U-Shaped Bus System Mitigating Skin Effect for Copper Reduction

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Solution Overview

Problem

Existing switchgear bus systems face issues with thermal dissipation and current distribution due to the 'skin effect' and 'proximity effect,' leading to uneven heating and increased copper usage, especially as conductor length increases.

Innovation Solution

A U-shaped bus system with strategically positioned conductors and air gaps to improve thermal dissipation and current distribution, reducing the need for excessive copper by promoting uniform current density and mitigating proximity effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If additional flat conductors are stacked together to counteract thermal effects, then thermal dissipation is improved, but copper usage increases

Engineering Contradiction:

Improvethermal dissipationVSAvoidcopper usage

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

The bus conductor is divided into multiple laminated flat conductors stacked together, with air gaps between them. This segmentation increases the surface area for thermal dissipation while the air gaps prevent direct thermal contact, reducing the need for excessive copper material to achieve the same thermal performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Air gaps are introduced as intermediary spaces between the laminated conductors. These air gaps serve as thermal insulators that prevent direct thermal contact between conductors, allowing each conductor to dissipate heat more effectively independently, thereby improving overall thermal dissipation without requiring additional copper.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If conductor length is increased to meet current rating requirements, then current capacity is improved, but thermal dissipation deteriorates

Engineering Contradiction:

Improvecurrent ratingVSAvoidthermal dissipation

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The conductors are arranged in a laminated configuration with air gaps, transitioning from a solid block structure to a multi-dimensional stacked structure. This dimensional change increases the exposed surface area for heat dissipation along the length of the conductor, allowing longer conductors to maintain effective thermal dissipation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Power

If laminated flat conductors are used to increase current capacity, then power handling is improved, but current distribution deteriorates due to skin effect

Engineering Contradiction:

Improvecurrent capacityVSAvoidcurrent distribution

Core Design Contradiction:

PowerVSManufacturing precision

Solution Approach 1:

The conductor is segmented into multiple thin laminated layers separated by air gaps. This segmentation reduces the effective thickness of each conductor layer, minimizing the skin effect that causes uneven current distribution. The current is distributed more uniformly across all laminated layers rather than concentrating at the surface of a thick conductor.

Inventive Principle:

Principle #1Segmentation

4Area of stationary object

If adjacent conductors of different phases are positioned close together, then space utilization is improved, but proximity effect causes uneven current distribution

Engineering Contradiction:

Improvespace utilizationVSAvoidcurrent distribution

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

Each phase conductor is segmented into multiple laminated layers with air gaps. This segmentation reduces the magnetic field interaction between adjacent phases by distributing the current across multiple separated layers, thereby reducing the proximity effect while maintaining compact spacing between phases.

Inventive Principle:

Principle #1Segmentation

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 U-shaped bus system achieves better thermal dissipation and current distribution, reducing power losses and copper usage by 25% while maintaining the same current rating, thus enhancing efficiency and reducing 'hot spots'.

Implementation Method 1

the temperature of the surrounding air due to natural convection increases, resulting in poor thermal dissipation

Methodology Applied

Scientific EffectNatural convection: Free Convection

Implementation Method 2

A related problem is a phenomenon called the 'skin effect,' which holds that the current density near the surface of the conductor is greater than at its core

Methodology Applied

Scientific EffectSkin effect: Skin Effect

Implementation Method 3

in multi-phase systems, adjacent conductors of different phases are subjected to another undesirable phenomenon called the 'proximity effect,' which relates to how current flowing through one phase interferes with current flowing through an adjacent phase

Methodology Applied

Scientific EffectProximity effect:

Data Source

PatentUS7952025B2Switchboard bus assembly in which material requirements are reduced without reducing performance

Publication Date: 2011.05.31 SCHNEIDER ELECTRIC USA INC

AI summary

A bus system for use in electrical distribution equipment includes a generally U-shaped arrangement of conductors for supplying very high amperage (e.g., above 2000 amps) alternating current to the electrical distribution system. Compared to prior-art conductor arrangements, using the present arrangement, the conductors of a phase can be fabricated from less copper, which is an expensive metal. They also achieve better thermal dissipation and current distribution and mitigate skin effects. As a result, resistive losses, which increase with increased temperature, are reduced.