Switchgear Interlock Release for Trolley and Grounding Switch Testing

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Solution Overview

Problem

Existing switchgear systems require complex and time-consuming manual operations to perform testing and maintenance, particularly during short power outage windows, due to interlock requirements between the main switch trolley and grounding switch, which hinder efficient testing and maintenance processes.

Innovation Solution

An interlocking and unlocking device is introduced, comprising an interlocking mechanism with a first and second engaging member, and an unlocking mechanism using a transmission member and unlocking rod, allowing for simple and safe release of mechanical interlocks between the main switch trolley and grounding switch, enabling automated testing and maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a forced mechanical interlocking mechanism is provided between main switch trolley and grounding switch to meet safety interlock requirements, then safety is improved, but device complexity and operation time increase

Engineering Contradiction:
ImprovesafetyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The interlocking mechanism is segmented into modular components: a limiting assembly with limiting members for the trolley, and engaging members with interlocking portions for the grounding switch. This segmentation allows each component to perform its specific function independently while maintaining overall system safety, reducing complexity compared to a monolithic interlock mechanism.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent inverts the traditional interlocking approach by using a limiting assembly that actively restricts trolley movement through limiting members, rather than relying solely on the grounding switch mechanism to prevent trolley movement. This inversion simplifies the grounding switch structure while maintaining the interlock function.

Inventive Principle:
Principle #13The other way round (Inversion)

2Productivity

If manual operations are performed to match inspection items during testing and maintenance, then testing and maintenance can be completed, but time consumption increases significantly

Engineering Contradiction:
Improvetesting and maintenance efficiencyVSAvoidtime consumption
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The limiting assembly is pre-configured with limiting members at specific positions along the guide rail that correspond to test and working positions. This preliminary arrangement allows the trolley to be quickly limited to required positions without manual intervention during testing, significantly reducing operation time while maintaining safety.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The interlocking mechanism enables the system to self-regulate trolley and grounding switch positions through the limiting and engaging members. During testing, the mechanism automatically prevents unauthorized movements while allowing required operations, eliminating the need for continuous manual monitoring and adjustment.

Inventive Principle:
Principle #25Self-service

3Productivity

If frequent operations are performed to match inspection items, then testing and maintenance can be completed, but operation complexity increases

Engineering Contradiction:
Improvetesting and maintenance efficiencyVSAvoidoperation complexity
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The limiting assembly serves multiple functions: it limits the trolley to test position, limits the trolley to working position, and works cooperatively with the grounding switch interlocking mechanism. This multi-functionality reduces the number of separate mechanisms needed, simplifying operations while enabling comprehensive testing and maintenance.

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

4Reliability

If interlocking mechanism is used to prevent erroneous operations, then safety is improved, but operation flexibility decreases

Engineering Contradiction:
ImprovesafetyVSAvoidoperation flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The interlocking mechanism is designed to be dynamic rather than static. The limiting members can be positioned at different locations along the guide rail to accommodate different operational requirements (test position, working position). The engaging members can engage or disengage based on grounding switch state, providing flexible control adapted to specific testing or maintenance needs while maintaining safety.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4679647A1Interlocking and unlocking device for main switch trolley and grounding switch, and switchgear comprising same
Publication Date: 2026.01.14 ABB (SCHWEIZ) AG
  • EP4679647A1 patent drawingFigure 1
  • EP4679647A1 patent drawingFigure 2
  • EP4679647A1 patent drawingFigure 3

AI summary

The present invention relates to an interlocking and unlocking device for a main switch trolley and a grounding switch of a switchgear (100, 200), and a switchgear comprising the interlocking and unlocking device. The interlocking and unlocking device comprises an interlocking mechanism and an unlocking mechanism. The interlocking mechanism comprises a first engaging member (12, 207) arranged on an operating shaft (15, 208) of the grounding switch so as to rotate therewith, a second engaging member (10, 209) adapted to engage with or disengage from the first engaging member, and a limiting assembly (101, 2101) arranged at a guide rail of the main switch trolley and capable of limiting the main switch trolley. The second engaging member moves in linkage with the limiting assembly, to realize interlocking of the main switch trolley and the operating shaft when the first engaging member and the second engaging member are in an engaged state. The unlocking mechanism is able to disengage the two members from each other to realize unlocking of the grounding switch and the main switch trolley. The device is able to realize interlocking, and also able to release the interlocking relationship therebetween as required while meeting safety requirements, thus improving testing efficiency and saving labor.