SUBMITTED TO THE FACULTY OF THE

RECTIFICATION ANALYSIS ON LIGHT RAIL TRANSIT AUTHORITY

LINE-1 RECTIFIER SUBSTATIONS

OHVID B. GRANADEROS

2004-18661

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

OCTOBER 2009

TABLE OF CONTENTS

Biographical Sketch iii

Acknowledgement iv

Table of Contents vi

List of Figures viii

List of Tables x

I. Introduction 1

A. Description of the Study 2

B. Significance of the Study 3

C. Objectives 3

D. Scope and Limitations 3

E. Date and Place of Study 4

F. Company Profile 4

G. Schedule of Activities 5

II. Review of Literature 8

A. Three-Phase Circuits 9

B. Transformers 11

C. Rectifiers 12

1.Uncontrolled Three-phase rectifier 13

2.Full-controlled Three-phase rectifier 14

3.Half-controlled Three-phase rectifier 16

D. Ripple Voltage 17

E. Silicon-Controlled Rectifier 19

F. Voltage Regulation 20

G. Harmonic Trap Filter / Snubber 21

III. Study Methodology 25

IV. Discussion and Analysis 27

A. Rectifier Units 28

B. Rectification Process 34

C. Advantages and Disadvantages 42

V. Observation 44

VI. Conclusion 46

VII. Recommendation 48

References 50

Appendices 52

Appendix A. Traction Rectifier Data Appendix B. Loader Rectifier Data

Appendix C. Substation One-line, Block, Network, and Traction Diagrams

Appendix D. Daily Time Record and Certification

LIST OF FIGURES

Figure No. Description Page Number

1

Location of LRTA line-1 Depot and SRTS Route Map

4

2

Three-phase voltage waveforms

9

3

Waveforms of a single-phase series resistance-

inductance circuit

10

4

Apparent power waveforms of a three-phase motor with

an inductive load

11

5

Half-wave rectifier circuit and output waveform

12

6

Center-tapped full-wave rectifier circuit and output

waveform

13

7

Full-wave bridge rectifier and output waveform

13

8

Basic uncontrolled three-phase rectifier design

14

9

Three-phase line voltage waveforms in ABC phase

sequence

14

10

Rectified Line Voltage Waveforms

14

11

Three-phase full-controlled rectifier

15

12

Graetz Bridge Output waveform

15

13

DC output voltage vs. delay angle α

16

14

Three phase half-controlled rectifier

16

15

Three phase full-controlled rectifier with a free-

wheeling diode

17

16

Illustration of the output ripple voltage of a converter

17

17

Thyristor switching characteristics

20

18

Commercially available RC snubbers

22

19

Filtering of a full-wave output voltage

22

20

Harmonic trap filters

24

21

Maintenance of Traction Rectifier 1 consisting of 72 diodes enclosed by heatsinks with flag relays on each

diode compartment

29 22

Inside view of the Traction Rectifier 2 unit showing its

heatsinks which protect the diodes

29

23

High speed circuit breaker units and mechanism

30

24

3 Step Characteristic of DCP 106

30

25

IOP operation on low-resistance short circuit near

substation

31

26

OCP predominate operation

31

27

The DCP 106 3-stage tripping logic

32

28

Underground cables in the substation basement for the

grounding system connected to the earth and railways

32

29

Loader Rectifier

33

30

Protection and Control Circuit

33

31

RC filter circuit and its analysis on DC operation

39

32

AC operation of the RC filter circuit

40

LIST OF TABLES

Table No. Description Page Number

1

Training Activities at LRTA Line-1 Rectifier Substations

5 2

Harmonic Current limits in percent of fundamental

24 3

Harmonic Voltage Limits in percent of fundamental

24 4

Actual data on Substation Low Voltage Switchboard and

Loader Rectifier taken in the first week of June

37