Ultrasonic Arc Detection in Closed Chambers Under Ambient Noise
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Solution Overview
Problem
Existing electric arc detection systems are not effectively transposable across different electrical systems and environments, particularly failing in noisy conditions due to their application-specific nature and susceptibility to false detections from mechanical vibrations.
Innovation Solution
An electric arc detection method and system utilizing an acoustic sensor with a frequency range of 60 kHz to 300 kHz, specifically filtering out frequencies below 60 kHz to distinguish ambient noise from arc signals, and employing a correlation with a model of the temporal response to validate detections, ensuring operation in noisy environments and reducing false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic detection is used in noisy environments with frequencies below 60 kHz, then the system can detect ambient sounds, but it suffers from false detections due to mechanical vibrations and ambient noise
Solution Approach 1:
The patent changes the frequency parameter of acoustic detection from below 60 kHz to above 60 kHz. This parameter change allows the system to avoid the ambient noise and mechanical vibration frequencies that dominate below 60 kHz, while still detecting electric arc signals that emit acoustic energy in the 60-300 kHz range. The high-pass filter with cutoff frequency of 60 kHz implements this parameter change by blocking frequencies below the threshold while allowing arc detection frequencies to pass through.
Solution Approach 2:
The patent applies local quality by creating a frequency-selective detection zone above 60 kHz. Instead of uniformly detecting all acoustic frequencies, the system focuses detection resources on the specific frequency band where electric arc signals are present but ambient noise is minimized. This localized frequency targeting improves signal-to-noise ratio and detection reliability in noisy environments.
2Reliability
If a high-pass filter with cutoff frequency of 60 kHz is applied, then false detections from ambient noise are reduced, but the system must maintain sensitivity to arc signals in the 60-300 kHz range
Solution Approach 1:
The patent optimizes the acoustic sensor's frequency response parameters to be sensitive in the 60-300 kHz range. By selecting sensors and configuring filters with specific frequency characteristics, the system maintains high sensitivity to arc signals while rejecting lower frequency ambient noise. The correlation template is also designed with frequency characteristics matching expected arc signals in this range, ensuring accurate detection despite the selective filtering.
Solution Approach 2:
The patent employs correlation between the filtered acoustic signal and a pre-established arc signal template as feedback to validate detections. This correlation process provides feedback confirmation that the detected signal above 60 kHz actually matches the temporal and spectral characteristics of electric arcs, rather than random noise. This feedback mechanism maintains measurement precision by verifying arc signal presence even after frequency filtering.
3Reliability
If existing arc detection systems are applied to different electrical systems, then detection capability is achieved, but the systems are not transferable due to being application-specific
Solution Approach 1:
The patent creates a universal arc detection system by focusing on the fundamental acoustic emission characteristics of electric arcs (60-300 kHz frequency range) rather than application-specific parameters. The high-pass filter design and correlation methodology can be applied across different electrical systems (power lines, transformers, switchgear, industrial equipment) without modification. This universal approach allows the same detection system to be transferred and deployed across multiple electrical applications while maintaining reliable arc detection capability.
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 reliable detection of electric arcs in noisy environments by differentiating arc signals from ambient noise, reducing false detections, and maintaining sensitivity to frequencies where arc signals are significantly higher than noise levels, thus improving safety and accuracy in various electrical systems.
Implementation Method 1
an acoustic sensor with a resonant frequency of 40 kHz is used, and an operator monitors for the appearance of an audible signal
Implementation Method 2
the measurement is filtered to eliminate frequencies below approximately 60 kHz
Data Source
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AI summary
The invention relates to a method for detecting electric arcs in a closed chamber having no openings larger than 5 mm and defining a gas volume to be monitored. Said method comprises: a step (11, 13) of measuring a sound level captured by a microphone (1), placed inside the chamber, at frequencies greater than about 60 kHz while filtering out the lower frequencies; and a step (15) of comparing said level with a threshold (TH).