Current Transformer Casing Integrates Support and Electrical Return

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Solution Overview

Problem

Current transformers in high-voltage switchgear, particularly in gas-insulated systems, face challenges in mechanical stability, safety, electrical connections, protection, and component complexity, which existing technologies have not adequately addressed.

Innovation Solution

A current transformer design featuring a core support with conductive ends and tubes, where the conductive casing provides mechanical strength, insulation, and serves as a protection against accidental contact and electrical return, reducing component count and simplifying assembly, while also sealing gas spaces and absorbing mechanical forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a current transformer uses separate support elements for mechanical stability, then mechanical strength is improved, but device complexity increases

Engineering Contradiction:
Improvemechanical strengthVSAvoidcomponent count
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent combines the support function and the casing function into a single integrated structure. The support ends are formed as integral parts of the current transformer casing, eliminating the need for separate support elements. This merging reduces component count while maintaining mechanical strength through the unified structural design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The current transformer casing is designed to serve multiple functions simultaneously: it provides mechanical protection, acts as a support structure for the cores, and serves as the outer housing. This multi-functionality eliminates the need for dedicated support elements, reducing overall device complexity while maintaining structural integrity.

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

2Device complexity

If the current transformer casing serves as the electrical return conductor, then device complexity is reduced, but electrical connection reliability must be maintained

Engineering Contradiction:
Improvecomponent countVSAvoidelectrical connection reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent merges the electrical return conductor function with the current transformer casing. The casing itself is designed to conduct electrical current back to the source, eliminating the need for separate return conductor components. This integration maintains reliability through proper material selection and design of the casing to ensure adequate electrical conductivity.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If insulating elements create electrical separation between support ends, then electrical insulation is improved, but device complexity increases

Engineering Contradiction:
Improveelectrical insulationVSAvoidcomponent count
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies insulating properties locally at specific critical points where electrical separation is needed between support ends, rather than making the entire structure complex. Insulating elements are strategically positioned only where electrical isolation is required, maintaining simplicity elsewhere in the design.

Inventive Principle:
Principle #3Local quality

4Ease of manufacture

If the current transformer casing provides mechanical strength and support, then ease of manufacture is improved, but the casing must handle both mechanical and electrical functions

Engineering Contradiction:
Improveassembly simplicityVSAvoidfunctional integration
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The current transformer casing is designed as a multi-functional component that simultaneously provides mechanical strength, structural support, electrical return conduction, and protective housing functions. This integration simplifies manufacturing and assembly by reducing the number of separate components that need to be manufactured and assembled, despite the increased functional requirements placed on the single casing structure.

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

Data Source

PatentEP3281214B1Current transformer and switchgear having a current transformer
Publication Date: 2021.04.14 SIEMENS ENERGY GLOBAL GMBH & CO KG
  • EP3281214B1 patent drawingFigure 1
  • EP3281214B1 patent drawingFigure 2~3
  • EP3281214B1 patent drawingFigure 4

AI summary

The invention relates to a current transformer (1) comprising: a core carrier (3) having two electrically conductive carrier ends (9, 11) and at least one electrically conductive carrier tube (13) arranged between the two carrier ends (9, 11); multiple current transformer cores (5), wherein each current transformer core (5) runs in a ring shape on an outer side of the carrier tube (13) about a longitudinal axis of the carrier tube (13); and an electrically conductive current transformer casing (7) which surrounds the current transformer cores (5) and is securely connected to both carrier ends (9, 11). In addition, a first carrier end (9) is electrically insulated from each carrier tube (13) via an insulating element (15), and the second carrier end (11) is connected in an electrically conductive manner to each carrier tube (13).