Switchgear Contact Finger Alignment via Conical Holes

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Solution Overview

Problem

In MV switchgears, dimensional variations between cubicle and circuit breaker contact arms lead to misalignment, causing high insertion torque and preventing proper electrical connections, as existing contact fingers lack flexibility without compromising structural integrity.

Innovation Solution

The introduction of conical holes in contact fingers with a flexible member and a nut and bolt assembly allows for resilient rotational motion, maintaining alignment and reducing insertion torque, while preventing contact fingers from dropping due to gravity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If contact fingers are made rigid to maintain structural integrity, then alignment precision is improved, but flexibility to accommodate dimensional variations is lost

Engineering Contradiction:

Improvealignment precisionVSAvoidflexibility

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The contact finger assembly is segmented into multiple contact fingers that can move independently relative to each other, allowing each finger to adjust to dimensional variations while maintaining overall alignment through the coupling mechanism

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The contact fingers are designed with dynamic characteristics, allowing them to move and adjust their position during the racking operation to accommodate misalignment, then stabilize once properly engaged with the contact arm

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If contact fingers are made flexible to accommodate dimensional variations, then adaptability is improved, but stability to prevent dropping due to gravity is reduced

Engineering Contradiction:

ImproveflexibilityVSAvoidstability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The stiffness parameter of the contact finger assembly is changed by introducing a flexible member that provides controlled compliance, allowing the system to be stiff enough to resist gravity but flexible enough to accommodate misalignment

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

A flexible member acts as an intermediary element between the contact fingers and the rigid structure, mediating between the need for stability and the need for flexibility to accommodate dimensional variations

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If contact fingers are designed without flexibility to maintain structural integrity, then strength is improved, but insertion torque becomes excessively high

Engineering Contradiction:

Improvestructural integrityVSAvoidinsertion torque

Core Design Contradiction:

StrengthVSForce

Solution Approach 1:

A flexible member is introduced as a thin, compliant element that allows the contact finger assembly to deform slightly during insertion, reducing the peak insertion torque while maintaining overall structural integrity

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The flexible member provides beforehand cushioning by allowing controlled deformation before full engagement, absorbing the shock of misalignment and reducing the peak forces required for insertion

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

This solution ensures proper alignment and reduced insertion torque, enabling smooth engagement of circuit breakers within the cubicle, maintaining performance and allowing for easy interchangeability without requiring new designs.

Implementation Method 1

a flexible member attached in contact with each of said contact fingers such that the contact fingers execute a resilient rotational motion

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

the rear end of each of said contact fingers is provided with a conical hole converging towards said longitudinal axis for receiving an alignment pin projected through the conical hole

Methodology Applied

Scientific EffectGeometry: Geometry

Data Source

PatentEP4012859A1Contact finger alignment arrangement for a switchgear cubicle

Publication Date: 2022.06.15 SCHNEIDER ELECTRIC IND SAS

Figure 1a~1c
Figure 2~3
Figure 4

AI summary

The present invention relates to a contact finger alignment arrangement (100) to facilitate electrical connections in a switchgear cubicle (102), said contact finger alignment arrangement (100) comprising a first contact finger (104-1) and a second contact finger (104-2) extending parallel to a longitudinal axis (106), each of said contact fingers (104-1,104-2) having a front end (108) defining a contact receiving portion to facilitate longitudinal insertion of a contact arm (114) fixed to said cubicle (102), a coupling portion (118) for mechanically coupling the first contact finger (104-1) and the second contact finger (104-2), and a rear end (112). The rear end (112) of each of said contact fingers (104-1,104-2) is provided with a conical hole (120) converging towards said longitudinal axis (106) for receiving an alignment pin (122) projected through the conical hole (120) of said first contact finger (104-1) to the second contact finger (104-2) such that the resilient rotational motion of the contact fingers (104-1,104-2) is executed in a restricted manner.