Switching Device Contact Welding Indicator Mechanism

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Solution Overview

Problem

Existing low-voltage electrical installation protection devices lack effective signaling mechanisms for indicating the closed-welded state of contacts, often relying on remote mechanisms that are not directly integrated with the contact system, leading to inefficiencies and increased stress on the contact components during short-circuit events.

Innovation Solution

A switching device with a movable main contact and a signaling mechanism that includes a latching lever with a hook to retain the manual reset member in an intermediate position, using a drive rod connected to the tripping mechanism and an electromagnet control actuator to reinforce contact pressure via a magnetic reinforcement circuit, ensuring the manual reset member is locked when contacts are closed, and allowing for controlled opening of the contacts during faults.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a remote signaling mechanism is used to indicate contact welding, then the signaling function is provided, but the mechanism is not directly integrated with the contact system leading to inefficiencies and increased stress on contact components

Engineering Contradiction:
Improvesignaling reliabilityVSAvoidmechanism integration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the signaling mechanism directly with the contact system by integrating the latching lever, hook, and drive rod components into the existing contact carrier structure. This merging eliminates the need for separate remote signaling mechanisms and creates a unified system where signaling and contact operation are inherently linked, resolving the contradiction between signaling reliability and device complexity.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of operation

If the manual reset member is freely movable, then easy operation is achieved, but the contact components experience increased wear and welding risks during short-circuit events

Engineering Contradiction:
Improvereset operationVSAvoidcontact component durability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent implements a dynamic locking system where the manual reset member's mobility is controlled by the latching lever and hook mechanism. The system transitions between locked and unlocked states based on contact position, providing ease of operation when contacts are open while preventing harmful movement during closed-welded states, thus resolving the contradiction between operational ease and component durability.

Inventive Principle:
Principle #15Dynamics

3Loss of information

If the latching lever is positioned to retain the manual reset member in intermediate position, then welding indication is achieved, but the mechanism complexity increases

Engineering Contradiction:
Improvewelding state indicationVSAvoidlatching mechanism
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The latching lever serves multiple functions: it acts as a signaling indicator for contact welding, provides mechanical locking for the manual reset member, and integrates with the drive rod mechanism. This multi-functionality reduces the need for separate components, thereby achieving reliable welding indication without proportionally increasing mechanism complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Reliability

If the contact pressure is increased to prevent welding, then welding risks are reduced, but the force required to operate the contacts increases

Engineering Contradiction:
Improvecontact welding preventionVSAvoidcontact operation force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The patent employs a preliminary action by using the latching mechanism to pre-position and secure the manual reset member in appropriate states before contact operation. The hook and latching lever prepare the system in advance, ensuring that reset operations occur only when contacts are open and safe, thereby preventing welding without requiring excessive force during normal contact operation.

Inventive Principle:
Principle #10Preliminary action

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 a robust and efficient signaling mechanism that reduces wear on contact components, minimizes arcing and welding risks, and allows for controlled opening of contacts during short-circuits, enhancing the overall performance and reliability of the switching device.

Implementation Method 1

the release mechanism acts on the movable main contact through an electromagnet control actuator

Methodology Applied
Scientific EffectElectromagnetism: Electromagnet

Implementation Method 2

a latching lever with a hook to retain the manual reset member in an intermediate position

Methodology Applied
Scientific EffectMechanical locking: Mechanical Fastener

Data Source

PatentEP2333804B1Switching device having a contact welding indicator
Publication Date: 2012.08.22 SCHNEIDER ELECTRIC IND SAS
  • EP2333804B1 patent drawingFigure 1A~1B
  • EP2333804B1 patent drawingFigure 2
  • EP2333804B1 patent drawingFigure 3A~3B

AI summary

The switchgear has a triggering mechanism (51) acting on a movable main contact (47) and another movable main contact via a solenoid actuator (53). The contacts are coupled to a moving part of the actuator by a contact carrier. The mechanism cooperates with the actuator via an internal switch, and has a movable contact that is opened to indirectly open the main contacts during triggering of the switchgear. A reset button closes the movable contact to allow an order to close the main contacts, and resets the switchgear. The button is retained in an intermediate position by a hook (243).