Circuit Breaker Actuator Micromotion Detection

Solution Overview

Problem

Existing medium voltage circuit breakers and reclosers face challenges in ensuring the actual movement and availability of the drive mechanism without interrupting the normal operation or compromising the switch position, due to issues like loose screws or increased friction, which can lead to uncertainty in the functionality of the drive.

Innovation Solution

An actuator system with a movable contact and electromagnetic or motor drive, coupled with a detection unit for micromotion activation, allowing for the registration of the drive's movability and availability through small physical motions without altering the switch position, using sensors like sliding resistors, acceleration sensors, or back e.m.f. to detect and control these micromotions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coil supervision test current is used to check drive functionality, then the current path integrity can be verified, but the actual movability of the drive mechanism cannot be confirmed

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent replaces electrical supervision methods with mechanical detection. A detection unit with sensors (acceleration sensors, displacement sensors, or force sensors) directly monitors the mechanical movement of the drive mechanism, contact stem, and movable contact, providing actual movability information that electrical coil supervision cannot detect.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a detection unit as an intermediary between the drive mechanism and the control system. This detection unit includes sensors that detect micromotions and transmit signals to the control unit, enabling indirect observation of drive movability without directly interfering with the switching operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If micromotion detection is implemented to verify drive movability, then actual drive availability can be registered, but the risk of dielectric problems may increase

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies partial action by using a spring to apply only a partial, reduced force during micromotion detection compared to full switching operation. The detection unit detects micromotions with forces significantly lower than switching forces, sufficient for verification but insufficient to cause dielectric breakdown or harmful effects.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent performs preliminary micromotion detection before actual switching operations. The detection unit verifies drive movability in advance, and only if micromotions are detected does the system proceed with full switching. This preliminary check prevents subsequent switching failures without exposing the system to prolonged risk.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the spring force is increased to ensure contact pressure, then contact reliability improves, but the detection of micromotions becomes more difficult

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent changes the parameter of spring force by using a variable spring force mechanism. The spring applies higher force during normal operation for reliable contact, and the detection unit detects micromotions that occur even under this higher force. The system adapts to different force conditions, allowing micromotion detection regardless of spring pressure level.

Inventive Principle:

Principle #35Parameter changes

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

Ensures the functional availability of the drive mechanism by confirming its movability without altering the switch position, reducing the risk of dielectric problems and maintaining the insulating properties, thereby enhancing the reliability of the circuit breaker or recloser.

Implementation Method 1

using sensors like sliding resistors, acceleration sensors, or back e.m.f. to detect and control these micromotions

Methodology Applied

Scientific EffectBack e.m.f. (back electromotive force): Electromagnetic Induction

Implementation Method 2

at least one movable contact with a contact stem, driven by an electromagnetic drive or a motor drive

Methodology Applied

Scientific EffectElectromagnetic drive: Electromagnetic Induction

Data Source

PatentUS11062867B2Actuator for a medium voltage circuit breaker

Publication Date: 2021.07.13

AI summary

An actuator for a medium voltage circuit breaker or recloser includes: at least one movable contact with a contact stem, driven by an electromagnetic drive or a motor drive; and a spring, the spring being positioned in a kinematic chain between the drive and the at least one movable contact or contact stem. An arrangement of the at least one movable contact and the electromagnetic drive or motor drive is coupled to a detection unit for detecting a micromotion activation in order to register an actual movability and availability of the electromagnetic drive or motor drive of the at least one movable contact without changing an actual switch position itself.