Electrical Contact Testing via Differential Resistance Measurement

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Solution Overview

Problem

Existing methods for testing electrical contacts are often destructive, time-consuming, and not suitable for rapid evaluation of industrial production batches, making them incompatible with the need for quick and non-destructive testing in the industrial sector.

Innovation Solution

A method based on Joule's and Ohm's laws, involving differential resistance measurement by applying an electric stress to an electrical contact, measuring initial and subsequent resistances, and evaluating compliance based on resistance changes, using a simple apparatus with an electric generator and measuring device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If temperature tests are used to evaluate electrical contacts, then reliable detection of flawed contacts is achieved, but the testing time becomes excessively long (hours) and the component cannot be reused

Engineering Contradiction:
Improvedetection accuracyVSAvoidtesting duration
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the measurement parameter from temperature (which requires long stabilization time) to electrical resistance (which can be measured immediately). By applying electric stress and measuring resistance changes, the method achieves rapid detection of contact flaws without waiting for thermal equilibrium, thus resolving the time-reliability contradiction

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal-based detection method (temperature measurement) with an electrical-based method (resistance measurement). This substitution allows for instantaneous measurement without the thermal inertia delays inherent in temperature-based methods, achieving both speed and reliability

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

2Reliability

If destructive type tests are performed on electrical contacts, then comprehensive evaluation of contact quality is achieved, but the tested component becomes unusable after testing

Engineering Contradiction:
Improvequality evaluationVSAvoidcomponent reusability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies partial action by using controlled electric stress that is sufficient to reveal contact flaws through resistance changes but insufficient to cause permanent damage. The test uses transient current pulses rather than continuous overload, enabling detection while preserving component functionality for reuse

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The electrical contact itself serves as the sensing element by exhibiting characteristic resistance changes when subjected to electric stress. The contact's own electrical properties are utilized to detect its condition, eliminating the need for external destructive testing mechanisms

Inventive Principle:
Principle #25Self-service

3Reliability

If mechanical extraction force tests are used to evaluate socket holding strength, then mechanical performance is assessed, but the test cannot be integrated into electrical testing apparatus

Engineering Contradiction:
Improvemechanical performance evaluationVSAvoidtesting apparatus integration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates a multi-functional testing system where the same electrical apparatus can perform both electrical resistance measurements and infer mechanical contact quality. By measuring resistance changes under electric stress, the system simultaneously evaluates both electrical and mechanical aspects of the contact, eliminating the need for separate mechanical testing equipment

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

4Reliability

If extensive type tests are conducted on electrical contacts, then compliance with regulations is ensured, but the testing process becomes too slow for industrial production evaluation

Engineering Contradiction:
Improveregulatory complianceVSAvoidproduction evaluation speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent performs preliminary screening using rapid resistance measurement under electric stress to identify obviously defective contacts before they undergo more extensive type testing. This preliminary action filters out non-compliant contacts early, allowing compliant contacts to be quickly cleared for production without requiring full extended type test procedures

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes from time-intensive temperature-based compliance testing to rapid electrical resistance measurement. By measuring resistance at operating temperatures through controlled electric stress application, the method achieves compliance verification in seconds rather than hours, enabling integration into production line testing

Inventive Principle:
Principle #35Parameter changes

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

This method allows for quick, non-destructive testing of electrical contacts, identifying flawed contacts through resistance changes, and is applicable as a type, routine, or quality test, providing clear and reliable results without damaging compliant contacts.

Implementation Method 1

subjecting the electrical contact to an electric stress in a second time following the first time so that said electric contact has a second resistance while it is subjected to a second instantaneous electric power

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

measuring a first resistance of the electrical contact while it is subjected to a first instantaneous electric power in a first time

Methodology Applied
Scientific EffectElectrical resistance measurement: Electrical Resistance

Data Source

PatentEP3362806B1Method and apparatus for carrying out testing of an electrical contact and/or of an electrical connection
Publication Date: 2022.05.18 ROSA MICRO
  • EP3362806B1 patent drawingFigure 1~4
  • EP3362806B1 patent drawingFigure 3~5

AI summary

The present invention relates to a method for carrying out electrical testing of an electrical contact (A;B), comprising the steps of measuring a first resistance (Rt1) of the electrical contact (A;B) while it is subjected to a first instantaneous electric power in a first time (t1); subjecting the electrical contact (A;B) to an electric stress (S1) in a second time (t2) following the first time (t1), so that said electric contact (A;B) has a second resistance (Rt2) while it is subjected to a second instantaneous electric power; measuring a third resistance (Rt3) of the electrical contact (A;B) while it is subjected to a third instantaneous electric power for a third time (t3), following the second time (t2); evaluating the state of the electrical contact (A;B) according to the difference between the value of the third resistance (Rt3) measured in step c) and the first resistance (Rt1) measured in step a). The present invention also relates to an apparatus (100;110) to perform the electrical test of at least one electrical contact (A;B) comprising at least two ends.