Loose Connection Detection via Negative Sequence Voltage Difference

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Solution Overview

Problem

Existing methods for detecting loose connections in electrical apparatus, such as motor control centers and switchgear, often rely on temperature sensors, which can be costly and difficult to implement effectively, particularly in complex bus bar arrangements.

Innovation Solution

The method involves collecting voltage samples for sources and loads, generating negative sequence voltage difference values, and identifying loose connections based on these values, thereby eliminating the need for additional sensors and reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If temperature sensors are used to monitor connection temperatures, then detection reliability is improved, but device complexity and cost increase

Engineering Contradiction:

Improvedetection reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/physical temperature sensor system with an electrical measurement system. Instead of using temperature sensors to directly detect thermal conditions, the system uses voltage measurements and negative sequence voltage difference calculations to identify loose connections. This substitution eliminates the need for physical sensors at connection points while maintaining detection capability through electrical parameter analysis.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces negative sequence voltage difference as an intermediary parameter that mediates between the physical state of connections and the electrical measurements. By calculating the negative sequence voltage difference from voltage samples, the system creates an indirect but reliable indicator of connection status, avoiding the need for direct temperature measurement while maintaining detection reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If multiple temperature sensors are deployed at multiple locations, then measurement precision is improved, but cost increases

Engineering Contradiction:

Improvemeasurement precisionVSAvoidcost

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent creates an electrical copy or representation of the physical connection state through voltage measurements. Instead of placing physical sensors at each connection point, the system uses voltage samples from the electrical network to generate negative sequence voltage difference values that represent the state of multiple connections simultaneously. This copying approach maintains measurement precision across multiple locations without requiring proportional increases in physical sensors.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent makes the voltage sampling and negative sequence voltage difference calculation system universal for monitoring multiple connections simultaneously. A single system architecture can detect loose connections across the entire electrical network without requiring separate temperature sensors for each connection point, thereby reducing overall cost while maintaining comprehensive monitoring capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If temperature sensors are placed near connections, then detection reliability is improved, but ease of operation deteriorates

Engineering Contradiction:

Improvedetection reliabilityVSAvoidease of operation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces the mechanical placement and operation of temperature sensors with an automated electrical measurement system. Instead of requiring physical access to connection points for sensor installation, the system uses existing voltage sampling infrastructure to automatically detect connection status through negative sequence voltage difference calculations, significantly improving ease of operation while maintaining reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12320863B2Apparatus, methods and computer-readable media for detection of loose connections in an electrical assembly

Publication Date: 2025.06.03 EATON INTELLIGENT POWER LTD

AI summary

Voltage samples are collected for a source and loads connected thereto by an electrical network. Respective negative sequence voltage difference values are generated for respective source/load pairs from the voltage sample. A connection (e.g., a loose connection) in the electrical network is identified based on the generated negative sequence voltage difference values. The identified connection is reported to a user. Identifying a connection in the electrical network may include identifying at least one source/load pair having an associated negative sequence voltage difference value that meets a predetermined criterion and identifying the connection based on the identified at least one source/load pair. Identifying the connection may include identifying at least one source/load pair having an associated negative sequence voltage difference value with a magnitude falling outside of at least one range associated with the at least one source/load pair.