Multi-frequency GFCI with Frequency-Adaptive Trip Reference
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Solution Overview
Problem
Existing ground fault circuit interrupters (GFCI) are inadequate in detecting and interrupting ground faults at higher frequencies and broader frequency ranges, and they suffer from complexity, power consumption, and failure modes.
Innovation Solution
A unique GFCI configuration that includes a current sensor system with a current transformer and a differential current transformer to detect leakage currents, a magnitude detector, and a reference signal generator to establish a trip curve based on frequency, enabling accurate detection and interruption of ground faults across a range of frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing GFCI focus on ground fault currents around 60 Hz, then they can detect faults at standard power supply frequency, but they fail to accurately detect and interrupt ground faults at higher frequencies or over a broader frequency range
Solution Approach 1:
The patent changes the operating parameters of the GFCI by designing the trip reference value to vary with frequency. The reference signal generator produces trip reference values that are frequency-dependent, allowing the GFCI to accurately detect faults across a broad frequency spectrum from 60 Hz to several kHz. This resolves the contradiction by adapting the detection parameters to match the varying frequency conditions.
Solution Approach 2:
The patent implements dynamic adaptation by making the trip reference value dynamic rather than fixed. The reference signal generator dynamically adjusts the trip reference value based on the detected frequency of the leakage current signal. This dynamic approach enables accurate fault detection across varying frequencies while maintaining adaptability to different operating conditions.
2Adaptability or versatility
If existing GFCI use complex detection circuits, then they may achieve broader frequency coverage, but they suffer from undesirable complexity, power consumption, and failure modes
Solution Approach 1:
The patent merges multiple functions into a unified detection approach. The trip reference value varies with frequency through a single reference signal generator that integrates frequency detection and reference value generation. This consolidation achieves broad frequency coverage while reducing circuit complexity compared to separate dedicated circuits for each frequency range.
Solution Approach 2:
The reference signal generator serves multiple functions: it generates trip reference values, detects frequency, and adapts the detection threshold dynamically. This multi-functional component achieves broad frequency coverage without requiring separate specialized circuits for different frequency ranges, thereby reducing overall device complexity.
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 ground faults and opens the circuit in response to fault conditions, improving accuracy and reliability across various frequency ranges while reducing complexity and power consumption.
Implementation Method 1
a current sensor system with a current transformer and a differential current transformer to detect leakage currents
Implementation Method 2
a current sensor system with a current transformer and a differential current transformer to detect leakage currents
Data Source
AI summary
A GFCI includes a current sensor system providing a current sensor signal indicating a leakage current of the AC power system. A magnitude detector is configured to provide a first channel signal indicating an RMS value of the current sensor signal. A reference signal generator is configured to provide a second channel signal indicating a trip reference value responsive to a frequency of the current sensor signal. A fault detector is configured to provide a fault trip signal indicating ground fault condition of the AC power system in response to the first channel signal and the second channel signal. A circuit breaker mechanism is configured to open a circuit of the AC power system in response to the fault trip signal.