Earthing Switch Interlock Arrangement Reducing Mechanical Complexity

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Solution Overview

Problem

Conventional interlock mechanisms for earthing switches in switchgear are complex, prone to mechanical failures, and rely on gravity for indication, compromising operator safety and reliability.

Innovation Solution

An air insulated switching device with a simplified interlock arrangement featuring an electromagnetic unit, a see-saw lever, and a shutter flap, reducing components and reliance on gravity for indication, ensuring reliable operation and cost-effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a four-bar mechanism with multiple levers is used to operate the earthing switch, then the switch can be opened and closed, but the number of moving parts increases and mechanical complexity increases

Engineering Contradiction:
Improveease of operationVSAvoidmechanical complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates unnecessary intermediate levers from the four-bar mechanism, retaining only the essential components (solenoid, shutter flap, and handle receiving space operation) to reduce mechanical complexity while maintaining operational functionality

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the complex mechanical four-bar linkage system with a simplified solenoid-actuated mechanism that directly operates the shutter flap, reducing the number of moving parts and mechanical connections required

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Loss of information

If multiple linkage parts and gravity-dependent indication mechanism are used, then the earthing switch position can be indicated, but the system becomes prone to malfunction and operational errors

Engineering Contradiction:
Improveposition indicationVSAvoidreliability
Core Design Contradiction:
Loss of informationVSReliability

Solution Approach 1:

The patent replaces the gravity-dependent mechanical indication mechanism with an electronic indication system that uses sensors and electrical signals to detect and display the earthing switch position, eliminating reliance on gravity and mechanical linkage stability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces electronic sensors and control circuits as intermediaries between the mechanical switch operation and the visual indication system, providing a reliable transmission of position information without direct mechanical coupling

Inventive Principle:
Principle #24Intermediary (Mediator)

3Duration of action of moving object

If lever springs and multiple fastening members are used in the interlock mechanism, then the mechanism can function, but the components are prone to damage with increased operations

Engineering Contradiction:
Improveoperational lifespanVSAvoidcomponent reliability
Core Design Contradiction:
Duration of action of moving objectVSReliability

Solution Approach 1:

The patent removes lever springs and multiple fastening members from the mechanism, retaining only the essential solenoid-actuated components that directly perform the switching function, thereby eliminating components prone to fatigue and failure

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs a simplified solenoid mechanism with fewer wear-prone components, accepting that the solenoid itself may be a replaceable component while eliminating the need for multiple springs and fasteners that would require frequent maintenance

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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, cost-effective, and reliable interlock mechanism that enhances safety and reduces operational errors by minimizing mechanical complexity and gravity-dependent failures, ensuring accurate earthing switch operation.

Implementation Method 1

The interlock mechanism has a solenoid that operates a shutter flap for allowing handle insertion and operates an ON-OFF indication for the earthing switch

Methodology Applied
Scientific EffectSolenoid: Solenoid

Implementation Method 2

an electromagnetic unit, a lever and a shutter flap operably connected with one another thereby, reducing number of overall components required whilst ensuring reliability of operation

Methodology Applied
Scientific EffectElectromagnetic unit: Electromagnet

Data Source

PatentEP3975355A1Earthing switch interlock arrangement
Publication Date: 2022.03.30 SIEMENS AG
  • EP3975355A1 patent drawingFigure 1
  • EP3975355A1 patent drawingFigure 2
  • EP3975355A1 patent drawingFigure 3

AI summary

A switching device (300) having a cable compartment (301) and an interlock arrangement (200) is provided. The interlock arrangement (200) is at least partially mountable within the cable compartment (301)and includes an electromagnetic unit (201), a lever (202) operably connected to the electromagnetic unit (201), and a shutter flap (203) operably connected to the lever (202). The lever (202) pivotably moves between a first position and a second position when the electromagnetic unit (201) is energized and de-energized. The shutter flap (203) slides over a handle receiving space (205) defined within a shaft (208) operably connected to an earthing switch of the switching device (300). The shutter flap (203) opens and closes the handle receiving space (205) corresponding to the first position and the second position of the lever (202).