Magnetic Thermal Subassembly Equipotential Design

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Solution Overview

Problem

Existing circuit breakers face challenges in ensuring electrical insulation between magnetic and thermal actuators, leading to complex and costly plastic insulation solutions that are difficult to implement effectively, especially in compact designs.

Innovation Solution

Designing a magnetic and thermal subassembly where all components form a single current path at the same potential, eliminating the need for electrical insulation and simplifying the arrangement by integrating a magnetic actuator with a contact carrier, coil, movable pallet, and spring, which allows for precise tripping and easy manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional magnetic and thermal actuators are arranged separately with different potentials, then functional performance is achieved, but electrical insulation complexity and manufacturing cost increase significantly

Engineering Contradiction:
Improvefunctional performanceVSAvoidelectrical insulation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies equipotentiality by electrically connecting all components of the magnetic actuator (coil, yoke, movable core) and thermal actuator (bimetallic strip, release lock) to the same potential through a common electrical connection. This eliminates potential differences between the two actuators, removing the need for complex insulation barriers and simplifying the overall device structure while maintaining functional performance.

Inventive Principle:
Principle #12Equipotentiality

2Reliability

If plastic insulation parts are integrated to protect components, then electrical isolation is achieved, but manufacturing complexity and assembly difficulty increase

Engineering Contradiction:
Improveelectrical isolationVSAvoidassembly difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the need for plastic insulation parts by reconfiguring the electrical potential arrangement. Instead of using insulation barriers to separate components at different potentials, the design connects all actuator components to the same potential, removing the harmful factor (potential difference) that necessitated the insulation parts in the first place.

Inventive Principle:
Principle #2Taking out (Extraction)

3Volume of moving object

If compact circuit breaker design is pursued, then space efficiency improves, but insulation implementation becomes more difficult

Engineering Contradiction:
Improvespace efficiencyVSAvoidinsulation implementation
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

By establishing equipotential connections across all magnetic and thermal actuator components, the patent eliminates the need for insulation barriers that would consume valuable space in compact designs. This allows for more efficient space utilization while maintaining electrical safety, as components can be arranged more freely without requiring insulating structures between them.

Inventive Principle:
Principle #12Equipotentiality

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 reduces component complexity, eliminates insulation challenges, and lowers manufacturing costs while ensuring reliable operation and ease of assembly, making the circuit breaker more attractive economically and reducing the risk of breakdowns.

Implementation Method 1

a coil surrounding part of the yoke and connected in series with the bimetallic strip

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

the mobile core driving a striker in translation, striking a rocker which pivots by driving a movable contact holder, thus causing the opening of said movable contact

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

a thermal release comprising a bimetallic strip capable of unlocking a mechanical lock of the device when an overload occurs in the line to be protected

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

a thermal release comprising a bimetallic strip capable of unlocking a mechanical lock of the device

Methodology Applied
Scientific EffectBi-metallic strip: Bi-Metallic Strip

Data Source

PatentEP2750158B1Thermal, magnetic subassembly for a selective circuit-breaker
Publication Date: 2015.08.26 HAGER ELECTRO SAS
  • EP2750158B1 patent drawingFigure 1~2
  • EP2750158B1 patent drawingFigure 3~4
  • EP2750158B1 patent drawingFigure 5~6

AI summary

The apparatus has a contact carrier (6) attached to a yoke (5) and carrying a movable contact (14). A coil (11) surrounds a portion of the yoke, and connected in series with a bimetallic strip (1). A blade (7) is rotated relative to the yoke and connected with pole surfaces of the yoke during short circuit. The yoke comprises a positioning and guiding unit for the blade. A drive unit is formed between the blade and the carrier for establishing correspondence between fraction of rotational movement of the blade and fraction of rotational movement of the movable contact. An independent claim is also included for a method for assembling a magnetic thermal sub-assembly integrated in an electrical apparatus.