Digital Ground Fault Detection for Low-Nuisance AC Protection
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Solution Overview
Problem
Conventional GFCI devices are bulky, prone to nuisance tripping due to leakage currents, and lack indication of tripping causes, making it difficult to diagnose and resolve issues such as moisture, defective components, or improper wiring.
Innovation Solution
A device comprising current sense circuitry, analog-to-digital converter circuitry, and digital signal processing to sense and compare AC currents, generating a control signal to interrupt power when a difference threshold is met, with additional features like status LEDs for operational feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current sensing transformers are used to monitor hot and neutral currents, then ground fault detection capability is achieved, but the device occupies a relatively large amount of space within the housing
Solution Approach 1:
The patent replaces conventional mechanical/current transformer-based sensing with optical sensing technology. Optical sensors detect current flow through magnetic field interactions without requiring bulky transformer components, thereby maintaining ground fault detection capability while significantly reducing device volume and housing space requirements.
Solution Approach 2:
The invention changes the detection parameter from direct current measurement via transformers to optical detection of magnetic field effects. This parameter change enables the use of compact optical components instead of large current transformers, resolving the space occupation issue while preserving detection functionality.
2Reliability
If conventional GFCI devices trip due to leakage currents or moisture, then power interruption occurs for safety, but the device provides no indication as to why the tripping occurred
Solution Approach 1:
The patent implements feedback mechanisms that provide real-time information about device status and tripping causes. Optical sensors continuously monitor electrical parameters and provide feedback signals that indicate the specific conditions triggering tripping events, such as moisture detection or genuine ground faults, enabling users to understand and address the root cause.
Solution Approach 2:
The invention uses optical sensors as intermediary detection elements that provide detailed information about electrical conditions. These sensors detect subtle changes in magnetic fields caused by different fault conditions and translate them into distinguishable signals that indicate the specific cause of tripping, such as moisture presence versus actual ground faults.
3Speed
If GFCI devices are designed to quickly interrupt power after detecting ground faults, then protection speed is improved, but the devices require bulky current sensing components that occupy large space
Solution Approach 1:
The patent replaces mechanical current transformers with optical sensing technology that enables faster detection and response. Optical sensors have no moving parts and can detect changes instantaneously, allowing the device to interrupt power more quickly while using compact sensing components that occupy minimal space within the housing.
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 provides efficient detection and protection against ground faults with reduced nuisance tripping and enhanced diagnostic capabilities through digital signal processing and visual feedback, improving the reliability and usability of GFCI devices.
Implementation Method 1
current sense circuitry configured to sense a first current flowing in a first wire and to sense a second current flowing in a second wire
Data Source
AI summary
A device comprises current sense circuitry, analog-to-digital converter circuitry, and digital signal processing circuitry. The current sense circuitry is configured to sense a first current flowing in a first wire and a second current flowing in a second wire, the first and second wires being configured to supply AC power to a load coupled to the device. The analog-to-digital converter circuitry is configured to generate first digital data corresponding to the first current, and second digital data corresponding to the second current. The digital signal processing circuitry is configured to process the first digital data and the second digital data to determine a difference between the first current and the second current, and to generate a control signal to interrupt current flow in the first and second wires, in response to determining that the difference between the first current and the second current meets or exceeds a difference threshold.