GFCI Self-Testing via Partial Plunger Actuation

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Solution Overview

Problem

Existing ground fault circuit interrupting (GFCI) devices require user intervention for periodic self-testing, which can disrupt power and is inconvenient, as they cannot automatically test the operability of the solenoid plunger mechanism without tripping the circuit.

Innovation Solution

A circuit interrupting device with a test assembly that enables partial movement of the solenoid plunger without opening the switch, using sensors like piezoelectric, resistive, capacitive, or optical elements to detect movement and perform self-testing on a periodic basis without user intervention, allowing for the testing of the solenoid plunger's operability and the fault sensing circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If user intervention is required for periodic self-testing of GFCI devices, then the testing can be performed, but it disrupts power and is inconvenient

Engineering Contradiction:

Improvesolenoid plunger mechanism operabilityVSAvoiduser convenience

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The GFCI device performs self-testing automatically without requiring user intervention. The microcontroller initiates test sequences, activates the solenoid coil, and monitors plunger movement through sensors, enabling the device to test its own operability independently.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The device performs preliminary testing of the solenoid plunger mechanism before actual fault conditions occur. By periodically actuating the solenoid and monitoring plunger position in advance, the system ensures readiness for fault interruption without waiting for user action or actual faults.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the solenoid plunger is moved during testing, then the operability can be verified, but the switch may open and disrupt power

Engineering Contradiction:

Improvefault sensing circuit functionalityVSAvoidpower disruption

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

During self-testing, the solenoid plunger is moved only partially through its travel distance rather than fully actuating the switch. The microcontroller controls the solenoid coil to achieve sufficient plunger displacement for sensor detection while preventing complete switch opening, thus verifying operability without causing power disruption.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

Sensors serve as intermediaries between the solenoid plunger and the microcontroller during testing. The sensors detect plunger position and movement without requiring full switch actuation, allowing the system to verify mechanical operability through intermediate measurement rather than complete action.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Extent of automation

If automatic periodic self-testing is implemented, then convenience is enhanced, but the device complexity increases

Engineering Contradiction:

Improveself-testing automationVSAvoidtest assembly components

Core Design Contradiction:

Extent of automationVSDevice complexity

Solution Approach 1:

The microcontroller serves multiple functions: it controls normal GFCI operation, manages periodic self-testing sequences, activates the solenoid coil, and processes sensor signals for plunger position detection. This multi-functionality reduces the need for separate dedicated testing hardware, thereby limiting complexity increase despite enhanced automation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 automatic periodic self-testing of GFCI devices without disrupting power, ensuring the solenoid plunger and fault sensing circuit are functional, enhancing convenience and reliability by allowing tests to be conducted without user interaction.

Implementation Method 1

a solenoid coil and plunger assembly disposed to open the switch wherein the solenoid coil and plunger assembly is actuatable by the circuit interrupting actuation signal

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

using sensors like piezoelectric, resistive, capacitive, or optical elements to detect movement

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

using sensors like piezoelectric, resistive, capacitive, or optical elements to detect movement

Methodology Applied

Scientific EffectOptical detection:

Data Source

PatentUS7990663B2Detecting and sensing actuation in a circuit interrupting device

Publication Date: 2011.08.02 LEVITON MFG CO INC

AI summary

A circuit interrupting device is disclosed that includes a first conductor, a second conductor, a switch between the first conductor and the second conductor wherein the switch is disposed to selectively connect and disconnect the first conductor and the second conductor, a circuit interrupter disposed to generate a circuit interrupting actuation signal, a solenoid coil and plunger assembly disposed to open the switch wherein the solenoid coil and plunger assembly is actuatable by the circuit interrupting actuation signal wherein movement of the plunger causes the switch to open, and a test assembly that is configured to enable a test of the circuit interrupter initiating at least a partial movement of the plunger in a test direction, from a pre-test configuration to a post-test configuration, without opening the switch.