My Mind, My Heart, My File

COORDINATED POWER SYSTEM PROTECTION
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1-1
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1-1
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1-1
Electrical power systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 1-1
Design procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 1-1
CHAPTER 2. ELECTRICAL POWER SYSTEM OVERCURRENTS
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2-1
Normal current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2-1
Overload current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 2-1
APPROVED FOR PUBLIC RELEASE: DISTRIBUTIONS IS UNLIMITED
Short-circuit current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 2-1
Ground-fault current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 2-1
Sources of short-circuit current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 2-2
Time variation of short-circuit current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2-3
Symmetrical and asymmetrical short-circuit current . . . . . . . . . . . . . . . . . . 2-8 2-5
CHAPTER 3. OVERCURRENT PROTECTIVE DEVICES
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3-1
Motor overload relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3-1
Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3-1
Motor short-circuit protectors (MSCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3-3
Circuit breakers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3-3
Protective relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 3-9
Automatic reclosing devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 3-10
CHAPTER 4. PROTECTIVE DEVICES COORDINATION
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 4-1
The coordination study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4-1
Primary and medium-voltage coordination . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 4-3
Low-voltage coordination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4 4-5
Ground-fault coordination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 4-5
Coordination requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6 4-6
Maintenance, testing, and calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 4-7
Example of phase coordination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8 4-7
Example of ground-fault protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9 4-23
CHAPTER 5. ELECTRICAL SYSTEM PROTECTION TECHNIQUES
Generator protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5-1
Transformer protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5-6
Conductor protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 5-15
Motor protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4 5-20
Bus and switchgear protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5 5-29
Ground-fault protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 5-34
Miscellaneous equipment protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7 5-44
Appendix A. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
Appendix B. TYPICAL PROTECTIVE DEVICE SETTINGS . . . . . . . . . . . . . . . . . . . B-1
Appendix C. TYPICAL TIME-CURRENT CHARACTERISTIC CURVES . . . . . . . . C-1
Appendix D. TYPICAL DEVICE AND EQUIPMENT RATINGS . . . . . . . . . . . . . . . . D-1
Appendix E. PARTIAL RELAY DEVICE NUMBERS LIST . . . . . . . . . . . . . . . . . . . . E-I
Appendix F. REPRESENTATIVE PROTECTIVE DEVICE OPERATING TIMES . . F-1
Appendix G. COORDINATION EXAMPLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1
Appendix H. COMPUTER SOFTWARE APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . H-1
BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bibliography-1
GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Glossary-1

See detail : Coordinated Power Systems Protection

 Application Guide

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INSTRUMENT TRANSFORMER

APPLICATION GUIDE

INTRODUCTION

The primary purpose of this guide is to give the reader a basic understanding of how to apply instrument transformers in a practical way while observing good engineering practice. It is not intended to make the reader an instrument transformer designer. A special effort will be made to keep to a minimum technical terms and language.

PURPOSE

The purpose of instrument transformers is to provide either a current or voltage at a useable level to monitor the voltage or current in a given circuit. For example, it would not be economical to have an ammeter to measure 600 amps in a conductor directly. It is economical to have an ammeter to measure current over a range of 0 - 5 amps. By inserting a current transformer in the circuit, it will produce a current which is precisely proportionate to the current in the conductor you wish to monitor over a range of 0 - 5 amps which corresponds to 0 - 600 amps. The ammeter will have a scale of 0 - 600 amps. Likewise, it would not be economical to measure a voltage of 14,400 volts directly. By inserting a voltage transformer in the circuit a directly proportionate voltage over a range of 0 - 120 volts will be present which corresponds to 0 - 14,400 volts. Current and voltage transformers are also used to provide the energy to operate various protective relays. The degree to which an instrument transformer produces a current or voltage that is proportionate to the one to be monitored is referred to as its accuracy. This subject will be covered in much greater detail later in this guide.

See detail : Application Guide : Instrument Transformer

ANALISA SISTEM TENAGA

I.           Pendahuluan
Dalam sistem tenaga, yang perlu diketahui dalam analisanya adalah :

·         Analisa aliran daya

·         Analisa hubung singkat

·         Analisa stabiltas sistem

 Analisa aliran daya.  Yang dipelajari adalah aliran arus beban yang mungkin mengalir di tiap cabang di dalam network, baik aliran daya pada cabang Trafo, Distribusi, Transmisi maupun yang mengalir dari Pembangkit dan beban yang tersebar di dalam sistem.  Analisa ini dilakukan untuk mengetahui apakah peralatan listrik akan mengalami beban lebih sebelum beban itu mengalir padanya sebelum kejadian yang sesungguhnya.

 Analisa hubung singkat adalah analisa yang mempelajari kontribusi arus gangguan hubung singkat yang mungkin mengalir pada setiap cabang di dalam sistem (di jaringan distribusi, transmisi, trafo tenaga atau dari pembangkit) sewaktu gangguan hubung singkat yang mungkin terjadi di dalam sistem tenaga listrik.

Tidak saja besar arus kontribusi yang dihitung, tetapi juga besarnya tegangan yang terjadi pada setiap Node pada saat gangguan hubung singkat tersebut.

 Analisa stabilitas sistem, analisa yang mempelajari kelakuan sistem dimana terjadi pergeseran besaran listrik berupa frekwensi, tegangan dan arus pada beberapa pembangkit yang dihubungkan oleh jaringan sewaktu terjadi perubahan.

Keadaan ini terjadi akibat lepasnya pembangkit besar di dalam sistem, sesaat setelah terjadi gangguan hubung singkat atau masuknya beban besar ke dalam sistem.

Pada kesempatan ini, analisa sistem tenaga yang ada hubungan dengan training bidang proteksi adalah analisa yang hasilnya sangat diperlukan oleh peralatan proteksi yaitu Analisa Hubung Singkat.  Besaran arus dan tegangan yang didapat dari hasil analisa ini yang dimanfaatkan oleh peralatan proteksi.

Analisa stabilitas sistem tidak dibahas dalam kesempatan ini walaupun analisa ini juga perlu dilakukan untuk mengetahui bagaimana reaksi peralatan proteksi bila terjadi guncangan di dalam sistem tenaga listrik. 

See detail :  Analisa Sistem Tenaga Listrik

As test equipment becomes more sophisticated with better features and accuracy, we risk turning our field personnel into test-set operators instead of skilled field service technicians. A test-set operator connects the leads, pushes the buttons, and records the results, hoping the numbers he records are good. A test technician connects the leads, pushes the buttons, and records the results. However, the test technician understands what the test set was doing while all the lights were flashing,
and why. The technician can also evaluate the results and determine if a retest is necessary with different connections or substitute external equipment for tests when the test equipment malfunctions. The purpose of this article is to help a test-set operator understand the tests he performs, reinforce a test technique, or add it to his repertoire.

Description of Operation
During normal operation, a current transformer (CT) transforms higher current into a more manageable secondary current. This transformation is made possible by copper coils wrapped around an iron core, with the ratio between primary and secondary currents determined by the ratio between the number of primary and secondary turns. Bar- and window-type CTs do not have a physical primary winding and are considered to have one primary turn.

See detail :  Current Transformer Testing

Protective Devices

            
Puzzle by choosing circuit protection devices?

Follow this guidelines and your electrical system will fall into place.

Protective Device Coordination

This guide covers practical application, general philosophy and economics consideration of power transformer protection.

Detail :

IEEE Guide for Protective Relay Applications to Power Transformer

Mission

•  All of electrical consumers can avoid electrocution and prevent fire hazards by using RCD as suggested on PUIL 2000.

•  To correct the earthing system implementation.

 Electrical risk

• Overload and short-circuit
• Leakage current:

            Deterioration of conductor insulation causes phase to earth current flow (Ph/Frame), consequences:

•         Fire hazard

•         Damage to load

•         Electrocution

See detail : Earth Leakage Circuit Breaker (ELCB) - Residual Current Device