Circuit Breaker Trip Unit Strain Relief Mechanism

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Solution Overview

Problem

Accidental disconnection of wiring in a circuit breaker's trip unit leads to loss of communication and functionality, often due to repeated breaker movement or rough handling, causing customers to mistakenly perceive the issue as a malfunctioning breaker.

Innovation Solution

A strain relief mechanism with a tether and thumb screw is installed on the trip unit, providing a preload to the wire connectors and resisting flexing to ensure connection integrity, while the tether permanently attaches the component to prevent loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wire connectors are directly connected to the trip unit without strain relief, then the installation is simple, but the wiring is vulnerable to accidental disconnection due to repeated breaker movement or rough handling

Engineering Contradiction:

Improvewiring connection integrityVSAvoidstrain relief mechanism structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The strain relief mechanism is divided into separate functional components: a clamp assembly for securing wires, a tether for permanent attachment to the trip unit, and a thumb screw for adjustable preload application. This segmentation allows each component to perform its specific function effectively while keeping the overall installation manageable.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The strain relief mechanism is pre-installed on the trip unit before wire connection, with the tether already attached and the clamp positioned to receive wires. This preliminary action ensures that the protective function is in place before wiring operations begin, preventing accidental disconnection from the start.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a strain relief mechanism is added to prevent wire disconnection, then the connection integrity is improved, but the installation and operation become more complex

Engineering Contradiction:

Improvewire connector stabilityVSAvoidinstallation simplicity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The thumb screw design allows the installer to manually apply the necessary preload force directly to the clamp assembly without requiring specialized tools or complex adjustment mechanisms. The mechanism is self-contained and can be installed by following straightforward steps: attach the clamp, thread the wires, and tighten the thumb screw.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The strain relief mechanism is designed as a simple, inexpensive component that can be easily installed and replaced if necessary. The use of basic materials like the tether and thumb screw keeps costs low while providing effective strain relief functionality.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If the trip unit is made more rigid to prevent wire disconnection, then the connection stability is improved, but the breaker movement and flexibility are reduced

Engineering Contradiction:

Improvewiring connection stabilityVSAvoidtrip unit flexibility

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The strain relief mechanism acts as an intermediary between the trip unit and the wire connectors, absorbing mechanical stresses and forces that would otherwise be transmitted to the wire connections. The tether and clamp assembly serve as a buffer zone that protects both the trip unit and wiring from each other.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The strain relief mechanism provides preemptive protection by absorbing and distributing mechanical stresses before they can reach the wire connectors. The flexible tether and adjustable clamp create a cushioning effect that prevents sudden forces from causing disconnection during breaker movement or installation.

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

Prevents accidental disconnection of wiring, maintaining communication and functionality of the circuit breaker, and alerts users to potential issues before they become malfunctions.

Implementation Method 1

The part's own geometry acts like a leaf spring that ensures a preload onto the wire connectors

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS9443686B2Trip unit strain relief

Publication Date: 2016.09.13 EATON INTELLIGENT POWER LTD

AI summary

A circuit breaker is described herein. The circuit breaker comprising: a first plurality of electrical wires to the circuit breaker; a strain relief connecting the plurality of electrical wires to the circuit breaker; a securing mechanism attaching the strain relief to the circuit breaker; and a plurality of tethers attached to the circuit breaker positioned over the strain relief.