GFCI Reinstallable Circuit Interrupter with Vibration-Resistant Miswire Protection
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Solution Overview
Problem
Conventional GFCI devices lack effective miswiring protection, particularly during re-installation and after removal, and often fail to robustly self-test without human intervention, leading to potential safety hazards due to incorrect wiring and malfunctioning mechanical locking mechanisms.
Innovation Solution
A GFCI device with a cylindrical reset pin and latch block mechanism that ensures proper wiring by preventing power connection to face terminals unless the device is correctly installed, combined with an auto-monitoring circuit for robust self-testing without human intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical locking mechanism is used to prevent reset in miswired conditions, then miswiring protection is provided at initial installation, but the mechanism is permanently disabled after installation and does not provide protection during re-installation
Solution Approach 1:
The patent transforms the static mechanical locking mechanism into a dynamic system that responds to electrical conditions. The latch mechanism is controlled by a solenoid that can be actuated by electrical signals from the monitoring circuit, allowing the device to adapt its locking state based on whether it is properly wired and whether it has been removed from the circuit. This enables the device to provide miswiring protection both at initial installation and during re-installation.
Solution Approach 2:
The patent replaces the purely mechanical locking mechanism with an electromechanical system. The solenoid-driven latch combines electrical control with mechanical action, allowing the monitoring circuit to control the locking state through electrical signals. This substitution enables the device to sense electrical conditions and respond appropriately, providing continuous miswiring protection rather than a one-time mechanical lock.
2Reliability
If the device is provided in a tripped condition with a locking mechanism, then power is not supplied to face terminals in miswired conditions, but the mechanism may malfunction due to vibrations or shock during shipping
Solution Approach 1:
The patent implements preliminary electrical monitoring before the device is put into service. The monitoring circuit continuously checks wiring conditions and controls the solenoid latch accordingly. This preliminary electrical verification provides a more reliable foundation for miswiring protection compared to relying solely on the mechanical state after shipping vibrations.
Solution Approach 2:
The patent incorporates a monitoring circuit that provides continuous feedback about wiring conditions to the control circuit. This feedback loop allows the device to detect miswiring conditions and respond by preventing reset or power supply to face terminals. The feedback mechanism is less susceptible to vibration-induced errors than pure mechanical systems because it uses electrical sensing to verify actual wiring conditions.
3Ease of operation
If conventional self-test mechanisms are used, then testing can be performed, but they require human intervention and do not provide robust automatic testing
Solution Approach 1:
The patent implements a self-service monitoring system where the device automatically tests its own wiring conditions and functionality without requiring human intervention. The monitoring circuit continuously verifies proper connection and controls the latch mechanism accordingly. The device can automatically detect miswiring conditions and prevent operation, and can automatically reset when properly wired, eliminating the need for manual testing or intervention.
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 reliable miswiring protection throughout the device's lifecycle, including re-installation, and ensures robust self-testing, enhancing user safety by preventing power delivery to face terminals in miswired conditions and automatically verifying the device's functionality.
Implementation Method 1
an actuator, such as a solenoid or a relay, activates a latched circuit breaker mechanism
Data Source
AI summary
A GFCI includes a latch assembly provided with a rigid electrically conducting bar connected thereto such that when a user presses a reset button the latch assembly is moved toward a pair of contacts provided as part of a reset circuit to initiate a reset operation. When the electrically conducting bar on the latch assembly connects the pair of contacts, the reset circuit is closed and an actuator is activated to place the GFCI device in the latched, reset, condition. If the GFCI device is correctly wired, the latch assembly enters the latched state. If the device is not properly wired no power is provided to the actuator and the device remains in the tripped, or open, state.