GFCI Self-Testing Circuit Interrupter with Autonomous Microcontroller

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Solution Overview

Problem

Existing GFCI devices require manual and time-consuming testing, which is impractical for widespread applications like hotels or large motels, and may reset without user knowledge if the trip mechanism is disabled by events like lightning strikes, compromising fault protection.

Innovation Solution

An autonomous periodic automated self-testing system for GFCI devices that performs tests without interrupting power to connected loads, using relays and a microcontroller to evaluate conditions and ensure the circuit interrupter is operational, with a reset lockout mechanism to prevent accidental reactivation if the device is non-operational.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual testing is required for GFCI devices, then fault protection can be verified, but user burden and time consumption increase significantly

Engineering Contradiction:

Improvefault protection verificationVSAvoiduser burden

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The GFCI device performs automatic self-testing without requiring user intervention. The microcontroller automatically initiates test sequences, activates the trip mechanism, and verifies operational status, allowing the device to monitor its own functionality independently.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The device performs periodic self-tests before faults occur to proactively verify the trip mechanism is operational. This preliminary verification ensures the device is ready to protect against ground faults before an actual fault condition arises.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If periodic testing is performed manually, then device functionality can be confirmed, but time and cost expenses increase

Engineering Contradiction:

Improvedevice functionality confirmationVSAvoidtesting time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The microcontroller automatically initiates testing at predetermined time intervals without user intervention. This periodic automated testing confirms device functionality continuously while eliminating the time and cost associated with manual testing schedules.

Inventive Principle:

Principle #19Periodic action

3Ease of operation

If the trip mechanism is disabled by external events, then the device may reset without user knowledge, but fault protection is compromised

Engineering Contradiction:

Improveautomatic resetVSAvoidfault protection

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The microcontroller continuously monitors the trip mechanism status and provides feedback to determine whether resetting is safe. Before allowing reset, the system verifies the trip mechanism is operational, preventing unsafe resets while maintaining automatic operation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs a preliminary verification of the trip mechanism before allowing reset to occur. This advance check ensures the protective function is intact before restoring power, preventing compromised fault protection.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If automatic self-testing is implemented, then continuous fault protection is ensured, but device complexity increases

Engineering Contradiction:

Improvecontinuous fault protectionVSAvoidtesting system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The microcontroller serves multiple functions: it controls the test button activation, monitors trip mechanism operation, performs self-diagnostics, and manages reset authorization. This multi-functionality consolidates what would otherwise require separate dedicated circuits into a single intelligent controller.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The microcontroller acts as an intermediary between the test button, trip mechanism, and reset button. It coordinates their interactions and ensures proper sequencing, simplifying the overall control architecture while enabling sophisticated automatic testing and protection logic.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 continuous fault protection without user intervention, ensuring the GFCI device remains functional and safe by automatically testing its operation without affecting connected loads and preventing accidental resets if the trip mechanism is inoperable.

Implementation Method 1

the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the connection between input and output conductors) includes a solenoid (or trip coil)

Methodology Applied

Scientific EffectSolenoid: Solenoid

Implementation Method 2

Predetermined or predefined conditions can include, without limitations, ground faults, arc faults, appliance leakage current faults, immersion faults and a test cycle

Methodology Applied

Scientific EffectGround fault detection:

Data Source

PatentUS7852606B2Self-testing circuit interrupting device

Publication Date: 2010.12.14 LEVITON MFG CO INC

AI summary

There is disclosed a self-testing circuit interrupting device which provides uninterrupted power to a load during a complete electronic and electromechanical components self test to allow autonomous periodic automated self testing without damaging or resetting connected load equipment.