Practical Partial Discharge Measurement on Electrical Equipment

Accessible reference dealing with (partial discharge) PD measurement in all types of high voltage equipment using modern digital PD detectors

Practical Partial Discharge Measurement on Electrical Equipment is a timely update in the field of partial discharges (PD), covering both holistic concepts and specific modern applications in one volume. The first half of the book educates the reader on what PD is and the general principles of how it is measured and interpreted. The second half of the book is similar to a handbook, with a chapter devoted to PD measurements in each type of high voltage (HV) equipment. These chapters contain specific information of the insulation system design, causes of PD in that equipment, off-line and on-line measurement methods, interpretation methods, and relevant standards.

The work is authored by four well-known experts in the field of PD measurement who have published hundreds of technical papers on the subject and performed thousands of PD measurements on all the different types of HV equipment covered in the book. The authors have also had relationships with PD detector manufacturers, giving them key insights into test instruments and practical measurements.

Sample topics covered in the work include:

• Physics of PD, discharge phenomena (contact sparking and vibration sparking), and an introduction to PD measurement (electrical, optical, acoustic, and chemical)
• Electrical PD detection (types of sensors), RF PD detection (antenna, TEV), and PD instrumentation and display
• Off-line and on-line PD measurements, general principles of PD interpretation, and laboratory PD testing of lumped test objects
• PD in different types of HV equipment (power cables, power transformers, air insulated metal-clad switchgear, rotating machines, gas-insulated switchgear, and more)

For HV equipment OEMs, users of HV equipment, or employees of companies that provide PD testing services to clients, Practical Partial Discharge Measurement on Electrical Equipment is an essential reference to help understand general concepts about the topic and receive expert guidance during specific practical applications.

Greg Stone is an electrical engineer specializing in electrical insulation. In the past, he provided specialized electrical testing on 200 generators and over 1000 motors to evaluate the condition of the rotor and stator windings.

Andrea Cavallini received his Master and PhD degrees in electrical engineering from the University of Bologna. His research focuses on partial discharges detection and identification in diverse types of apparatus (cables, rotating machines, transformers, and GIS) through innovative detection systems.

Glenn Behrmann received a B.S.E.E. from Union College, Schenectady, NY, in 1979. He has authored papers and holds patents in the field, and is active in CIGRE D1 and IEC TC42.

Claudio Serafino is Head of the test and measurement department at Terna SpA. He is an expert in partial discharge measurements on large power and high voltage transformers performed in testing rooms of manufacturers.

0. Preface

Dedication

Author Biographies

Preface

Acknowledgements

Acronyms

1. Introduction

1.1 Why measure PD?

1.2 Partial discharge and Corona

1.3 Categories of PD Tests

1.4 PD Test Standards

1.5 History of PD Testing

1.6 The Future

1.7 Roadmap for the book

1.8 References

2. Electric Fields and Electrical Breakdown

2.1 Electric Fields in High Voltage Equipment

2.2 Electrical Breakdown

2.3 Breakdown in Gases

2.4 Breakdown in Solids

2.5 Breakdown in Liquids

2.6 Dielectric Strength

2.7 References

3. Physics of PD

3.1 Introduction

3.2 Classification of partial discharge

3.3 PD current pulse characteristics

3.4 Effects of PD

3.5 Corona due to non-uniform electric fields around conductors

3.6 Partial discharge in voids

3.7 PD on insulation surfaces

3.8 Effect of ambient conditions and conditioning

3.9 Summary of measured PD quantities

3.10 Understanding the PD Pattern with respect to the AC cycle

3.11 References

4. Other Discharge phenomena

4.1 Introduction

4.2 PD as a Disturbance

4.3 Circuit Breaker Arcing

4.4 Contact Arcing and Intermittent Connections

4.5 Metal Oxide Layer Breakdown

4.6 Dry Band Arcing

4.7 Glow (or Pulseless) Discharge

4.8 References

5. PD Measurement Overview

5.1 Introduction

5.2 Charge-based and electromagnetic measurement methods

5.3 Optical PD Detection

5.4 Acoustic PD Detection

5.5 Chemical Detection

5.6 References

6. Charge-Based PD Detection

6.1 Introduction

6.2 Basic detection circuits using coupling capacitors

6.3 Sensors

6.4 Electrical Detection Models

6.5 Quasi integration for Charge-Based Measuring Systems

6.6 Calibration into Apparent Charge

6.7 References

7. Electromagnetic PD Detection

7.1 Why measure electromagnetic signals from PD

7.2 Electromagnetic Terminology

7.3 Basic electrical detection circuits

7.4 Types of RF sensor/

7.5 Measuring Instruments

7.6 Performance and sensitivity checks

7.7 PD source location

7.8 references

8. PD Measurement System Instrumentation and Software

8.1 Introduction

8.2 Frequency Range Selection

8.3 PD Detector Hardware Configurations

8.4 Hardware-Based Disturbance Suppression and PD Source Identification

8.5 PD Calibrator Hardware

8.6 Special Hardware Requirements for Continuous Monitors

8.7 PD System Output Charts

8.8 PD Activity Indicators

8.9 Post Processing Software for Interference Suppression and PD Analysis

8.10 References

9. Suppression of External Electrical Interference

9.1 Impact of External Electrical Interference

9.2 Typical Sources of Noise and External Interference

9.3 Interference Suppression for Off-line PD Testing

9.4 On-Line Interference Suppression

9.5 References

10 General Principles of PD Interpretation

10.1 Introduction

10.2 PDIV/PDEV Measurement

10.3 PD Magnitude and PRPD Test Procedure

10.4 Interpretation of PD magnitude

10.5 PRPD Pattern Interpretation

10.6 PD Root Cause Identification Using Changes in Ambient and Operating Conditions

10.7 References

11 PD testing of lumped capacitive test objects

11.1 Lumped capacitive objects

11.2 Test Procedures

11.3 Measures to suppress electrical interference

11.4 Sensitivity check

11.5 References

12 PD Measurement in Power cables

12.1 Introduction

12.2 Cable system structure

12.3 Cable system failure mechanisms

12.4 Cable PD test standards

12.5 PD test sensors

12.6 PD pulse propagation and detector bandwidth

12.7 Factory quality assurance (QA) testing of power cable

12.8 Energizing cables in off-line/on-site tests

12.9 off-line/on-site testing

12.10 Pros and cons of off-line versus on-lin PD measurements for condition assessment

12.11 On-line monitoring

12.12 Interference suppression

12.13 PRPD patterns

12.14 PD source localization

12.15 References

13 PD Measurement in GIS and GITL

13.1 Introduction

13.2 Relevant Standards and Technical Guidance

13.3 The GIS Insulation System

13.4 Typical PD Sources in GIS and Their Failure Modes

13.5 Detection of PD in GIS

13.6 Charge-based PD measurement in GIS

13.7 Application of acoustic techniques for PD measurement on GIS

13.8 Radio-frequency PD measurement on GIS: the UHF method

13.9 GIS routine factory test

13.10 PD measurement during on-site acceptance tests

13.11 On-Line continuous PD monitoring (PDM) of GIS

13.12. GIS PD signal examples and PRPD patterns

13.13 HVDC GIS: Special considerations

13.14 References

14 Air Insulated switchgear and isolated phase bus

14.1 Introduction

14.2 AIS Insulation Systems

14.3 Insulation Failure Processes

14.4 PD Sensors

14.5 Commissioning and Off-Line/On-Site Testing

14.6 On-line PD Monitoring

14.7 PD Interpretation for AIS

14.8 PD Measurement in Isolated Phase Bus

14.9 References

15 Power transformers

15.1 Introduction

15.2 The Transformer Insulation System

15.3 Typical causes of PD in dry-type (cast resin) transformers

15.4 Typical causes of PD in liquid-filled transformers

15.5 Relevant Standards

15.6 PD pulses propagation and PD detection

15.7 Sensors for PD detection

15.8 AC Supply for off-line testing

5.9 Precautions for background noise and Interference

15.10 Factory acceptance testing

15.11 On-site Off-line Testing

15.12 On-line PD monitoring

15.13 PRPD Patterns

15.14 References

16. Rotating Machine stator windings

16.1 Introduction

16.2 Relevant Standards

16.3 Stator Winding Insulation Systems

16.4 Stator Winding Insulation Failure Processes

16.5 PD pulse propagation in windings

16.6 PD sensors

16.7 Factory Acceptance Tests

16.8 On-Site/Offline tests

16.9 On-line testing and monitoring

16.10 Differences between on-line and off-line tests

16.11 Interpretation

16.12 Root cause identification

16.13 Locating PD Sites

16.14 References

17 PD Detection in DC Equipment

17.1 Why is HVDC so popular now

17.2 Insulation system design with DC

17.3 The reasons for testing using DC

17.4 Off-line PD testing with DC excitation

17.5 Interpretation of PD measurements under DC excitation

17.6 Perspectives

17.7 References

18 PD Detection under voltage impulses

18.1 Introduction

18.2 Insulation failure due to short risetime impulse voltages

18.3 Electrical PD detection

18.4 Non-electrical sensors

18.6 Sensitivity and interference check

18.7 Test procedures

18.8 Interpretation

18.9 References

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