Reed Switch Current Detection with Shielding

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Solution Overview

Problem

Existing devices for detecting electrical currents on or near conductors using reed contacts are limited in their ability to accurately record and differentiate between surge currents and long-term currents, often requiring complex and fault-prone electronic circuits, and are not suitable for harsh environments or high dynamic forces.

Innovation Solution

A device with a quasi spatially staggered arrangement of reed contacts, each with varying sensitivity, that can detect and differentiate between long-term and short-term impulse currents by adjusting the response behavior through shielding and spatial positioning, allowing for reliable recording of pulse currents up to 250 kA without mechanical damage, and integrating evaluation electronics to determine current quantities and pulse shapes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complex electronic circuits are used to detect and differentiate surge currents and long-term currents, then measurement precision is improved, but device complexity increases and reliability decreases

Engineering Contradiction:
Improvecurrent differentiation accuracyVSAvoidcircuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The device segments the current detection function into multiple reed contacts (first, second, and third reed contacts) positioned at different spatial locations and sensitivities. Each reed contact responds to different current thresholds, allowing the system to differentiate between surge currents and long-term currents through combinatorial patterns of activation rather than complex electronic analysis

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces complex electronic detection circuits with a mechanical field-based detection system using reed contacts. The reed contacts mechanically respond to magnetic fields generated by current flow, eliminating the need for sophisticated electronic signal processing while maintaining detection capability through the physical arrangement and sensitivity characteristics of the reed contacts

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If reed contacts are arranged with high sensitivity to detect small currents, then measurement precision is improved, but the device becomes vulnerable to mechanical damage from high dynamic forces

Engineering Contradiction:
Improvecurrent detection sensitivityVSAvoidmechanical durability
Core Design Contradiction:
Measurement precisionVSStrength

Solution Approach 1:

The detection system is segmented into multiple reed contacts with different sensitivity levels and spatial positions. The first reed contact has higher sensitivity for detecting smaller currents, while the second and third reed contacts are positioned or configured to respond to larger currents. This segmentation allows the system to maintain high sensitivity for precision detection while the distributed arrangement reduces mechanical stress on any single contact

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent positions and configures the reed contacts beforehand to withstand expected mechanical forces. The spatial arrangement and mounting structure are designed to cushion and distribute the mechanical impact of high dynamic forces during surge events, protecting the sensitive reed contacts from damage while maintaining their detection capability

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 device enables reliable detection and differentiation of current pulses and surge currents without requiring expensive electronic circuits, operates trouble-free in harsh environments, and provides a cost-effective alternative to complex measuring systems like Rogowski coils, with the ability to record both interference current pulses and long-term currents.

Implementation Method 1

in the event of a significant current flow through the conductor, the resulting magnetic field triggers the switch

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

the contact tongues of which can be moved in different directions to open and close the respective reed contact

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP3775941B1Device for detecting electrical currents on or in the vicinity of electrical conductors
Publication Date: 2025.01.22 DEHN SOHNE GMBH CO KG
  • EP3775941B1 patent drawingFigure 1
  • EP3775941B1 patent drawingFigure 2
  • EP3775941B1 patent drawingFigure 3

AI summary

The invention relates to a device for detecting electrical currents on or in the vicinity of electrical conductors with at least one Reed switch as a magnetically responsive switch, which is arranged in the vicinity of the electrical conductor such that, when there is a significant current flow through the conductor, the magnetic field created triggers the switch and initiates an evaluation electronics connected to the switch. For the detection of surge current variables and the differentiation between long-term pulsed currents and short-term pulsed currents, a plurality of Reed switches are arranged at a predetermined distance from the electrical conductor, wherein the evaluation electronics determines the response and the switching times of the respective Reed switches, determines die surge current variable from the allocation of the determined values to the respective Reed switch and the pulse form from the switching time, wherein, for the purpose of adjusting the response behavior, at least one of the Reed switches comprises a shielding for influencing the magnetic field acting on the respective Reed switch.