Earth Connection Tester Using AC Signal Frequency Analysis

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Solution Overview

Problem

Current earth resistance testers require trained personnel, are time-consuming, and lack fail-safe mechanisms, especially when testing earth connections not supplied by mains electricity, such as those in hazardous environments like flammable liquid or gas storage facilities, where accurate and efficient dissipation of electrostatic charge is critical.

Innovation Solution

A device that generates an AC signal and compares its frequency with pre-determined ranges to determine if the resistance between an earth connection and earth reference potential is within a safe limit, allowing for effective dissipation of electrostatic charge without additional apparatus or connections, and automatically connects the conductive item to earth if the resistance is suitable.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional earth resistance testers are used, then resistance measurement is achieved, but the testing process becomes time-consuming and requires trained personnel

Engineering Contradiction:
Improveresistance measurement accuracyVSAvoidtesting time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces complex manual testing procedures with an automated electronic system that uses AC signal generation and frequency comparison to determine earth resistance. The microprocessor automatically analyzes the frequency of the AC signal to assess resistance levels, eliminating the need for manual calibration and interpretation by trained personnel.

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

Solution Approach 2:

The device performs self-testing and automatic assessment of earth resistance by comparing the frequency of the generated AC signal with predetermined ranges. The system autonomously determines whether the resistance is within acceptable limits without requiring external expert intervention or complex manual procedures.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If conventional earth resistance testers are used, then resistance measurement is achieved, but the complexity of operation increases due to calibration and interpretation requirements

Engineering Contradiction:
Improveresistance measurement accuracyVSAvoidoperational simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces manual calibration and interpretation processes with automated electronic frequency analysis. The microprocessor automatically compares the AC signal frequency with stored reference ranges to determine resistance levels, eliminating the need for operator expertise in calibration and data interpretation.

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

Solution Approach 2:

The system provides immediate automated feedback by comparing the measured AC signal frequency with predetermined ranges and directly determining whether earth resistance is within acceptable limits. This closed-loop feedback mechanism eliminates the need for manual analysis and reduces operational complexity.

Inventive Principle:
Principle #23Feedback

3Device complexity

If fail-safe mechanisms are not implemented, then device simplicity is maintained, but safety in hazardous environments is compromised

Engineering Contradiction:
Improvedevice simplicityVSAvoidsafety in hazardous environments
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements automated feedback mechanisms that continuously monitor earth resistance levels by analyzing AC signal frequency. The system provides immediate alerts when resistance exceeds acceptable thresholds, ensuring safety in hazardous environments without adding significant complexity to the device.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces manual monitoring and safety assessment with automated electronic frequency analysis and microprocessor-based decision making. This substitution provides reliable fail-safe functionality while maintaining device simplicity through integrated electronic control.

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

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

Enables quick, accurate, and safe verification of earth connections for electrostatic charge dissipation, reducing the need for trained operators and ensuring effective grounding in hazardous environments, with a fail-safe mechanism to prevent unsafe resistance levels.

Implementation Method 1

testing whether the resistance between an earth connection and earth reference potential is less than a maximum earth resistance value

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

dissipating any charge before a dangerous level can be reached

Methodology Applied
Scientific EffectElectrostatic charge dissipation: Electrostatic Discharge

Data Source

PatentEP2153238B1Improvements relating to the testing of an earth connection
Publication Date: 2016.03.16 NEWSON GALE
  • EP2153238B1 patent drawingFigure 1~2
  • EP2153238B1 patent drawingFigure 3~4
  • EP2153238B1 patent drawingFigure 5~6

AI summary

A device (10) is disclosed that is suitable for testing an earth connection (30) that is isolated from a mains electricity supply. The device (10) comprises means (14, 40) for electrically connecting the device(10) to the earth connection (30), and means (16, 32) for electrically connecting the device (10) to an electrically conductive item (20) having a capacitance relative to an adjacent surface of the earth that is within a pre-determined range of capacitances. Furthermore, the device (10) includes means for generating an AC signal and delivering the AC signal to the electrically conductive item, and means for determining whether the resistance between the earth connection (30) and earth reference potential is less than a maximum earth resistance value. This determination is achieved by comparing the frequency of the generated AC signal with a pre-determined range of frequencies.