PARTIAL DISCHARGE MONITORING OF POWER TRANSFORMER USING
POWERPD DONE BY NATIONAL TRANSMISSION CORPORATION
MA. ANGELICA M. BOBADILLA
2004-40051
SUBMITTED TO THE FACULTY OF THE
COLLEGE OF ENGINEERING AND AGRO-INDUSTRIAL TECHNOLOGY, UNIVERSITY OF THE PHILIPPINES LOS BAÑOS,
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
BACHELOR OF SCIENCE IN ELECTRICAL ENGINEERING
MARCH/2010
The report attached hereto entitled Partial Discharge Monitoring of Power Transformer Using Power PD Done by National Transmission Corporation, prepared and submitted by Ma. Angelica M. Bobadilla in partial fulfillment of the requirements for the degree of Bachelor of Science in Electrical Engineering is hereby accepted.
Engr. Rodolfo A. Aguirre Jr. Engr. Noah G. Badayos Engr. Billy Jonh Q. Valdez Panel Member Panel Member Panel Member
Date Signed Date Signed Date Signed
Engr. Roderick L. Catriz Academic Adviser
Date Signed
Engr. Roderick L. Catriz Officer-in-Charge
Department of Electrical Engineering
Date Signed
Dr. Arsenio N. Resurreccion Dean
College of Engineering and Agro-Industrial Technology UPLB
Date Signed
TABLE OF CONTENTS
Biographical Sketch iii
Acknowledgement iv
Table of Contents v
List of Figures vii
List of Tables viii
I. Introduction 1
A. Description of the Study
B. Significance of the Study
C. Objectives of the Study
D. Scope and Limitations
E. Date and Place of Study
F. Company Profile
G. Training Activities
2 2 3 3 4 4 5
II. Review of Literature
A. Partial Discharge
A.1. Discharge Mechanism A.1.1. Partial Discharge Currents
A.1.2. Apparent Charge
A.2. Effects of Partial Discharge in Insulation Systems B. Acoustic partial discharge systems
B.1. The all-acoustic system
B.2. The acoustic system with an electrical pd trigger B.3. The on-line (continuous) acoustic monitoring system C. Acoustic signal transmission characteristics
D. On-line (continuous) acoustic partial discharge monitoring systems D.1. Acoustic emission field test procedure (typical)
D.2. Test setup
D.2.1. Sensor placement and initial scan D.2.2. Monitoring techniques
D.2.3. Locating the source of the signal E. Online acoustic system
F. Signal processing
G. Acoustic activity from thermal faults, the core, mechanical noises and other sources
H. Comparison between electrical and acoustic signals I. Acoustic activity interpretation
7 8 8 9 9 10 12 12 13 15 15 18 19 20 20 22 23 24 26 28 29 31
III. Study Methodology 34
IV. Discussion and Analysis A. How PowerPD works
A.1. Components and Specifications of PowerPD A.2. Safety Precautions
36 37 38 41
A.3. Safety Instructions in Using PowerPD B. Installation
B.1. Sensors installation B.1.1. AE sensor B.1.2. HFCT sensor
B.2. Local Station (PD-TP500A) Installation B.3. Connection of Cables
B.4. PC installation B.5. Software installation
C. System operation C.1. Main window C.2.Auto mode C.2. Wave window
C.2.1. Waveform display C.2.2. Waveform analysis C.2.3. Spectrum Analysis C.2.4. Signal detection
C.3. Trending partial discharge D. Actual field operation
D.1. Installation of sensors
D.2. Partial discharge location detection D.3. Actual field data
E. Benefits of On-Line Partial Discharge Monitoring
41 41 41 41 42 43 44 45 45 45 45 47 49 50 50 52 53 54 55 56 57 59 65
V. Observations 66
VI. Conclusion 68
VII. Recommendations 70
Literature Cited Appendices
LIST OF FIGURES
Figure Description Page
1 Location Map 4
2 Illustration of typical propagation paths for the acoustic PD signal 17 3 Illustration of the longitudinal and transversal waves in the enclosure and
how they are created from direct waves. Note: the wavelengths are not to scale
18
4 Signal waveforms detected by different sensors 25
5 System Configuration Bock Diagram 37
6 The PD-TP500A 39
7 Connectors and Operating Controls of PD-TP500A 39
8 AE Sensor 41
9 10 11
HFCT Sensor (Ring Type) Connection of Cables
Main window of PowerPD Software
42 44 47
12 Auto Mode screen 48
13 Wave Display 49
14 15
Three Condition of PD Signal Spectrum Analysis Window
52 53
16 Signal Detection Window 54
17 Acoustic (top) and Electrical Signal (bottom) 55
18 Engineers inspecting the Transformer 56
19 Installation of AE Sensors 57
20 Top view of transformer indicating location of sensors, (large balls), and source, (small interior ball).
58
21 PD Location 58
22 Actual Field Data of TO5 at Dasmariñas Substation 59
23 24 25
PD pattern occurring from the inside of the transformer Egg-shaped PD pattern occurring from the winding
Another egg-shaped PD pattern occurring from the winding
60 61 61
26 PD pattern indicating mechanical problem 62
27 28 29
Internal inspection of the 115 kV bushing ob phase B
Melted copper beads were scattered below the bushing connection Tiny melted copper beads were scattered below the bushing connection
63 64 64
LIST OF TABLES
Table Description Page
1 Accomplishment during practicum 5
2 PD Detector types and their time lags 14
3 Estimates of the velocity of sound in oil 14
4 Comparison between electrical and acoustic signals 30
5 Specifications of PowerPD PD-TP500A 40
6 Sensor Specifications 40
