materi ujian mesin listrik dasar

Perancangan Sistem Listrik Industri (TEE 542)

Preview Perancangan Listrik Industri

Perancangan Sistem Listrik Industri TEE 542

DAFTAR ISI

Lingkup Bahasan

1

Standard-standard

2

3

Pendahuluan


Model Perkuliahan Student centre learning

Penugasan individu dan kelompok

Materi penilaian : – Tugas kecil

– Tugas besar

– Ujian mid

– Ujian akhir

Semua tugas melalui “Papirus2”

Dispensasi keterlambatan hanya karena : – Tugas/sesuai aturan “negara”

– Papirus error saat upload (dlm interval 1 jam sebelum deadline dan dibuktikan dg screenshoot). Tanpa bukti tidak diterima

– File tidak bisa dibuka


Dilarang Keras !!!


Fokus Pembahasan

1. Industrial Power System Studies

2. Drawing

3. Engineering Procurement Construction

4. Study case


Materi Kuliah

1. Mengetahui dan memahami gambaran

umum ruang lingkup perancangan sistem

kelistrikan di industri beserta standardnya.

2. Engineering Work and Its Management

3. Power System Studies

Distribution System

Power and Control

Cables

Load Flow

Short Circuit Analysis

Sistem Proteksi

Arch-Flash Hazard

Calculation

Grounding System

Switchgear and MCC

DC System

Proteksi petir


Materi Kuliah

4. Drawing

PFD dan PID

Plant Layout and Modelling

Hazardous Area Classification

Detail Design and Drafting

5. Engineering Development and Detail

Specification, Selection and Purchase

6. Study Case (surface facilities oil and gas)


Skill Software

1. MS. Excel

2. MS. Word

3. MS. PowerPoint

4. AutoCad

5. ETAP

6. MS Project


Accreditation Board for Engineering and Technology

1. Apply knowledge of math, science and engineering

2. Identify, formulate and solve EE problems

3. Design and conduct experiments and analysis and interprete data

4. Design a system, component or process to meet the desired need within realistic constrains

5. Comunicate effectively

6. Function in multidisciplinary team

7. Use the technique, skills and modern engineering tools and technologies necessary for EE practice

8. The broad education necessary to understand the impact of engineering solution in global, economic, environmental and diverse social context

9. A knowledge of contemporary issue

10. An understanding of professional and ethical responsibility

11. A recognation of the need for and an ability to engage in life long-learning


Job Duties and Task for “Electrical Engineer”

1. Provide technical assistance and resolution when electrical or engineering problems are encountered before, during and after construction

2. Analyze and interpret test information to resolve design-related problems

3. Write commissioning procedure for electrical installation

4. Prepare project cost and work-time estimates

5. Evaluate engineering proposals, shop drawings and design comments for sound electrical engineering practice and conformance with established safety and design criteria, and recommend approval or disaproval.

6. Draw or modify diagrams and write engineering specifications to clarify design details.

7. Prepare contracts and initiate, review and coordinate modifications to contract specifications and plans throughout construction process

8. Plan, schedule and monitor work of support personnel to assist supervisor.

9. Review existing electrical engineering criteria to identify necessary revision, deletions or amendment to outdated material

10.Perform supervisory duties such as recommending work assignments, approving leaves and completing performance evalutions


Engineering work and its management

1. Define the objectives, i.e. the end product of the project.

2. Decide how the objectives will be achieved – what methods will be employed.

3. Plan in detail each item of work (‘work package’) and schedule the performance of the packages in a logical sequence.

4. Do the engineering work and check that it is correct.

5. Ensure that the engineering designs and specifications are acceptably implemented in plant procurement, manufacture, and construction.

6. Commission the plant and finalize all technical documentation needed for operation and maintenance.


Simplified work

engineering sequence

Electrical Deliverables :

1. Design of philosophy

2. Calculation

3. Drawing

4. Material take off, bill of

quantity


Interface Engineering & Electrical Work Flow


Engineering Work Flow


ENGINEERING STANDARDS

Standard: A standard is a document that defines the

characteristics of a product, process or service, such as

dimensions, safety aspects, and performance

requirements.

Code: Laws or regulations that specify minimum standards to

protect public safety and health such as codes for

construction of buildings. Voluntary standards are

incorporated into building codes

Specification: A set of conditions and requirements of precise

and limited application that provide a detailed description of a

procedure, process, material, product, or service for use primarily

in procurement and manufacturing. Standards may be referenced

or included in specifications.

Technical Regulation: A mandatory government requirement

that defines the characteristics and/or the performance

requirements of a product, service or process (see also

Regulation).


Some Background:

The U.S. federal government is the largest single creator and user of standards: more than 45,000 (by current estimates)!

About 210 organization are designated Standard Development Organizations (SDO’s)

Most Standards (about 90%) come from about 20 of these SDO’s

ASTM, ASME, IEEE, AISI (ASM), ASCE, MilStd (Mil Specs), are some of the most important SDO’s


Taking them Global!

ANSI and (U.S. National Committee (USNC)) are the U.S. clearing house for Standards and a founding member of ISO!

Internationally we see Standard Organization in each of the major Industrial Nations and several Umbrella Groups: – International Organization for

Standardization (ISO)

– International Electrotechnical Commission (IEC)

– International Telecommunication Union (ITU)


How they’re used:

Standards are a “COMMUNICATION” tool that allows all users to speak the same language when reacting to products or processes

They provide a “Legal,” or at least enforceable, means to evaluate acceptability and sale-ability of products and/or services

They can be taught and applied globally!

They, ultimately, are designed to protect the public from questionable designs, products and practices

Thus they fall (in engineering terms) into the “MOM AND APPLE PIE” area of our profession!

They teach us, as engineers, how we can best meet environmental, health, safety and societal responsibilities


http://www.toyo-

eng.co.jp/en/advantage/synthesis/

Electrical Deliverables and its

Interdisciplinary Interfaces, Foster

Wheeler

Handbook for Process Plant Project

Engineers, Watermeyer

http://www.toyo-eng.co.jp/en/advantage/synthesis/




Nuwun

http://www.flickr.com/photos/valanne/432271395/


Distribution System and

Power & Control Cables



Distribution System

Pertimbangan Desain Sistem Distribusi Industri

1

Panduan Perencanaan untuk Sistem Distribusi Industri

2

3

Pendahuluan

Tipe-tipe Sistem Distribusi 4

Voltage Considerations 5


Pendahuluan Sistem tenaga listrik memainkan peran penting dalam

suatu industri. Operasi pabrik dan produksi tergantung

pada sistem tenaga yang aman dan terpercaya. Setiap

desain sistem pembangkit listrik, baik baru atau ekspansi

ke sistem yang ada, harus dianalisis untuk memastikan

bahwa sistem aman, dapat diandalkan, dan

memungkinkan perencanaan untuk kebutuhan masa

depan.


Tegangan Nominal

Sistem Tenaga Listrik


Pertimbangan Desain Sistem

Distribusi Industri Perencanaan sistem tenaga listrik harus

mencakup beberapa pertimbangan dasar yang

akan mempengaruhi keseluruhan desain dan

operasi sistem tenaga. Dalam merancang sistem

tenaga di Industri harus mempertimbangkan :

1. Safety

2. Keandalan Utilitas Suplai Tenaga

3. Keandalan Sistem Distribusi

4. Keandalan peralatan sistem tenaga listrik


Pertimbangan Desain Sistem

Distribusi Industri

5. Kemudahan dalam operasi sistem tenaga

6. Regulasi Tegangan

7. Maintenance

8. Fleksibilitas

9. Biaya investasi


Load Survey


Tipe-tipe Sistem Distribusi

Simple Radial



Expanded Radial



Primary Selective System



Secondary Selective System



Sparing Transformer System



Ring Bus System


Voltage Considerations

Tegangan Nominal

Tegangan yang diterapkan pada sistem itu, sehingga

karakteristik kerja tertentu yang disyaratkan dari sistem itu

ditunjukkan.

Tegangan Tertinggi Suatu Sistem

Nilai tegangan tertinggi yang terjadi dalam keadaan kerja

normal pada setiap saat dan di setiap titik pada sistem itu.

Tegangan Terendah Suatu Sistem

Tegangan terendah yang terjadi pada keadaan kerja

normal pada setiap saat dan setiap titik pada sistem itu..


Kelas Tegangan

• Tegangan nominal sistem dibawah 1.000 V

Tegangan Rendah

• Tegangan nominal sistem antara 1.000 V hingga 100.000 V

Tegangan Menengah

• Tegangan nominal sistem antara 100.000 V hingga 230.000 V

Tegangan Tinggi


Konfigurasi Sistem

Single-Phase System


Konfigurasi Sistem

Three-Phase System


Voltage Drop Jatuh tegangan merupakan besarnya tegangan yang

hilang pada suatu penghantar. Jatuh tegangan pada

saluran tenaga listrik secara umum berbanding lurus

dengan panjang saluran dan beban serta berbanding

terbalik dengan luas penampang penghantar.


Voltage Drop


Power and Control Cables

Pertimbangan Desain Sistem Distribusi Industri

1

Panduan Perencanaan untuk Sistem Distribusi Industri

2

3

Pendahuluan

Tipe-tipe Sistem Distribusi 4

Voltage Considerations 5


Pendahuluan

Fungsi utama dari kabel adalah untuk

membawa energi dari pembangkit ke

sumber sumber beban.

Dalam menyalurkan energi ini, ada rugi-

rugi panas yang dihasilkan dalam kabel.

Kemampuan untuk mengurangi rugi-rugi

panas ini tergantung pada bagaimana

kabel terpasang, dan rating kabel yang

digunakan


Cable Design


Fungsi Isolasi pada Kabel

Untuk membatasi medan listrik dalam kabel

Untuk menyamakan stres tegangan dalam isolasi, meminimalkan surface discharges

Untuk melindungi kabel dari tegangan induksi

Untuk membatasi interferensi elektromagnetik atau elektrostatik pada sistem komunikasi, misalnya, radio, TV

Untuk mengurangi bahaya sengatan listrik


Pertimbangan Pemilihan

Ukuran Konduktor Kriteria Arus/beban

Batas Overload

Batasan Besar Drop tegangan

Kriteria Arus Gangguan

Nilai frekuensi

Kriteria suhu hot-spot

Panjang kabel di daerah suhu tinggi

Persyaratan pemutusan peralatan


Tugas 1. Sebuah kota memiliki 6870

pelanggan dengan Kapasitas

daya masing-masing 2200 VA.

Dengan pemakaian listrik sesuai

dengan tabel disamping. Hitung

Daya rata-rata, Load Factor,

Demand Factor, Coincidence

Factor, dan Diversity Factor,

serta Gambarkan Kurva Beban.

2. Sebutkan Kelebihan dan kekurangan konfigurasi loop

(ring) dan radial, beserta aplikasinya.


Referensi

PUIL 2000

IEEE-Red Book IEEE Recommended Practice for Electric Power

Distribution for Industrial Plants

Industrial Power System – Shoaib Khan


Arc-Flash Hazard



Arc Flash Event

Every Day An

Electrician Is

Severely

Injured by an

Arc Flash Event


Introduction What is an Arc Flash Hazard?

• Arc flash is defined by the CSA Z462 Standard on Workplace Electrical Safety as “a dangerous condition associated with the release of energy caused by an electric arc.”

• Arc flash is the explosive release of energy when electrical current jumps the distance from one conductor to another, or when it jumps from a conductor to ground.

• That jump is called an “arc”. “Flash” refers to the release of light and heat energy.

• Lightening is an example of an arc flash, when current jumps from sky to ground. The results are heat, light, and a pressure wave which you hear as thunder.

• In the workplace, arc flash can be deadly. It can happen anywhere you find energized electrical equipment or conductors.


What is an Electric Arc? • Simply put, an electric arc is a short circuit through the air.

• When insulation or isolation is breached or can no longer withstand the applied voltage between phase conductors or between a phase conductor and ground, the air between the conductors becomes ionized. Ionized air will conduct electricity and an arc fault occurs between those conductors.

• The power source will pump as much current into the arc fault as the supplying transformer, conductors, and arc impedance will allow until the fault is cleared by a protective device such as a fuse or circuit breaker or the fault burns itself out.

• The amount of energy released depends, in part, on the amount of energy in the circuit. The more energy, the more powerful the arc.

• Electric arcs produce some of the highest temperatures known to occur on earth.


Characteristics of an Electric Arc

An electric arc will oscillate and escalate if

not constrained.

A single-phase electric arc can engulf a

second or third conductor in only two

cycles.

An electric arc’s current propels the arc

away from the power source.


What Causes Arc Flash?

Dust, impurities, corrosion, condensation,

animals

Spark discharge from:

– Accidental touching

– Dropping tools

Over-voltages across narrow gaps

Failure of insulating materials

Equipment failure


What is Arc Blast?

1. The flash causes an explosive expansion

of air and metal.

– For example: When copper vapourizes it

expands by a factor of 67,000.

2. The blast produces dangerous:

– Pressure waves

– Sound waves

– Molten steel and shrapnel.


Arc Flash Events

PB/RH -- March 3, 2009 Arc Flash Hazards -- Construction Safety Association of Ontario

Electric arc Arc flash Arc blast

Compliments of Salisbury Electrical

Safety L.L.C.


Forms of Arc Flash Energy

Noise

Expansion

Vaporization

Thermal radiation


Arc Flash Injuries

Electric shock

Severe burns

Blindness

Blast injuries

– Shrapnel wounds

– Lung blast injuries

– Ruptured eardrums

– Pressure wave injuries


Standards

US Occupational Safety &

Health Administration

US National Fire Protection Association

-Standard NFPA 70E

Institute of Electrical &

Electronics Engineers

-Standard 1584

Canadian Standards Association

-Standard Z-462

Occupational Health & Safety Act

-Applicable regulations

Canadian Electrical Code

-Rule 2-306

http://www.osha.gov/as/opa/osha35yearmilestones.html

http://www.ieee.org/


What is NFPA 70E?

National Fire Protection Association

“Standard for Electrical Safety in the Workplace”

• Standard for electrical safety in United Sates

• “Harmonized” with CSA Z462


NFPA 70E

• In the United States in 1979 the National Fire Protection Association (NFPA) created what is now called: “NFPA 70E Standard for Electrical Safety in the Workplace.”

• This US standard has evolved over the last 25 years to become the North American Standard for electrical safe work practices.

• The new 2009 edition is harmonized with the Canadian electrical safety Standard CSA Z462.


What is CSA Standard Z462?

The standard for workplace electrical

safety in Canada.

“Harmonized” with NFPA 70E.


CSA Standard Z462 • A National Standard for workplace electrical

safety titled CSA Z462 Standard on Workplace Electrical Safety is currently available.

• It was developed in parallel with the 2009 Edition of NFPA 70E and is harmonize with NFPA 70E as much as practicable for Canadian workplaces.

• CSA Z462 was developed by a voluntary Technical Committee with stakeholders (industry, labour, government) from around the country.


CSA Standard Z462 addresses:

Electrical Safety Program

Arc Flash Hazard Analysis

– Flash Protection Boundary

– Fault Current Calculations

– Arc Fault Clearing Time

– Incident Energy Exposure

Required PPE


Institute of Electrical and Electronics Engineers

Offers a method for performing arc flash hazard calculations.

What is IEEE Standard 1584?

http://www.ieee.org/


EEE Standard 1584 • The IEEE, a non-profit organization, is a leading

professional association for the advancement of technology.

• The full name of the IEEE is the Institute of Electrical and Electronics Engineers, Inc., although the organization is referred to by the letters I-E-E-E and pronounced Eye-triple-E

• IEEE Standard 1584 “Guide to Performing Arc Flash Hazard Calculations” provides a method for determining the arc flash hazard distance and incident energy that workers may be exposed to from electrical equipment.

• The IEEE method is a different method (from NFPA 70E and CSAZ462) of conducting arc flash calculations.


What is CEC Rule 2-306?

Canadian Electrical Code

“Rule 2-306 Shock and Flash Protection”

A requirement for field-marking electrical

equipment to warn persons of potential

electric shock and arc flash hazards.


CEC Rule 2-306?

The Canadian Electrical Code (CEC) has a rule that improves safety for workers by

requiring special field marking of electrical equipment in the workplace to warn about:

1. Potential electric shock hazards, and

2. Arc flash hazards.

• The CEC is an installation code, so the responsibility for marking is with the installer.

• The rule is as follows:

– Rule 2-306 Shock and flash protection

(1)Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centres that are installed in other than dwelling units and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field marked to warn persons of potential electric shock and arc flash hazards.

(2)The marking referred to in Subrule (1) shall be located so that it is clearly visible to persons before examination, adjustment, servicing, or maintenance of the equipment.

• Generally, “field marked” means the equipment supplier does not have the responsibility to mark the equipment. The installer in the field would be required to provide the markings when the installation is done.

• This labeling is required for all new or modified installations after May 1, 2006.

• Labels only require providing a warning of the potential for shock and arc flash.

• The requirement to perform an analysis to determine energy incident levels does not come from this rule.


Arc Flash Hazard -- Construction

Safety Association of Ontario

Sample label that complies with CEC Rule 2-306.

Required Warning Label


Optional Warning Label


Protective Clothing and

Equipment

Flame-Resistant (FR) Clothing Protects a worker from receiving severe

burns if the worker is exposed to a flame.

Is self-extinguishing when the source of the

flame is removed.


PB/RH -- March 3, 2009 Arc Flash Hazards -- Construction


Flame-Resistant (FR) Clothing

Protects a worker from receiving severe

burns if the worker is exposed to a flame.

Is self-extinguishing when the source of the

flame is removed.


What is a Calorie?

A calorie is the amount of heat needed to raise

the temperature of one gram of water by 1°C.

Thermal energy is measured in calories/cm².

1.2 calories/cm² = Holding your finger

in the blue part of the

flame for one second.


Limit the ‘Incident Energy’ level of the

arc flash to 1.2 cal/cm² against the

worker’s chest.

Look for a label that states:

– 1506 approval (ASTM F1506)

– Arc rating of the garment.

All materials in the garment

should be FR Rated:

– Thread

– Buttons

– Insulation

– Zippers, etc.

FR Rated Clothing

Photo compliments of

Salisbury Electrical Safety L.L.C.


Arc Flash PPE Categories Category 0

Untreated Cotton

(Long Sleeve)

Untreated Cotton

Pants (Long)

Voltage Rated Gloves

Safety Glasses

Hard Hat

Category 1

FR Long Sleeve Shirt

Untreated Cotton Pants

(Long)

FR Pants (Long)

Safety Glasses


Hard Hat


Arc Flash PPE Categories

Category 2

Untreated Cotton T-Shirt

Untreated Cotton Shirt (Long

Sleeve)

FR Shirt (Long Sleeve)

Untreated Cotton Pants (Long)

FR Pants (Long)

Safety Glasses


Hard Hat

Double Layer Bee Keepers Hood



Category 3 Untreated Cotton T-Shirt

Untreated Cotton Shirt (Long Sleeve)



FR Pants (Long)


Safety Glasses

FR Hard Hat Liner

Hard Hat


Hearing Protection



Category 4 Untreated Cotton T-Shirt

Untreated Cotton Shirt (Long Sleeve)



FR Pants (Long)

FR Coveralls


Safety Glasses

FR Hard Hat Liner

Hard Hat


Hearing Protection




Typical PPE Requirements

Hazard/Risk

Category

Eye protection, ear canal

inserts, long sleeve shirt

and pants

Arc rated

clothing

Face & Head

Protection

Flash Suit

Hood

0

1

2

3

4


Typical Protective Clothing

Hazard/Risk

Category Clothing Description Required Minimum

Clothing Arc Rating

0 Non-melting, flammable material

with fabric weight of at least 4.5 oz/yd2

Not applicable

1 Arc-rated FR shirt + FR pants or FR coveralls 4 calories/cm²

2 Arc-rated FR shirt + FR pants or FR coveralls 8 calories/cm²

3 Arc-rated FR shirt + FR pants or FR coveralls,

and Arc-rated flash suit, the layered system

must meet the required minimum rating.

25 calories/cm²

4 Arc-rated FR shirt + FR pants or FR coveralls,

and Arc-rated flash suit, the layered system

must meet the required minimum rating.

40 calories/cm²


Synthetic Clothing

Synthetic clothing that melts shall not be

worn, such as:

– Acetate

– Nylon

– Polyester

– Polypropylene

– Spandex.




Arc Flash Rated PPE

Required minimum clothing:

– Non-melting, flammable material,

– Fabric weight of at least 4.5 oz/yd.

PPE must also provide

arc flash protection:

– Face shield

– Gloves, etc.




Increases level of protection.

May be lighter than a single

heavy garment.

Manufacturer must provide

the new combined arc rating

afforded by layering.

FR Clothing Can Be Layered




Tell the supplier that you need

arc flash rated PPE and clothing.

PPE must have some resistance to:

– Flame

– Ignition

– Melting.

obtain PPE from a known and

trusted supplier.

When Purchasing PPE

Not all FR clothing is tested to ASTM F1506




Tasks with Potential for Arc Flash

Operating a switch or circuit breaker

Inserting or removing a circuit breaker

Opening an enclosure door

Removing a cover (bolted or hinged)

Testing for voltage

In each task:

Worker is interacting with energized equipment.


Conduct a Flash Hazard Analysis to determine the

Flash Protection Boundary

Incident Energy exposure

Type and arc rating of PPE

If work must be done on or near

energized electrical equipment,

identify the potential for arc flash.

Arc Flash Hazard Analysis


Reduce the fault clearing time.

Reduce the short-circuit current.

Improve equipment maintenance.

CONTROLLING ARC FLASH HAZARDS

At the Source


Use flash-resistant equipment.


At the Source

These disconnect switch-plugs have been

designed with built-in flash-protection. Photos courtesy of Meltric Corporation




Increase the working distance.

Reduce the energy exposure.

Use hinged doors instead of bolted

doors to eliminate the risk of bolts

falling into the panel.

Work de-energized.


Along the Path


Energized electrical work permit

Barriers

Training and skills

Job briefings

PPE

Tools


At the Worker




Prevention Summary

1. Include Electrical Safety in your Occupational

Health and Safety Management Program.

2. Use an electrical work permit system.

3. Conduct regular equipment maintenance and label

equipment that poses a flash hazard.

4. Confirm single-line diagrams for accuracy and

available fault current.

5. Maintain documentation process.

6. Provide training and job briefings.

7. Conduct periodic safety audits.


Reference

Arc Flash Hazard - Construction Safety

Association of Ontario

Arc Flash Hazard and Protection - EWB

Engineering

Arc Flash Hazard - Progressive Business

Publications


Sistem Proteksi



Distribution System

Proteksi Generator

1

Proteksi Transformator

2

3

Pendahuluan

Trafo Instrumen 4

Perhitungan OCR 5


Pendahuluan

Listrik memiliki peran vital dan strategis, ketersediannya harus memnuhi aspek andal, aman dan akrab lingkungan.

Keandalan sistem tenaga listrik ditentukan oleh sistem dan konstruksi instalasi listrik yang memenuhi ketentuan dan persyaratan yang berlaku.

Keamanan sistem tenaga listrik ditentukan oleh sistem pengaman (protection system) yang baik, benar, andal atau tepat sesuai dengan kebutuhan sistem yang ada.


Pendahuluan

Pengertian/ definisi : Proteksi : perlindungan/ pengaman.

Sistem tenaga listrik : suatu sistem yang terdiri dari dari beberapa sub sistem, yaitu : pembangkitan (pembangkit tenaga listrik), penyaluran (transmisi), pendistribusian (distribusi) dan instalasi pemanfaatan.

Proteksi sistem tenaga listrik : perlindungan/ pengaman pembangkitan (pembangkit tenaga listrik), penyaluran (transmisi), pendistribusian (distribusi) dan instalasi pemanfaatan.


Pendahuluan

Dua fungsi utama proteksi, adalah : Mendeteksi adanya gangguan atau keadaan

abnormal lainnya pada bagian sistem yang diamankannya.

Melepaskan bagian sistem yang terganggu, sehingga bagian sistem lainnya yang tidak mengalami gangguan dapat terus beroperasi.


Pendahuluan Untuk pengaman sistem yang lebih kompleks, diperlukan komponen (alat) pengaman yang lebih lengkap (terdiri dari berbagai jenis alat pengaman), misalnya :

Relay pengaman, berfungsi sebagai elemen perasa yang mendeteksi adanya gangguan.

Pemutus Tenaga (PMT), berfungsi untuk pemutus arus dalam rangkaian listrik, untuk melepas bagian sistem yang terganggu.

Trafo arus dan/ atau trafo tegangan, berfungsi untuk meneruskan arus dan/ atau tegangan pada sirkit tenaga (sirkit primer) ke sirkit rele (sirkit sekunder).

Battery (Accu), berfungsi sebagai sumber tenaga untuk men-trip PMT atau catu daya untuk rele (static relay) dan rele bantu.


Kriteria Sistem Proteksi Kepekaan (sensitivity) :

Peralatan proteksi (rele) harus cukup peka dan mampu mendeteksi gangguan di kawasan pengamannya.

Meskipun gangguan yang terjadi hanya memberikan rangsangan yang sangat minim, peralatan pengaman (rele) harus mampu mendeteks secara baik.

Keandalan (reliability) : Dependability :

• Peralatan proteksi (rele) harus memiliki tingkat kepastian bekerja (dependability) yang tinggi.

• Peralatan proteksi (pengaman) harus memiliki keandalan tinggi (dapat mendeteksi dan melepaskan bagian yang terganggu), tidak boleh gagal bekerja.

Security : • Peralatan proteksi (pengaman) harus memiliki tingkat kepastian untuk tidak salah kerja

atau tingkat security (keamanannya) harus tinggi.

• Yang dimasksud salah kerja adalah kerja yang semestinya tidak kerja, misal : karena lokasi gangguan di luar kawasan pengamannya atau sama sekali tidak ada gangguan.

• Salah kerja bisa mengakibatkan terjadinya pemadaman, yang semestinya tidak perlu terjadi.


Kriteria Sistem Proteksi Selektifitas (selectivity) :

Peralatan proteksi (pengaman) harus cukup selektif dalam mengamankan sistem

Dapat memisahkan bagian sistem yang terganggu sekecil mungkin, yaitu hanya sub sistem yang terganggu saja yang memang menjadi kawasan pengaman utamanya

Rele harus mampu membedakan, apakah gangguan terletak di kawasan pengaman utamanya, dimana rele harus bekerja cepat, atau terletak di sub sistem berikutnya, dimana rele harus bekerja dengan waktu tunda atau tidak bekerja sama sekali.

Kecepatan (speed) : Peralatan proteksi (pengaman) harus mampu memisahkan sub

sistem yang mengalami gangguan secepat mungkin. Untuk menciptakan selektifitas yang baik, ada kemungkinan

suatu pengaman terpaksa diberi waktu tunda (time delay), tetapi waktu tunda tersebut harus secepat mungkin.

Dengan tingkat kecepatan yang baik, maka terjadinya kerusakan/ kerugian, dapat diperkecil.


PROTEKSI GENERATOR

1- 51V, backup overcurrent relay, pengendalian

tegangan atau kontrol tegangan

1-51G, backup ground time overcurrent relay

GENERATOR KECIL (sistem isolated) Daya: 500 s/d 1000 kVA tegangan 600 volt (maksimum)

3 - 51V, backup overcurrent relay, pengendalian

tegangan atau kontrol tegangan

1 -51G, backup ground time overcurrent relay

1 - 87, differential relay

1 - 32, reserve power relay untuk pengendalian

protection

1 – 40, impedance relay, untuk pengaman

kehilangan medan

GENERATOR SEDANG (sistem isolated/ paralel)

Daya: 500 s/d 12 500 kVA tegangan 600 volt (maksimum)


PROTEKSI GENERATOR

3 - 51V, backup overcurrent relay,

pengendalian tegangan atau kontrol tegangan

1 - 51G, backup ground time overcurrent

relay


1 - 32, reserve power relay untuk peng

endalian protection


kehilangan medan

1 – 46, Negative phase sequence over

current relay untuk protection kondisi unbalanced


PROTEKSI GENERATOR

3 - 51V, backup overcurrent relay,

pengendalian tegangan atau kontrol tegangan

1 -51G, backup ground time overcurrent

relay


1 – 87G, ground differential relay

1 - 32, reserve power relay untuk peng

endalian protection


kehilangan medan

1 – 46, Negative phase sequence over

current relay untuk protection kondisi unbalanced.

1 – 49, temp relay untuk monitor belitan

temp stator

1 – 64F, generator field relay, hanya untuk

mesin yg mempunyai medan supply slip rings

1 – 60, voltage balance relay


Pengaman Hubung Singkat

BUS GEN.

OCR

CT CB

GEN.

MCCB

Beban

Relai ini mengamankan generator dari beban lebih atau

gangguan hubung singkat.

PENGAMAN : OCR (51) -- untuk generator sedang dan besar

MCCB - - untuk generator kecil


Pengaman Tegangan Kurang

PENYEBAB:

Generator mengalami beban lebih

AVR generator mengalami kerusakan

BUS GEN.

UVR

PT

CB

GEN.

Beban

AKIBAT: Dapat merusak belitan rotor

Gangguan hubung singkat di sistem

PENGAMAN : UNDER VOLTAGE RELAY (27)


Pengaman Tegangan Lebih

Generator mengalami kapasitif.

AVR generator mengalami kerusakan bila berlanjut, merusak instalasi alat bantu di generator bisa rusak.

PENGAMAN : DEVICE NUMBER OVER VOLTAGE RELAY : 59

BUS GEN.

OVR

PT

CB

GEN.

Beban

PENYEBAB:

Lepas nya beban (Ppemb > P beban)

AKIBAT:

Frekwensi naik > 50 Hz.


Pengaman Stator ke Tanah

PENYEBAB:

Terjadi kebocoran isolasi di stator, sehingga terjadi gangguan hubung

Singkat fasa ketanah antara stator dan tanah

AKIBAT:

Kerusakan pada belitan stator

PENGAMAN: PENGAMAN ARUS LEBIH (51N)

BUS GEN.

OCR

CT

CB

GEN. Rn

TRF Beban

51N


Pengaman Daya Balik Prime

Mover

PENYEBAB:

PRIME-MOVER DARI SALAH SATU GENERATOR RUSAK , MENGAKIBATKAN GENERATOR TIDAK BERPUTAR. AKIBAT:

ADA PASOKAN LISTRIK DARI GENERATOR LAIN ATAU SISTEM SEHINGGA GENERATOR MENJADI MOTOR.

PENGAMAN -- REVERSE POWER (32)

BUS GEN.

GEN.

CT

PT

SISTEM

32

40


Pengaman Loss of Excitation

PENYEBAB: Hilangnya eksitasi

AKIBAT:

Daya reaktif balik dari sistem masuk ke generator,

atau generator menyerap var sistem

Memanaskan ujung belitan generator

BUS GEN.

GEN.

CT

PT

SISTEM

32

40

PENGAMAN -- LOSS OF EXCITATION (40)


Pengaman Temperatur

Generator

pembebanan melebihi kapasitas generator

kerusakan sistem pendingin

belitan generator bisa panas bisa merusak konduktor stator dan isolasi

antara belitan ke inti

AKIBAT:

PENGAMAN -- PENGAMAN TEMPERATUR (26)

PENYEBAB:

GEN.

RTD

CB

26


Pengaman Overspeed

gangguan pada sistem sehingga lepas beban

governor tidak mampu kembalikan put. normal

bisa terjadi vibrasi balancing pada put. tertentu

bisa rusakkan bearing dan shaft frekwensi naik

CB

SPEED SENSOR

GEN.

TRANSDUCER

MESIN.

PENYEBAB:

AKIBAT:

over speed

PENGAMAN : UNDER SPEED (81 – U)

OVER SPEED (81- O)


Pengaman Differensial

Generator

GANGGUAN PADA BELITAN GENERATOR

KERUSAKAN ISOLASI BELITAN GENERATOR

PENGAMAN: DIFFRENTIAL RELAY (87 G).

GEN. CB

DIFERENSIAL GENERATOR

SET

PENYEBAB:

AKIBAT:


Pengaman Beban Lebih

Arus beban melebihi nominal dan bertahan lama

DEVICE NUMBER OVER LOAD RELAY : 49

PENYEBAB:

BUS GEN.

OLR

CT CB

GEN.

BEBAN

AKIBAT:

Memanaskan belitan generator. merusak konduktor dan isolasi belitan

PENGAMAN :


Pengaman Temperatur

Generator

KETIDAK SEIMBANGAN ARUS FASA BEBAN

GEN. CB

NEG.SEQ FILTER

OCR

NEGATIVE SEQUENCE RELAY ( 46)

PENYEBAB:

AKIBAT:

MEMANAS KAN ROTOR GENERATOR BILA BERTAHAN LAMA

PENGAMAN :


PENGAMAN

TRANSFORMATOR Trafo tenaga diamankan dari berbagai macam gangguan, diantaranya

dengan peralatan proteksi (sesuai SPLN 52-1:1983) Bagian Satu, C) :

Relai Buchollz

Relai Jansen

Relai tangki tanah

Relai suhu

Relai diffrential

Relai beban lebih

Relai gangguan tanah terbatas

Rele arus hubung tanah


Relay Bucholz

Mengerjakan alarm (Bucholz 1st) pada kontak bagian atas 1.

Mengerjakan perintah trip ke PMT pada kontak bagian bawah 2.

Relai buchholz dipasang pada pipa dari maintank ke konservator ataupun dari

OLTC ke konservator tergantung design trafonya apakah di kedua pipa tersebut

dipasang relai bucholz.

Gunanya: untuk mengamankan trafo dari gangguan internal trafo yang menimbulkan

gas dimana gas tersebut timbul akibat adanya hubung singkat di dalam trafo

atau akibat busur di dalam trafo.

Cara kerja: yaitu gas yang timbul di dalam trafo akan mengalir melalui pipa dan

besarnya tekanan gas ini akan mengerjakan relai dalam 2 tahap yaitu:

1

2

KE CONSERVATOR

TANGKI TRAFO

PELAMPUNG

KRAN

TUAS ALARM

TUAS TRIP

ALARM

TRIP


Relay Bucholz

Analisa gas yang terkumpul di dalam relai Bucholz

H2 dan C2H2 menunjukkan adanya busur api pada minyak antara bagian-bagian

konstruksi.

H2, C2H2 dan CH4 menunjukkan adanya busur api sehingga isolasi phenol terurai,

misalnya terjadi gangguan pada sadapan.

H2, C2H4 dan C2H2 menunjukkan adanya pemanasan pada sambungan inti.

H2, C2H, CO2 dan C3H4

menunjukkan adanya pemanasan setempat pada lilitan inti.


Relay Jansen

Relai Jansen adalah relai untuk mengamankan transformator dari

gangguan di dalam tap changer yang menimbulkan gas. Dipasang pada pipa yang menuju conservator.

Cara Kerja Sama seperti relai bucholz tetapi hanya mempunyai

satu kontak untuk tripping.


Relay Sudden Pressure

Relai Sudden Pressure. Relai Pressure untuk tangki utama Trafo bekerja

apabila di dalam tangki Trafo terjadi kenaikan tekanan udara akibat terjadinya gangguan di dalam Trafo.

Tipe Membran

Plat tipis yang didisain sedemikian rupa yang akan pecah bila menerima tekanan melebihi disainnya. Membran ini hanya sekali pakai sehingga bila pecah harus diganti baru.

Pressure Relief Valve

Suatu katup yang ditekan oleh sebuah pegas yang didisain sedemikian rupa sehingga apabila terjadi tekanan di dalam transformator melebihi tekanan pegas maka akan membuka dan membuang tekanan keluar bersama-sama sebagian minyak.

Katup akan menutup kembali apabila tekanan di dalam transformator turun atau lebih kecil dari tekanan pegas.

Indikator trip

Reset Mekanis


Relay HV/LV Winding

Temperature

Urutan kerja relai suhu kumparan / winding ini dibagi 2 tahap:

Mengerjakan alarm (Winding Temperature Alarm)

Mengerjakan perintah trip ke PMT (Winding Temperature Trip)

Relai HV/LV Winding Temperature bekerja

apabila Suhu kumparan Trafo melebihi seting dari pada relai HV/LV Winding, besarnya kenaikan suhu adalah sebanding dengan faktor pembebanan dan suhu udara luar Trafo.

Relai HV/LV Oil Temperature bekerja apabila suhu minyak Trafo melebihi

seting dari pada relai HV/LV oil. Besarnya kenaikan suhu adalah sebanding dengan faktor pembebanan dan suhu udara luar Trafo.

Urutan kerja relai suhu minyak / oil ini dibagi 2 tahap:

Mengerjakan alarm (Oil Temperature Alarm).

Mengerjakan perintah trip ke PMT (Oil Temperature Trip).


Relay Arus Lebih (Over

Current Relay)

Relai ini berfungsi untuk mengamankan transformator terhadap gangguan

hubung singkat antar fasa didalam maupun diluar daerah pengaman

transformator.

Diharapkan Relai ini mempunyai sifat komplementer dengan Relai beban lebih.

Relai ini berfungsi pula sebagai pengaman cadangan bagi bagian instalasi

lainnya.


Relay Tangki Tanah

Berfungsi untuk mengamankan trafo terhadap hubung singkat antara fasa

dengan tangki trafo dan titik netral trafo yang ditanahkan.

F51G

Relai 51 G yang terpasang, mendeteksi arus gangguan dari tangki trafo

ketanah, kalau terjadi kebocoran isolasi dari belitan tarafo ke tangki, arus yang mengalir ke tanah akan dideteksi relai arus lebih melalui CT. Relai akan mentripkan PMT di kedua sisi (TT dan TM). Jadi arus gangguan kembali kesistem melalui pembumian trafo.


Restricted Earth Fault

Y

87N 87N

Relai gangguan tanah terbatas atau Restricted Earth Fault (REF) untuk

mengamankan transformator bila ada gangguan satu satu fasa ke tanah di dekat titik netral transformator yang tidak dirasakan oleh rele differensial.


Relay Differensial

PRINSIPNYA :

membandingkan arus yang masuk ke peralatan dengan arus yang keluar dari peralatan tersebut

PERALATAN IIN IOUT

Fungsi:

untuk mengamankan transformator terhadap gangguan hubung singkat yang terjadi didalam daerah pengaman transformator.

Cara Kerja:

Membandingkan antara arus yang masuk dengan arus yang keluar


DIFFERENSIAL SEBAGAI PENGAMAN TRAFO (lanjutan)

DALAM KEADAAN NORMAL ARAH IP DAN IS SEPERTI

PADA GAMBAR

DOT POLARITY

IP

iP

IS

iS

TRAFO TENAGA

DIFF. RY

CTP CTS

BEBAN

DISISI SEKUNDER MASING-MASING CT, ARUS KELUAR DARI TERMINAL DOT, SEHINGGA ARAH ARUSNYA :

KARENA IP SAMA BESAR IS TAPI ARAH BERLAWANAN MAKA DIFFERENSIAL RELAI TIDAK DILALIRI ARUS


DIFFERENSIAL SEBAGAI PENGAMAN TRAFO (lanjutan)

DALAM KEADAAN GANGGUAN

DOT POLARITY

IP

iP

TRAFO TENAGA

DIFF. RY

CTP CTS

BEBAN

ARAH IP SEPERTI PADA GAMBAR DAN HANYA IP

DISISI SEKUNDER CTP, ARUS iP KELUAR DARI

TERMINAL DOT, DAN MENGERJAKAN DIFF RY

PERHATIKAN : TERMINAL SEKUNDER CTP DAN CTS TERHUBUNG KE DIFF. RY DI FASA YANG BERLAWANAN ATAU BEDA SUDUT 180o


TRAFO INSTRUMEN

PERALATAN PENGUKURAN LISTRIK

kWh meter : untuk mengukur pemakaian energi listrik

kVAr meter : untuk mengukur pemakaian daya reaktif

Ampere meter : untuk mengukur arus

Volt meter : untuk mengukur tegangan

Watt meter : untuk mengukur pemakaian daya aktif

Cos meter : untuk mengukur power factor

PERALATAN PROTEKSI

Over Current Relay

Ground Fault Relay

Adalah trafo yang mana dipergunakan bersama dengan peralatan

lain seperti: relai proteksi, alat ukur atau rangkaian kontrol, yang

dihubungkan ke arus bolak balik

Trafo instrumen: current transformers dan voltage transformers.

Differential Relay

Distance Relay


Trafo Arus

DEMI KEAMANAN & KETELITIAN, TRAFO ARUS UNTUK :

• HARUS PUNYA KETELITIAN TINGGI PADA DAERAH ARUS PENGUKURAN BEBAN NOMINAL

• HARUS JENUH PADA ARUS GANGGUAN YANG BESAR, UNTUK KEAMANAN ALAT UKUR

PENGUKURAN

• HARUS PUNYA KETELITIAN / ERROR KECIL PADA DAERAH ARUS GANGGUAN HUBUNG SINGKAT BESAR

• TIDAK JENUH PADA ARUS GANGGUAN YANG BESAR, UNTUK KEANDALAN ALAT PROTEKSI

PROTEKSI


Trafo Arus

P1/K P2/L

IP

A

S2/l S1/k

IS

RANGKAIAN EKIVALEN CT

P1/K masuknya arus primer & P2/L keluaran arus primer S1/k masuknya arus sekunder dari primer dan S2/l keluaran arus sekunder Pembumian : pada S2/l -- sudut IP dan IS = 00 pada S1/k -- sudut IP dan IS = 1800


Trafo Arus

Kesalahan arus Perbedaan arus yang masuk disisi primer dengan arus disisi sekunder % = [(Kn Is - Ip)/Ip] x 100%

Kesalahan fasa Akibat pergeseran fasa antara arus sisi primer dengan arus sisi sekunder

Composite Error

c = 100/ Ip 100/T (Knis – ip)2 dt

is dan ip merupakan nilai arus sesaat sisi sekunder dan sisi primer.


Sesuai IEC 60044-1 spesifikasi class untuk CT:

Kelas ketelitian

+/- % kesalahan ratio arus pada % dari arus pengenal

+/- % pergeseran fase pada % dari arus pengenal , menit (centiradians)

5 20 100 120 5 20 100 120

0,1 0,4 0,2 0,1 0,1 15 8 5 5

0,2 0,75 0,35 0,2 0,2 30 15 10 10

0,5 1,5 0,75 0,5 0,5 90 45 30 30

1,0 3,0 1,5 1,0 1,0 180 90 60 60

Kelas ketelitian


+/- % pergeseran fase pada % dari arus pengenal , menit (centiradians)

1 5 20 100 120 1 5 20 100 120

0,2S 0,75 0,35 0,2 0,2 0,2 30 15 10 10 10

0,5S 1,5 0,75 0,5 0,5 0,5 90 45 30 30 30

Kelas ketelitian


50 100

3 3 3

5 5 5


TRAFO ARUS

MASING –MASING CLASS TRAFO ARUS

UNTUK PENGUKURAN

Untuk kebutuhan industri : CL2 or CL1

Untuk kWh meter di pelanggan : CL0.5

Untuk memperkecil kesalahan : CL0.2S

Untuk kebutuhan laboratorium : CL0.1

Akurasi burden pengenal:

Untuk kebutuhan instrument : CL3 or CL5

2,5 VA; 10 VA; 30 VA

5 VA ; 15 VA

7,5 VA ; 20 VA


Trafo Arus

CT Proteksi

CT Metering

IeXct

ES

Kurva CT untuk pengukuran

Kurva CT untuk proteksi

Knee point

Kurva magnetisasi CT


Trafo Tegangan

Trafo tegangan:

Instrumen trafo yang dipergunakan untuk memperkecil tegangan

tinggi ke tegangan rendah , dipergunakan untuk pengukuran atau

proteksi

Accuracy classes sesuai IEC 60044-2

Class Burden Voltage Ratio Phase Application

(%) (%) (%) displacement

(min)

0,1 25 - 100 80 - 120 0,1 5 laboratory

0,2 25 - 100 80 - 120 0,2 10 Precision and revenue metering

0,5 25 - 100 80 - 120 0,5 20 standard revenue metering industrial

1,0 25 - 100 80 - 120 1,0 40 grade meters intruments

3,0 25 - 100 80 - 120 3 -

3P 25 - 100 5-Vf 3,0 120 Protection

6P 25 - 100 5-Vf 6,0 240 Protection

Range Limit of Errors


Trafo Tegangan

Untuk pengukuran tegangan jatuh disisi sekunder 0,05 % s/d 0,1 % x

tegangan pengenal sekunder PT

Tegangan pengenal primer : kV (150 kV, 20 kV atau 150 kV/3 , 20 kV/3)

Tegangan pengenal sekunder: volt (110 V , 110 V atau 110 V/3 , 100 V/3)

R S T

Primer 20.000/3

Sekunder 100/3

s r t

Rangkaian ekivalen

Tipe trafo tegangan:

Inductive voltage transformers

Capacitive voltage transformers


Klasifikasi Trafo Tegangan

Jenis INDUKTIF (PT)

Terdiri dari belitan Primer dan belitan sekunder, Belitan

primer akan menginduksikannya ke belitan sekunder

melalui core.

Jenis KAPASITIF (CVT)

Terdiri dari rangkaian kondensor yang berfungsi sebagai

pembagi tegangan tinggi dari trafo pada tegangan

menengah yang menginduksikan tegangan ke belitan

sekunder melalui media capasitor.


Trafo Tegangan Induktif

7

6

5

1

2

3

4

8

Keterangan gambar:

1. Kertas/Isolasi Minyak Mineral/Quartz filling.

2. Belitan Primer: vernis ganda-isolasi kawat

tembaga, tahan pada suhu tinggi.

3. Inti: bukan orientasi listrik baja memperkecil

resiko resonansi besi

4. Belitan Sekunder

5. Isolator Keramik

6. Dehydrating Breather

7. Terminal Primer

8. Terminal Sekunder


1). HV.T adalah terminal tegangan tinggi

2) kapasitor C1 & C2 pembagi tegangan (capacitive voltage divider) yang berfungsi sebagai pembagi tegangan tinggi untuk diubah oleh trafo tegangan menjadi tegangan pengukuran yang lebih rendah

3). L0 adalah induktor penyesuai

tegangan (medium voltage choke) yang berfungsi untuk mengatur/menyesuaikan supaya tidak terjadi pergeseran fasa antara tegangan masukan (vi) dengan tegangan keluaran (vo) pada frekuensi dasar.

1

5

4

3 7

2

4) Belitan primer 5) Isolator keramik 7) Terminal sekunder


Kesalahan rasio trafo tegangan

Kesalahan besaran tegangan karena perbedaan rasio name plate dengan rasio sebenarnya dinyatakan dalam % = 100 (Kn Vs - Vp)/Vp

Composite Error

c = 100/ Vp 100/T (Knvs – vp)2 dt

vs dan vp merupakan nilai tegangan sesaat sisi sekunder dan sisi primer.


PERHITUNGAN OCR

IEEE Extremely Inverse

IEEE Very Inverse

IEEE Moderately Inverse

ANSI Standard


Grounding System



Introduction

From an electrical point of view, the world

is effectively a huge conductor at zero

potential and is used as a reference point

which is called ‘ earth ’ (in the UK) or ‘

ground ’ (in the USA).


The meaning

Earthing is a process that is used to connect all of the parts that could become charged, to the general mass of earth and in so doing, provide a path for fault currents which will hold these parts as close as possible to earth (i.e. zero) potential.

Earthing system is the electrical potential of the conductors relative to that of the earth’s conductive surface.


Electrical supply systems and equipment

are grounded in order to maintain the

voltage at any part of the system at a

known potential relative to true earth and

to provide a path for current flow under

earth fault conditions so that protective

devices operate correctly.


Ungrounded System

Power systems are always grounded

through the system capacitance, even if

the system neutral(s) is ungrounded.

Operate without a grounded conductor.

An ungrounded system does not have a

grounded (neutral) conductor routed

between the supply transformer and the

service equipment because the supply

transformer is not earth grounded.


Ungrounded System


Ungrounded System Advantage:

An ungrounded system can ride through the ground fault on one phase.

Disadvantage:

It can produce high transient line-to-ground overvoltages. The insulation system in rotating machines (motors and generators) is then severely stressed and can cause insulation breakdown.

The recommended solution to the above disadvantage is to add a resistor in the neutral, which will reduce potential phase-to-ground overvoltages


High Resistance Grounded System

Shall not be used unless they are provided with ground fault indicators or alarms, or both, and qualified personnel are available to quickly locate and eliminate such ground faults.

A high-impedance grounding system has a high-impedance unit, installed between the grounded (neutral) conductor and the grounding electrode conductor, which is used to regulate fault current.



For correctly installed, the following can be

concluded:

1. Suppresses transient overvoltage

caused by line-to-ground faults

2. Limited to systems with charging

current not exceeding 5.5 A

3. Not enough ground current for selective

relaying


High Resistance Grounded

System High-resistance grounding is

recommended for the following systems,

with the associated precautions listed:

1. Low-voltage systems with

predominantly three phase loads (Delta

or ungrounded Wye)

2. Medium-voltage systems up to 4.16 kV

where power interruption will be

detrimental to the process


Low-Resistance (LR) Grounded

System To protect power transformers and

generators from damaging fault currents

LR Grounding for Wye-Connected

System

In these systems, a resistor sized for and

rated at 100–400 A is connected to the

neutral of the transformer secondary

winding.



System LR Grounding for Wye-Connected

System



System LR Grounding for Delta-Connected System

The preferred arrangement is to use a three-phase zig-zag grounding transformer with a resistor connected to its neutral.

The short time rating of the zig-zag grounding transformer is the same as the resistor rating

the continuous rating shall be at least 10% of the available ground-fault current



System LR Grounding for Delta-Connected

System



System

Additional :

The neutral can shift to the system phase-to-ground voltage, and the first ground fault must be detected to remove the fault circuit from the system.

This grounding method suppresses the transient phase-to-ground overvoltages.

Selective ground-fault relaying is possible.

Burning damage at the point of fault is considerably reduced.

Requires that the cable insulation be 133%, as the ground fault is cleared quickly.



System

Recommended to be applied :

Where a network is extensive and

subsidiary switching stations exist, and

Where selective tripping is required to

achieve the objective level of service

reliability.

It is also appropriate for overhead line

feeders.


Solidly Grounded Neutral System

The neutral is solidly connected to ground, and hence the neutral is always at ground potential.

Having the following characteristic :

1. It eliminates transient phase-to-ground overvoltages during ground faults.

2. The first ground fault, due to the unrestricted operation of the ground-fault

3. protection, quickly removes the faulted circuit from operation.

4. Can cause extensive damage from arcing ground faults.


Solidly Grounded Neutral

System


Solidly Grounded Neutral

System The use of solidly grounded neutrals is

recommended for:

1. Low-voltage systems (three-phase, four-wire) when the majority of the load is connected between phase and neutral

2. HV, EHV, or UHV systems (above 34.5 kV) for better surge protection and for the application of lower BIL (basic insulation level) equipment, as the healthy phase voltages during faults are significantly reduced and lowerrated surge arrestors can be safely applied


Types of Earthing System



System classification

In order to identify the different systems, the IEE Regulations for Electrical Installations recognize the following designations of grounding systems using a two-, three- or four-letter code as follows:

The first letter indicates the type of supply earthing

The second letter indicates the earthing arrangement in the installation

The third and fourth letters indicate the arrangement of the earthed supply conductor system




The first letter

T indicates that one or more points of the supply are directly earthed (for example, the earthed neutral at the transformer);

I indicates either that the supply system is not earthed (at all) or that the earthing includes a deliberately inserted impedance, the purpose of which is to limit fault current.




The second letter

T indicates that all exposed conductive

metalwork is connected directly to earth;

N indicates that all exposed conductive

metalwork is connected directly to an

earthed supply conductor provided by the

electricity supply company.




The third and fourth letter

S – ensure that neutral and earth

conductor systems are quite separate;

C – ensure that neutral and earth are

combined into a single conductor.



TN systems



TN systems The integrity of the earthing of the installation

depends on a reliable and effective connection of the PEN or PE conductors to earth;

One or more points in the generator or transformer are connected to earth (usually the star point in a three-line system).

The body of the electrical device is then connected with earth via this earth connection at the transformer and exposed conductive parts of the installation are then connected to that point by protective conductors .



TN systems The conductor that connects together the

exposed metallic parts of the consumer installation is called the protective earth (PE),

The conductor that connects to the star point in a three-line system (or which carries the return current in a single-line system) is called the neutral (N)

There are three variants of TN systems: TN-C, TN-S and TN-C-S.



TN systems 1. TN-C system

is one where the neutral (N) and protective

earth (PE) functions are combined in a

single conductor throughout the system

and this combined neutral and earth wiring

is then used both by the supply and from

within the installation itself .



TN systems 1. TN-C system



TN systems 1. TN-C system (disadvantages)

RCDs (residual current devices) are far less likely to detect an insulation fault.

They are vulnerable to unwanted triggering caused by contact between earths of circuits, on different RCDs or with real ground.

Any connection between the combined neutral and earth core and the body of the earth could end up carrying significant current under normal conditions.

If there is a contact problem in the PEN conductor, then all parts of the earthing system beyond the break will rise to the potential of the live conductor(s).



TN systems 2. TN-S system

have separate protective earth (PE) and neutral (N) conductors from the transformer to the consuming device and these conductors remain separated throughout the system.

The TN-S is the most common earthing system in the UK and one where the electricity supply company provides an earth terminal at the incoming mains position



TN systems 2. TN-S system



TN systems

2. TN-S system

Advantages :

Concerns Electromagnetic Compatibility The consumer has a low-noise connection to earth and does not suffer from the voltage that appears on the neutral conductor as a result of the return currents and the impedance of that conductor

Save costs by having a fairly low-impedance earth connection near each consumer



TN systems

3. TN-C-S system

Is one that uses a combined PEN

conductor between the transformer and

the building distribution point substation

and the entry point into the building and

then splits up into separate PE and N lines

within the building to fixed indoor wiring

and flexible power cords

So, it will save the cost of an additional

conductor



TN systems

3. TN-C-S system



TN systems

3. TN-C-S system

The use of TN-C-S is not recommended for locations such as petrol stations etc., where there is a combination of lots of buried metalwork and explosive gases.

Owing to the possibility of a lost neutral, the use of TN-C-S supplies is banned for caravans and boats in the UK and it is often recommended to make outdoor wiring TT with a separate rod.



TT systems

Is one which has one point of the energy source directly earthed and the exposed conductive parts of the consumer’s installation are provided with a local connection to earth, independent of any earth connection at the generator.

TT systems (similar to TN-S systems) have a low-noise connection to earth, which is particularly important with some types of telecommunication and measurement equipment.



TT systems



TT systems

This type of installation is usually found in

rural locations where the system is not

provided with an earth terminal by the

electricity supply company and the

installation is fed from an overhead supply



IT systems

Is one which has no direct connection

between live parts and earth and where

the exposed conductive parts of the

electrical installation are earthed

The supply earthing in an IT system can

either be from an unearthed supply or one

which is connected to earth through a

current-limiting impedance.



IT systems



IT systems

This lack of earth will usually mean that

normal protective methods cannot be used

For this reason, IT systems are not

normally allowed in the UK public supply

system

Except for hospitals and other medical

locations where they are recommended for

use with circuits supplying medical

equipment intended for life-support of

patients.


References . . .

http://www.csanyigroup.com/grounded-or-

ungrounded-systems diakses 19-05-2013

jam 19.00 WIB

http://www.postglover.com/lowresistance.h

tml diakses 19-05-2013 jam 19.10 WIB

Shoaib Khan. 2007. Industrial Power

Systems. London & New York : CRC

Press & Taylor and Francis Group

Ray Tricker. 2008. Wiring Regulations in

Brief. UK: Elsevier Ltd

http://www.csanyigroup.com/grounded-or-ungrounded-systems








http://www.postglover.com/lowresistance.html



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