Toroidal Bus Connector Field Shaping and Heat Sink

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Solution Overview

Problem

Switchgear and electrical isolation equipment face challenges in reducing the minimum clearance between electrical conductors and ground while maintaining industry-standard compliance and improving heat sinking capabilities, particularly due to bulky low-voltage current transformers and the need for larger cabinet sizes to accommodate clearance requirements.

Innovation Solution

A shaped bus-connector with smooth and rounded surfaces is designed to reduce clearance between electrical conductors and ground, featuring a cylindrical head with a toroidal shape and an elongated body, allowing for offset connections and enhanced heat sinking, thereby reducing the size of switchgear cabinets while meeting industry standards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If conventional conductors with sharp edges and corners are used, then electrical discharge prevention requires larger clearance distances, but this increases the size of switchgear cabinets

Engineering Contradiction:
Improveclearance distanceVSAvoidswitchgear cabinet size
Core Design Contradiction:
Length of stationary objectVSVolume of stationary object

Solution Approach 1:

The conductor is designed with a toroidal shape featuring smooth curved surfaces and rounded edges instead of sharp corners. This curvature distributes the electric field more evenly, preventing concentrated field intensification at sharp edges that would lead to electrical discharge. The toroidal geometry specifically eliminates corners and sharp edges while maintaining effective electrical connection, thereby reducing the required clearance distance to grounded surfaces and allowing compact switchgear cabinet design.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If larger clearance distances are maintained to comply with industry standards, then electrical discharge is prevented, but the switchgear cabinet size increases

Engineering Contradiction:
Improveelectrical discharge preventionVSAvoidswitchgear cabinet size
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The toroidal conductor shape with its smooth curved surfaces eliminates sharp edges and corners that would concentrate electric fields and initiate discharge. The continuous curved geometry ensures uniform electric field distribution, providing reliable electrical discharge prevention while allowing reduced clearance distances that enable compact switchgear cabinet sizes.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Measurement precision

If bulky low-voltage current transformers are mounted around power buses, then current monitoring is achieved, but greater separation between buses is required increasing cabinet size

Engineering Contradiction:
Improvecurrent monitoring capabilityVSAvoidbus separation distance
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The toroidal conductor design serves multiple functions simultaneously: it provides the main electrical power bus connection, acts as a current-carrying conductor with optimized field distribution, and enables compact bus arrangement through its reduced clearance requirements. This multi-functionality eliminates the need for bulky external current transformers that would require additional separation space, as the conductor itself is optimized for both electrical connection and compact spatial arrangement.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Volume of stationary object

If power buses and breaker terminals are vertically offset to accommodate smaller circuit breakers, then breaker footprint is reduced, but heat generation increases requiring additional heat sinks

Engineering Contradiction:
Improvecircuit breaker footprintVSAvoidheat generation at connections
Core Design Contradiction:
Volume of stationary objectVSTemperature

Solution Approach 1:

The toroidal conductor design merges the electrical connection function with optimized thermal management. The continuous curved geometry provides enhanced surface area for heat dissipation and improved electrical contact characteristics. By integrating the field-shaping geometry into the conductor itself rather than adding separate heat sink components, the design handles the thermal load from vertically offset connections while maintaining compact breaker footprint.

Inventive Principle:
Principle #5Merging (Combining)

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 achieves a 30-35% reduction in clearance to the grounded isolation barrier and reduces temperatures near electrical connections by 3-6 degrees Celsius, eliminating the need for external heat sinks, thus optimizing space and thermal management in switchgear.

Implementation Method 1

The shaped bus-connector has mostly or only smooth and rounded surfaces so there are no hard or sharp edges or corners from which electrical discharge from/to ground or other conductors may occur. This use of smooth and rounded surfaces to limit or prevent electrical discharge from/to an electrical conductor is generally known as 'field shaping'

Methodology Applied
Scientific EffectField shaping: Electric Field

Implementation Method 2

The power bus and breaker terminal can become extremely hot due to the large amounts of current flowing through them and heat sinks are typically needed to keep their temperature at or below a target level

Methodology Applied
Scientific EffectHeat sinking: Heat Sink

Data Source

PatentUS9646793B2Offset bus connection with field shaping and heat sink
Publication Date: 2017.05.09 SCHNEIDER ELECTRIC USA INC
  • US9646793B2 patent drawing
  • US9646793B2 patent drawing
  • US9646793B2 patent drawing

AI summary

Method and apparatus for reducing the minimum clearance needed between an electrical conductor and ground in switchgear and similar electrical isolation equipment provide a bus-connector having an extended toroidal shape that is designed to allow the size of the switchgear cabinet to be reduced while complying with industry-standard performance requirements. The toroidal shaped bus-connector has mostly or only smooth and rounded surfaces so there are no hard or sharp edges or corners from which electrical discharge from/to ground or other conductors may occur. The shaped bus-connector also has an elongated body that produces an offset connection resembling a “Z,” which allows power buses and breaker terminals that do not vertically line up to connect.