Current Signature Analysis for Condition Monitoring of Cage Induction Motors

Industrial Application and Case Histories

William T. Thomson, Ian Culbert

• Publisher: Wiley-IEEE Press
• Year: 2016
• Print ISBN: 9781119029595
• eBook ISBN: 9781119175469
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Provides coverage of Motor Current Signature Analysis (MCSA) for cage induction motors

This book is primarily for industrial engineers. It has 13 chapters and contains a unique data base of 50 industrial case histories on the application of MCSA to diagnose broken rotor bars or unacceptable levels of airgap eccentricity in cage induction motors with ratings from 127 kW (170 H.P.) up to 10, 160 kW (13, 620 H.P.). There are also unsuccessful case histories, which is another unique feature of the book. The case studies also illustrate the effects of mechanical load dynamics downstream of the motor on the interpretation of current signatures. A number of cases are presented where abnormal operation of the driven load was diagnosed. Chapter 13 presents a critical appraisal of MCSA including successes, failures and lessons learned via industrial case histories.

• The case histories are presented in a step by step format, with predictions and outcomes supported by current spectra and photographic evidence to confirm a correct or incorrect diagnosis
• The case histories are presented in detail so readers fully understand the diagnosis
• The authors have 108 years of combined experience in the installation, maintenance, repair, design, manufacture, operation and condition monitoring of SCIMs
• There are 10 questions at the end of chapters 1 to 12 and answers can be obtained via the publisher

Current Signature Analysis for Condition Monitoring of Cage Induction Motors serves as a reference for professional engineers, head electricians and technicians working with induction motors. To obtain the solutions manual for this book, please send an email to [email protected].

William T. Thomson is Director and Consultant with EM Diagnostics Ltd, in Scotland. Prof. Thomson received a BSc (Hons) in Electrical Engineering in 1973 and an MSc in 1977 from the University of Strathclyde. He has published 72 papers on condition monitoring of induction motors in a variety of engineering journals such as IEEE Transactions (USA), IEE Proceedings (UK), and also at numerous International IEEE and IEE conferences. He is a senior member of the IEEE, a fellow of the IEE (IET) in the UK and a Chartered Professional Engineer registered in the UK.

Ian Culbert was a Rotating Machines Specialist at Iris Power Qualitrol since April 2002 until his very untimely death on 8th September, 2015. At this company he provided consulting services to customers, assisted in product development, trained sales and field service staff and reviewed stator winding partial discharge reports. He has co-authored two books on electrical machine insulation design, evaluation, aging, testing and repair and was principal author of a number of Electric Power Research Institute reports on motor repair. Ian was a Registered Professional Engineer in the Province of Ontario, Canada and a Senior Member of IEEE.

CHAPTER 1
MOTOR CURRENT SIGNATURE ANALYSIS FOR INDUCTION MOTORS

William T. Thomson

1.0 Introduction

In 1824, Francois Arago initially formulated the concept of a rotating magnetic field which was subsequently known as Arago's rotations. On June 28, 1879, Walter Bailey presented to the Royal Society of London, a paper entitled A Mode of Producing Arago's Rotations, in which he proposed an early form of the induction motor. On May 16, 1888, Nikola Tesla presented a paper on a “New System of Alternate Current Motors and Transformers” to The American Institute of Electrical Engineers [1]. This paper and Tesla's practical demonstrations proved how a rotating magnetic field could be produced and also verified its application to the principles of operation of an induction motor. Also, in April 1888, The Royal Academy of Sciences of Turin published Galileo Ferraris' research findings on his ac polyphase motor in which he presented the basis for the operation of an induction motor.

Nikola Tesla's contributions, which, very importantly, he patented in the United States in 1888 are considered to be the catalyst for the subsequent industrial development of the modern generation and distribution of electricity using the 3-phase alternating current (ac) system, which is universally used throughout the modern world. It is now generally accepted that Nikola Tesla's greatest achievement was his invention of the induction motor and these motors dwarf all other electric motors in industrial importance since they are used in their millions throughout industry around the world. Without this electrical machine, modern society as we know it today would probably not exist. The induction motor, without doubt is one of the greatest inventions of all time but one of which, it is sad to state, the world at large is completely unaware.

Induction motors typically consume 40–50% of the generated electricity in an industrialized country. In 2008, the United States was the largest consumer of electricity at 4,401,698 GWhrs/annum [2], hence the vast number of these motors used in industry becomes very clear. Induction motors are the “workhorses” of a modern industrialized country and as such, a condition assessment of their operational integrity via condition monitoring is normal practice by end users to avoid the following:

1. Unscheduled downtime and lost (delayed) production and income
2. Catastrophic failures
3. Hazardous operating conditions that may lead to major accidents

There are a number of key categories that cause failures in induction motors and these are

1. Bearing failures
2. Stator winding failures
3. Broken rotor bars or end rings in cage induction motors
4. High airgap eccentricity and unbalanced magnetic pull that may lead to a consequential rotor to stator rub

Vibration monitoring and analysis to detect bearing faults in rotating plant (which includes induction motors) is well documented via thousands of published papers and also in text books and is therefore not the subject of this book. Stator winding failures and on-line partial discharge monitoring to assess the operational condition of high voltage (HV) stator windings are covered by Stone et al. [3].

This book is dedicated to motor current signature analysis (MCSA) for condition monitoring of 3-phase induction motors (SCIMs) and its content is specifically focused to suit the needs of industry. It differs from all other books on condition monitoring of electrical machines, for example, by Tavner et al. [4] which has a small part content (pp. 207–212) on current monitoring for rotor faults but does give a broad coverage of all the different condition monitoring technologies applicable in industry to electrical...

Table of contents

• Cover
• IEEE Press
• Title page
• Copyright
• About the Authors
• Obituary to Ian Culbert (1943–2015)
• Acknowledgments
• Foreword
• Preface
• Nomenclature
• Acronyms and Abbreviations
• Relevant Units of Equivalence Useful for this Book
• Chapter 1 Motor Current Signature Analysis for Induction Motors
• Chapter 2 Design, Construction, and Manufacture of Squirrel Cage Rotors
• Chapter 3 Causes of Breaks in Squirrel Cage Windings During Direct-On-Line Starts and Steady-State Operation
• Chapter 4 Motor Current Signature Analysis (MCSA) to Detect Cage Winding Defects
• Chapter 5 MCSA Industrial Case Histories—Diagnosis of Cage Winding Defects in SCIMs Driving Steady Loads
• Chapter 6 MCSA Case Histories—Diagnosis of Cage Winding Defects in SCIMs Fitted with End Ring Retaining Rings
• Chapter 7 MCSA Case Histories—Cyclic Loads Can Cause False Positives of Cage Winding Breaks
• Chapter 8 MCSA Case Histories—SCIM Drives With Slow Speed Gearboxes and Fluctuating Loads Can Give False Positives Of Broken Rotor Bars
• Chapter 9 Miscellaneous MCSA Case Histories
• Chapter 10 MCSA to Estimate the Operational Airgap Eccentricity in Squirrel Cage Induction Motors
• Chapter 11 Case Histories—Successful and Unsuccessful Application of MCSA to Estimate Operational Airgap Eccentricity in SCIMs
• Chapter 12 Critical Appraisal of Mcsa to Diagnose Short Circuited Turns in LV and HV Stator Windings and Faults in Roller Element Bearings in SCIMS
• Chapter 13 Appraisal of MCSA Including Lessons Learned via Industrial Case Histories
• List of Equations
• Index
• IEEE Press Series on Power Engineering
• EULA