Side-Mounted Lock-Off for Circuit Breakers

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Solution Overview

Problem

Existing lock-off devices for circuit breakers are often mounted on the front, rely on the shackle for interference, and are limited to specific handle geometries, making them less effective and adaptable during electrical maintenance.

Innovation Solution

A side-mounted lock-off device with a planar body and pivotable lock-off arm that engages the circuit breaker handle without physical contact, using adhesives or complementary apertures for securing devices like padlocks, and accommodates various handle geometries, with features like frangible hooks for tampering evidence and a biasing washer for secure mounting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lock-off devices are mounted on the front handle-containing surface of the circuit breaker, then the locking function is achieved, but the device blocks markings on the circuit breaker and reduces visibility

Engineering Contradiction:

Improvelocking functionVSAvoidvisibility of markings

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent moves the lock-off device from the front mounting surface to the side mounting surface of the circuit breaker. This dimensional relocation allows the device to perform its locking function while no longer obscuring the front markings and indicators, thus resolving the contradiction between reliability and information visibility.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If lock-off devices rely on the shackle for interference with the circuit breaker handle, then the locking mechanism is simple, but the device cannot accommodate various breaker handle geometries

Engineering Contradiction:

Improvelocking mechanismVSAvoidaccommodation of handle geometries

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent employs a pivotable arm that can rotate between a retracted position (allowing handle operation) and an extended position (engaging the handle to prevent operation). This dynamic mechanism maintains simplicity while adapting to various handle geometries, as the arm can be positioned to engage different handle types without requiring complex adjustable mechanisms.

Inventive Principle:

Principle #15Dynamics

3Reliability

If lock-off devices are designed for individual circuit breaker handle geometries, then the locking function is precise, but the device lacks adaptability to various breaker types

Engineering Contradiction:

Improvelocking precisionVSAvoidcompatibility with breaker types

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent designs the lock-off device with a universal side mounting interface that can be attached to various circuit breaker types, and a pivotable arm that can engage different handle geometries. This universal design allows a single device to maintain reliable locking precision across multiple breaker types, resolving the contradiction between precision and adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If the lock-off arm is made rigid to ensure stable engagement, then the locking is secure, but the device cannot be easily installed or removed in the field

Engineering Contradiction:

Improveengagement stabilityVSAvoidfield installability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent uses a pivotable arm that can be manually rotated between retracted and extended positions, allowing easy installation and removal in the field. When engaged, the arm provides stable locking through its pivot connection, which maintains reliable engagement while enabling field operability, thus resolving the contradiction between security and ease of operation.

Inventive Principle:

Principle #15Dynamics

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 solution provides a rugged, field-installable lock-off accessory that effectively prevents accidental re-energization of circuit breakers, accommodating various geometries and providing evidence of unauthorized removal, while maintaining visibility of markings and minimizing space usage.

Implementation Method 1

have a biasing washer included therewith

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

adhesives of the like may be used

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS7355132B1Side-mounted lock-off accessory for a circuit breaker

Publication Date: 2008.04.08 SQUARE D CO

AI summary

A circuit breaker lock-off device is side-mounted to a circuit breaker case in a tenacious engagement. The lock-off device has a generally planar body carrying a lock-off arm pivotable in a plane parallel to the body to place an engagement tab extending therefrom into a position for preventing movement of the breaker handle without being physically attached to the breaker handle. The lock-off arm and the body further have complementary rings for accepting a padlock shackle in the locked off position. The invention allows a rugged lock-off accessory which is field installable and which can accommodate various breaker handle geometries.