I-Shaped Lamination Stack for Current Transformer Magnetic Coupling

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional current transformers suffer from inefficient magnetic coupling, leading to high power loss, large size, and reduced transformation efficiency, along with limited integration of electronics for condition monitoring and communication, which complicates preventative maintenance and increases manufacturing costs.

Innovation Solution

A current transformer design featuring an inline dual coil system with an integrated magnetic actuator and I-shaped lamination stack that improves magnetic coupling between the core plates, reducing physical dimensions and enhancing transformation efficiency, while incorporating embedded electronics for real-time monitoring and communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional magnetic core design is used, then the structure is simple, but magnetic coupling is inefficient leading to high power loss and large size

Engineering Contradiction:
Improvepower lossVSAvoidmagnetic core structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The magnetic core is divided into multiple I-shaped lamination segments that are stacked together. Each lamination has a specific orientation and shape designed to guide magnetic flux efficiently. This segmentation allows optimization of magnetic coupling while maintaining manageable structural complexity through modular assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs composite magnetic core construction using multiple lamination materials with different magnetic properties. The I-shaped laminations are composed of ferromagnetic materials selected for optimal magnetic coupling characteristics. This composite approach improves power efficiency by reducing eddy current losses while managing the complexity through standardized material selection.

Inventive Principle:
Principle #40Composite materials

2Productivity

If conventional magnetic core design is used, then the structure is simple, but transformation efficiency is reduced

Engineering Contradiction:
Improvetransformation efficiencyVSAvoidmagnetic core structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The magnetic core is divided into multiple I-shaped lamination segments that are stacked together. Each lamination has a specific orientation and shape designed to guide magnetic flux efficiently. This segmentation allows optimization of magnetic coupling while maintaining manageable structural complexity through modular assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The I-shaped laminations introduce a new dimensional arrangement in the magnetic path, creating multiple flux paths through the core in different spatial dimensions. This multi-dimensional flux distribution improves transformation efficiency by reducing magnetic reluctance and enhancing coupling between primary and secondary windings.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Measurement precision

If conventional magnetic core design is used, then manufacturing is simpler, but current measurement linearity is poor

Engineering Contradiction:
Improvecurrent measurement linearityVSAvoidmagnetic core manufacturing
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The magnetic core is divided into multiple I-shaped lamination segments that are stacked together. Each lamination has a specific orientation and shape designed to guide magnetic flux efficiently. This segmentation allows optimization of magnetic coupling while maintaining manageable structural complexity through modular assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent optimizes specific parameters of the I-shaped laminations including thickness, width, and stacking arrangement to achieve linear current measurement characteristics. By carefully controlling these geometric parameters and the resulting magnetic flux distribution, the system achieves improved measurement linearity while maintaining manufacturability through standardized lamination components.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If excessive magnetic flux is shunted away, then the magnetic circuit is protected, but breaker trip current becomes high compromising trip function

Engineering Contradiction:
Improvetrip functionVSAvoidmagnetic flux
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The I-shaped laminations are strategically positioned to create localized magnetic flux paths with different properties. The core structure provides different magnetic conductance in different regions, allowing optimal flux distribution that ensures sufficient flux reaches the trip mechanism while protecting other portions of the magnetic circuit.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The I-shaped lamination structure acts as an intermediary element that mediates magnetic flux distribution between the primary winding and the trip mechanism. It guides and regulates flux flow, ensuring adequate flux reaches the trip function while preventing excessive flux from causing premature tripping or compromising reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 design achieves reduced size, higher transformation efficiency, improved current measurement linearity, and cost-effective integration of electronic overload protection, enabling faster response to short circuits and delayed overload shutdowns without heat generation issues.

Implementation Method 1

improving magnetic coupling between the core plates

Methodology Applied
Scientific EffectMagnetic coupling: Magnetism

Implementation Method 2

reducing the amount of shunted magnetic flux

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Implementation Method 3

a primary coil component for providing current based short circuit protection

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 4

a secondary coil component for providing voltage based overload protection

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2535916B1Improved magnetic core coupling in a current transformer with integrated magnetic actuator
Publication Date: 2016.03.30 ROCKWELL AUTOMATION TECH INC
  • EP2535916B1 patent drawingFigure 1
  • EP2535916B1 patent drawingFigure 2A
  • EP2535916B1 patent drawingFigure 2B

AI summary

A system comprising a magnetic actuator, a current transformer and operational electronics in a dual-coil circuit breaker. The system includes an inline, but non concentric, implementation of the primary and secondary coils to maintain a narrow width suitable for retrofitting in standard industrial rack mounted enclosures. The system further comprises an I-shaped lamination stack that is designed to abut on the ends of an upper and lower plate of the current transformer. The I-shaped lamination stack significantly increases the overlap between the lamination and the upper and lower plates, which results in lower magnetic reluctance and improves magnetic coupling.