LOGIC ANALYSIS OF DIGITAL PROTECTIVE RELAYS AT SUBIC
ENERZONE CORPORATION
ANDREW MIGUEL YEE ARLOS
2004-68816
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
MAY 2009
in partial fulfillment of the requirements for the degree of Bachelor of Science in Electrical Engineering is hereby accepted.
__________________________ ___________________________
Engr. John D.G. Agsalud Engr. Isabelo C. Mercado, III Panel Member Panel Member
__________________________ ___________________________
Date Signed Date Signed
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Engr. Anthony Hilmer S. Medrano 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
v
TABLE OF CONTENTS
Biographical sketch iii
Acknowledgement iv
Table of Contents v
List of Figures and Tables vii
I. Introduction 1
A. Description of the Study 2
B. Significance of the Study 3
C. Objectives of the Study 4
D. Scope and Limitations 5
E. Date and Place of Study 5
F. Company Profile 6
G. Training Activities 8
II. Review of Related Literature 10
A. Faults 11
A.1. Short Circuit 11
A.2. Overloading 11
A.3. Abnormal Voltage 11
A.4. Abnormal Frequency 12
B. Function of Protective Relaying 12
C. Transducers 13
C.1. Current Transformers 14
C.2. Potential Transformers 15
D. Power Circuit Breakers 16
E. Protective Relays 17
E.1. Electro-mechanical Relays 17
E.1.1. Magnetic Attraction Relay 18
E.1.2. Induction Relays 18
E.2. Solid State Relays 20
E.3. Digital Relays 21
III. Study Methodology 23
IV. Discussion and Analysis 25
A. Protective Relaying in Subic Enerzone Corporation 26
B. Digital Protective Relays 27
C. Logic Analysis 29
C.1. Overall Operation 29
C.2. Overcurrent Protection 32
C.2.1. Definite Time Overcurrent Protection 32 C.2.2. Inverse Time Overcurrent Protection 34
C.3. Inrush Restraint 39
C.4. Breaker Failure Protection 43
C.5. Negative Sequence Protection 44
V. Observations 47
VI. Conclusions 50
VII. Recommendations 52
Literature Cited 54
Appendices
vii
LIST OF FIGURES AND TABLES
Figure Page
A burning Power Circuit Breaker caused by a fault 2
A burning Distribution Transformer 4
Subic EnerZone Corporation Location Map 6
Subic EnerZone Corporation Administration Office 7
Training Activities at Subic EnerZone 8
Current Transformer attached on the bushing of the Circuit Breaker 14
Potential Transformers 16
Electromechanical Relay 17
Siemens Siprotec 74SJ61 - a multifunction digital relay 22
Functional Diagram of Protective Relaying 26
Hardware Structure of 74SJ61 29
Definite-time Overcurrent function (50-1) of the 74SJ61 33 Definite-time ground overcurrent function (50N-1) of the 74SJ61 34
Logic diagram of 51 relay function 35
Logic diagram of 51N relay function 36
Very Inverse ANSI characteristic curve 37
General parts of the Overcurrent protective function of the relay 39
Logic Diagram for Inrush Restraint 40
Parts of the inrush restraint function 41
Functional Principle of the Breaker Failure Protection Function 43
Logic Diagram for Negative Sequence Protection 44
Definite Time Characteristic for Negative Sequence Protection 45 Inverse Time Characteristic for Negative Sequence Protection 46
