Switchgear Cradle Automation to Replace Mechanical Interlocks

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Solution Overview

Problem

The design, assembly, wiring, and testing of high-voltage switchgear units are complex and error-prone, requiring skilled expertise and mechanical interlocks that complicate integration and increase risk.

Innovation Solution

A self-contained cassette with integrated programmable logic controllers (PLCs) and sensors for controlling and monitoring switching devices, replacing mechanical interlocks with electrical controls, allowing for modular, customizable, and automated testing and commissioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional mechanical interlocks and manual assembly methods are used, then safety and reliability are maintained, but device complexity and assembly difficulty increase significantly

Engineering Contradiction:
ImprovesafetyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical interlocks with electronic sensors and programmable logic controllers (PLCs). Optical sensors detect the position of moving parts and electrical contacts, while PLCs process signals and control operations, eliminating complex mechanical linkage systems while maintaining safety functions.

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

Solution Approach 2:

The system performs self-diagnosis and self-control through integrated sensors and PLCs that automatically monitor contact positions, detect faults, and control switching operations without requiring manual intervention or complex mechanical safety interlocks.

Inventive Principle:
Principle #25Self-service

2Adaptability or versatility

If numerous mechanical interlocks and customizations are integrated during final assembly, then functionality and safety are ensured, but assembly time and skill requirements increase

Engineering Contradiction:
ImprovecustomizationVSAvoidassembly
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent employs universal PLC modules and standardized sensor interfaces that can be configured through software programming to perform different functions. This allows the same hardware platform to accommodate various customizations and options without requiring different mechanical assemblies or specialized components for each configuration.

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

Solution Approach 2:

Customization is achieved by changing software parameters and control logic in the PLCs rather than modifying physical components. The system can be reconfigured for different applications by programming different control sequences, contact positions, and operational parameters, eliminating the need for mechanical reassembly.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If complex wiring and mechanical interlocks are used, then control precision and safety are maintained, but wiring complexity and error risks increase

Engineering Contradiction:
Improvecontrol precisionVSAvoidwiring complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces extensive electrical wiring with digital communication protocols between sensors and PLCs. Optical sensors provide precise position detection without requiring complex electrical connections, and digital signals transmit control commands with high precision while minimizing wiring requirements.

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

4Reliability

If traditional assembly and testing procedures are used, then reliability is ensured, but testing time and on-site commissioning duration increase

Engineering Contradiction:
ImprovereliabilityVSAvoidtesting speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent enables pre-testing and validation of control logic, sensor functionality, and safety interlocks during the assembly phase before installation. The PLC-based system allows programming and testing of control sequences in advance, so that upon installation, the system is already verified and requires minimal on-site commissioning.

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

Facilitates easier, more reliable, and faster assembly and testing of high-voltage switchgear units with reduced mechanical complexity, enhancing safety and customization options.

Implementation Method 1

at least one coil for releasing the operating springs

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Both the first and second automation units are programmable logic controllers (PLCs)

Methodology Applied
Scientific EffectElectrical signal processing:

Data Source

PatentEP3454438B1Cradle for switchgear
Publication Date: 2025.10.29 SCHNEIDER ELECTRIC IND SAS
  • EP3454438B1 patent drawingFigure 1

AI summary

A cassette intended for integration into a high-voltage electrical switchgear cell, comprising a mobile trolley 10 carrying a switch 12 having movable contacts 15, an operating mechanism (13) for the movable contacts via operating springs and at least one release coil (14) for the operating springs, a motorized protective cover 21 intended to prevent access to the conductor bars A, B of the switchgear cell, and motorized drive means 20 for the mobile trolley 10 intended to connect the switch 12 to the conductor bars A, B. A first automation unit 19 is mounted on the mobile trolley 10 to control the operating mechanism 13 and the release coil 14, and a second automation unit 29 is mounted in the cassette 1 to control the protective cover 21 and the drive means 20 of the mobile trolley 10.