Engineering management

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Engineering Management
For
Power System
CASE STUDY ON OPTIMIZATION TECHNIQUES IN THE
OPERATION AND MANAGEMENT
HYDROTHERMAL POWER STATION, GOMA/BO.
BO – KENEMA POWER SERVICES.
SIERRA LEONE
July 16, 2010
By
Emile SANDY

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This thesis investigates the application of optimization techniques in the Engineering Management of the Power
Operating system and Maintenance of the Goma Hydro Power Station and Bo Power Station (Thermal) that are
running in parallel.

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Abstract
Hydropower is a renewable source of energy of which ecological benefits include very low average greenhouse gas
emissions. As a result of dams, however, more than 20% of all freshwater fish species are now considered
threatened or endangered. Such negative ecological impacts are a focus of broad public concern in regions where
hydropower production is most intense. The liberalization of electricity markets now provides an economic
rationale for selling hydropower as green energy. This offers an opportunity to improve the ecological performance
of hydropower plants. The lessons learned from this large-scale economic and ecological experiment in the
industrialized world might be important in other mountain regions where hydropower production is being
developed or needs ecological upgrading. As a step in this direction, gives an overview of recent developments in
Africa concerned with the ecolabeling of hydropower. Different initiatives for green hydropower in liberalized
electricity markets are useful, followed by analysis of the shortcomings of simplistic ecolabels. Finally, a new
method for ecological assessment of green hydropower plants is required to be implemented in Sierra Leone.
Nowadays, there is no formal method to evaluate the overall performance of Hydroelectric Generating Units
(HGUs). Hence, an economic performance evaluation method for HGUs is used, and the corresponding quantitative
indices and criteria are introduced. Several new concepts for evaluating the performance of HGUs, such as ideal
performance, reachable performance, operational performance, overall efficiency, index of efficiency maintenance,
index of operational efficiency, are stated and defined. Based on analysis of the energy flow of an HGU, a method
and related formulas to calculate the energy indices of the unit are presented. Using these proposed qualitative
factors, the efficiency characteristics and maintenance state of an HGU can be evaluated. A real case study
illustrates the evaluation process of this method. The methodology stated below in this document paves a new way
to evaluate the overall condition and performance of the HGU and provides a new approach to assess the
performance of other similar equipment.

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Acknowledgements
I would like to express the deepest gratitude and acknowledgement to my Advisor, and Evaluators for his careful
review of my application and opportunity to pursue my MSc ambition.
I am greatly indebted to the Ministry of Energy and Water Resources for opportunity given to me to attend the
Mastership training courses in the Operation and Management of Hydro Power Technology program, in Hangzhou,
China. The application of the knowledge acquired was used to pursue a case study assignment on optimization of
Goma Hydro dam in Sierra Leone. I also thank all staff members at the Nanjing Hydraulic Research Institute, China,
I very much appreciate the staff of Suffield University for evaluation of my work and experience in my professional
career.
I also thank the Hangzhou Regional Center for Small Hydro (HRC), for lectures in Engineering management on
Hydro Power Projects.
I am grateful to my colleagues shearing knowledge with me, and how to acquire lectures on the Frame work of
Project Management application, and Engineering systems.
I also wish to thank the Acting Personnel and Training Manager, staff of the Bo/Kenema Power Services and
Registrar of the Eastern Polytechnic Institute for the support given to me.
Above all I would like to thank my family for their ongoing support during my career.

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Table of Contents
Abstract...........................................................................................................................................................................3
Acknowledgements.........................................................................................................................................................4
Table of Contents............................................................................................................................................................5
Background (Brief History of the Goma Hydro and Bo Power Stations)........................................................................8
Engineering Management..............................................................................................................................................8
The Effectiveness of a Project Engineer...................................................................................................................11
Project Management Cycle...........................................................................................................................................13
Diesel Engine (Thermal Plant).......................................................................................................................................17
Concept of turbine......................................................................................................................................................25
Process and Method of Installation.........................................................................................................................27
Starting, Revolving, Stopping of turbine..................................................................................................................27
Running and Maintenance of turbine......................................................................................................................28
Common faults and Treating methods of turbine...................................................................................................29
Optima techniques for Dam Efficiency.....................................................................................................................30
Hydropower System & Potential map......................................................................................................................31
Geographical preview..............................................................................................................................................34
Topography – Goma Dam Location.........................................................................................................................44
Main technical Data of Plant Dam and Reservoir....................................................................................................45
Technical Data of Power Plant, auxiliaries and Transmission system.....................................................................47
Technical Specification: Diesel Generating Sets Installed Bo Power Station...........................................................51
Study to expand the existing Reservoir....................................................................................................................56
Reservoir Operation.................................................................................................................................................63
Hydrological chart of Reservoir, e.g. Goma ............................................................................................................67
Methodology for harnessing a stream for a Hydro Plant for a river turbine..........................................................68
Load curve of Reservoir outputs..............................................................................................................................71
River Planning and Cascade development...............................................................................................................71
Cascade Development..............................................................................................................................................72
Economic Operation of Hydro & Bo Power Plant.....................................................................................................73
Automation system in Hydro Plant optimization running cost ...............................................................................74
Operation instruction of Plant.................................................................................................................................75
Technical data of the Operating System – Goma and Bo........................................................................................75
Line diagram of the Transmission system and Transformer location......................................................................75

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Maintenance work plan – Goma..................................................................................................................................76
Gnat chart system application.................................................................................................................................76
Critical part Analysis application.............................................................................................................................76
Maintenance instruction of Plant............................................................................................................................76
Refurbishment of Goma Plant.................................................................................................................................76
Computer Application..............................................................................................................................................76
Electrical Equipment of Hydro power Station..........................................................................................................76
Hydraulic Turbine (Automated)...............................................................................................................................76
Co-operate Work Plan..................................................................................................................................................77
Generation – Bo and Goma.....................................................................................................................................77
Distribution Department..........................................................................................................................................77
Commercial Department..........................................................................................................................................77
Finance..........................................................................................................................................................................78
Budget Preparation Procedures and methods (Goma)............................................................................................78
Procurement Policy..................................................................................................................................................78
Revenue Collection...................................................................................................................................................78
Perspective Consumer status on regional base, specific Bo and Kenema cities......................................................78
Tariff structure, consumption (Kilowatts)................................................................................................................78
Commercial Department monthly activities............................................................................................................78
Economic Appraisal Methodology................................................................................................................................79
Economic Benefit in the Expansion of Goma Hydro Rservoir..................................................................................79
Economic Benefit in Developing the Hydro potential in Sierra Leone.....................................................................79
Equation concerning Time value..............................................................................................................................79
Cost and Benefit.......................................................................................................................................................79
Environmental and Ecological benefits....................................................................................................................79
Cross cutting issues.......................................................................................................................................................79
Energy Policy – Sierra Leone....................................................................................................................................79
Energy Planning.......................................................................................................................................................79
Energy information System and Dissemination.......................................................................................................79
Electricity sub sector (interrelation with BKPS)........................................................................................................79
Legal ans Regulatory frame work............................................................................................................................79
Supply sole policy option and strategies..................................................................................................................79
Problems.......................................................................................................................................................................79

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Management Problems in Operation......................................................................................................................80
Geological Problems................................................................................................................................................80
Hydrological Problems.............................................................................................................................................80
Recommendations........................................................................................................................................................80
comprehensive exploitation and utilization of Water Resources............................................................................80
River Planning and Cascade Development..............................................................................................................80
Conclusion.....................................................................................................................................................................80
Project being feasible or unfeasible.........................................................................................................................80
Equation concerning time value..............................................................................................................................80
Cost and Benefit analysis and scope........................................................................................................................80
Role of a System Analyst as a Project Manager......................................................................................................80
Keywords & Glossary....................................................................................................................................................81
About the Author..........................................................................................................................................................82
Table of Figures.............................................................................................................................................................85
Table of Tables..............................................................................................................................................................85

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Introduction
Background (Brief History of the Goma Hydro and Bo Power Stations)
Optimization of the Goma Hydro Power Station is to improve and effect its long term operating system. The Hydro
Reservoir capacity is not standard enough to meet the effective annual supply of Electricity to the entire grid of Bo
and Kenema. The capacity of the Reservoir is only limited to seasonal operation. During the rains, the Bundoye
River which is the main source of inflow of water entering the Reservoir is only 10.5Meter3
/sec and dwindles
considerably during the dry season to 0.28Meter cube/sec. It indicates that a total of 193x10cubic meters of water
will flow to the Reservoir during the seven months of the rainy season. The water usage by the turbines is however
computed to be only 98.2x10cubic meters ,with a relatively small reservoir capable of holding only 1.9x10 cubic
meters ,it can be assumed that the rest of the water is lost mainly by spilling into downstream areas. A small
amount is lost through evaporation. In essence, 49.1% of the water is lost. During the dry season ,the water flow
average only 0.28m/s .This rate of flow water is inadequate to meet the requirements for the turbines even under
minimal power output conditions .The water does not spill and the hydraulic head of water available is also
inadequate in the dry season.
Bo Power Station: the thermal plant in Bo was constructed and commissioned in 1987 by the Danish International
Development Agency (DANIDA), through foreign aid and its technical cooperation effort.
In 1986, China on soft loan to the Government of Sierra Leone constructed and commissioned a 4MW Hydro
Electric Plant at Goma in the Kenema District.
In 1987 the two development assistance projects were integrated in order to ensure continuous supply of electricity
to Bo and Kenema with a hydrothermal combination at Kenema and Bo respectively.
The Bo power Station consists of 1 piece of 6 cylinder and 2 pieces 9 cylinder each M.A.N.B & W engines
manufactured in Holeby, Denmark. Its output capacity now is 1.2MW.
In 2007, the Goma Power Station was refurbished, that is 4 x 1.5MW was installed; thereby make its entire system
automated.
Engineering Management.
Simply, an Engineering Manager is still an engineer but an engineer who is skilled in management. The "Master of
Science in Engineering Management" program provides an opportunity for Engineers seeking career prospects in
engineering management. It is believed that the MS is of benefit to practicing engineers who wish to gain in-depth
management skills beyond training in the form of workshops or professional development.

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Rationale:
Many engineering managers come to management by being assigned managerial tasks at their companies of
work. Although they may have had plenty of engineering training and mentoring, they learned management skills
the hard way, e.g. through trial and error and on the job. It is widely agreed upon and accepted that future
engineering mangers need training, and universities across the world have been active in providing professional
training outlets. This educational training allows engineering students to walk a bridge that connects the science
and engineering side of an organization to its management aspects.
Therefore, the purpose of this educational experience is to provide engineers the tools to become successful and
effective manager.
Additionally, by looking at our regional market and especially the production capacity that need expansion, we
notice the growth of engineering and management sectors and the need for Engineering Managers to handle such
growth.
Objectives:
The main objectives of the program are to:
1. Provide engineers with needed business skills.
2. Equip Engineers with the process of envisioning, designing, developing and supporting new products and
services.
3. Add value to Engineers, the engineering skill through the ability to manage its logistics and its application fields.
4. Aid Engineers in gaining the ability to work on multidisciplinary tasks.
5. Instill in engineers effective project engineering management skills.
6. Integrate concepts of total quality management into engineering practice.
Guided by the above board objectives and through fundamental of Product Development, Systems Engineering,
and Project Management, one can define with relative clarity typical task of an Engineering Manager.
Tasks:
 Analyze technology, resource needs, product cost, and market demand, to assess projects feasibility.
 Work with management, production, and marketing personnel to discuss specifications and procedures.

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 Coordinate and direct projects, marking detailed plans to accomplish goals.
 Direct the integration of technical activities.
 Direct, review, and approve product design and changes.
 Prepare budgets and supervise bidding process and contracts.
 Set goals within outlines provided by top management.
 Execute company objectives and organize staff work.
 Consult or negotiate with clients to prepare project specifications.
 Develop and implement policies, standards and procedures for the engineering and technical work.
 Review and write reports, approve expenditures, enforce rules and make decisions about the purchase of
materials or services.
 Plan and direct the installation, testing, operation, and maintenance of facilities.
 Present and explain proposals, reports, and finding to clients.
 Participate in employees’ recruitment; assign, direct and evaluate their work; and oversee the
development and maintenance of staff competence.
 Be responsible for completing projects on time and within budget.
 Plan, direct, and coordinate survey work with other staff activities, certifying survey work,
 Direct the engineering of distribution projects related to water control in the Dam and the running of the
HFO system.
 Plan, direct, and coordinate survey work with other staff activities, certifying survey work, and writing land
legal descriptions.
 Motivate subordinates and be skilled with conflict resolution.
 Be ethical, professional, and responsible for decisions made.

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The Effectiveness of a Project Engineer.
After attending several of these seminars and reading many books on the topic, I have concluded that there is a
need when practicing project management to discuss the qualities that one must possess to be a successful project
manager (PM).
I believe, and will demonstrate to you, that there is a distinct difference between the topic of project management
and that of the PM. Thousands of men and women each year read books and attend project management classes;
only a few will aspire to be a good PM.
Motivating Factors:
In my 25-plus years in the engineering and power industry I have met many PMs, some very good and some not so
good. What intrigued me was that some of the not-so-good PMs were brilliant people and in some way were more
educated and well versed in the technical aspects of the project they were managing than their more successful
counterparts.
Why weren't these brilliant PMs successful? By successful, I mean that they had control of their project and project
team, and that they were capable of completing the job on time and within budget, provided they are not asked to
get blood from a stone? Yesterday.
Some believe that PM dates to the building of the pyramids and the Great Wall of China. These great structures
have stood the test of time; but there exists no evidence that there were PMs, as we know them today, involved in
building these structures.
Regardless of the type of project (software development, engineering and building a power station or moving an
office) they all require the same four basic components of a project (schedules, budgets, people and sponsors) and
they all require a PM to pull it all together.
The single most talked about tool in successful project management is scheduling. An experienced scheduler who is
knowledgeable in the work that is being performed is extremely valuable to a project's success. A smart PM will
keep the scheduler close to him or her.
The second hottest topic when discussing project management is cost control. Many organizations monitor the cost
of projects with current working estimates (CWE). The CWE tracks the money spent to date, money already
committed and the estimated amount to complete the project. Both these topics are of great importance and a
good PM knows how to use them to make his or her project a success.
I recently took an intense two-day course in PM covering everything from the history of project management to the
need for project management in today's high tech world. We were taught how to set up a work breakdown
structure, how to build the project schedule, the importance of communication and how to get buy-in from project
sponsors.

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We were put into groups, given assignments and asked to play games that helped teach how to better use the tools
needed to manage a project. It was a great course and I learned a lot.
However, as a PM I am not going to be the one developing a schedule; that task is left to the scheduler and more
often than not the sponsor is committed to his project and is seeking a PM to run it.
It is important for the PM to know how these tools work and how they can be used to make a project successful,
but it is not his or her job to do them.
If the scheduler develops the schedule and the bookkeepers and accountants develop the projects cast and
expenditures reports, than what does the PM do?
His or her primary role is to lead and orchestrate a team of individuals to complete a set of specified tasks within a
set period of time and budget to the satisfaction of the sponsor.
Defining success
What separates the successful Project Manager from the rest of the pack?
Have you ever heard the saying "He's a jack-of-all-trades and a master of none"?
To me a successful PM is a jack-of-all-trades but the master of one. The one and most important trait that a
successful PM must possess is the ability to "Get the Job done". To do this you don't need to know every detail of
the job or how to perform every function of every team member. You need to know how to bring all the resources
together to reach the same goal.
The PM must know how to extract the necessary information from each team member and how to separate vital
data from garbage data. This process is critical for a PM to be successful in "getting the job done", and do it, on
time and within budget.
Defining the difference
I struggled trying to figure why I felt that there was something missing from each book and each class I attended. I
found it even harder to explain how I felt to fellow PMs who left the classes feeling great. Then one day I sat with
pen and paper and defined each as independent topics.
My definitions:
a. Project Management is the means by which the tasks of a project are organized, prioritized and resources
assigned and tracked.
b. The Project Manager is the individual with the sole responsibility to assure that a project is completed on
time and within budget to the satisfaction of the sponsor. This is accomplished by controlling the resources
provided to him or her to do the job. What separates the successful PM from the rest of the pack is the
individual's ability to get the Job Done. What they don't teach us in project management classes is how to
be a PM. I start develop qualities that a PM must possess to be successful, and chose what I considered to
be the top three and called it the "LDL Method to Becoming a Successful PM."

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The LDL method:
LEAD—the first and most important quality of a successful PM is leadership. The most important thing about
leading is leading by example. Conduct yourself as you want each individual of your team to conduct themselves.
Don't be late for anything.
I remember the movie "Entrapment" with Sean Connery and Catherine Zeta-Jones. In one scene Zeta-Jones tells
Connery not to be late for a rendezvous. Sean Connery looked straight into her eye and says "I'm never late. If I'm
late it's because I'm dead." A leader who is chronically late is telling his team that it is acceptable to be late. That
attitude will kill a project. As the PM, make it a practice to be early and your team will follow your example.
The second important factor that makes a good leader is accountability. Everyone on the project team must be
accountable, including the PM. If a team member fails to complete a task on time he or she must be held
accountable, but before doing so the PM must make sure that he gave the individual the tools needed to do what
was required and a reasonable amount of time to do it in. Don't expect the impossible, only the improbable.
Finally, the PM must be dedicated to the project. If you are not dedicated and enthusiastic or if you are not putting
your heart into the project, don't expect anyone else to either. This is not to say that because you don't have a life
that your team members shouldn't have one. What it does mean is that during the course of a project each team
member may be asked to make some personal sacrifices. Don't expect your team to do so if you are not willing to.
Be DECISIVE—If there is one thing that can kill a PM's credibility it is his or her inability to make decisions. Ninety
percent of a PM's job is making decisions. It is equally important for a PM to determine if his or her decision is
working. If the decision is taking the project off track, the PM must be ready to put Plan B into action. Every
successful PM has a plan B and C waiting in the background. A good PM always expects and is prepared for the
unexpected.
Ideas are not decisions. Don't get these two confused. Any team member can suggest taking certain actions or
implementing an idea. It is up to the PM to decide what ideas to act on. As a PM you will not, cannot and should
not expect to have all the ideas. In fact, you may have very few. The path a project takes does not have to be the
idea of the PM. It can and should be a culmination of ideas of the project team. It is up to the PM to decide what
route will best serve the project. Having the team develop the path or help resolve issues gives them ownership in
the project.
LEARN—after you make a decision learn from it. Ask yourself, was it a good decision? Is the decision taking the
project forward in the direction that will maximize the team's efforts and allocation of funds?
It is also imperative for the PM to learn the project by studying what needs to be done, assess the risks that may be
faced and be ready to implement Plan B (C or even D) if and when needed. Learn from all the Einstein’s on your
team. Draw from their knowledge and increase your understanding of what their specialties are. Just because you
are the PM doesn't mean you know everything. Remember it is the job of the PM to pull the team together, give
them the tools to perform their jobs and to let them develop ownership in the project. These are the important
qualities you need to build within yourself to be a successful project manager. These qualities cannot be learned
from a text book or taught in a class, they come from years of experience. They come from learning how to ask the
right questions. They come from learning how to bring individuals with varying personalities together for a
common goal.
Project Management Cycle

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Project Management Life Cycle comprises four phases...
Initiation involves starting up the project, by documenting
a business case, feasibility study, and terms of reference,
appointing the team and setting up a Project Office.
Planning involves setting out the roadmap for the project
by creating the following plans: project plan, resource
plan, financial plan, quality plan, acceptance plan and
communications plan.
Execution involves building the deliverables and controlling
the project delivery, scope, costs, quality, risks and issues.
Closure involves winding-down the project by releasing
staff, handing over deliverables to the customer and
completing a post implementation review.
A more detailed description of the MPMM Project
Management Methodology and Life Cycle follows:
Project Initiation
Project Initiation is the first phase in the Project Life Cycle and essentially involves starting up the project. You
initiate a project by defining its purpose and scope, the justification for initiating it and the solution to be
implemented. You will also need to recruit a suitably skilled project team, set up a Project Office and perform an
end of Phase Review. The Project Initiation phase involves the following six key steps:
Project Planning

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After defining the project and appointing the project team, you're ready to enter the detailed Project Planning
phase. This involves creating a suite of planning documents to help guide the team throughout the project
delivery. The Planning Phase involves completing the following 10 key steps

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Project Execution
With a clear definition of the project and a suite of
detailed project plans, you are now ready to enter the
Execution phase of the project.
This is the phase in which the deliverables are physically
built and presented to the customer for acceptance.
While each deliverable is being constructed, a suite of
management processes are undertaken to monitor and
control the deliverables being output by the project.
These processes include managing time, cost, quality,
change, risks, issues, suppliers, customers and
communication.
Once all the deliverables have been produced and the
customer has accepted the final solution, the project is
ready for closure.
Project Closure
Project
Closure
involves
releasing the final deliverables to the customer, handing over project
documentation to the business, terminating supplier contracts,
releasing project resources and communicating project closure to all
stakeholders. The last remaining step is to undertake a Post
Implementation Review to identify the level of project success and note any lessons learned for future projects.
Words used in... Project and Program Management

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Diesel Engine (Thermal Plant)
In relation to optimization, Diesel Engine Plant has the following operational features: good efficiency, specially
ranging from 5 - 10 MW; wide range of usable fuels; quick start up and simple maintenance. The engine is a prime
mover suitable for installations of small and medium size for mobile plant, commercial and industrial stand-by, for
generation in isolated areas especially in developing nations.
Output and dimensions: Because of heat loss the permissible mean effective pressure decreases with increase of
cylinder diameter, hence fort large-diameter cylinders are used in bigger engines. Power increase can be obtained
by raising the engine speed (1500 to 3000 rev/min) with corresponding increase in piston speed (up to 6m/sec). For
engines of about 2.5 MW, the optimum ratio of piston stroke/diameter is 1.7 – 2.0, hence this result in multi-
cylinder constructions.
Lubrication: Gear-type pumps circulate oil to all bearing surfaces at a pressure of 150 to 200kN/m.sq. Also the
pistons are lubricated by oil (Argentina T-40) from crank chamber. Effectively, 1 kg of fuel oil is required per 300 to
500 kWh of output and the outlet temperature is about 70˚C.
Engine cooling: It is rated that 30% of the energy input is dissipated to cooling water that is circulated around the
cylinder jackets. For efficiency 100 kg of water per kilowatt-hour is needed in tropical countries, especially in the
thermal station in Bo. The outlet temperature should not exceed 70˚C in order to avoid corrosion. The water is
cooled by perfect circulation through a water/air heat exchanger or a small cooling tower (radiators).
Exhaust gases: It is estimated that 20% to 30% of the energy is dissipated in the exhaust gases hence, at full load,
will have high temperature. In the running of the thermal plant in Bo, heavy fuel oil is used. The exhaust is noisy
and silencers will be fitted. It will be possible to utilize the exhaust heat on the total energy principle but the Diesel
engine is less effective.
Determine the choice of Generating Plant: A typical daily load curve for generating station indicate this by data
plotted, the curves can show seasonal variations between the Thermal and the Hydro Plant. In operating the two
stations in parallel the must run on the parameters for nominal sequences stated in typical values given in brackets.
Load factor=average-load/maximum load (0.1-0.7)
Plant factor=average-load/plant capacity (0.05-0.7)
Plant operating factor=Service-hours/total-hours (0.1-0.9)
Diversity factor=Sum of consumers maximum demands / System maximum demand (1-3)

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Thermal efficiency:
In thermodynamics, the thermal efficiency (η
th
) is a dimensionless performance measure of a device that uses
thermal energy, such as an internal combustion engine, a boiler, a furnace, or a refrigerator for example. The input,
Q
in
, to the device is heat, or the heat-content of a fuel that is consumed. The desired output is mechanical work,
W
out
, or heat, Q
out
, or possibly both. Because the input heat normally has a real financial cost, a memorable, generic
definition of thermal efficiency is η
th
= Q
out/
Q
in
From the first law of thermodynamics, the energy output can't exceed the input, so
When expressed as a percentage, the thermal efficiency must be between 0% and 100%. Due to inefficiencies such
as friction, heat loss, and other factors, thermal engines' efficiencies are typically much less than 100%. For
example, a typical gasoline automobile engine operates at around 25% efficiency, and a large coal-fueled electrical
generating plant peaks at about 46%. The largest diesel engine in the world peaks at 51.7%. In a combined cycle
plant, thermal efficiencies are approaching 60%.
There are two types of thermal efficiency
1. Indicated thermal efficiency
2. Brake thermal efficiency
Heat engines

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Heat engines transform thermal energy, or heat, Qin into mechanical energy, or work, Wnet. They cannot do this task
perfectly, so some of the input heat energy is not converted into work, but is dissipated as waste heat Q
out
into the
environment .
The thermal efficiency of a heat engine is the percentage of heat energy that is transformed into work. Thermal
efficiency is defined as
The efficiency of even the best heat engines is low; usually below 50% and often far below. So the energy lost to the
environment by heat engines is a major waste of energy resources, although modern cogeneration, combined cycle
and energy recycling schemes are beginning to use this heat for other purposes. Since a large fraction of the fuels
produced worldwide go to powering heat engines, perhaps up to half of the useful energy produced worldwide is
wasted in engine inefficiency. This inefficiency can be attributed to three causes. There is an overall theoretical limit
to the efficiency of any heat engine due to temperature, called the Carnot efficiency. Second, specific types of
engines have lower limits on their efficiency due to the inherent irreversibility of the engine cycle they use. Thirdly,
the nonideal behavior of real engines, such as mechanical friction and losses in the combustion process causes
further efficiency losses.
HCV and Gross CV or LCV, and Net CV
To complicate matters, there are at least two different definitions of Calorific Value in wide use, and which one is
being used significantly affects any quoted efficiency. Not stating whether efficiency is HCV or LCV renders such
numbers very misleading.
Carnot efficiency
The second law of thermodynamics puts a fundamental limit on the thermal efficiency of all heat engines.
Surprisingly, even an ideal, frictionless engine can't convert anywhere near 100% of its input heat into work. The
limiting factors are the temperature at which the heat enters the engine T
H
, and the temperature of the

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environment into which the engine exhausts its waste heat, T
C
, measured in an absolute scale, such as the Kelvin or
Rankine scale. From Carnot's theorem, for any engine working between these two temperatures:
This limiting value is called the Carnot cycle efficiency because it is the efficiency of an unattainable, ideal,
reversible engine cycle called the Carnot cycle. No device converting heat into mechanical energy, regardless of its
construction, can exceed this efficiency.
Examples of T
H
are the temperature of hot steam entering the turbine of a steam power plant, or the temperature
at which the fuel burns in an internal combustion engine. T
C
is usually the ambient temperature where the engine
is located, or the temperature of a lake or river that waste heat is discharged into. For example, if an automobile
engine burns gasoline at a temperature of and the ambient temperature is
the units’ maximum possible efficiency is:
As Carnot's theorem only applies to heat engines, devices that convert the fuel's energy directly into work without
burning it, such as fuel cells, can exceed the Carnot efficiency.
It can be seen that since T
C
is fixed by the environment, the only way for a designer to increase the Carnot
efficiency of an engine is to increase T
C
, the operating temperature of the engine. This is a general principle that
applies to all heat engines. For this reason the operating temperatures of engines have increased greatly over the
long term, and new materials such as ceramics to enable engines to stand higher temperatures are an active area
of research.

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Engine cycle efficiency
The Carnot cycle is reversible and thus represents the upper limit on efficiency of an engine cycle. Practical engine
cycles are irreversible and thus have inherently lower efficiency than the Carnot efficiency when operated between
the same temperatures T
H
and T
C
. One of the factors determining efficiency is how heat is added to the working
fluid in the cycle, and how it is removed. The Carnot cycle achieves maximum efficiency because all the heat is
added to the working fluid at the maximum temperature T
H
, and removed at the minimum temperature T
C
. In
contrast, in an internal combustion engine, the temperature of the fuel-air mixture in the cylinder is nowhere near
its peak temperature as the fuel starts to burn, and only reaches the peak temperature as all the fuel is consumed,
so the average temperature at which heat is added is lower, reducing efficiency.
Automobiles: Otto cycle The Otto cycle is the name for the cycle used in spark-ignition internal combustion engines
such as gasoline and hydrogen fueled automobile engines. Its theoretical efficiency depends on the compression
ratio r of the engine and the specific heat ratio γ of the gas in the combustion chamber.
Formula for Air Standard Efficiency:
The higher the compression ratio, the higher the temperature in the cylinder as the fuel burns
and so the higher the efficiency. However the maximum compression ratio usable is limited by the need to prevent
pre-ignition (knocking), where the fuel ignites by compression before the spark plug fires. The specific heat ratio of
the air-fuel mixture γ varies somewhat with the fuel, but is generally close to the air value of 1.4. This standard
value is usually used in all the engine cycle equations below, and when this approximation is used the cycle is called
an air-standard cycle.
Trucks: Diesel cycle In the Diesel cycle used in diesel truck and train engines, the fuel is ignited by compression in
the cylinder. The efficiency of the Diesel cycle is dependent on r and γ like the Otto cycle, and also by the cutoff
ratio, rc, which is the ratio of the cylinder volume at the beginning and end of the combustion process:

22
The Diesel cycle is less efficient than the Otto cycle when using the same
compression ratio. However, practical Diesel engines are 30% - 35% more efficient than gasoline engines. This is
because, since the fuel is not introduced to the combustion chamber until it required igniting, the compression ratio
is not limited by the need to avoid knocking, so higher ratios are used than in spark ignition engines.
Power plants: Rankine cycle The Rankine cycle is the cycle used in steam turbine power plants. The overwhelming
majority of the world's electric power is produced with this cycle. Since the cycle's working fluid, water, changes
from liquid to vapor and back during the cycle, their efficiencies depend on the thermodynamic properties of water.
The thermal efficiency of modern steam turbine plants with reheat cycles can reach 47%, and in combined cycle
plants it can approach 60%.
Gas turbines: Brayton cycle, The Brayton cycle is the cycle used in gas turbines and jet engines. It consists of a
compressor turbine that increases pressure of the incoming air, then fuel is continuously added to the flow and
burned, and the hot exhaust gasses are expanded in a turbine.
The efficiency depends largely on the ratio of the pressure inside the combustion chamber p2 to the pressure
outside p1
Other inefficiencies
The above efficiency formulas are based on simple idealized mathematical models of engines, with no friction and
working fluids that obey simple thermodynamic rules called the ideal gas law. Real engines have many departures
from ideal behavior that waste energy, reducing actual efficiencies far below the theoretical values given above.
Examples are:
• friction of moving parts
• inefficient combustion
• heat loss from the combustion chamber
• departure of the working fluid from the thermodynamic properties of an ideal gas
• aerodynamic drag of air moving through the engine
• energy used by ancillary equipment like oil and water pumps
• inefficient compressors and turbines
• imperfect valve timing

23
Another source of inefficiency is that engines must be optimized for other goals besides efficiency, such as low
pollution. The requirements for vehicle engines are particularly stringent: they must be designed for low emissions,
adequate acceleration, fast starting, light weight, low noise, etc. These require compromises in design (such as
altered valve timing) that reduce efficiency. The average automobile engine is only about 35% efficient, and must
also be kept idling at stoplights, wasting an additional 17% of the energy, resulting in an overall efficiency of 18%.[5]
Large stationary electric generating plants have fewer of these competing requirements as well as more efficient
Rankine cycles, so they are significantly more efficient than vehicle engines, around 50% Therefore, replacing
internal combustion vehicles with electric vehicles, which run on a battery that is charged with electricity generated
by burning fuel in a power plant, can greatly increase the thermal efficiency of energy use in transportation, thus
decreasing the demand for fossil fuels.
When a gas is compressed, its temperature rises (as stated in Charles' law); a diesel engine uses this property to
ignite the fuel. Air is drawn into the cylinder of a diesel engine and compressed by the rising piston, at a much
higher compression ratio than for a spark-ignition engine. At the top of the piston stroke, diesel fuel is injected into
the combustion chamber at high pressure, through an atomizing nozzle, mixing with the hot, high-pressure air. The
resulting mixture ignites and burns very rapidly. This contained explosion causes the gas in the chamber to expand,
driving the piston down with considerable force and creating power in a vertical direction. The connecting rod
transmits this motion to the crankshaft which is forced to turn, delivering rotary power at the output end of the
crankshaft. Scavenging (pushing the exhausted gas-charge out of the cylinder, and drawing in a fresh draught of
air) of the engine is done either by ports or valves. (See direct injection vs. indirect injection for a discussion of the
types of fuel injection.) To fully realize the capabilities of a diesel engine, use of a turbocharger to compress the
intake air is necessary; an after cooler/intercooler to cool the intake air after compression by the turbocharger
further increases efficiency.
A vital component of a diesel engine system is the governor, which limits the speed of the engine by controlling the
rate of fuel delivery. Modern electronically controlled engines achieve this through the electronic control module .
Energy conversion
For an energy conversion device like a boiler or furnace, the thermal efficiency is
So, for a boiler that produces 210 kW (or 700,000 BTU/h) output for each 300 kW (or 1,000,000
BTU/h) heat-equivalent input, its thermal efficiency is 210/300 = 0.70, or 70%. This means that the 30% of the
energy is lost to the environment.
An electric resistance heater has a thermal efficiency of at or very near 100%, so, for example, 1500W of heat are
produced for 1500W of electrical input. When comparing heating units, such as a 100% efficient electric resistance

24
heater to an 80% efficient natural gas-fueled furnace, an economic analysis is needed to determine the most cost-
effective choice.
Heat pumps, and Refrigerators are use work to move heat from a colder to a warmer place, so their function is the
opposite of a heat engine. The work energy (Win) that is applied to them is converted into heat, and the sum of this
energy and the heat energy that is moved from the cold reservoir (QC) is equal to the total heat energy added tothe
hot reservoir (QH)
Their efficiency is measured by a coefficient of performance (COP). Heat pumps are measured by the efficiency with
which they add heat to the hot reservoir, COP heating; refrigerators and air conditioners by the efficiency with which
they remove heat from the cold interior, COPcooling:
The reason for not using the term 'efficiency' is that the coefficient of performance can often be greater than 100%.
Since these devices are moving heat, not creating it, the amount of heat they move can be greater than the input
work. Therefore, heat pumps can be a more efficient way of heating than simply converting the input work into
heat, as in an electric heater or furnace.
Since they are heat engines, these devices are also limited by Carnot's theorem. The limiting value of the Carnot
'efficiency' for these processes, with the equality theoretically achievable only with an ideal 'reversible' cycle is:
The same device used between the same temperatures is more efficient when considered as a heat pump than
when considered as a refrigerator:
This is because when heating, the work used to run the device is converted to heat and adds to the desired effect,
whereas if the desired effect is cooling the heat resulting from the input work is just an unwanted byproduct.

25
Concept of turbine
This is a Francis turbine machine with a horizontal main shaft. The flows pass by inlet valve, erection joint, Inlet
tube, spiral case, guide vanes and push the runner working. This unit adopts a steel made spiral case with a
vertical-inlet. The turbine is composed of the following parts:
Inlet tube Assembly
The inlet tube assembly is composed of front pipe, inlet valve, erection joint, bend inlet tube and etc. It is the first
part of turbine. The inlet valve cutting off the flow when the turbine occurs emergency accidents or overhaul
stopping.
The center line of scroll case inlet is a vertical line. The bend inlet tube is embedded in concrete.
The bend inlet tube adopts weldment, with advantageous withstanding pressure and hydraulic performance.
The Φ800 erection joint is installed between the front pipe and the inlet valve, it used for compensating the
length error of installation and easy overhauling. And the front pipe should be welded with the penstock..
Principal part
Principal part is mainly composed of scroll case with stay ring, head cover, bottom ring, stay vane, etc.
The guide vane with three bearing support, made of steel ZG230-450(Q) the head cover and bottom ring adopt
caste steel ZG230-450(Q).
Their waterway surface is covered with stainless steel plate 1Cr18Ni9 by welding.
Gate mechanism
The distributor adopts gate link plate structure. Gate gate link plate can transfer the force from governor
shaft, pull and push gate link plate, the gate shear pin is installed at the joint of gate arm and gate link plate, shear
signal device is installed in center hole of shear pin, It can send out a signal when big body is blocked between near

26
two guide vanes.
Rotating part Assembly
The runner is set on the extended part of the turbine main shaft with key, runner cone and blot. The runner
adopt cast stainless steel ZG0Cr13Ni4Mo, it has good cavitations resistance and abrasion performance. The
flywheel is set on the turbine main shaft, it act a role making of inertia.
Draft tube Assembly
The draft tube assembly is composed of a throat pipe with aeration pipe, a bent pipe and a conical tube. The
throat pipe is between the bottom ring and the bent pipe. For reducing the hydraulic vibration and cavitations
damage, the aeration pipe can naturally supply air at the off-rating area of passage.
Main shaft seal
The main shaft seal is composed of sealing box, rotating seal ring, rubber sealing plate. It is a contact-less
sealing type with advantageous sealing effect. The rotating seating throws all the escaping water to inside wall of
the sealing box and dumps the water into the tail channel.
Tools
The special tools are used to dismantle the runner and the runner Cone and bigger bolts.
Method and Process of turbine installation
Preparation before installing
According to the products delivery casting list provided by the manufacturer, make an inventory of parts of the
equipment, the accessories with the unit, the spare parts and the technical document.
To know well the drawings of the turbine with the unit, and read carefully this instructions and other technical
document.
Check the concrete foundation which concerned with the unit. Make sure the elevation, installing position and
preset holes conform to the drawings.
Prepare the tools, measuring instruments and other assistant tools which will be used for installing, and check the
precision of precision tools, such as micrometer, horizon. Check the strength of the hoist tools.
Not to destroy and discard the antirust measure adopted by manufacturer early. To avoid the unit be moisten and
become rusty.
Should check up the ground floor, foundation plate, spare parts and attachment, etc. The spare parts should be
erased clean, there are not oil stains, rust and impurity on them.

27
Process and Method of Installation
Water turbine installation should abide by the principle: from up to down; from inside to outside. In the course of
installation, should pay attention with the X, Y coordinate and elevation of established parts, make them conform
to design. And supervise the installed parts’ horizontality, verticality, etc which would affect the installing quality at
any time. To ensure installation successfully.
Base on the shaft line of units in the powerhouse and shaft line of intake pipe, take the spiral case in position, and
rectify the verticality and elevation of spiral case center.
Take the draft tube parts to join with the spiral case which had been rectified and reinforced. Pay attention to
supervise the verticality of spiral case. To ensure installing position and elevation of draft conical tube. Install the
front pipe, valve, erection joint, etc. Let the erection joint run through with the inlet bend pipe.
Install the parts of gate mechanism; check the date opening, clearance between vanes, wicket gate end clearance.
To make them conform to demand.
Dismantle the throat pipe, take the runner to join with the turbine shaft. To turn and check the runner band
clearance, make them conform demand.
Install main shaft seal.
Install throat pipe and draft bend.
According to turbine pipeline system and turbine assembly, join the pipe elements.
Install control, adjust the push-and-pull rod through joining the governor shaft with the governor, make the control
moving flexible and accurate.
Starting, Revolving, Stopping of turbine
Starting of turbine
Before starting, should check the rotating part, make it is able to turn round smoothly, not rubbing and other
abnormal phenomenon.
Pour water into turbine, and check leaking at the sealing parts and the bolts between joining parts.
Check the water piping, ensure them unblocked and conform to design.
Check the working condition of inlet valve, governor and other complete equipment.
Check the working condition of all gauges and monitoring device.
Pour water into penstock after above-mentioned working, then open the by-pass valve, let water into spiral case,
get rid of air in the spiral case. Open inlet valve when the pressure in the spiral case and in the penstock before inlet

28
valve is approach. and then open vane slowly, Let the unit no-load run at the rated speed, but should avoid
raising speed too fast.
Check the underwater depth of the draft outlet pipe which should be no less than 300mm.
When the unit is on no-load run without abnormal phenomenon for 4 hours, check the bearing temperature,
vibration and swing whether conform to design. Then gradually increase load of unit, and place in automation
control of the governor.
Preliminary operation of turbine
Before the turbine formally place in service, the preliminary operation must be done. The objective of this work is
that you can observe the operating state of every part of the turbine and the generator, and running the rotating
parts of the turbine in.
According to the starting program, let unit run for 30 minutes each at the 25%, 50%,70%,100% of rated speed, then
raise speed to rated speed and continue the unit no-load running for 4 hours. If the running is normal without
abnormal phenomenon, let the unit run at 25%,50%,75%,100% of rated load, and the load test ought to last for 72
hours, pay attention to observe the state of every part. Stop the unit and eliminate faults at once if there is any
abnormal phenomenon. After eliminating the faults, do the load test lasting for another 72 hours again.
Stopping of Turbine
Close the distributor, and stop unit by braking when the speed descending at 30% of rated speed.
Operator should close inlet valve if stopping is over 24 hours.
If stopping for a long time, should open the discharge valve at the bottom of spiral case and the erection joint to
get rid of inner water.
Emergency stopping
You ought to stop the unit quickly at following condition, and report to manager, then find out the reason and
solve it.
Output of the turbine apparently reduces.
Some fault happen to the generator or the governor.
Hard vibration happens to the unit or abnormal sound sends from the unit.
Bearing overheat (over 70℃).
The unit runs away.
Running and Maintenance of turbine
Check the leaking condition and oil level in each bearing.
Frequently check every blot and nut whether they are tightened.
Fix a time for observing and recording hydraulic pressure, vacuum, temperature, output and vane opening.
Pay attention to observe the rotating part without abnormal phenomenon and running smoothly.

29
Check the cavitations of the rotating part and worn condition after flood season every year. Then repair or renew it
according to the condition.
Starting, running, stopping of the unit must strictly observe technical operating rules. If faults occur during running,
you ought to make records.
Keep workshop clean during running and maintenance daily. Should store spare parts, useful material, tools, etc.
Common faults and Treating methods of turbine
Output of turbine reduce
Faults Reason a
1.The underwater depth of the draft tube is not
is not deep enough to prevent air into from
outlet, so vacuum is destroyed.
1.At every condition, the underwater depth of the
draft tube should be no less than 300mm.
2. Blockage at trash rack lead dynamic head to
reduce.
2. Get rid of the block at trash rack.
3. Silting up or blocking up at tail channel leads
dynamic heads reduce.
3. Clean and unblock the tail channel to
guarantee the design size of the tail channel.
4. The gate opening is unattainable.
4. Check the distributor and the guide vane,
delimitate faults.
5. The runner is damaged. 5. Repair or renew the runner.
6. The sealing was damaged. 6. Check or repair the sealing.
7. There are crack on the drft tube or air leaks
from flange joint.
7. Weld the draft tube or tighten the flange seal.
The unit no-load runs at the rated speed, in the save head, the gate opening is over the gate no-load opening.
1. The inlet valve is not full opening. 1. Full opens the inlet valve.
2. The sealing damaged leads escaping water
rise.
2. Check and repair the sealing.
3. Blockage at the trash rack. 3. Get rid of the block at the trash rack.
5.3 Turbine vibration
1.The turbine vibration at some load range. 1. Avoid the unit running at vibration load range.

30
2.The turbine works at bad operating mode of
cavitation.
2. Check the work condition, change the
operating mode, or replenished air into the draft
tube. Let the turbine runs at permissible draft
head.
3.The rotating part is unbalanced. 3. Check and rectify unbalanced degree.
4. Partly block up between runner blades, so
water asymmetrically flow into the runner.
4. Get rid of the block.
Optima techniques for Dam Efficiency
Planning of the long operating conditions a cascade of hydroelectric station is carried out on the basis of
dispatching control schedules which are worked out and confirmed as optimizing the water resources of reservoir.
Furthermore various techniques have been applied in an attempt to improve the efficiency of reservoir(s)
operation. These techniques include –
1. Linear Programming (LP)
2. Nonlinear Programming (NLP)
3. Dynamic Programming (DP)
4. Stochastic Dynamic Programming (SDP)
5. Heuristic Programming
In reservoir operation, LP is well known as the most favored optimization technique with many advantages.
Structure Operation (SO); is one of the add-on modules. It is used to define operating strategies from structures
such as Sluice gates, Overflow gates, Radial gates, Pumps, and Reservoir releases, which will be included in the
river network.
By using several control strategies the user can simulate multi-purpose reservoirs taking into account a large
number of objectives, including flood protection, energy production and water supply.
Optimization problems can be solved by using "Local" or "Global" search methods. The Local search methods such
as gradient based methods and direct search methods have been widely applied in water management.
It requires more robust optimization techniques to find the global optimization solution of complex problems.
A cascaded reservoir system as a mean of flood control is increasingly being considered, especially as it can be
combined with harnessing the hydropower potential. The reservoir is regulated by spillways and bottom sluice
gates. In operation each gate has to be open or close entirely without any intermediate adjustment.

31
The reservoir is design to keep the peak flood level of the extreme historical flood level. The regulations consist of
three curves (upper, lower and critical limit).
When the water level is above the upper limit, hydropower generation is operated with maximum discharge
through turbines.
In the post-flood season, in order to save water for the following dry season, the maximum discharge through
turbines is determined according to the present head water level for the turbine to work at maximum capacity.
When the water level is between the lower and upper limits, hydropower generation is operated with a discharge
through turbines between the minimum downstream discharge requirements.
When the water level is between the critical and the lower limits, hydropower generation is operated with a
discharge through turbines that meet the minimum downstream discharge requirement.
When the water level is below the critical limit, hydropower generation is halted. This is illustrated in geographical
condition of the power house location and the weather condition in the rainy season and dry season. Hydrological
graphs can help in the planning of the seasonal operation of the turbines.
Notwithstanding that, the system of operation is up dated to automation system. That is, the operation system is
computerized. The protection system is very much reliable to sustain the Plant life span of operation. The
operations of the units are accurately put into running condition where all the monitoring parameters are set to
protect the devices/equipment from problems and outages. Also the system of maintenance is pertinent to my
work which I made reference to. The maintenance application is periodic .The condition base maintenance/ repairs
is base on daily checking of the power plant system .Every moment the unit is check before starting ,and shut down
parameters are taking into consideration to bring the shutdown unit back to readiness for starting when required.
Hydropower System & Potential map
The generating system is well guided to prevent abnormalities that will damage the unit while under operation
.The electrical equipment have protection devices installed to prevent the system from accident that will be caused
by natural phenomenon There are now three types of hydroelectric installations: storage, run-of-river, and
pumped-storage facilities. Storage facilities use a dam to capture water in a reservoir. This stored water is released
from the reservoir through turbines at the rate required to meet changing electricity needs or other needs such as
flood control, fish passage, irrigation, navigation, and recreation. Run-of-river facilities use only the natural flow of
the river to operate the turbine. If the conditions are right, this type of project can be constructed without a dam or
with a low diversion structure to direct water from the stream channel into a penstock. Pumped-storage facilities,
an innovation of the 1950s, have specially designed turbines.
These turbines have the ability to generate electricity the conventional way when water is delivered through
penstocks to the turbines from a reservoir. They can also be reversed and used as pumps to lift water from the
powerhouse back up into the reservoir where the water is stored for later use. During the daytime when electricity
demand suddenly increases, the gates of the pumped-storage facility are opened and stored water is released from
the reservoir to generate and quickly deliver electricity to meet the demand. At night when electricity demand is
lowest and there is excess electricity available from coal or nuclear electricity generating facilities the turbines are
reversed and pump water back into the reservoir. Operating in this manner, a pumped-storage facility improves the

32
operating efficiency of all power plants within an electric system. Hydroelectric developments provide unique
benefits not available with other electricity generating technologies. They do not contribute to air pollution, acid
rain, or ozone depletion, and do not produce toxic wastes. As a part of normal operations many hydroelectric
facilities also provide flood control, water supply for drinking and irrigation, and recreational opportunities such as
fishing, swimming, water-skiing, picnicking, camping, rafting, boating, and sightseeing.
Figure 1: Hydro potential map of Sierra Leone

33
The Hydropower potential of Sierra Leone is estimated at 1513MW scattered in sites across the country. At present,
two sites have been developed. A 2 x 25MW plant is being built at BUMBUNA with an installed capacity of 50MW.
The transmission line is 203 Km long from Bumbuna to Freetown. Also the Goma Hydro is refurbished from 4MW to
6MW. It consists of 4 x 1.5 MW units.

34
Table 1: Hydro Potential with Firm Energy in Sierra Leone
Project Power
MW
Annual Energy
(GWh)
Firm Energy (GWh)
Bumbuna 1 50 290 157
Bumbuna 11+ 90 510 394
Bumbuna 11+ Bumbuna Falls 1 180 906 711
Bumbuna 111+ Bumbuna Falls 11 225 1018 963
Bum. 11+ Bum. Falls 11+ Yiben 275 1400 1174
Benkongor 1 34,8 237,2 199,7
Benkongor 11 80 413,7 338,3
Benkongor 111 85,5 513,1 421,1
Kuse 11 91,8 679,7 549
Kambatibo 52,5 268,5 212,4
Bitmai 1 52,5 268 212,4
Bitmai 111 36,6 249,5 210,7
Mano River 45 186,6 186,6
Geographical preview

35
Geology
Sierra Leone is mostly underling by a series of ancient folded and crystalline rocks of varying lithology, belonging to
the Pre-Cambrian age (Achaean and Proterozoic). These Pre-Cambarian outcrops covers 75% of the country mainly
as granite green stone, typically falling into the following groups:
• Rokel River groups
• Marampa group – schists
• Kambui group – schist
• Mano-Moa granulites & Kasila group, etc.
The country also has a north-west to south coastal strip (Bullom Group) comprising marine and estuarine
sediments of tertiary and Quaternary to recent age. On the west coast, the Freetown complex forms an intrusive
body on the coast with acute out crops of conclave composed of a layered complex of gabbros, norite, troctolite
and anorthosite.
Tertiary and more recent weathering has led to lateritisation across a large part of Sierra Leone affecting mainly
the greenstone belts and the extensive dolerite intrusions.
Most of the country’s basement is cut by many fractures and minor intrusions have been found to have no porosity
or permeability in an unaltered state.

36
Figure 2: Geology Map of Sierra Leone
Climate
Sierra Leone has a tropical humid climate with two predominantly distinct seasons, referred to as the wet season
which starts from May-October and the dry season that starts from November to April, each of which lasts for
about six months. Temperatures vary from 24 degree to 30 degree Celsius although they could be as low as 16
degree Celsius at night during the harmattan period (Dec-Feb) and as high as 360
C in the lowlands towards the end
of the dry season. The average monthly temperatures are around 26 degree Celsius. The average annual rainfall
varies from about 2500mm in the drier areas of the north- west and north-east of the country to about 3000mm in
the southeast and about 5000mm in the Freetown Peninsula. The rainfall pattern is unimodal with most of the
rainfall occurring from late April to early November. The wettest months in most parts of the country are July and
August. Heavy rains in the wet season usually result in high discharges and runoff which ranges from 20 to 50 % of
the total annual rainfall. Rivers overflow their banks during this period, and later reduced in the dry season from
November to March. The heavy rains and maritime influence leads to high humidity. Relative humidity is usually
about 90 % in the wet season but drops to about 20 % inland in the harmattan during the dry season. Pan
evaporation is generally less than 2.0mm per day due to high diurnal humidity. Normal wind speed averages 8
knots throughout the year. There is plentiful of sunshine which varies substantially with the amount of cloudiness
averaging 6-8 hours per day during the dry season and 2-4 hours per day during the wet season.

37
Figure 3: Climate Map of Sierra Leone
Vegetation
The vegetation of Sierra Leone can be classified into seven vegetation types include moist rainforest, semi-
deciduous, montane, savannah, farm bush, mangroves and swamp forests. However, at present, the country is
covered by more of mosaic secondary forests and farm bush which arise from the slash-and –burn agricultural
practices. The moist and semi-deciduous forests are found in the protected areas especially on the tops of
mountains and slopes. The woodland savanna is restricted to the northern part of the country and is increasingly
subjected to frequent bushfires. Swamps are found in the coastal creeks, estuaries of the Scarcies, Sierra Leone,
Sherbro and Malan Rivers; while mangroves extensively cover the Atlantic coastline.

38
Figure 4: Vegetation Map of Sierra Leone
Table 2: Land Sierra Leone

39
Water Assessment
Very few regional water balance studies have been carried out in Sierra Leone. Furthermore, the reports and data
from such studies these have however been hard to come by. A general quantitative potential as obtained from
AQUASTAT for the country are as shown in the Table 3 below.
Table 3: Water Potential in Sierra Leone
Average amount Value (mm)
Pecipitation P 2550
Evapotranspiration E 1550
Surface run-off I 908
Ground water recharge 142
Table 4: Water balance for Northern Sierra Leone
Source: Master Plan Studies Sierra Leone: HowardHumphreys & Partners.
Surface Water
Sierra Leone is well drained by numerous rivers and creeks. The main rivers in the country with a length of over 40
km are as shown in the Table 6. Of these five have their sources in neighbouring countries Guinea and Liberia. The
Great Scarcies, Little Scarcies and Moa have their sources in Guinea whilst the Mano river has its source in Liberia.
The Internal renewable water resources are estimated at 160km3
/year, with the surface water accounting for
150km3
/year.
Average Precipitation
1961-1990
(mm/yr)
Average Precipitation
1961-1990
(km3/yr)
Internal renewable
water resources
AQUASTAT (km3/yr)
Groundwater:
produced internally
AQUASTAT (Km3/yr)
Surface water:
produced
internally
AQUASTAT
(Km3/yr)
2526 181.22 160.00 50 150.00
Overlap: Surface and
Groundwater
AQUASTAT (Km3/yr)
Total renewable
water
Resources (natural)
AQUASTAT (Km3/yr)
Total renewable
water
Resources (actual)
AUASTAT (Km3/yr)
Total renewable
water
Resources (natural)
AUASTAT
(Km3/capital/yr)
Dependency
ratio
AQUASTAT (%)
40.00 160.00 160.00 36322 0
Table 5: Surface Water potential

41
Table 6: Length and Area of Principal Rivers of Sierra Leone
Source: Governmental Central Statistics.
The major river systems flowing through the country is in the north-east to south-west direction.
Due to lack of long term information on river flows and the lack of comprehensive hydrometric networks, it is
difficult to estimate the surface water resource available for the country. However, based on some existing flow
and climatic data, the internally produced surface runoff is estimated to be about 160 km³/year, although this
figure is probably an overestimate. Seasonal variations are important: 11-17% of the annual discharge occurs
between December and April, with minimum discharge in April. Figure 5 shows the river basins of the country.
RIVERS LENGTH (KM) AREA (SQ. KMS.)
1 Rokel 290 396
2 Moa 266 256
3 Sewa 209 303
4 Wange 177 67
5 Mabole 161 114
6 Little Scarcies 161 202
7 Pampana 153 91
8 Bagba 137 15
9 Great Scarcies 129 91
10 Mongo 105 67
12 Mano 105 16
13 Jong 97 119
14 Bagru 89 78
15 Teye 89 36
16 Tabe 80 39
17 Meli 80 10
18 Ribbi 56 39
19 Bafin 56 16
20 Kukuli 43 31

42
Figure 5: River Basins of Sierra Leone
Data on the river basins are poorly documented and hardly accessible. In fact the hydrological databases of the
country containing much information on all the river basins have all been destroyed.
However, it has been observed that the discharges from these rivers are very low in the dry season between the
months of December and April with temperatures ranging from 28.3˚C to 30.2˚C; and with pH values in the range
of 6.2 to 6.9. In the rainy season, approximately 90% of the volumes of discharges in these rivers occur between the
months of May and November with temperatures of between 24.5˚C and 27.5˚C with pH values of 6.5 to 7.0.

43
Other water quality parameters noted in some of the various freshwater creeks and swamp wetlands include pH
values of 5.2 to 6.0; total dissolved solids of varying from 10mgl-1
to 50 mg l-1
; electrical conductivity values below
20µmho; Calcium ion concentrations between 2.0 mgl-1
and 4 mgl-1
. The general indications are that surface water
is of good quality except in a few isolated cases.
Groundwater
Groundwater is very widespread in Sierra Leone; however, there is an absence of local scientific knowledge about
how much of it is available in the country and how it is distributed. From an analysis of available climatic
information and geological characteristics, it is generally accepted that groundwater occurs as follows;
i) in soft rock areas consisting of mainly sedimentary rocks, and ii) hard rock areas which are characterize by folded
igneous and metamorphic rocks.
The quantification of the annual groundwater replenishment is difficult; most of the methods used to evaluate
recharge make use of generalizations and approximation and often give only a rough indication of the availability
of the resources. Table 23 illustrates the hydrogeology of the country with some properties.
Aquifer System
Geological
setting
Hydraulic Properties
Porosity Permeability Transmissivity Storability
Yield
(m3
/day)
Crystalline
basement
Granite-
Greenstone;
Kasila
Group;
Marampa
Group;
Freetown
complex
Secondary
due to
weathering
and
fracturing of
bedrock
Secondary Not available
Not
available
20-60
Consolidated
Rokel river
Group,
Saionia
Scarp Group
Intergranular
& Secondary
Primary Not available
Not
available
Not
available
Unconsolidated,
poorly
consolidated
Bullom
Group;
Recent
Alluvium,
River Gravel
Intergranular Primary Not available
Not
available
20-50
Table 7: Groundwater Characteristics in Sierra Leone
Source: Geology Department, Sierra Leone.

44
Topography – Goma Dam Location
Figure 6

45
Main technical Data of Plant Dam and Reservoir
Dam structures of Goma Hydro Power Station
Type of Dam…………………Gravity dam Earth dam.
Length of Dam crest…………..413.6m, inclusive of the earth dam of 355.6m,
Concrete dam of..45.5m, sluice way and intake of 12.5m.
Maximum dam height…………15m
Elevation of overflow dam crest……….102.0m.
Elevation of earth dam crest…………...107.0m.
Type of conduct……………….Open air Penstock.
Length of Penstock…………….754.080m, inclusive of the main branch and branches pipe.
Internal diameter of Penstock…1.71m to 1.60m and branch one 0.8
Type of surge tank……………..Simple cylinder type
Internal diameter of surge tank …4m.
Height of surge tank measured from ground surface…25.6m
Surge tank location……………………………………..23,7m from the Power House.
Design Head………………………………………… 72m./66.4m
Maximum Head………………………………………..77m
Average Head…………………………………………72.08m.
Characteristics of Reservoir.
Catchments area upstream from the Dam site…………283km2
Length of Main River upstream from the Dam site 33.6km
Mean annual discharge………………………………..10.5m3/sec.
Discharge during (p) =2% flood……………………….420m3/sec.
Discharge during (p) =0.2% flood……………………..670m3/sec.
Check floods Level…………………………………….105.6m.
Designs flood Level…………………………………….104.85m.
Normal high water Level………………………………102.0m
Dead water Level……………………………………...99.0m.
Total Storage capacity…………………………………1,900,000m3
Effective regulating capacity……………………………1,320,000m3
Dead storage capacity…………………………………590,000m3
Regulating characteristics………………Seasonal regulation.
Dimension of trash rack………………………………..6m x 3,5m
Dimension of emergency gate……………………..1.6m x 1.6m. This is driven by hydraulic oil.
(Operated by crane).
Elevation at bottom of gate’s slot…………………………..96m.
Power House.
Location of Power station………………Bundoye River. (Tributary of the Main Sewa River.)
Dimension of the Plant building Length- 49.36m
Width- 12.0m Heights – 20.5m

46
Space between two units……………………………………9m
Elevation of Draft tube floods………………………………..18.79m.
Elevation of Turbine-generation floods……………………….21.29m.
Elevation of Auxiliary Power House Flood………………….32.2m.
Elevation of Turbo-generator set……………………………22.2m
Elevation of the Rail Top of bridge crane in the Power House……….27.4m
Lowest Level of tail water…………………………………..20.22m
Design Level of tail water…………………………………………20.7m
Design flood level…………………………………………………25.8m
Maximum flood level……………………………………………...27.32m
Elevation of Tail water platform…………………………………... 27.4m
Ground elevation outside the plant building……………………….. 29.9m
Hall of Loading and Unloading at entrance of the building………….29.9m
Power House Data.
Area of Unloading bay……………………………………………6.1m x 12m
Area of Opening used for handling equipment to the Turbine hall…..2.6m x 3.4m
Area of Control room up stairs…………………………………...13.52m x 6m
Area of 6.3kv Switch cabinet……………………………………..14m x 6m
Area of battery Chamber…………………………………………7.67m x 6m
Area of Testing Laboratory room………………………………….5.45m x 3.3m
Area of Carrier wave cabinet……………………………………...5.45m x3.3m
Between the Power house and the Auxiliary plant, there is cable interlayer.
The height of under plate of cable interlayer ……………………….29.49m
Area of 33KV high voltage switchgear cabinet is out the Power house…………25.45m x 7m
Area of oil tank and oil treatment room lay beside the 33KV room…………….8.52m x 7m
Area of Generator vent axial blower air vent…………………………………..5ocm x 94cm
The elevation of the vent channel bottom is at 19.79m.One axial blower mounted on the elevation of
29.39m
In the cable interlayer. The other two axial blowers are mounted on the upstream of the Power house
With the elevation of 29. 93m.

47
Technical Data of Power Plant, auxiliaries and Transmission system
TECHNICAL DATA:-
Units (Turbine-1, 2, 3&4) Specification:
Type: HLFJ 3001B – WJ -60
Horizontal Francis Turbine
1. Design head: 66.4meters
2. Model Power Out put: 1613kW
3. Highest efficiency: 91.5%
4. Rated running speed: 1000 rpm
5. Hydraulics (Oil) pump motor: 380V AC
6. Automatic Touch screen operating voltage: 110V DC
7. Main Valve:
Type - Z945T -16 Diameters: 0.8meter
8. Ball valve for cooling water system:
Type - ZBF22QS-40-150 Model dual- driving.
Rated pressure: 1.6Mpa.
Power supply voltage: DC220V DC24V AC220V AC110V
(Prior to select AC level)
9. AC Panel Voltage: 400V
TECHNICAL DATA:-
Generators – (1, 2, 3&4) Specification:-
Type: SFW 1500 – 6/1430
1. Capacity: 1500kW
2. Voltage: 6.3kV
3. Current: 114.5A
4. Power Factor: 0.85
5. Frequency: 50Hz
6. No. Of Phase: 3
7. Connection: Y
8. Stator Insulation: Grade B
9.Rotor Insulation: Grade F
10. Excitation Voltage: 43.5V
11. Max. Excitation Current: 732.6A 12. Rated Speed: 1000 rpm
Goma Hydro Running Daily Report Form (Electric Characteristics) Power amount
Generating Unit in Operation. Unit-1
Time Uab(V
)
Ubc(V
)
Uca(V
)
F(Hz) Ia(A) Ib(A) Ic(A) P(KW) Q(KVar) Cos Active. React. Exc.Cu.
15:00 6319 6340 6325 50 125 124 134 1136 605 0.8
8
14571
8
39650 206.4
16:00 6261 6281 6279 50 118 117 127 1035 645 0.8
5
92576 22591 206.2
17:00 6329 6329 6319 49.9 119 118 125 1039 633 0.8
5
93618 23209 209.2

48
18:00 6288 6311 6297 50.1 117 116 123 1034 607 0.8
6
94678 23801 203.6
Daily total electric.......... Active. Reactive.
Generating Unit in Operation. Unit-2
Time Uab(V
)
Ubc(V
)
Uca(V
)
F(Hz) Ia(A) Ib(A) Ic(A) P(kW) Q(kVar) Cos Active React. Exc.Cu.
0:00 6329 6334 6326 50 121 121 131 1094 621 0.87 14685
4
40238 206.4
1:00 6334 6324 6318 49.9 128 128 134 1146 636 0.87 14804
3
40842 209.2
2:00 6312 6329 6324 50 121 121 127 1081 610 0.86 14913
9
41430 203.6
3:00 6321 6321 6326 50 105 103 111 924 550 0.86 14188
1
37523 192.0
Operating Power amount of Electric Characteristics of Units 3 and 4 are of the same format as Unit 1 & 2
The Excitation Time Constant is expressed as T= 1/λ Using the factor 0.85, then T=1/0.85= 1.2sec.
The 11kV conductor is steel/aluminium. Diameter of conductor is 25mm.sq
The Rated Power of the 33/0.4 distributing transformers is 315 kVA each.
TRANSMISSION SYSTEM.
The 33kV transmission system consists of approximately 127.2km overhead lines going from Bo Power Plant
through Kenema Power Station and further to Goma Hydro Power Plant. Overhead
line length from Bo to Kenema is 69.2 km and from Kenema to Goma the overhead line length is 58km.
From Bo to Kenema the conductor cross section area is 129mm.sq Steel/aluminum (St/Al) and from Kenema to
Goma the conductor cross section area is 99mm.sq St/Al. Along the line three 33/11 kV 630 kVA
transformers are connected in Blama, Mano and Panguma substations. These transformers supplies 11kV
distribution net work with respectively 11/0.4 kV transformers connected in the three villages.
Furthermore three 315kVA 33/0.4kV transformers are planned to be connected to the 33kV overhead line in
Gerihun, Yamadu and Baoma.
Recommendations.
1. The upgrading of the Goma Hydro to 10MW, by installing a 4MW Hydro plant with and up stream dam big
enough to maintain the dry season.
2. To develop the Hydro potential site Gandrohun 75.2MW located in the Bumpe Chiefdom in south of Sierra
Leone.
3. To develop the Hydro potential site Benkongor II, 88.5MW located the Eastern province of Sierra Leone.
4. To develop the Hydro potential site Rokon 66.9MW located in Portloko District of Sierra Leone.
MAIN 33KV TRANSFORMER – Goma Hydro Plant
Rated Power: 4000kVA Rated Voltage: 36300/6300V

49
Transformer Plant Dam & Nearby Area.
Station Transformer
33kV TRANSFORMER - Kenama Power Station
Rated Power: 2000kVA Rated Voltage 33000/1100V
Station Transformer
Rated Power: 300kVA Rated Voltage: 11000/430/240
33KV TRANSFORMER - Bo Power Station
Station Transformer
Main 33KV Transformer Goma Hydro Power Station
Specification -
Rated Power...........4000KVA
Rated Voltage......... (36300) ± 2 Х 2.5% (6300) Volts.
Frequency................ 50Hz.
Untanking Weight..... 5402Kg.
Total Weight............. 9700Kg
Oil Weight................ 1930Kg.
Percentage Impedance........ 7, 03%
Ampere................... 366.57
Production No. ....... 1TB-710.511.2
Type........................ S 9. 4000/36.3
Vector group Symbol... YN dII
Type of Cooling........... ONAN (OIL &Air Cool)
Serial No..................... 2006-071
Insulation Level.......... L I 200 AC 85
Manufacturer- Tian Jin Tian Transformer Co. Ltd.
The People Republic of China.

50
HV Winding LV winding
Tap Changing method...... (Off load)
Service.... (Out door.) Year of Manufacture.......2006. 8.
Standard. GB 1098. 3:511.2
STEP UP TRANSFORMER 11KV
Specification:-
Rated Power............400 KVA
Rated Voltage.......... (12000)± 5% (6300) V
Frequency................ 50Hz.
Untanking Weight..... 1144Kg.
Total Weight............. 2050 Kg
Percentage of Impedance.. 3.92%
Ampere....................... 36.66A
Type............................ S9.400/12
Production No............ 1TB. 710. 148
Vector group symbol.... Y dII
Insulation Level........... LI 75 AC 35
Serial No...................... 2006-075
Type of Cooling......ONAN.
HV Winding LV Winding
Tapping Position V A
1 38815
2 37208
3 36300 63.62
4 35393
5 34485
V A
6300 366.57
V A
6300 36.66
Tapping Position V A
1. 12600
2. 12000 19.25
3. 11400

51
Tap Changer.... (Off Load)
Service Out door.
Technical Specification: Diesel Generating Sets Installed Bo Power Station.
Make: MAN B&W, Holeby.
Types: 6L28/32 and 9L28/32.
Engine Nos. : 20230 (6L28/32)
20231 (9L28/32)
20232 (9L28/32)
Scope of Supply for Sierra Leone:
Required for burning fuel according to British Standard Institution BSMA 100, M9.
Specification: Diesel Engine: Works No. 20230
1. MAN B&W Holeby diesel engine, type 6L28/32
with 6 cylinders, four-stoke, water cooled, with oil cooled pistons, exchangeable cylinder Liners,
intermediate cooler, 1 (one) MAN B&W turbocharger, type NR 26/254.
Diesel Engine: Works No. 20231 and 20232.
2. MAN B&W Holeby diesel engines, type 9L28/32
with 9 cylinders four-stroke, water cooled, with oil cooled pistons,
exchangeable cylinder liners, intermediate cooler, 1 (one) MAN B&W turbocharger, type NA 34/K 74.
Engine Rating: 6L28/32: 1320 kW Out put. RPM: 750.
9L28/32: 1980 kW Output. RPM: 750.

52
The output is started at:
1000 mBar barometric pressure
48○
C water inlet temp. (Cold system). 35○
C ambient temp.
The Engines are supplied with the following Equipment.
1. Fuel oil system
2. Lubrication oil system
3. Cooling water system
4. Starting air system
5. Combustion air system
6. Exhaust gas system
7. Governing system
8. Instrumentation
9. Safety system
10. Generator
11. Fuel oil units:- Lub oil purifier, HFO separator, Pre-Heater (HFO).
12. Turbocharger and Radiator.
Axillaries Description:
1. Fuel System
1.1 HFO Separator
ALFA-LAVAL. Heavy Fuel Oil Separator-
ONE Off Automatic Discharge S-Type Separation System Module.
Suitable for up to 2200 liters/hr on HFO, type 180cst.
S815 Type Separator + Tools
-Combined starter for centrifuge & pump motors.
-Control unit EPC-50 Controller
-Ancillary kit including valve blocks for orocess, operating water & air
-ACP 025N 0.75kW feed pump – supplied loose
-Suction strainer – supplied loose
-40kW heater system.
1.2 Diesel Oil Booster Pump
ALLWEILER Diesel Oil Booster Pump Complete – TBA
1.3 HFO Injection Filter & accessories.
Air Reservoir, Air Pressure Reg. AR20-F02, Pressure gauge, Safety Valve, Air Filter AF 2000/02 R ¼,
Filter candle, Two way Ball Cock, Complete Vent Assembly, Differential Pressure Indicator,
Gasket, O-Ring Assorted, High Pressure Gasket, Air Cylinder CA2B50-85-XB6, Limit Switch, Flat
Gasket, Pressure Switch.
1.4 HFO Injection Preheated -40kW.

53
1.5 Viscotherm
ViscoSense 2-B Assembly (includes the Viscosense Sensor, Controller 7 interface Box),
1 inch 220 vac control valve for steam control.
1.6 Pressure Gauge
R19188/100003/675. Tempress Pressure Gauges, 0/6bar, 63mm dia, glycerin filled, black enamel steel
Casing, rear flange mount with1/4’’ BSP bottom connection.
1.7 Temperature Gauge
WIKA S550/4, NS100….100○
C, 250×6mm Bimetal Thermometer, Process-Industry Series.
Auxiliaries Description
2. Cooling Water System
2.1 Jack Water Pump
ALLWEILER Mechanical Seal – TBA

54
Figure 7
Gasket – TBA
2.2 Cooling Water Pump
ALLWEILER Mechanical Seal – TBA
Gasket – TBA
2.3 Thermostatic Valve
ARMOT Element
4B Gasket
2.4 Radiator Cooler Motor
ABB, TEFC Low Voltage Motor, 15kW, 160 MLB, aluminum,
IP55, IC 411, single speed.
2.5 Hot Water Pump Complete
ALLWEILER Hot Water Pump Motor
Complete – TBA
Mechanical seal - TBA
2.6 Temperature Gauge
2.7 WIKA S550/4, NS100…., 100×6mm
Bimetal Thermometer, Process-Industry –Series
Part No. 63233061

55
2.8 Pressure Gauge
Tempress Pressure Gauge, 0/4bar,
63mm dia. Glycerin filled, black enamel steel casing, rear flange mount with ¼’’
BSP bottom connection
Part No. R19187/10003/675
Tempress Pressure Gauges, 1/+1.5 bar,
63mm dia. Glycerin filled, black enamel steel casing, rear flange mount with ¼’’
BSP bottom connection
Part No. R37210/10003/675
Lube Oil System
3. Lube Oil Separator
3.1 ALFA-LAVAL Lube Oil Separator – ONE off Automatic Discharge P – Type Separation
Module. Suitable for up to 1,450 liters/hr on Lube Oil Trunk engines types.
- P150 Type Separator + tools
- Combined starter for centrifuge & pump motor
- Ancillary kit including valve blocks for orocess, operating water & air
- ACP 025N 0.75kW feed pump – supplied loose
- Suction strainer – supplied loose
- 40kW heater system
3.2 Pressure Gauge
Tempress Pressure Gauges, 0/6 bar, 63mm dia, glycerin filled, back enamel steel casing,
Rear flange mount with ¼’’ BSP bottom connection
WIKA S550/4, NS 100……100○
C, 100×6mm
Bimetal Thermometer, Process-Industry Series
4. Electrical Compressor
5. Mechanical Compressor
6. Generator – Engine 1.
Type – D1BN140 / 130L / 8
Nr. 510994
11000Y Volts, 83 Amps. 1570 KVA, Current AC. Year of Manuf: 1986.
Rotor Direction (Anti clock wise), RPM 750/min. Coolant 50○
C, Cos =0.8,ɵ 3 Phase.
Insulation Class F. Excitation: 80 Volts, 4.0 Amps. Weight: 9.8Tons.
VDE 0550. IEC 34.
Cooling Water Max. 48○
C. Operating hours – 1500.
7. Generator – Engine 2 & 3
Type – D1 DBN 150/140L/8
Nr. 8510995
11,000 Y Volts. 124 Amps.
2365 KvA. Current AC. Year of Manuf: 1986. Rot. Direction: (Anti Clockwise), RPM 750/min.

56
Coolant 50○
C, Cos = 0.8, 3 Phase.ⱷ
Insulation Class: F. IP - 44
K 680. 05. 02 Cir. - Design. Excitation: 80 V. 4.0Amps.
Aux. Excitation 90V. 200Hz/cps. VDE o530 IEC 34. Weight 11.8Tons.
Cooling Water Max. 48○
C, Operation hours: 1000.
Study to expand the existing Reservoir
Goma Power Station Project situates, the Republic of Sierra Leone, Kenema region, is part of rain forest area; with
most precipitation occurring. Vegetation in good condition, river sediment is small and the estimated drainage area
is 286km2
.

57
Estimated average annual runoff is 45,200million m3
.
Estimated mean annual discharge is 14.33m3
/sec.
The local economy is relatively backward, power shortages, besides the installed capacity is 4 x 1.500kw, water
head is 66.4m, reservoir storage capacity is 1.9million m3
.
Climatologically data of Bo / Kenema Region, (Sierra Leone)
Location of weather station: west longitude 11.8˚, north latitude 7.9˚, elevation 93m, information age 1961 –
1990.
Item Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Year
Mean temp.
(˚C )
25.4 26.6 27.3 27.3 26.5 25.6 24.7 24.4 24.9 25.5 25.9 25.4 25.8
Max.Mean
Temp. (˚C )
32.2 33.8 34.3 33.4 32.0 30.4 28.6 28.4 29.4 30.8 31.2 31.2 31.3
Min. mean
temp. (˚C )
19.2 20.3 20.5 22.0 22.1 21.9 21.9 21.9 21.7 21.5 21.5 20.3 21.2
Average
Rainfall
( mm )
5.8 15.8 41.6 114.2 254.7 328.5 429.3 488.9 428.2 338.4 148.9 22.3 2617
Rainy day 1.0 2.0 5.0 9.0 16.0 21.0 25.0 26.0 25.0 24.0 12.0 2.0 168
Daily
Average
sunlight (h)
6.4 7.0 6.1 6.1 5.9 4.8 3.2 2.7 4.0 5.8 6.3 5.4 64
Runoff
Sierra Leone is located in a low latitude regions, looks on the Atlantic Ocean, average elevation is only
100~600 m, the internal highest peak Dintumani peak reach up to 1948m. Climate is moist, forest is found
everywhere,there is large tracts of wetlands at littoral, the hihgest yearly precipitation could reach up to 5000mm.
So, the formation reasons of river within its borders are rainfall, also little fountain groundwater.Influnced by
topographic condition and climate, runoff interannual variations within the year is relatively large. The time of this
survey is May,2007. In this time all the four units are under refurblishment at Goma. All the water in the reservoir

58
passes the downflow weir, according to data of site survey, width and depth of water passed downflow weir, use
the formula: Q = b*h*(9.8) (1/2)
to count, the flow capacity is about 10m 3
/sec.
In the rainy season, which the is period the rainfall (pricipitation) is quit a lot, the flow capacity is great, fully
satisfy the condition of full capacity of Goma hydropower station. In this time, the flow capacity has relation to the
rainfall, so we can estimate the flow capacity according to the data of Bo weather station. View the flow capacity
of May as the standard, according to proportion of every month in the year, estimate flow capcity every month.
We shall operate on the flow capacity every month according to practical situation.
The average discharge every month of GOMA first level hydropower station is counted according to the
given date.
List of average discharge every month of Goma first level hydropower station.
Item Jan. Feb. Mar. Apri. May June July Aug. Sep. Oct. Nov. Dec. Year
Flowrat
e
(m 3
/sec
3 2 2 3 10 14 33 36 33 16 10 6 14
Flood weir bottom elevation is 102 m, passing water depth is 3.6 m. Using the down weir leakage now formula to
count, we cipher out check flood peak flow capacity is about 571.5 m 3
/sec.
From 80´s to now, project grading standard of Water Conservancy and Hydroelectric project of our country does
actual change, we will confirm check the return period flood according to engineering grade of Goma Hydro
station. The total holding capacity of Goma Hydro station is 0.019 x 108
m3
( 1.9Mega M3
), its engineering grade is
IV level, check flood standard is 300 ~ 1000 years return period, so we could estimate that the design flood peak
300 ~ 1000 years return period is 571.5 m3
/sec.
Engineering Geology
Project area locate boundoye river the tributary of sewa river, belong to hilly region, topography is that east and
north is higher, west and south is lower, north-eastern is Futajulon plateau, there are Luoma and Yangh mountain
system, Bindimani mountain of Luoma mountain system is 1945 m above the sea. Western is hills and fluvial plain,
Sewa river flow into the Atlantic from north-east to south-west. The bottom width is 40 ~ 100 m, terrain along the
river is flat, grade of slope is 20 ~ 45˚, height is 90 ~ 150 m, peak elevation is 2400 ~ 3500 m. At upstream of the

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