the raceway cover and filling material causing corrosion
Solution Approach 1:
A passivating material layer is introduced as an intermediary between the raceway cover and the wet filling material. This layer prevents direct contact between the metal cover and the electrolyte-containing filling material, thereby eliminating the electrochemical corrosion pathway while maintaining the shielding and thermal dissipation functions of the raceway system.
Solution Approach 2:
The pH of the environment at the raceway cover surface is changed from acidic/neutral (corrosive) to basic (protective) by applying a passivating material with basic properties. This parameter change creates a protective atmosphere that prevents corrosion, transforming the chemical environment from harmful to beneficial.
2Reliability
If a thick zinc layer is applied to the raceway cover for corrosion protection, then corrosion resistance is improved, but material costs and manufacturing complexity increase
Solution Approach 1:
The passivating material layer serves as a mediator that provides corrosion protection without requiring thick zinc layers. This intermediary layer simplifies manufacturing by eliminating the need for extensive galvanization processes while achieving equivalent or superior corrosion protection.
Solution Approach 2:
The protection mechanism is changed from relying on material thickness (thick zinc layer) to relying on chemical properties (basic passivating layer). This parameter change enables simpler manufacturing processes that apply a thin chemical barrier rather than requiring thick metal deposition.
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 significantly reduces corrosion rates to below 1 µm per year, simplifies the laying process, and allows for the use of thinner zinc layers, thereby reducing material costs and extending the lifespan of the transmission line.
Implementation Method 1
a layer of a basic passivating material is in contact with the whole inner surface of the raceway cover facing the wet basic filling material
Implementation Method 2
The Applicant has also observed that the difference in salinity between the condensed pure water wetting the bare lower surface of the raceway cover and the aqueous solution impregnating the filling material can cause an electrochemical potential difference which triggers harmful corrosion phenomena of the cover.
Implementation Method 3
using a combination of cement mortar, alkaline sand, and water-swellable materials to ensure contact with the filling material and prevent air gaps
Implementation Method 4
the wet filling material helps to dissipate the heat generated by Joule effect by the cables during use so as to maintain their operating temperature below a threshold temperature
Implementation Method 5
the wet filling material helps to dissipate the heat generated by Joule effect by the cables during use
Implementation Method 6
part of the water contained in the filling material may evaporate and condense on the exposed areas of the lower surface of the cover creating a thin film of condensed pure water thereon
Implementation Method 7
part of the water contained in the filling material may evaporate and condense on the exposed areas of the lower surface of the cover
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~5
AI summary
An electrical power transmission line (1) is described, comprising: at least one electrical cable (3); a raceway (2) made of ferromagnetic material comprising a base (5) and a cover (6) defining an inner housing space (9) for housing the electrical cable (3); a wet basic filling material (7) having a pH comprised between 11 and 13 housed in the inner housing space (9) and embedding said at least one electrical cable (3). In order to achieve corrosion protection of the raceway (2) the inner surface of the cover (6) is in contact with a basic passivating material having a pH comprised between 11 and 13.