INDUSTRIAL TRAINING REPORTATTENAGA NASIONAL BERHAD33KV
DISTRIBUTION, SELANGOR
BYTHIBAN RAAJ A/L SENTHILAN(EP086518)
DEPARMENT OF ELECTRICAL POWER ENGINEERINGUNIVERSITI TENAGA
NASIONALSTART DATE: 17/2/2014END DATE: 09/05/2014
THIBAN RAAJ A/L SENTHILAN(EP086518)DEPARMENT OF ELECTRICAL
POWER
CONTENTS OF REPORT
CHAPTER 1INTRODUCTION1.1 COMPANY NAME1.2 HISTORY OF TNB1.3
COMPANY PROFILE1.4 COMPANY VISION1.5 COMPANY MISSION
CHAPTER 2
TNB POWER SYSTEM
2.1 TNB GENERATION2.2 TNB TRANSMISSION2.3 TNB DISTRIBUTION2.3.1
PENCAWANG MASUK UTAMA2.3.2 PENCAWANG PEMBAHAGIAN UTAMA2.3.3 STESEN
SUIS UTAMA2.3.4 PENCAWANG ELETRIK
CHAPTER 3
WORK EXPERIENCE BASED ON DEPARTMENTS
3.1 PLANNING DEPARTMENT3.2 PROJECT DEPARTMENT3.3 SUBSTATION
MAINTENANCE DEPARTMENT3.4 CABLE MAINTENANCE DEPARTMENT3.5 OVERHEAD
LINE MAINTENANCE DEPARTMENT3.5 PROTECTION DEPARTMENT
CHAPTER 4
DISCUSSION AND CONCLUSIONAPPENDIX
1.6
ABSTRACT
This industrial training report is done as per requirement set
by University academic regulation for the completion of industrial
training and to present the knowledge gained in the 3 months we are
in the training. We were required to complete 3 months/12 weeks of
training at the company or organization we have chosen.The company
that I have joined for my internship is Tenaga Nasional Berhad, or
better known as TNB. TNB is the largest power utility company in
Malaysia and South East Asia, with MYR 99.03 billion worth of
assets. Tenaga Nasional Berhad is divided to several main
divisions, mainly TNB Generation, TNB Transmission and finally TNB
Distribution;which serves the end user customers. I applied to
undergo training at TNB Distribution office for the state of
Selangor. I was posted to the 33kV division of TNB Distribution.
TNB Distribution of also known as TNBD is divided to 2 main
division, 33kV and 11kV. TNBD 33kV deals with 33kV voltage which is
stepped down from 132kV supplied from TNB Transmission network.
Therefore, 33kV division is the first division to handle incoming
voltages from the Generation and Transmission. TNB D 11kV deals
with voltages from 11kV until 415V which is supplied to light
industries and home users.TNBD Selangor main office is situated at
ARAS 9, MENARA MRCB, NO. 2, JALAN MAJLIS 14/10, SEKSYEN 14, 40000
SHAH ALAM, SELANGOR and the Yard is situated at Seksyen 15, Shah
Alam. The TNB Yard operates as the store for equipments,vehicles
and for technical staff offices. These two places are the place
where I spent my 3 months of training , with most of the time, I
would follow the technical team to site projects or some days where
I will drive myself to the site if it is nearby or late at
night.Safety is the main priority in TNB and in the first day of
site visitation, I was given a new safety helmet and TNB safety
vest to be wore at every site that I go. During the training, I was
joined by another trainee from UNITEN, named Nurul who is also
posted to TNBD Selangor. We both would go to the same site visit
and projects.
Figure 1 Technician and myself in cable pit. Example of safety
helmet and safety vest
The training schedule provided to me was comprehensive and
complete, as I was posted to all the department in 33kV division.
There are 5 department and 3 sub-department as shown below; The
departments in TNBD 33kV are depended on each other to ensure a
smooth and safe operations of electricity supply to customers and
reduce downtime and complains rate. Tagging along the technical
team showed me the tough job in providing uninterrupted power
supply to our customers. We had to go through jungles, mud, heavy
traffic and late nights to ensure TNB customers can enjoy the ease
of life electricity has given us. During this time, I have learned
good work ethics and team work among the staffs.
CHAPTER 1INTRODUCTION TO THE COMPANY
1.1 COMPANY NAME
The name of the company is Tenaga Nasional Berhad or better
known as TNB. There are several sub companies under TNB and the
subcompany I am interning is the TNB Distribution 33kV
Selangor.
1.2 HISTORY OF TNB
On 22 June 1965, Central Electricity Board (CEB) of the
Federation of Malaya was renamed as the National Electricity Board
of the States of Malaya (NEB). Committed to long term programme of
growth and expansion backed by plans carefully crafted and laid
down in the period of CEB, NEB is now firmly led by a Malaysian as
the CEO.The National Grid was one of the plans in full motion. The
National Grid or Grid Nasional in Malay is the primary electricity
transmission network linking the electricity generation,
transmission, distribution and consumption in Malaysia. Electricity
generating plants are strategically located at Paka in Terengganu,
Temengor, Kenering, Bersia and Batang Padang in Perak, Connaught
Bridge, Kapar and Serdang in Selangor, Cameron Highlands in Pahang,
Prai in Penang, Port Dickson in Negeri Sembilan, Pergau in
Kelantan, Pasir Gudang in Johor and in Malacca.The central area
network with Connaught Bridge Power Station in Klang was the
precursor of the energy grid; it also tapped into the Cameron
Highlands Hydro scheme from the Sultan Yussuf Power Station, and
was extended into a western network.Later in the 1980s, the loop
was finally complete; it prevailed over some of the most formidable
terrain in the northern Peninsula, and Kota Bahru was successfully
placed within the grid.The National Grid is also interconnected to
the transmission network of the Electricity Generating Authority of
Thailand (EGAT) through a 117 MVA, 132 kV Single Circuit Line,
which has since been upgraded to a HVCD line. The Grid is connected
to Singapore Power Limited (SP) through a capacity of 250 MVA 230
kV transmission lines and submarine cables. These significant
connections provided us the first evidence of rudimentary ASEAN
grid on the map.Plants within the Grid form a power bloc governed
by technological alliances and careful arrangements to further the
common good for all. The National Load Despatch Centre made active
communications possible in order to identify the needs of the
community we serve.
Keeping the nation's interest in mind, the government
relentlessly pursued its ultimate objective and two pieces of
legislation were passed to replace the existing Electricity Act,
and to provide for the establishment of a new corporation TENAGA
NASIONAL BERHAD (TNB), purposefully replacing the NEB (Successor
Company Act). Datuk Hj. Ibak bin Abu Hussein became the last Deputy
Chairman and General Manager of the NEB and the first Managing
Director of TNB.
On 1 September 1990, Prime Minister Dato Seri Dr. Mahathir bin
Mohamad officially proclaimed TNB as the heir and successor to NEB.
TNB became a private company wholly-owned by the government; on the
same day, Tan Sri Dato Haji (Dr) Ani bin Arope was appointed
Chairman.1.3 COMPANY PROFILETenaga Nasional Berhad (TNB) is the
largest electricity utility in Malaysia and a leading utility
company in Asia. Listed on the Main Board of Bursa Malaysia with
almost RM87 billion in assets, the Companys more than 33,500
employees serve an estimated 8.3 million customers in Peninsular
Malaysia, Sabah and Labuan. TNB has been Keeping the Lights On in
Malaysia ever since it was set up as the Central Electricity Board
in 1949, powering national development via the provision of
reliable and efficient electricity.TNBs core businesses are in the
generation, transmission and distribution of electricity. In
Peninsular Malaysia, the Company supplies households and industry
with electricity generated from six thermal stations and three
major hydroelectric schemes. It also manages and operates the
National Grid which links TNB power stations and IPPs to the
distribution network. The grid is connected to Thailands
transmission system in the north and Singapores transmission system
in the south. In East Malaysia, TNB has an 80% equity in Sabah
Electricity Sdn. Bhd. (SESB), which manages the Sabah Grid.Other
than its core business, TNB has diversified into the manufacture of
transformers, high voltage switchgears and cables; the provision of
professional consultancy services; and architectural, civil,
electrical engineering works and services, repair and maintenance.
The Company also engages in research and development, property
development and management services. Tapping into opportunities
available overseas, TNB is making inroads into emerging markets,
focusing on the Asia-Pacific, Middle East and North Africa
regions.In 2005, the Company embarked on a 20-Year Strategic Plan
with the ultimate objective of transforming into a world-class
player by the year 2025. To support this vision, TNB invests
significantly in the continuous professional development of its
employees through structured programmes. There is also renewed
emphasis on sustainability, both of the organisation and of the
Malaysian environment. The Strategic Plan entails greater focus on
green initiatives such as the development of renewable sources of
fuel, and more effective demand side management via energy
efficiency, thus complementing the Governments carbon reduction
agenda.As a leading Government-linked company, TNB also places
strong emphasis on its social responsibilities. Through its
foundation Yayasan Tenaga Nasional (YTN), established in 1993, the
Company runs numerous CSR programmes that benefit the
underprivileged. Among its many successful social outreach
programmes are those that education via scholarships and better
health for all.1.4 COMPANY VISION"To Be Among the Leading
Corporations in Energy and Related Businesses Globally"1.5 COMPANY
MISSION"We Are Committed to Excellence in Our Products and
Services"
CHAPTER 2TNB ELECTRICAL POWER SYSTEM
Figure 2 General view of TNB Electrical System2.1 TNB
GENERATIONGeneration station is the main source in TNB for generate
electricity. The Generation division owns and operatesthermalassets
and hydroelectric generation schemes in Peninsular Malaysia and it
has a generation capacity of 11,296 MW.2.1.1 TNB GENERATION POWER
STATIONS2.1.1.1 HYDROPOWERED POWER PLANTSSungai Perak hydroelectric
schemes, with 649 MW installed capacity: Sultan Azlan Shah Bersia
Power Station72 MW Chenderoh Power Station40.5 MW Sultan Azlan Shah
Kenering Power Station120 MW Sungai Piah Upper Power Station14.6 MW
Sungai Piah Lower Power Station54 MW Temenggor Power Station348
MWSungai Terengganu hydroelectric scheme, with 400 MW installed
capacity: Sultan Mahmud Power Station400 MWSungai Pergau
hydroelectric scheme, with 600MW installed capacity: Sultan Ismail
Petra Power StationPergau Dam600MWCameron Highlands hydroelectric
scheme, with 262 MW installed capacity: Sultan Yusof Jor Power
Station100 MW Sultan idris Woh Power Station150 MW Odak Power
Station4.2 MW Habu Power Station5.5 MW Kampong Raja Power
Station0.8 MW Kampong Terla Power Station0.5 MW Robinson Falls
Power Station0.9 MWIndependent hydroelectric schemes Sg Kenerong
Small Hydro Power Station inKelantanat Sungai Kenerong, 20 MW owned
by Musteq Hydro Sdn Bhd, a subsidiary ofEden Inc Berhad
2.1.1.2 GAS FIRED POWER PLANTS Connaught Bridge Power Station
Genting Sanyen Kuala Langat Power Plant Karambunai Power Station
Lumut GB3 Power Station Lumut Power Station Nur Generation Plants
Paka power station Pasir Gudang power station Petronas Gas
Centralized Utilities Facilities (CUF) Port Dickson Power Station
Prai power station Putrajaya Power Station Sarawak Power Generation
Plant Sepanggar Bay Power Plant Sultan Iskandar Power Station
Sultan Ismail Power Station Tanjung Kling Power Station Telok Gong
Power Station 1 Telok Gong Power Station 2 Teknologi Tenaga Perlis
Consortium Tuanku Jaafar Power Station2.1.1.3 COAL FIRED POWER
PLANTS Jimah Power Station Manjung Power Station PPLS Power
Generation Plant Sejingkat Power Corporation Plant Sultan
Salahuddin Abdul Aziz Shah Power Station Tanjung Bin Power
Station
2.1.1.4 OIL FIRED POWER PLANTS Gelugor Power StationPenang at
Teluk Ewa Melawa Power StationSabah in Melawa Sandakan Power
Corporation PlantSabah at Sandakan Stratavest Power StationSabah at
Sandakan Tawau Power PlantSabah at Tawau
2.2 TNB TRANSMISSION
TNB has transmission including theNational Gridwhich is
energized at 132, 275 and 500kilovolt(kV), with its
tallestelectricity pylonin Malaysia and the National Grid is linked
via 132 kV HVAC and 300 kV HVDC interconnection to Thailand and 230
kV cables to Singapore. More than 420[4]transmission substationsin
the Peninsular are linked together by approximately 11,000km[5]of
transmission lines operating at 132, 275 and 500kilovolts(kV). The
500 kV transmission system is the single largest transmission
system to be ever developed in Malaysia. Begun in 1995, Phase 1
involved the design and construction of the 500kV overhead
transmission lines fromGurun,Kedahin the North along the west coast
toKapar, in the central region and fromPasir GudangtoYong Pengin
the south of Peninsular Malaysia.The total distance covered for the
500 kV transmission lines is 522km and the 275 kV portion is 73km.
Of the lines constructed, only the Bukit Tarek to Kapar sections
had been energized at 500 kV. The remaining lines are presently
energized at 275 kV. Later, in order to cater for the additional
power transmission requirements from the 2,100megawatt(MW)Manjung
Power Station, the 500 kV system was extended fromBukit TarektoAir
Tawarand from Air Tawar to Manjung Power Station. In 2006, the 500
kV lines betweenBukit BatuandTanjung Binwere commissioned to carry
the power generated by the 2,100 MWTanjung Bin Power Station.
2.3 TNB DISTRIBUTIONThe Distribution division conducts the
distribution network operations and electricity retail operations
of TNB. The division plans, constructs, operates, performs repairs
and maintenance and manages the assets of the 33 kV, 22 kV, 11 kV,
6.6 kV and 415/240 volt in the Peninsular Malaysia distribution
network. To conduct itselectricity retailingbusiness, it operates a
network of state and area offices to purchase electricity from
embedded generators, market and sell electricity, connect new
supply, provide counter services, collectrevenues, operate call
management centers, provide supply restoration services, and
implements customer and government relationshipsThe substations
under the governance of TNB Distribution is the PMU-Pencawang Masuk
Utama , PPU- Pencawang Pembahagian Utama, SSU-Stesen Suis Utama,
PE-Pencawang Eletrik and feeder pillars.
2.3.1 PENCAWANG MASUK UTAMAPencawang Masuk Utama is the
interconnection point of 132kV or 275kV to the distribution
network. The standard transmission capacity and voltage
transformation provided at the PMU are as follows:-
- 132/33kV, 2 x 90 MVA- 132 /11 kV, 2 x 30 MVA
Figure 3 90MVA Step Down TX
Figure 4 30MVA Step Down TX
2.3.2 PENCAWANG PEMBAHAGIAN UTAMAMain Distribution Sub-station
is normally applicable to 33kV for interconnecting 33kV networks
with 11 kV networks. It provides capacity injection into 11 kV
network through a standardized transformation of 33/11 kV.
2.3.3 STESEN SUIS UTAMASSU at 33kV, 22kV and 11 kV are
established to serve the following function:-1. To supply a
dedicated bulk consumer ( 33kV, 22kV, 11 kV)2. To provide bulk
capacity injection or transfer from a PMU/PPU to a load center for
further localized distribution.
2.3.4 PENCAWANG ELEKTRIKDistribution sub-stations are capacity
injection points from 11 kV, 22kV and sometimes 33kV systems to the
low voltage network (415V, 240V). Typical capacity ratings are
1000kVA, 750kVA, 500kVA and 300kVA.
Conventional substation designs are of indoor type (equipment
housed in a permanent building) and out-door type (ground-mounted
or pole-mounted). Standardized M & E design of 11/. 433kV
sub-station is available at TNB offices. Compact substation (11 /.
415kV) has limited application and is to be strictly applied in
selective situations under the following circumstances:-
System reinforcement projects for highly built-up areas where
substation land is difficult to acquire. Any request to use compact
substation for dedicated supply to a single or limited group of low
voltage consumers is subject to TNB approval in accordance to site
constraints situation, and to be considered as special feature
design schemes.
Figure 5 Standalone Substation
Figure 6 Pole Mounted Substation CHAPTER 3
WORK EXPERIENCE BASED ON DEPARTMENTS
3.1 PLANNING DEPARTMENTPlanning department is the first
department I was posted to during the training period. The planning
department is responsible in planning out the entire TNB system in
the region they are in control. Application for new power supply to
new housing or industrial projects are forwarded to this department
for consideration and feasibility. Ms.Kumutha is one of the
engineer in Planning Department. She taught me and my intern
partner, Nurul valuable lesson of Planning Guidelines and
Distribution Code for TNB system planning. This department handles
a lot of guidelines and law in creating the perfect and stable
system for the applicants before approval is given. Many meetings
will be held before a project approval is given. Other than
planning system for new applications, Planning Department also does
Planning Cycle study at 33kV system. It is done to accommodate
changes to the 33kV system.3.1.1 SINGLE LINE DIAGRAM Single line
diagram are mostly used to visualize the complex detailed drawing
of TNB system map. It simplifies the map to a manageable size to
see where and which substation are connected to each other.
Planning engineers should be good in reading and making a single
line diagram to assess the stability of the system. I was tasked to
do a single line diagram based on a system map given by my engineer
on the Puchong area. I was given the detailed plan of the Puchong
area system map and asked to convert it into SLD.
Figure 7 Detailed System Map of Puchong
The blue lines represents the existing cables that are between
these substations and the green lines represents the cables that
are planned to be connected between these stations. The reason of
using multiple cables are to carry more load between stations and
ensure less fault time.3.1.2 NTL (NON TRANSFERABLE LOAD) AND
BOTTLENECKBottleneck are a situation where required amount of power
ie.MW could not be supplied to a substation during outage. The
causes of bottleneck is mainly due to cables used are not in the
same type or the load is more than what the cable could carry. TNB
uses XLPE,630mmp , Aluminium 1 core cable. The maximum load
carrying capacity of this XLPE cable is 30MVA,equivalent to 27MW at
0.9power factor. In some area in other states, there are cables
which are the Copper core cables. Copper core cables are the cables
laid during the 1970s and now discontinued. Bottleneck can occurs
in circuits utilizing this 2 type of cables in the same circuit
because Copper core cables can carry 42.5MVA,a significantly higher
load then Aluminium XLPE cable.
In the figure above we can see a simple Single Line Diagram
representing an electrical circuit. 2 PMUs and 2 PPU are connected
together with Aluminium cables with one NOP( normally off point )
between the 2 PPU. NOP are switch point which are usually in open
position during normal operation. In the event of shutdown or
breakdown in either PPU, this NOP will be closed to join PMU A and
PPU 1 to take care of loads in PPU 2.CASE STUDY
PMU A is connected to PPU 1 which has a load of 20MW with a
single Aluminum cable.PMU B is connected to PPU 2 which has load of
20MW with a single Copper cable.CASE 1
Cable connecting PMU A and PPU 1 has been broken. NOP must be
closed to bring supply from PPU 2. PPU 2 is connected to the PMU B
via a Copper cable which can carry 42.5MVA load which is far higher
than the combined load of 40MW. Therefore bottleneck does not
occur.
CASE 2
Cable connecting PMU B and PPU2 has been broken and NOP has been
closed to ensure continuous supply. However PMU A and PPU 2 cannot
handle the total load of 40MW because this circuit is using an
Aluminum cable which is only rated until 27MW load. Therefore 13MW
of load cannot be supported by the PPU 2.This kind of bottleneck
will increase fault and tripping in the circuit as many PPU might
not be able to support the increase of load above its rated usage.
If similar type of cables are used in the circuit, the Planning
Department can accurately find out high load area and approved the
installation of more cables to connect the substations together to
ensure system stability.Most of the PPU and PMU are connected via 2
cables running parrallel carrying 50% of load each to reduce this
bottleneck and downtime problem. In the case of one cable going
faulty, the 2nd cable can automatically carry full load of 27MW to
continue supplying power.
3.1.3 PLANNING CYCLEPlanning cycle is an annual exercise carried
out by the Planning Department to foresee and forecast the load
requirement of the existing system and making adjustments to
accommodate any changes that might occur. STEP 1-LOAD
FORECASTINGUsing historical data of Electrical Sales in Selangor
since 1994, we come up a trend line to see how the electrical
growth is going to be and we will forecast for 20 years of
development. A software called Forecast Pro is used to find out the
percentage of growth in the area the forecasting is carried out.
STEP 2 LOAD DISAGGREGATIONAfter finding out the percentage of load
growth, we model it into the current load of the area. Example :
Petaling Jaya. In 2014 , Petaling Jaya requires 1000MW of load for
a stable system. In Petaling Jaya alone ,we have 7 PMU with 2 x
90MVA transformers each. Lets take PMU A with 2 x 90MVA
transformers. PMU A 2014 --------------------70 MW 2015
---------------------72MW 2016 ---------------------74MW YEARLY
GROWTH
85MW
Every transformer in every TNB substations are loaded up to 50%
capacity only as standard practice. The reason for this practice is
that in an event of fault in one transformer, the 2nd transformer
can carry the full load and the station can continue supplying
power as usual. In this case, this PMU A can carry the load for
several years without needing any modification and staying at the
50% loading capacity limit.
3.1.4 33KV NETWORK
TNB Selangor employs n-1 network for most of its electrical
network. N-1 source network means if the is any fault in one
source,which is the PMU , the PPU can be supplied from another PMU,
ensuring a steady supply. N-1 feeder element means 2 cable
connecting the PPU and PMU. This n-1 network system is used to
reduce downtime caused by fault and for steady supply. In high risk
areas such as Putrajaya and KLIA, n-2 feeder element is used. N-2
feeder element has 2 cables carrying load parallel,ie if the load
is 10MW, each cable carries 5MW each so if there is any fault in
any cable, the second cable can start carrying the full load
automatically whereas in n-1 feeder element, an Authorised
Personnel has to go the substation to turn on the NOP and connect
the two PPUs together.A 33kV PPU usually has 2 transformers rated
at 30MVA each. Each transformers are loaded at 50 % capacity which
is known as firm capacity. Any loading above 50% is known as above
firm capacity and load desegregation exercise has to be carried out
by Planning Department to move the extra load to either a low
loading PPU or build a new PPU nearby to accommodate the extra
loading.33kv Network in Selangor utilizes 2-1-2 network which
complies to n-1 feeder element-cable backup and n-1 source-PMU
backup. All this system and exercise is in place to make sure the
customers receives uninterrupted power supply all day long.3.1.5 DC
SYSTEMIn a substation, DC system is used to supply DC voltages to
protection devices and support system in Switchgears, Control Panel
and Relay activation. 11kV substation uses 30V of DC voltage
whereas in 33kV substation uses 110V DC. The DC system is supplied
via a battery bank located inside the substation building to
support the DC system during power outage. A PPU has a battery bank
of 88 cells@ 1.25V each. The batteries are usually made off Lead
Acid or Nickel Cadmium cells.
3.1.6 DISTRIBUTION SUBSTATIONS
PMU 275/33/11KV , 132/33/11KV , 132/11KVPPU - 33/11KVPE
33KV/415V , 33KV/0.433V ,
3.2 PROJECT DEPARTMENTProject and Construction Department is the
department where new approved substations, underground cable
projects are carried out after approval from Planning Department is
given. These department are responsible for every new project TNB
carries out and must ensure all projects are down up to TNBs
standards. These department also deals with a lot of procedures and
laws to ensure a quality station is built and commissioned.3.2.1
PROCEDURES INVOLVED1. Project Implementation Report2. Prosidur
Proses Tender Projek 33kV3. Prosidur Proses Mesyuarat Kick-off4.
Prosidur Mendapatkan Kelulusan Lukisan dan Permit Mula Kerja5.
Prosidur Proses Factory Acceptance Test6. Prosidur Proses Kerja di
Tapak Bangunan7. Prosidur Proses Kerja di Tapak Pepasangan 33kV8.
Prosidur Sijil Pelepasan Pepasangan (Clearance Certificate)9.
Prosidur Pengeluaran Take Over Certificate ( TOC)10. Prosidur
Proses Completion Cert dan Pembayaran Wang Tahanan Akhir11.
Prosidur Mendapatkan Kelulusan Perubahan Harga12. Prosidur Proses
Pembayaran untuk Perkhidmatan dan Bekalan13. Prosidur Mendapatkan
Kelulusan Tambahan Masa14. Prosidur Proses Dokumen Tender Bahagian
Pentadbiran, Jabatan Perancangan dan Pembangunan Aset15. Prosidur
Proses Mesyuarat Pemantauan3.2.2 HOW PROJECT DEPARTMENT WORKS
In the work done by Project Department can be divided into 2
main jobs. One is cabling works and also substation works. Cabling
works is about laying new cables between an existing station to a
new one or adding new cables between 2 old stations to improve
bottlenecks. TNB utilizes 33kv XLPE Aluminum single core cables in
its system. The cables are laid in bundles of 3, the red phase,
blue phase and yellow phase. Pilot cables are also laid parallel to
the power cables. Pilot cables are communication cables that
connects 2 substations protection equipment to carry fault data.
Each cable drum has 500metres of XLPE cable. Pilot cable
For substation works, Project Department are tasked to build and
commission new PPU and P/E. PMU building and commissioning comes
under TNB Transmission therefore 33kV Project Planning is not
involved in PMU building. Project Department must install new
transformers, Switchgears, Low Voltage Distribution Box, Battery
Equipment for DC System and Control Panel Relay. Project Department
also has to carry out Installation and Commissioning Test with the
Substation Maintenance Department and building contractor to ensure
all equipment is installed and working as it should.3.2.3 MAJOR
EQUIPMENTS IN A SUBSTATION3.2.3.1 SWITCHGEARSwitchgear is a common
term used to describe a switching device and their combination with
associated control, measuring, protective and regulating equipment
with is accessories, enclosure and supporting structures.
Switchgear is a combination of two units of switches for the
incoming and outgoing feeders and also as circuit breaker for the
transformer feeders. Operations of the breakers are done via a
control panel remotely, or by operating handle manually. Current
switchgears fitted in TNB substation are SF6 gas insulated
switchgears or commonly known as GIS. There are also Vacuum Circuit
Breakers or known as VCB, Oil Circuit Breaker and also Gas circuit
breaker. Gas Insulated Switchgear can reduce the risk of arcing and
flashovers during switching as the process is done within the
confines of the switchgear enclosure. The same goes to the VCB
switchgear.
Figure 8 VCB Switchgears at PPU Setiawalk
Figure 9 Inside GIS Switchgear
Figure 10 Back of the SwitchgearCOMPONENTS IN SWITCHGEARI. Fuse
in transformer feederSwitch is capable to trip and isolate the
supply automatically during overload and fault conditions. In order
to trip and isolate, a medium voltage fuse is used to trigger the
tripping mechanism. The size of fuse depends on the ability of
transformer and incomer feeder voltage.II. InterlocksIt is is
prepared with mechanical interlocking facilities to ensure
safety.
III. IndicatorsEvery feeder to give indication if the every
phase of the feeder is live or not.IV. Gas GaugeThe level of gas in
gauge indicates whether enough level of SF6 is presentinside the
tank especially prior to operation of the switches.
FUSE RATING IN SWITCHGEAR
1. Pedestal11. Mechanism Front Cover2. Cable Clamp12. Ledge for
Voltage Indicator3. High Voltage Compartment13. HRC Fuse Tripping
Linkage(gas tight tank)14. Plug Fixing Bracket4. Cable Connection
Adapter15. Upper Fuse Plug 5. Bushing16. Fuse Cover6. Operating
Shaft Socket17. Lower Fuse Plug7. Position Indicator18. Interlocked
Front Cover8. Voltage Indicator9. Gas Pressure Gauge10. Lifting
Lug3.2.3.2 TRANSFORMERTransformer is a static piece of equipment
with two or more windings which by electromagnetic induction,
transfers alternating voltage (AC Voltage) from a primary coil
winding to a secondary coil winding. A transformer may be used as a
safe and efficientvoltage converter to change the AC voltage at its
input to a higher or lower voltage at its output without changing
the frequency. Other uses include current conversion, isolation
with or without changing voltage andimpedance conversion. An
alternatingelectric currentflowing through the primary winding
(coil) of a transformer generates a varying electromagnetic field
in its surroundings which induces a varyingmagnetic fluxin the core
of the transformer. The varying electromagnetic field in the
vicinity of the secondary winding induces anelectromotive forcein
the secondary winding, which appears as a voltageacross the output
terminals. If a load is connected across the secondary winding, a
current flows through the secondary winding drawing power from the
primary winding and its power source. Rated power is a conventional
value of apparent power indicating the capacity of the transformer
in kVA or MVA. In normal TNB Distribution substations, 2
transformers are usually utilised and rated at 7.5MVA , 15MVA,
30MVA, and 90MVA.
COMPONENTS AND TYPES OF TRANSFORMERSI. Hermitical Seal
Transformer
1. High Voltage Bushing 10. Low Voltage Bimetal Lug2.
Sampling/Drain Valve11. Low Voltage Bushing3. Jacking Pad12.
Top-Mounted Thermometer4. Corrugated Fin Wall5. Off Circuit Tap
Changer6. High Voltage Bimetal Lug7. Pressure Relief Device (PRD)8.
Oil Level Gauge9. Low Voltage Bushing Flag
Hermetically sealed type is more advantageous compared with the
conservator type transformer. The main advantage is that the oil is
not in contact with the atmosphere, thus avoiding absorption of
moisture and oxygen from the environment that can speed up the
degradation process of the insulation.II. Conservative Tank
Transformer
1. Cooling Radiator12.Main Conservator2. Main Tank13.OLTC
Conservator3. Motor Drive Unit (MDU)14.Pressure Relief Device
(PRD)4. Lifting Lug for Complete Unit15.CT Terminal Box5. High
Voltage Cable Box16.Local Control Panel (LCP)6. Oil Level
Indicator17.Inspection Vent7. Cable Box Breather18.Low Voltage
Cable Box8. Buchholz Relay19.Lifting Lug for Cover9. Cooling
Fan20.On Load Tap Changer (OLTC)10. Core Earth Box21.Top Cover11.
Air Leak Detector
Figure 11 30MVA Conservative Tank Transformer
Inside of the transformer, the coils are kept cool using
insulating fluid which is a mineral oil, called Hyrax oil. This oil
keeps the coils in normal operating temperature and reduces
electrical flashovers. The transformer also has to water and
moisture proof so silica gel is used to remove moisture from the
air that goes into the transformers and into the oil. New Silica
GelOld Silica Gel
TYPE OF COOLING SYSTEM IN TRANSFORMERS
Usually in the substation, ONAN cooling system are used in
transformers. It indicates oil natural air natural. The heated oil
circulates in the transformer tank by the principle of natural
convection and it is cooled by the natural air. Cooling fins and
radiators provide the means of increasing the area for heat
dissipation.
3.3 MAINTAINANCE UNIT SUBSTATIONAs the name suggests, TNB
Distribution 33kV has a maintenance unit that comprises maintains
its assets and equipment in proper working condition. This unit
ensures all switchgears and transformers are working in proper
condition. This substation maintenance unit is responsible in
making sure a substation is operating well. There are several
maintenance procedures such as Preventive Maintenance, Condition
Based Maintenance, Scheduled Shutdown and also Breakdown Shutdown.
Scheduled shutdown are usually half substation shutdown or one
transformer shutdown to do periodical maintenance whereas breakdown
shutdown are usually if there are any catastrophic failure to the
equipment such as fire or transformer fault which requires the
substation to go offline. Authorized Personnel or known as AP is
the main man in the technical part of this unit as he is the only
person who has the license or the rights to do switching to the
switchgears. AP has to do the switching in order for maintenance
work to be carried out in an orderly and safe manner. He has to
issue a Work Permit and carry out safety checks before handing over
to the technicians.
3.3.1 SWITCHING Every step of switching is very important and
must take it seriously. The switching steps are shown as below:1.
Before we do anything, we must write down all the switching
procedure clearly and explain to competent person (CP).2. Every
switching, authorize person (AP) must accompany by a CP because CP
will observe whether AP is doing the right procedure for switching.
3. AP must make sure inside the substation has enough lighting to
do switching.4. AP must ensure in front of switching panel has a
rubber map on floor for safety purpose.5. AP must wear personal
protective equipment (PPE) fully such as fire redundant suit,
glove, safety helmet with vessel and safety boots.6. AP have to
make sure and check all the tools are in good condition and fulfill
TNB standard and record down in a check list.7. AP must record down
every load reading before and after inside a log book for their
reference.8. Before switching, AP must check whether switch gear is
in good condition to do switching. Standard checking can be done
with checking SF6 gas gauge at the switch gear or checking whether
get ozone smells from the switch gear.9. Every switching activities
must come out with four important steps which are switch off, rank
out, prove dead and earth on.10. Phasing stick is used to prove the
system is dead. There are two types of phasing stick: Subtraction
phasing stick in phase will show 0V. Addition phasing stick in
phase will show 12.6V.11. Non-standard lock is need to lock at the
switch gear handle termination partial discharge spout (PDS) to
prevent anonymous people go and do dangerous switching. 12.
Precaution notice need to put on the non standard lock and written
person in charge and contact number.13. Dangerous notice needed to
put in front of work space to aware public on safety.14. Permit to
work (PTW) can be issued to contractor when the system is proven
dead and earth on.
PERSONAL PROTECTIVE AND IMPORTANT EQUIPMENT FIRE REDUNDANT
SUITSAFETY HELMET WITH VISOR
HAND GLOVE
FULL SUIT DURING SWITCHING
PHASING STICK
3.3.2 OLTC (ON LOAD TAP CHANGER) MAINTENANCEAtap changeris a
connection point selection mechanism along a
powertransformerwinding that allows a variable number of turns to
be selected in discrete steps. A transformer with a variable turns
ratio is produced, enabling steppedvoltageregulation of the output.
The tap selection may be made via an automatic or manualtap changer
mechanism. For many power transformer applications, a supply
interruption during a tap change is unacceptable, and the
transformer is often fitted with a more expensive and complex
on-load tap-changing (OLTC, sometimes LTC) mechanism. On-load tap
changers may be generally classified as either mechanical,
electronically assisted, or fully electronic.3.3.2.1 OLTC
MAINTENANCEOLTC maintenance is done in this following steps :
Transformer tap has to be changed manually to tap 9B or MR branded
tap changer or tap 9 for other brand of tap changer. These tap are
d maintenance tap and the diverter switch can be lifted out.
Draining the on-load tap changer oil from the diverter switch oil
compartment. Old mineral oil is removed from the tank and stored in
empty barrel Removing the diverter switch insert using the lifting
device. Performing maintenance on the diverter switch insert and
cleaning the diverter switch oil compartment. Diverter switch is
wiped clean off carbon and dirt. Installing the diverter insert
with the lifting device. Filling the diverter switch oil
compartment and the oil conservator with fresh oil. Hyrax oil is
used as the insulating oil Performing maintenance on the motor
drive, protective relay and drive shafts. Performing operational
checks and recommissioning.ON TOP OF TRANFORMER. DIVERTER SWITCH
CAN BE SEEN. MINERAL OIL HAS BEEN REMOVED
THIS MODEL OF TAP CHANGER IS SIDE LOADED. THIS IS A VERY OLD TAP
CHANGER AND DOESNT HAVE A REMOVABLE DIVERTER SWITCH
DIVERTER SWITCH REMOVED AND CLEANED
3.3.3 PREVENTIVE MAINTENANCEAs we have known earlier, preventive
maintenance is done to avoid major preventable fault from occurring
and ensure the system is stable and functioning well. Preventive
maintenance is done is a scheduled way where half busbar will be
shutdown to allow preventive maintenance to be carried out. Half
bus bar shutdown means one transformer is shut down and the load is
carried by the 2nd transformer, in line with the 50% load
requirement set by the Substation guidelines.3.3.3.1 CIRCUIT
BREAKER MAINTENANCECircuit breaker maintenance is done to remove
dusts and ensure all moving parts are moving freely. Switching is
done to isolate the breakers and circuit breakers are racked out.
WD40 lubricant is used prevalently and a cleaning solution is used
to wipe the dirt as water may cause moisture condensation in the
breaker and cause flashover.Cleaning the inside of the
busbarOpening the front over of 11kV Circuit Breaker truck
33kV Vacuum Circuit Breaker racked out
11kV circuit breaker with front cover removed
VCB NAME PLATE
3.3.4 CONDITION BASED MAINTENANCE (CBM)Condition-based
maintenance(CBM), shortly described, is maintenancewhen need
arises. This maintenance is performed after one or more indicators
show that equipment is going to fail or that equipment performance
is deteriorating.This concept is applicable to mission critical
systems that incorporateactive redundancyandfault reporting. It is
also applicable to non-mission critical systems that lack
redundancy and fault reporting.Condition-based maintenance was
introduced to try to maintain the correct equipment at the right
time. CBM is based on using real-time data to prioritize and
optimize maintenance resources. Observing the state of the system
is known ascondition monitoring. Such a system will determine the
equipment's health, and act only when maintenance is actually
necessary. Ideally condition-based maintenance will allow the
maintenance personnel to do only the right things, minimizing spare
parts cost, system downtime and time spent on maintenance.3.3.4.1
TECHNIQUES USED IN CBMTransformersThermography HotspotsOil analysis
-Oil condition & contentFrequency response analysis -Frequency
responseSurface conductivity measurement -Pollution levelCircuit
breakersThermography -HotspotsCoil current analysis (CCA) Coil
currentDynamic resistance measurement Dynamic resistanceSurface
conductivity measurement -Pollution level
Partial Discharge detection toolCircuit Breaker Timing Test
3.4 MAINTENANCE UNIT CABLE As the name suggests, Cable
maintenance unit deals with medium voltage underground cable
maintenance. Medium voltage underground cables are cables that
carries 33kV load from PMU to PPU and henceforth. This unit also
deals with breakdowns and repair works as cables are the main
lifeline in power transmission.3.4.1 TYPES OF CABLESTNB utilized
several types of underground cables in the past but currently in
the process of standardizing all cables to the same type to reduce
bottleneck in the power system. 33 kV, XLPE, single core, 630 mm2
Aluminium 11 kV, XLPE, single core, 500 mm2 Aluminium, with M16
bolts 11 kV, XLPE, three core, 240 mm2 Aluminium, with M12
boltsXLPE, is a form ofpolyethylenewithcross-links. It is formed
into tubing, and is used predominantly inbuilding services pipework
systems, hydronic radiant heating and cooling systems, domestic
water piping, andinsulationfor high tension (high voltage)
electrical cables.
CROSS SECTION OF A 630MM ALUMINIUM SINGLE CORE CABLE
3.4.2 CABLE LAYINGTNB underground cables are laid in trenches or
through HDD technique. 2 set of cables with red, yellow and blue
phase are laid together with pilot cable between them. The depth of
the cable pit are usually 6 feets.Pilot cable33kV cable
Concrete slabPower cable and pilot cable
Concrete slab indicating the cables are laid on top of the power
cables. The purpose of this slab is to avoid accidental damage
during excavation. Below the concrete slab, the cable pit is filled
with fine sand and on top of the slab with more fine sand and rocks
and finally sealed with premix tar.
3.4.3 JOINTS
Connector: Aluminum or Copper depending on conductor type. For
crimped type the size depends on conductor size whereas mechanical
type has range taking capability. Semi-conducting conductor shield:
Same function as conductor shield of cable. Insulation: Usually
EPDM (Ethylene Propylene Diene Monomer) rubber material and
silicone. Semi-conducting insulation shield: Same function as
insulation shield of cable. Metallic Shield: Breaded Copper Strip
or Copper stocking bonded with the main cable copper tape at both
ends. Outer Protection: Resin to protect joint body from mechanical
damage.3.4.4 CABLE FAULT DETECTIONCable fault are fault that occurs
at joints or on the cable itself. This type of faults required that
section of cable to be dug up and replaced. Joint fault requires
new joints to be done.Medium Voltage Cable joints dominant failure
modes identified by TNB Distribution Division are localized defect
caused by assembly error, localized defect caused by material
defect and insulation ageing. For terminations additional dominant
failure modes
identifiedbyTNBDistributionDivisionarelocalizeddefectcausedbyenvironmentalstresses,
localized defect caused by insulator tracking and insulation ageing
due to water penetration. Most of the above failure modes progress
slowly to deteriorate the condition of the joints and terminations
over time.3.4.4.1 DEVICES USED IN FAULT DETECTIONThe steps in a
correct approach for cable fault location are in the proper
sequence as follows: Analysis of fault Pre location Pin Pointing
Confirmation and re-test
The exact location of cables and conductors is an essential
aspect of modern cable fault finding and helps to save existing
cable networks from damage. Pin-pointing is the application of a
test that positively confirms the exact position of the fault.
Before the commencement of pin-pointing, the pre located fault
distance should be marked on the cable route which is measured by
means of a trumeter. The fault can be detected by the use of a
semisphone. This method is also known as thumping method as a
thumping sound can be heard at the fault location.
Fault detected
Fault marked
Fault found
Cable has been replaced and joint
3.5 MAINTENANCE UNIT OVERHEAD LINES Overhead maintenance unit is
responsible for medium voltage overhead lines that runs in the
interior parts of Selangor. Overhead lines are used in long lines
where underground cables are not feasible and too costly to
install. Places such as Kuala Selangor and Rawang has a lot of
overhead lines to carry supply to those areas. In some areas, 33kV
overhead lines run in parallel with 132kV TNB Transmission lines.
Cables used in overhead lines are bare aluminium 150mmp Silmalec
cables.
3.5.1 MAIN COMPONENTS OF OVERHEAD LINES Conductor which carries
electrical power from substations to another Supports which maybe
the poles or tower to keep the conductors in a suitable height. In
this case its poles. Insulators which are attached to support and
insulate the conductor from ground.
H-PoleLine Tensioner pole
These two type of poles are predominately used in TNB overhead
system. Conductor cables hangs from insulating dish and kept in
tension. These insulating dish are usually made of glass or ceramic
for its insulating properties.
3.5.2 AUTO RECLOSERAutorecloser, is acircuit breakerequipped
with a mechanism that can automatically close the breaker after it
has been opened due to afault.Reclosers are used on overhead
distribution systems to detect and interrupt momentary faults.
Since many short-circuits onoverhead linesclear themselves, a
recloser improves service continuity by automatically restoring
power to the line after a momentary fault. Two main brands used in
TNB is NuLec and Entec. Autorecloser comes with its own control
panel which can be operated remotely via SCADA.Auto Recloser
The control system for a recloser allows a selected number of
attempts to restore service after adjustable time delays. For
example a recloser may have 2 or 3 "fast" reclose operations with a
few seconds delay, then a longer delay and one reclose; if the last
attempt is not successful, the recloser will lock out and require
human intervention to reset. If the fault is a permanent fault
(downed wires, tree branches lying on the wires, etc.) the
autorecloser will exhaust its pre-programmed attempts to
re-energize the line and remain tripped off until manually
commanded to try again. About 80-90% of faults on overhead power
lines are transient and can be cured by autoreclosing.NuLec Control
Panel
Fault data is being downloaded to be analysed
3.6 PROTECTION UNITProtection unit is the unit responsible for
maintenance of control panels, relays, battery banks and other
power protection equipment inside of a substation. Protection
systems usually comprise five components: Currentandvoltage
transformersto step down the high voltages and currents of the
electrical power system to convenient levels for the relays to deal
with; Protective relaysto sense the fault and initiate a trip, or
disconnection, order; Circuit breakersto open/close the system
based on relay and autorecloser commands; Batteriesto provide power
in case of power disconnection in the system. Communication
channels to allow analysis of current and voltage at remote
terminals of a line and to allow remote tripping of equipment.TNB
utilizes a combination of analogue and digital relays for its
tripping circuit such as Over current earth fault, alarms and earth
faults. Protection Unit also carries out transformer ratio test to
ensure the tap changer is attached back properly after an OLTC
maintenance is done.
3.6.1 CONTROL PANELControl panels are essentially an enclosure
to mount relays and meter to monitor and remotely trip the
switchgears in cases of shut down or automatically due to fault.
Control panels also will indicate the source and type of fault that
has occurred so proper actions can be taken.
3.6.2 RELAYSProtective relayis a device designed to trip
acircuit breakerwhen a fault is detected. The first protective
relays were electromagnetic devices, relying on coils operating on
moving parts to provide detection of abnormal operating conditions
such as over-current, over-voltage, over- and under- frequency.
Microprocessor-based digital protection relays now emulate the
original devices, as well as providing types of protection and
supervision impractical with electromechanical relays.Over current
relayA digital over current relay is a type of protective relay
which operates when the load current exceeds a preset value. In a
typical application the over current relay is connected to a
current transformer and calibrated to operate at or above a
specific current level. When the relay operates, one or more
contacts will operate and energize to trip (open) a circuit
breaker. An analogue relay uses electromagnetic to activate the
coils to trip the circuit.
Analogue Relay
An overcurrent and earth fault relay test to ensure the required
tripping time is achieved
3.6.3 SCADAThe full form of SCADA system is Supervisory Control
and Data Acquisition. It is a concept used to describe a system
that enables control and monitoring of devices or equipment
remotely. SCADA system is used to assist the operation and
management of transmission and distribution of electricity. The
advantages of using SCADA system are optimization of plant
processes and provide operations that are more efficient, reliable
and safer. There are three main mechanism in SCADA system, master
system, communication system and remote terminal unit (RTU). The
flow of communication is like this, remote terminal unit is
collecting field data and sending data back to a master system via
a communication system. The master system is located in Regional
Control Centres (RCC). RCCs are located at Kuala Lumpur for
southern areas and Seberang Jaya for northern areas.
Master SystemMaster System is fundamentally a network of
computer subsystems with many functions to support the operation of
the SCADA based control centre. Master system consists of three
main subsystems, front-end subsystem, back-end subsystem and Human
Machine Interface (HMI) subsystem.
Function of Subsystems:I. Front-End Subsystem Receive data from
RTU then send it to back-end system Receive control requests from
back-end system and send it to RTUII. Back-End Subsysten processes
control commands received from (HMI), packages it and sends to
front-end subsystem processes data received from front-end
subsystem and sends to HMIIII. Human Machine Interface Subsystem
(HMI) processes controller commands and send to back-end subsystem
receives information from back-end subsystem and presents it
visually on monitorsCommunication SystemThe main function of
communication system is to transfer data between RCC and RTU. The
communication mediums as shown below:I. Fibre OpticsIV. GPRSII.
Pilot Cable V. RadioIII. Leased LinesVI. MicrowaveRemote Terminal
Unit (RTU)Generally the RTU is installed in a substation. The
function of RTU is to collect data from the remote station,
processes and executes control commands from the master system. RTU
can be classified into 2 types as shown below:I. RTU for SSU 33kV
RTU cubicle is Floor-Standing type DC supply is 110 VDC Generally
located in Control Room beside Supervisory Interface Panel
3.6.4 BATTERY BANK AND DC SYSTEMBattery is used as support to
supply station auxiliaries whenever station AC supply fails. It is
intended to supply for 5 hours during any station AC supply
blackout. It also serves as an extra DC source whenever the station
DC load requires supply more than what can be delivered by the
charger. While the charger is a tool that rectifies AC supply into
DC. It is to charge the standby battery bank during usual
operation. Battery banks and battery chargers should be well
maintained to make sure that the protection system functions
properly. DC system is required as the tools in the switchgears and
control relay panels run on 110V DC voltage. For a PMU, it needs 86
batteries and total 110V.
Battery charger
CHAPTER 4DISCUSSION AND CONCLUSIONInterning with TNB 33kV
Selangor, Ive learned the inner working of TNB and its systems, how
each and every unit works together to keep a stable power system.
As the largest power utility company in Malaysia, there is a lot of
stakes and consideration has to be taken when each actions are
done. Each unit has its own procedure on how the work is done so
consumers will not be affected by the works carried out. While in
TNB, Ive learnt as much as possible by tagging along the team and
also helping in some works as hands-on learning is the best
teacher.While in Substation Maintenance unit, I help out in OLTC
maintenance job, to clean the diverter switch, unscrew the cable
box and sorting out tools from the truck. I did help too in
Preventive Maintenance by opening up the front cover of the VCB
truck.While in Cable Maintenance unit, the biggest project or task
Ive been involved is fault tracing and replacement of cable at
Sunway Mentari. This job is carried out at night, approximately
10.00pm onwards and we walked the whole length of the cable to find
the fault location and also to dig out the faulty cable. Several
problem arose during this project where cable fault was misjudged
as one cable fault whereas the actual fault was on 3 cables.
Therefore my supervisor and I had to drive to TNB Main Store at
Rawang to get extra 40m of cables for replacement. While in
Overhead Maintenance unit, there was a major breakdown which lasted
1 week to recover. It was due to severe rain storm which caused
nearly 7 overhead poles to fall and power outage to occur. This
event took 1 week for the teams to rectify. They had to replace the
stay cables which are responsible in keeping the poles upright but
faced problems as groundwater fills up the dug pit. I liked
Overhead Maintenance as most of the job task is far as also in the
wilderness. Meanwhile in Protection Unit, my supervisor taught me
on how to reset a battery charger and change the battery charger
card. The battery charger was not supplying enough DC voltage to
the battery bank, therefore battery bank did not have enough power
to sustain and battery water is drying up too fast. Being in TNB
has taught me on how to be a good and diplomatic person as well as
an engineer. We have to be diplomatic with our staffs so they will
not feel pressured or feel hatred towards myself if I were to ask
them to do a job. Safety is also paramount in TNB as we deal with
deadly voltages that can kill. Therefore safety must be observed at
all time to avoid such disaster.
REFERENCES1. Buku Panduan Piawai Baru Rekabentuk Pencawang
Elektrik (Jenis Bangunan),Bahagian Pembahagian, TNB
2. Substation Design Manual, TNB Distribution
3. Electricity Supply Handbook, TNB
4. DISTRIBUTION SYSTEM PLANNING:PRINCIPLES ,CRITERIA
&METHODS,ISSUES & WAY FORWARD, Halim Osman,General
Manager,Asset Management,TNB Distribution- UNITEN ARSEPE 2008
5. XLPE Insulated Cables, Tenaga Cable Industries.
http://www.tcisb.com.my/XLPE%20Insulated%20Cables.pdf
6. Mechanical Design of Overhead
Lineshttp://www.nct-tech.edu.lk/Download/Technology%20Zone/Mechanical%20Design%20of%20Overhead%20Lines..pdf
APPENDIXTRANSFORMER RATIO TEST SHEET
OVERCURRENT AND EFI TEST SHEET
CBM REPORT SHEET