Flexible Mast Crawler for Narrow Generator Air Gap Inspection

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Solution Overview

Problem

Conventional generator field and stator core inspection methods require disassembly and removal, which is costly, time-consuming, and hazardous, and are limited by entrance gaps larger than 12.7 millimeters, making in-situ inspections ineffective for smaller gaps.

Innovation Solution

A miniature air gap inspection device with an extendable mast made of flexible materials like spring steel, nickel alloy, or carbon fiber, allowing the inspection head to pass through narrow gaps, equipped with a camera, ultrasonic transducer, and drive mechanism for visual and ultrasonic inspections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional inspection methods are used, then inspection can be performed on generator field and stator core, but complete disassembly and removal of generator field are required which increases cost, time, and hazard

Engineering Contradiction:

Improveinspection completenessVSAvoiddisassembly requirement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The inspection device is nested within the air gap between the rotor and stator, with the mast containing the inspection head that can be inserted through the air gap without disassembling the generator. The device fits within the existing structural space, eliminating the need for field removal.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The flexible mast acts as an intermediary that transmits the inspection head through the air gap to reach the stator core and field winding areas. This mediator enables access to inspection zones without requiring physical disassembly of the generator components.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional inspection methods are used, then inspection can be performed, but the process is time-consuming due to disassembly and removal procedures

Engineering Contradiction:

Improveinspection qualityVSAvoidinspection duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The inspection device is pre-positioned on the rotor outer periphery before entering the air gap, with the mast already containing the inspection head. This preliminary configuration allows immediate insertion and inspection upon entering the air gap, eliminating time-consuming disassembly steps.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If conventional inspection methods are used, then generator field and stator core can be inspected, but hazards inherent in generator field removal occur

Engineering Contradiction:

Improveinspection capabilityVSAvoidsafety hazard

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The inspection function is extracted from the traditional disassembly process and embodied in a separate, self-contained device that operates within the air gap. This extraction eliminates the need to remove the generator field, thereby removing the associated safety hazards while preserving inspection capability.

Inventive Principle:

Principle #2Taking out (Extraction)

4Device complexity

If inspection device is designed for standard air gap entry, then device structure can be simplified, but entrance gap must be greater than about one half inch (about 12.7 millimeters)

Engineering Contradiction:

Improvedevice structureVSAvoidgap size accommodation

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The mast is designed with dynamic flexibility, allowing it to bend and conform to the curvature of the rotor and stator surfaces. This dynamic property enables the rigid inspection head to reach through narrow air gaps that would be inaccessible to rigid structures, accommodating various gap sizes without complicating the overall device design.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The mast is constructed as a flexible element that can bend and flex to navigate the curved geometry of the air gap and reach the inspection targets. This flexible structure allows the device to adapt to narrow gaps while maintaining structural integrity and functional capability.

Inventive Principle:

Principle #30Flexible shells and thin films

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

Enables in-situ inspections of generator fields and stator cores through narrow gaps, reducing costs and hazards by providing detailed visual and ultrasonic assessments, including wedge tightness and core condition evaluations, without the need for disassembly.

Implementation Method 1

The extendable mast is made of flexible materials like spring steel, nickel alloy, or carbon fiber

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a high resolution video camera may provide a clear view of the stator core laminations, stator wedges, field wedges

Methodology Applied

Scientific EffectOptical detection: Light

Implementation Method 3

commonly owned U.S. Patent Application Nos. 11/163,196, 11/306,600, and 11/306,601 describe the ultrasonic inspection of the field and the stator core

Methodology Applied

Scientific EffectUltrasonic inspection: Ultrasound

Data Source

PatentEP1863153B1Tape fed miniature air gap inspection crawler

Publication Date: 2011.10.19 GENERAL ELECTRIC CO

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AI summary

An air gap inspection device (100). The air gap inspection device (100) may include a mast (100) and an inspection head (160) attached to the mast (110). The mast (110) may be in the form of a collapsible tube.