MOC Driver Spring Mechanism for Circuit Breaker Motion Control

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Solution Overview

Problem

Modern vacuum-operated circuit breakers face challenges with faster mechanism travel and reduced energy availability, which can lead to increased friction and reduced tolerance for sudden accelerations in older, retrofitted switchgear systems, necessitating an improved mechanism-operated cell (MOC) operator structure that slows down motion and ensures energy compatibility with the circuit breaker's operation.

Innovation Solution

The MOC operator structure incorporates a cam, follower, first lever, free-floating spring structure, and linkage system, where the cam drives the first lever to compress the spring, and the spring's force moves the cable and linkage structure, controlling motion and energy transfer to the breaker-panel interface, ensuring smooth operation and compatibility with the circuit breaker's energy constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If modern vacuum circuit breaker mechanism is used with faster travel and higher velocity, then circuit breaker operation speed is improved, but friction increases and tolerance for sudden accelerations decreases in older switchgear systems

Engineering Contradiction:
Improvecircuit breaker operation speedVSAvoidfriction and sudden accelerations
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary mechanism consisting of a cam, follower, and spring structure between the circuit breaker operating shaft and the MOC switch. This intermediary system converts the high-speed motion into controlled motion through mechanical multiplication and spring-mediated acceleration reduction, thereby protecting the older switchgear from excessive friction and sudden accelerations while maintaining compatibility with modern vacuum circuit breakers

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the motion parameters by using a cam profile designed to multiply travel distance while reducing velocity. The spring structure further modifies the acceleration profile by providing a gradual force application rather than sudden impulses, thus adapting the high-speed circuit breaker output to the lower-speed tolerance of legacy switchgear components

Inventive Principle:
Principle #35Parameter changes

2Length of moving object

If motion multiplication is implemented to drive panel mounted components, then travel distance is improved, but energy consumption increases

Engineering Contradiction:
Improvetravel distanceVSAvoidenergy consumption
Core Design Contradiction:
Length of moving objectVSUse of energy by moving object

Solution Approach 1:

The spring structure is pre-compressed during the cam rotation to store potential energy, which is then released to drive the MOC switch actuator. This preliminary energy storage allows the system to achieve the required travel distance multiplication without proportionally increasing energy consumption from the circuit breaker operating mechanism

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses dynamic motion multiplication where the cam profile and spring combination create a time-varying mechanical advantage. The mechanical advantage is highest when energy input is needed and lowest when energy output is delivered, optimizing the energy efficiency of the motion multiplication process

Inventive Principle:
Principle #15Dynamics

3Reliability

If MOC operator structure is added to provide redundant contacts, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvecircuit breaker status controlVSAvoidMOC operator structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cam-follower-spring mechanism serves multiple functions simultaneously: it multiplies motion distance, controls velocity, manages energy transfer, and provides the mechanical linkage for MOC switch actuation. This multi-functionality reduces the need for separate components for each function, thereby limiting the increase in overall device complexity despite the added reliability capability

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

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 configuration slows down the motion of the mechanism, maintains energy compatibility, and minimizes adverse effects on the circuit breaker's performance, achieving a stable and efficient operation by controlling the energy transfer and motion, similar to the original air-magnetic breaker systems.

Implementation Method 1

a free-floating spring structure associated with the first lever... force of the spring structure moves the cable structure and thus the second lever

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

a cam constructed and arranged to be coupled to the operating shaft of the circuit breaker, a follower in engagement with the cam

Methodology Applied
Scientific EffectCam: Cam

Implementation Method 3

due to the friction and inertia of system driven by the second lever, full motion of the cam and first lever is accomplished prior to any movement of the cable structure

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 4

due to the friction and inertia of system driven by the second lever, full motion of the cam and first lever is accomplished prior to any movement of the cable structure

Methodology Applied
Scientific EffectInertia: Inertia

Data Source

PatentEP2689504B1Modular MOC driver and interlock assembly for circuit breaker
Publication Date: 2015.01.07 ABB TECHNOLOGY AG
  • EP2689504B1 patent drawingFigure 1
  • EP2689504B1 patent drawingFigure 2
  • EP2689504B1 patent drawingFigure 3

AI summary

A MOC operator structure for a vacuum circuit breaker includes a cam coupled to an operating shaft of the circuit breaker, a follower in engagement with the cam, a first lever coupled with the follower, free-floating spring structure associated with the first lever, a second lever, a linkage structure coupled with the second lever and constructed and arranged to be associated with a breaker-panel interface for moving auxiliary switches, and movable cable structure operatively coupled between the first and second levers. The first lever and spring structure are configured such that when the contacts are closed, movement of the cam via the operating shaft drives the first lever to a maximum position compressing the spring structure, prior to any movement of the cable structure, and wherein force of the spring structure moves the cable structure and thus the second lever, causing movement of the linkage structure.