Switching Device With Arc Voltage Booster For Lightning Protection

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Solution Overview

Problem

Standard fuse elements and circuit breakers are inadequate for protecting surge arresters from lightning-induced shocks, requiring oversized internal connections and increased costs due to their lack of reactivity in breaking electrical circuits quickly.

Innovation Solution

A switching device combining an arc voltage booster with a fuse, specifically designed to enhance short-circuit current breaking capacity and responsiveness, featuring a fuse section of between one and three square millimeters, and removable pin terminals for easy installation and maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard fuse elements or circuit breakers are used to protect surge arresters, then the protective device can withstand overvoltage due to lightning, but the breaking device lacks reactivity to open the electrical circuit in sufficiently short time

Engineering Contradiction:
Improvewithstand overvoltageVSAvoidbreaking speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The fuse element's physical parameters (cross-sectional area of 1-3 mm², length-to-diameter ratio between 20-50) are optimized to achieve both high breaking speed and lightning withstand capability. This parameter optimization allows the fuse to respond rapidly to short-circuit currents while maintaining reliability under overvoltage conditions.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If standard fuse elements or circuit breakers are used, then the protective device can function as a switching device, but the internal connections must be oversized to respond to lack of reactivity

Engineering Contradiction:
Improvestandard component availabilityVSAvoidinternal connection size
Core Design Contradiction:
Ease of manufactureVSWeight of stationary object

Solution Approach 1:

The fuse element dimensions are precisely controlled with a cross-sectional area of 1-3 mm² and length-to-diameter ratio of 20-50, enabling rapid response without requiring oversized internal connections. This resolves the contradiction by achieving both manufacturability and compact design.

Inventive Principle:
Principle #35Parameter changes

3Speed

If the fuse element cross-sectional area is reduced to increase breaking speed, then the responsiveness improves, but the mechanical and thermal resistance decreases

Engineering Contradiction:
Improvebreaking speedVSAvoidmechanical and thermal resistance
Core Design Contradiction:
SpeedVSStrength

Solution Approach 1:

The fuse element's cross-sectional area is optimized to 1-3 mm² and length-to-diameter ratio to 20-50, achieving the optimal balance between breaking speed and mechanical/thermal strength. This parameter optimization allows the thin fuse element to respond rapidly while maintaining sufficient structural integrity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The fuse element is made of copper or copper alloy, which combines high electrical conductivity with adequate mechanical strength. This material selection enables the fuse to achieve both rapid breaking response and sufficient mechanical/thermal resistance despite the reduced cross-sectional area.

Inventive Principle:
Principle #40Composite materials

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 protects electrical installations against lightning by rapidly breaking short-circuit currents, reducing the need for oversized components and lowering production costs while ensuring mechanical and thermal resistance.

Implementation Method 1

The fuse element (11) is made of copper or copper alloy and is characterized by a cross-sectional area of between one and three square millimeters and a length-to-diameter ratio between 20 and 50. The fuse element (11) is able to withstand an overvoltage due to lightning.

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

A switching device (1) combining an arc voltage booster with a fuse, specifically designed to enhance short-circuit current breaking capacity and responsiveness

Methodology Applied
Scientific EffectElectric Arc: Electric Arc

Data Source

PatentEP2998976B1Cut-off member of a device for protecting an electrical installation against lightning
Publication Date: 2019.11.27 ABB (SCHWEIZ) AG
  • EP2998976B1 patent drawingFigure 1~3
  • EP2998976B1 patent drawing

AI summary

The present invention relates to a switching device intended to be electrically connected in series to an electrical circuit comprising a device for protecting an electrical installation against lightning, the switching device (1) comprising: - a first conductive armature (7) electrically connected to a first connection terminal (3) to the electrical circuit and a second conductive armature (9) electrically connected to a second connection terminal (5) to the electrical circuit; - at least one fusible element (11) disposed between the first armature (7) and the second armature (9) and electrically connected to the first armature (7) and to the second armature (9), the at least one fusible element (11) being arranged to melt when it is traversed by a current of a threshold intensity over a threshold time period;- a device for increasing an arc voltage (15) between the first armature (7) and the second armature (9) in the event of melting of at least one fusible element (11).;