Series Arc Fault Interrupter With Filtered Signal Analysis
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Solution Overview
Problem
Existing AC electrical systems lack effective detection and interruption mechanisms for series arc faults, which can lead to fires, especially in older residential and commercial buildings, as conventional circuit interrupters often fail to trip in such conditions.
Innovation Solution
A circuit interrupter equipped with separable contacts, a trip mechanism, a bimetal, a microprocessor, a series arc detection sequence, a low-pass filter circuit, and a high-pass filter circuit, which processes signals to identify series arc faults by calculating statistical features and activating the trip mechanism when predefined conditions are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional circuit interrupters are used, then the system structure remains simple, but series arc faults cannot be detected and interrupted
Solution Approach 1:
The patent combines multiple functions into a single circuit interrupter device: conventional overcurrent protection, series arc fault detection, and parallel arc fault detection. The microprocessor integrates signal processing, statistical analysis, and control functions, merging what would traditionally require separate devices into one unified system that maintains both simplicity and enhanced reliability.
Solution Approach 2:
The circuit interrupter is designed with multi-functionality to handle various fault types. The same device structure and microprocessor can detect and respond to overcurrent conditions, series arc faults, and parallel arc faults, making it a universal protection device that adapts to different fault scenarios without requiring separate specialized interrupters.
2Measurement precision
If statistical features are calculated from filtered signals, then series arc detection accuracy improves, but processing time and computational complexity increase
Solution Approach 1:
The patent applies filtering operations (low-pass and high-pass filters) to the current signal before statistical feature calculation. This preliminary signal conditioning removes irrelevant frequency components and noise, preparing the data in advance for more efficient statistical analysis. By pre-processing the signal, the system reduces the computational burden during the actual detection phase, balancing accuracy with processing speed.
3Reliability
If multiple filter circuits and algorithms are implemented, then detection reliability improves, but device complexity increases
Solution Approach 1:
The microprocessor serves as an intermediary that manages the complexity of multiple filter circuits and algorithms. Rather than requiring complex hardware logic for each filtering and analysis function, the microprocessor software-controls the low-pass and high-pass filters, performs statistical calculations, and implements detection algorithms. This software-based mediation simplifies the hardware architecture while maintaining detection reliability through sophisticated signal processing.
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
The solution effectively detects series arc faults by filtering and analyzing current signals, allowing for timely interruption of power to prevent fires, thereby enhancing safety in AC electrical systems.
Implementation Method 1
The microprocessor senses a current across the bimetal
Implementation Method 2
The low-pass filter circuit removes high frequency signals, such as arcing
Implementation Method 3
The high-pass circuit removes the 60 Hz frequency content
Data Source
AI summary
A circuit interrupter for interrupting current on a line conductor is provided. The circuit interrupter includes separable contacts, a trip mechanism, a bimetal, a microprocessor, a series arc detection sequence, a low-pass filter circuit, and a high-pass filter circuit. The trip mechanism selectively opens the separable contacts when activated. The series arc detection sequence is resident on the microprocessor and includes a plurality of series fault detection algorithms. The low-pass filter circuit provides a low-pass signal to the series arc detection sequence. The high-pass filter circuit provides a high-pass signal to the series arc detection sequence. The sequence selects a particular algorithm from the plurality of algorithms based on the low-pass signal. The sequence calculates a plurality of statistical features from the high-pass signal and sends an output signal to activate the trip mechanism based on a comparison of the plurality of statistical features to the particular algorithm.