Circuit Breaker Monitoring via Instantaneous Current Waveform Analysis

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Solution Overview

Problem

Existing methods for monitoring circuit breakers in electrical power supply networks are inefficient in quickly and reliably detecting continuous or interrupted current flows, often requiring time-consuming Fourier transformations or threshold value comparisons, which can lead to delayed decision-making and potential unnecessary shutdowns of parts of the network.

Innovation Solution

The method analyzes the time profile of instantaneous current flowing through the circuit breaker, evaluating criteria such as periodicity, decay behavior, and amplitude to determine if the current flow is continuous or interrupted, allowing for rapid and flexible assessment without the need for frequency domain transformations or high sampling rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Fourier transformation is used to transform current signal into frequency range for analysis, then detection reliability is improved, but decision time is delayed

Engineering Contradiction:
Improvedetection reliabilityVSAvoiddecision time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the Fourier transformation method (frequency domain analysis) with a time domain analysis method that examines the time profile of instantaneous current. This substitution eliminates the computational overhead of frequency transformation while maintaining detection reliability through direct time-domain pattern recognition of current interruption characteristics.

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

Solution Approach 2:

The patent skips the intermediate step of frequency transformation and directly analyzes the time profile of current. By rushing through the detection process using time-domain examination of current characteristics (such as zero-crossing detection and amplitude analysis), the system achieves faster decision-making without sacrificing reliability.

Inventive Principle:
Principle #21Skipping (Rushing through)

2Device complexity

If threshold value comparison method is used to detect continuous current flow, then device complexity is reduced, but detection precision deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoiddetection precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent employs dynamic analysis of the time profile of instantaneous current rather than static threshold comparison. By examining the temporal characteristics of current (including rate of change, duration, and pattern recognition), the system achieves higher detection precision while maintaining relatively simple device architecture through software-based time-domain processing.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the detection parameter from simple current magnitude (threshold comparison) to time-profile characteristics of instantaneous current. This parameter transformation enables more precise detection of current interruption by analyzing temporal patterns, while the computational approach keeps device complexity manageable.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If high sampling rate is used to accurately capture current waveform, then measurement precision is improved, but data processing complexity increases

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddata processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies partial sampling approach, capturing only the essential time profile characteristics of current rather than continuously sampling at high rates. By focusing on critical moments (such as expected zero-crossings or interruption points), the system achieves sufficient measurement precision with reduced data volume, thereby lowering processing complexity.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3171473B1Method and protection device for monitoring a power circuit breaker in an electrical energy supply network
Publication Date: 2021.04.21 SIEMENS AG
  • EP3171473B1 patent drawingFigure 1
  • EP3171473B1 patent drawingFigure 2
  • EP3171473B1 patent drawingFigure 3~4

AI summary

The invention relates to a method for monitoring a circuit breaker (13d) in an electrical power supply network, in which a section of the electrical power supply network is monitored for the occurrence of a fault, a trip signal is sent to a circuit breaker (13d) delimiting the section upon detection of a fault on the monitored section, and a circuit breaker fault signal indicating a fault when the circuit breaker (13d) opens is generated if a continuous current flow through the circuit breaker (13d) is detected after the trip signal has been sent. In order to detect a continuous current flow or an interruption of the current flow as quickly and reliably as possible when monitoring a circuit breaker, it is proposed that a waveform of the instantaneous current flowing through the circuit breaker (13d) be analyzed to detect a continuous current flow.The invention also relates to a protective device (16) with a correspondingly configured control device.