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Practical Work Report
24th November 2015 – 14th December 2015
Chung Yee Sim
Department of Electrical and Electronics Engineering
Employer: CSR Kuala Lumpur Maintenance
Address: EMU & ETS Maintenance Depot No.2, Sentul West, 51100 Kuala Lumpur,
Malaysia
Date of report written: 23rd
December 2015

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Summary
This report outlines the summer work experience of the author, Chung Yee Sim, an electrical and
electronics engineering undergraduate. The work took place in a train maintenance depot in
Sentul West, Kuala Lumpur, Malaysia. A total of 200 hours was spent maintaining the class 93
electrical train sets or EMUs. These trains were brought into service early 2012 by CSR Zhuzhou
Electric Locomotive Company Ltd of China. These trains serve Kuala Lumpur as one of the
main means of transport between KL central and Padang Besar (, the boarder of Thailand), as
well many other destinations. Chung has also spent time doing administrative and managerial
tasks which includes updating and analyzing data, and planning for the car sets to return for
inspection and maintenance.
A non-disclosure agreement between CSR Kuala Lumpur Maintenance and the author was made,
stating that no pictures of internal electronics and technical diagrams of company assets were
allowed to be taken. All photos included in this report are cleared by Li Meng, manager of the
engineering and quality control department. Simplified schematic diagrams included in this report
are drawn from the authors own understanding.
Sub Professional - UG Handbook:
Installation of lines, trunking systems, switchboards and machines; design, fabrication and
testing of electrical components; electrical draughting, computing; application of wiring
regulations, electrical safety

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Acknowledgements
The author would like to thank:
Juliet Choo, human resources senior executive. Juliet has given the author an excellent
opportunity to learn and improve. Li Bing, supervising engineer. Li Bing has given ongoing
support, guidance and understanding throughout the internship. Lastly, to all the staff and
colleagues, for their help and friendship.

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Contents
1.0 Introduction.......................................................................................................................... 5
2.0 Environment......................................................................................................................... 5
3.0 Staff...................................................................................................................................... 6
4.0 Description of EMU and maintenance................................................................................. 7
5.0 Description of Work on Site ................................................................................................ 8
5.1 Electrical System.............................................................................................................. 8
5.2 Bogie .............................................................................................................................. 10
6.0 Description of Work in Office ........................................................................................... 11
7.0 Reflective Appraisal........................................................................................................... 11
8.0 Conclusions........................................................................................................................ 11

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1.0 Introduction
CSR Kuala Lumpur Maintenance (CKM), was established in 2011. Its parent company is CSR
Zhuzhou Electric Locomotive Co. Ltd (ZELC), which is a sub-company of the organization China
South Rail (CSR) located in Beijing, China. CSR is the largest manufacturer in rail transportation
equipment and railway related solutions in Asia. Its products include railway locomotives,
coaches, wagons, electric multiple units (EMUs), and urban rail subway cars. CSR also has a huge
R&D department responsible for development of crucial electrical and mechanical components
for its products. CKM is responsible for the repair, management and maintenance of the CSR
infrastructure of railway transportation in Kuala Lumpur, Malaysia. CKM stands as a spearhead
for CSR, effectively conducting business in South-east Asia. The nature of the work Chung has
conducted throughout his internship is maintenance, repair and overhaul to the EMUs of the
Central KL to Padang Besar route.
The EMUs serviced by the author belong to the Ministry of Transportation and Kereta Tanah
Melayu Berhad (KTMB), the main rail operator in Peninsular Malaysia.
2.0 Environment
The CKM maintenance depot Chung was stationed at is located beside KTM Sentul Station. It is
a large hanger-like structure. When any of the EMUs are not in service, they are re-directed to the
maintenance depot from KTM Sentul Station. The EMU is docked into a special station where the
engineers and technicians can access the under frame and top of the EMU through special tracks
(known as pit lines) and over top access ways respectively. Proper footwear and headwear is
essential when entering the depot.
Figure 1 - SCS20 at pit line 4; offices can be seen at second floor at right side of the picture

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The building on the ground floor includes the valve testing room, motor repair room, facilities
room, technician’s office, component repair room and electronic device repair room. Above the
facilities room is where CKM office is located. The toilet is located between ZELC (after sales)
and CKM offices, which are accessible via the stairs located between the toilet on ground floor
and the facilities room. Figure 2 below shows the depot’s second floor layout from top view. CKM
office contains the Engineering and Quality Control (EQC) department.
3.0 Staff
There are no days when the rail system is not in service, thus the maintenance depot is always
operational with no days off, even on public holidays. This means that several groups of
maintenance teams are required to carry out inspections on EMUs every day. Five engineers from
the EQC department along with twenty-three technicians constituting each of the four maintenance
teams are on standby at a moment’s notice to inspect an EMU that comes into the depot. Most of
the technicians work for KTMB while all the EQC engineers work for CKM. This combination of
staff from two companies is due to the site, machinery and all the EMUs belonging to KTMB,
while CKM engineers are contracted to provide specialized expertise to KTMB technicians.
The author was assigned to a desk the EQC department. The EQC department provides engineers
to assist the technicians during the maintenance work. More often than not, complications do arise
due to unanticipated faults in electrical or mechanical equipment such as the traction control,
converters, transformers, and bogies. Solutions to these problems must be found quickly. However,
KTMB technicians are not qualified to make decisions regarding the solutions of these issues.
CKM EQC engineers are qualified to make propositions, however they must go through the chain
of command and be cleared by the KTMB office before work is carried out.
This interdependent relationship is harmonious most of the time, but occasionally there are
disputes between the KTMB staff and CKM engineers. Examples observed include CKM
proposing an optimum solution, however because of KTMB policy, monetary or time budgets, or
Figure 2 - Floor 2 of the maintenance depot

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simply misunderstandings between staff, the proposition is denied. Misunderstandings happen
mostly because of the language barrier, as KTMB staff speak the Indonesian native language,
Bahasa, while CKM staff speak Chinese and are semi-fluent in Bahasa.
4.0 Description of EMU and maintenance
There are two dozen EMUs owned by KTMB. Each EMU is known as a six car set (SCS) train.
This means that each EMU has six units connected end to end. There are two unit types – the trailer
unit and the motor unit. The trailer unit is where the passengers seating is located, it also contains
the main transformer and the pantograph connection between the train and the catenary wire. The
motor unit are found on either side of the four trailer units, for bi-directional travel. The motor
units contain the main converter and the driver’s cab. There are two bogies on each unit and each
bogie has two axels which supports two wheels. See section 5.2 for bogie overview.
Figure 3 - CKM staff hierarchy

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There are three tiers of inspections carried out on EMUs. Firstly, the daily inspection which
involves inspecting whether the screws are aligned to their locking marks and whether everything
is supposed to function as it should. Secondly, the weekly inspection, which is similar to the daily
inspection but is much more thorough in every aspect. Lastly, the monthly inspection involves all
aspects of a weekly inspection, however, with the addition of measurements and troubleshooting
of all electronics, apertures, and essential parts on every unit to ensure that they meet the safety
criteria of operation. Measurements involve measuring the wheel flange of the units, traction
systems, air conditioning systems, drivers control panel, converters, and transformers.
Furthermore, each time a monthly inspection is carried out, the carbon conductor layer of the
pantograph is replaced as it gets worn out during service. A monthly inspection can take upwards
of two days.
5.0 Description of Work on Site
Chung was assigned to Li Bing, one of the five maintenance engineers of the EQC department.
Each of the five engineers are specialized in maintaining a narrow area of an EMU. Li Bing is
specialized in maintaining the bogies.
On one occasion Chung followed an assistant technician Wei Jie to investigate and measure the
bogie’s wheel diameter and flange using a method known as wheel skimming. Wheel skimming
is an essential step in wheel inspection and repair and must be heavily scrutinized. Most monthly
wheel skimming events take place at Batu Gajah, where advanced machinery is available but
because of tight schedules, sometimes the wheel skimming events take place at Sentul depot,
where the machinery is around 20 years old. At Batu Gajah, the skimming is mostly automated
however with older equipment at Sentul depot, a KTMB operator must manually adjust and
measure the blade depth thus there is a higher chance of failure. Often when failures occur, due to
incompetent KTMB technicians who are severely under qualified, KTMB pushes the
responsibility to CKM.
Therefore, when issues regarding the bogies are too problematic, CKM collaborates with Careion,
a non-destructive testing (NDT) company. Careion NDT technicians are far more certified and
trained than KTMB technicians and they follow a strict set of regulations from IEC to ISO.
5.1 Electrical System
Figure 4 describes the top level description of the electrical system of each EMU. This system is
comprised of the catenary side circuit, main transformer and converter and traction motor. The
catenary wire, which supplies the EMU with power through the pantograph, is an exposed
conductor carrying 25kV AC. The pantograph is located at the rooftop of the trailer units and
receives the power and transfers it to the main transformer.

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There are four independent traction windings of main transformer which supplies power to four
quadrant rectifiers on each motor unit. These rectifiers then supply power to two voltage-mode
PWM inverters. Each traction inverter is controlled by a corresponding train control unit (TCU)
which independently supplies power to two asynchronous traction motors to realize independent
bogie-control. The main transformer also steps down voltage for other uses such as the air
conditioning of each car, main transformer oil pump (and fan) and sockets in the trailer units.
During one of the maintenance events, the pantograph wasn’t responding even though it was in
the risen state, Chung and other interns were tasked to help with the maintenance team to diagnose
the problem. Initially the Chung and his colleagues thought it was a mechanical problem, regarding
pantograph isolating valve, which isolates the pantograph gas circuit, since the pantographs
deployed on the trains are controlled pneumatically. However, after closer inspection, it was found
that the issue lies within the CCU (central control unit) of the TCMS (train control monitoring
system) that caused the HMI (human machine interface) to not display correctly. The CCU is a
microprocessor-based control unit which controls the entire vehicle via logic control and MVB
(multifunction vehicle bus) management. The senior supervising engineer on duty then made
arrangements to repair the problem shortly after the problem was diagnosed correctly.
Figure 4 - Electrical System of three car set

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Figure 5 - CCU troubleshooting
5.2 Bogie
The function of the bogie is to support the car-body, transfer load, enable the units to pass curves
successfully and is responsible for the physical manifestation of traction and braking. There are
two types of motor unit bogies, the difference between the two are the installation positions of the
axles, flange lubricators, location and quantity of leveling valves, and control level of air springs.
There are also two types of trailer bogies that are slightly different to the motor bogies however
they are also equipped with an APC antenna and are not equipped with motor and gear boxes.
Figure 6 - Underside view of trailer unit bogie

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5.2.1 Bogie replacement
One of the events the author observed is exchanging a damaged bogie in risk of derailment with a
healthy bogie from another damaged car set. The involved EMUs are placed on the same line so
the bogies can be exchanged easily. The KTMB operators on duty are responsible for removing
the bogie by disassembling the various parts of the bogie attached to the car body. Then with the
large mobile lifting jacks (which are the yellow stands that can be seen on the right side of Figure
1), the three car sets were lifted so the damaged bogie can be manually pushed out from under the
car sets. During this phase, the mobile lifting jacks did not synchronize, and the operation was
forced to halt, causing significant delay to the operation and taking an additional day to complete.
6.0 Description of Work in Office
Chung was also assigned to administrative and managerial tasks by Mr. Lim, project coordinator
of CKM in the EQC department. These tasks involve the collection of relevant data and records
from the engineers, such as recording damaged equipment, (e.g. MC2 left3 small window, and
fault PIS). Furthermore, careful planning of certain EMUs to return to the depot for maintenance
and repair was carried out. However, before the plan was executed, it must be acknowledged and
signed by the CKM depot control center. CKM does not coordinate with KTMB with
administrative tasks due to ineptitude of KTMB staff shown in the past. The plans are multi-level
and must account for delays, short and long, in order to cope with the uncertainty of maintenance
and repair. Delays are common due the number of technicians and pit lines available.
7.0 Reflective Appraisal
The first few days of learning were daunting, there were many responsibilities and many
unknowns. Learning quickly and strong memory retention were key in effective execution of work.
Though this knowledge seems only applicable to EMUs, it in fact fundamental and applies to
maintaining, leveling, and dealing with pneumatic systems (mechanical), additionally maintaining
power supplies and distribution (electrical) using control systems (embedded electronics). These
fundamentals are akin to most electrical and mechanical machinery in industries today.
Chung’s supervisor, Li Bing, graduated as a materials engineer, however is now designated as a
rolling stock and maintenance engineer, specializing in the bogie which requires mechanical
engineering knowledge. This is common behavior; career paths for engineers may not necessarily
relate to their respective studies. However, all engineering careers have a common underlying trait
– the mastery of systematic and analytical approach to problem solving, an excellent ability to
communicate effectively, and the desire and competency to acquire knowledge fast.
8.0 Conclusions
With 200 hours completed in 21 days, there was no time to waste. In this short period, the author
has learnt fundamental mechanical, electrical, embedded electronics, and maintenance theory

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along with communication skills, file keeping, organization and planning. The most valuable
lesson is effective communication. When communication is sound, everyone knows their job and
the organization works as a well-coordinated team. Once communication breaks down, so does the
work efficiency, issues and delays are likely to occur, everyone wants to blame each other and
plans are rarely completed.