Loose Joint Detection in Medium Voltage Switchgears
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Solution Overview
Problem
Current methods for detecting loose joints in medium voltage switchgears are complex, expensive, and unable to identify issues in one panel without data from other panels, leading to inefficient energy use and potential damage from increased electrical resistance.
Innovation Solution
A method involving temperature measurements at specific points in a three-phase system, comparing temperatures across phases to set alarms for discrepancies, with temperature sensors at busbar, circuit breaker, and cable connection joints, and a central evaluation unit for efficient detection and data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex temperature and current measurements are collected at multiple points for centralized processing, then loose joint detection accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent divides the switchgear system into multiple independent measurement zones, each with its own temperature sensors and evaluation unit. Each evaluation unit independently processes temperature data from its assigned measurement points, eliminating the need for complex centralized processing while maintaining detection accuracy through local thermal relationship analysis.
Solution Approach 2:
The patent introduces intermediate evaluation units that act as mediators between temperature sensors and the central control system. These evaluation units pre-process temperature data locally, performing initial loose joint detection and filtering before transmitting results centrally, thereby reducing the complexity of centralized processing while preserving detection capability.
2Loss of information
If centralized data collection and processing is used, then comprehensive analysis is improved, but detection of single panel faults becomes impossible without other panels' data
Solution Approach 1:
The patent segments the detection system into autonomous local evaluation units, each capable of independently detecting loose joints in its assigned panel by analyzing local temperature relationships. This segmentation ensures that single panel faults can be detected without requiring data from other panels, while still allowing comprehensive system-wide analysis through aggregation of local results.
Solution Approach 2:
The patent implements local quality by enabling each evaluation unit to perform complete loose joint detection functionality at the local level, with each unit having the authority and capability to detect faults in its own zone independently. This local autonomy ensures reliability for single panel detection while maintaining comprehensive analysis capability through systematic integration of local findings.
3Measurement precision
If many measurement points are used for centralized processing, then detection coverage is improved, but operating expenses increase
Solution Approach 1:
The patent segments the data processing function across multiple distributed evaluation units, each handling a subset of measurement points. This segmentation reduces the computational burden on any single unit and enables more efficient use of processing resources, thereby lowering operating expenses while maintaining comprehensive detection coverage through the collective capability of all evaluation units.
Solution Approach 2:
The patent implements self-service by enabling each evaluation unit to autonomously process its own measurement data and perform detection functions without requiring intensive centralized processing resources. This distributed self-processing reduces overall system operating expenses while maintaining comprehensive detection coverage through the coordinated operation of multiple autonomous units.
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 approach allows for quick and accurate detection of loose joints, reducing operating expenses while enhancing diagnostic capabilities and enabling retrospective analysis with event-triggered data storage.
Implementation Method 1
Loose joints in aforesaid switchgears produce local heat as a consequence of higher transition resistances of such loose joints
Data Source
AI summary
A method for loose joint detection in medium voltage switchgears with busbar joints, circuit breaker upper and lower spouts, and cable connection joints, arranged in an air insulated housing, and medium voltage switchgear itself, in order to create an effective loose joint detection with lower operating expense, but with high performance and accuracy, involves measuring actual temperatures at a first phase as a first temperature (T1), at a second phase as a second temperature (T2), at a third phase as a third temperature (T3), at predefined critical points, such as at the busbar joints, and/or at the circuit breaker upper spouts, and/or at the circuit breaker lower spouts, and/or the cable connection; and comparing temperatures in a logical dependency Ti>(Tj+dT), with i≠j, permuted with i from 1, 2, 3, and j from 1, 2, 3, and setting the alarm if the logical dependency is fulfilled.