Rotating Field Transceiver Probe for Circumferential Defect Detection

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Solution Overview

Problem

Conventional eddy current probes are limited in detecting circumferential defects around vessels due to parallel eddy current orientation, mechanical scan processes that are time-consuming and prone to wear, and noise contamination from probe vibration, necessitating a more efficient and reliable method for defect detection across the entire circumference.

Innovation Solution

A rotating field probe design with three windings that operate in both transmit and receive modes, generating a rotating magnetic field to detect defects by measuring phase differences in terminal voltages, eliminating the need for a bobbin coil and reducing sensitivity to lift-off and probe wobble.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional bobbin coil probes are used for fast initial detection, then inspection speed is improved, but the ability to detect circumferential defects deteriorates

Engineering Contradiction:

Improveinspection speedVSAvoiddefect detection capability

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The probe is segmented into three separate winding coils arranged at 120-degree intervals around the tube, with each coil independently driven by a signal generator. This segmentation allows each coil to contribute to detecting defects at different angular positions, enabling circumferential defect detection while maintaining inspection speed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The three winding coils are driven with periodic alternating current signals that are phase-shifted by 120 degrees relative to each other. This periodic action creates a rotating magnetic field pattern that sequentially excites eddy currents at different angular positions around the tube, enabling fast circumferential scanning without mechanical movement.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If rotating probes with mechanical scan processes are used, then defect characterization ability is improved, but mechanical wear and reliability deteriorate

Engineering Contradiction:

Improvedefect characterization abilityVSAvoidmechanical wear resistance

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The mechanical rotation system is replaced with an electromagnetic field rotation system. Three stationary winding coils generate a rotating magnetic field through phase-shifted electrical signals, eliminating mechanical moving parts while maintaining the ability to characterize defects at different angular positions around the tube.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The three winding coils serve multiple functions: they act as both transmit coils (generating the magnetic field) and receive coils (detecting eddy current responses). This multi-functionality eliminates the need for separate transmit and receive systems, reducing mechanical complexity while maintaining defect characterization capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If array probes with sophisticated excitation schemes are used, then inspection resolution is improved, but noise from probe vibration deteriorates signal quality

Engineering Contradiction:

Improveinspection resolutionVSAvoidnoise from probe vibration

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The probe is segmented into three spatially separated winding coils arranged at 120-degree intervals, with each coil independently excited and sensed. This segmentation allows the system to resolve defects at different angular positions while the stationary configuration eliminates vibration-induced noise associated with mechanically rotating arrays.

Inventive Principle:

Principle #1Segmentation

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 accurate defect detection over the entire circumference of a vessel with high inspection speed and resolution, improving reliability and reducing mechanical wear, while being insensitive to probe wobble and noise, as demonstrated by initial results in nuclear power plant steam generator tube inspections.

Implementation Method 1

the three winding coil conducting elements... to produce a rotating magnetic field at a rate of rotation dependent upon a frequency of the current provided to the coils and that rotates circularly over an outer circumferential detection region

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

eddy current detection assembly... to produce a rotating magnetic field... to detect defects

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Data Source

PatentUS10101301B2Rotating field transceiver nondestructive inspection probe

Publication Date: 2018.10.16 BOARD OF TRUSTEES OPERATING MICHIGAN STATE UNIV

AI summary

A rotating magnetic field probe includes three (or more) windings that work in both transmit and receive mode, to form an eddy current detection transceiver. In a transmit mode, the windings are driven with a drive signal (e.g., an alternating current) having similar or the same magnitude at each winding, but differing in phase from one another. In a receive mode, the terminal voltages of the windings is measured and summed to determine the location of a defect.