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INDUSTRIAL ATTACHMENT REPORT

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1.0 DECLARATION

I hereby declare that this report is my original work done during my attachment and has not been

presented anywhere else. It is a compilation of the activities carried out at James Finlay Kenyalimited and the practical knowledge and experience gained during my attachment period at the

company.

Signature

Name

Date


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2.0 DEDICATION

This work is dedicated to my Industrial supervisor, Mr. George Morara and Julius Rugut, all the staff

that helped me during that period, my family members, and fellow attaches.


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3.0 ACKNOWLEDGEMENT

I appreciate the human resource manager and the administration of James Finlay Kenya

limited for giving me the opportunity to be attached to that company. I also acknowledge Masinde

Muliro University lecturers, without forgetting Mr. Okanya (Chairman of department) for the

knowledge they have given me which helped me during the attachment. I also acknowledge my

supervisors at James Finlay Kenya limited who we worked together closely during my attachment. I

cant forget to thank the entire staff for their cooperation and support during that period. My

appreciation also goes to my colleagues who we were attached together in the company for the

encouragement and advice during that period. Thanks to all who contributed towards the success

of my attachment.


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4.0 ABSTRACT

This report gives a description of activities and responsibilities I was involved in at James

Finlays Kenya limited. It contains the duties and responsibilities carried out, the problems

experienced and a possible solution to each have also been highlighted. A clear relationship

between the practical skills gained and the theoretical knowledge acquired in class has been shown.


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Table of Contents1.0 DECLARATION ...................................................................................................................... 1

2.0 DEDICATION ......................................................................................................................... 2

3.0 ACKNOWLEDGEMENT .......................................................................................................... 4

4.0 ABSTRACT ............................................................................................................................. 6

5.0 INTRODUCTION .................................................................................................................... 8

6.0 CHAPTER ONE ...................................................................................................................... 9

6.1 TELEPHONE EXCHANGE SWITCH (PABX) .......................................................................... 9

6.2 Pre-digital automatic exchanges ...................................................................................... 9

6.3 Manual service exchanges ............................................................................................. 10

6.4 Main distribution frame ................................................................................................. 10

6.5 Maintenance tasks ......................................................................................................... 106.6 VOIP (voice over internet protocol) ............................................................................... 10

6.7 Contents in the control panel ........................................................................................ 11

6.8 Cisco phone network architecture ................................................................................. 11

6.9 Description of components ............................................................................................ 11

7.0 CHAPTER TWO ................................................................................................................... 14

7.1 Fiber optic transponder.................................................................................................. 14

7.1.0 Block diagram of a transponder (optical) ................................................................ 14

8.0 CHAPTER THREE: ELECTRICAL INSTALLATIONS .................................................................. 14

8.1.CPW and CCW machines installation at Chomogonday factory ................................ 14

8.1.1 Other installation and general maintenance .......................................................... 15

8.1.2 Causes of electrical faults ........................................................................................ 15

8.2 WIRING CIRCUITS ........................................................................................................... 16

8.2.1 Lighting circuits ........................................................................................................ 16

8.2.2 Socket outlet circuits: .............................................................................................. 16

8.3 LIGHTNING ARRESTORS: ................................................................................................ 16

8.4 SMOKE DETECTORS: ....................................................................................................... 17

8.5 INTRODUCTION TO MOTORS ......................................................................................... 17

8.5.3 Torque and Horsepower .......................................................................................... 17

8.5.4 Motor troubleshooting techniques ......................................................................... 17

8.6 ADJUSTABLE SPEED DRIVE SYSTEMS .............................................................................. 18

9.0 CHAPTER THREE: MOTOR REWINDING: ............................................................................ 19

9.1Introduction .................................................................................................................... 19

9.2Parts of a motor .............................................................................................................. 19


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9.3 MOTOR REWINDING AND SERVICING ............................................................................ 20

9.4 TERMS USED IN MOTOR REWINDING. ........................................................................... 21

9.5 MOTOR CONNECTION .................................................................................................... 21

9.6 VARIOUS TYPES OF MOTOR USED WITHIN THE COMPANY ........................................... 22

9.6.2 Ac motors .................................................................................................................... 22

9.6.3Hydraulic motors .......................................................................................................... 22

9.6.4Servo motors ................................................................................................................ 23

9.7 Braking of motors ........................................................................................................... 23

10.0 CHAPTER FOUR: MOTOR STARTING TECHNIQUES .......................................................... 25

10.1 DIRECT ONLINE STARTING ............................................................................................ 25

10.2 STAR-DELTA CONNECTION IN AN ELECTRIC MOTOR (AC-STARTING) .......................... 27

11.0 CHAPTER FIVE: GENERATORS AND TRANSFORMERS ...................................................... 2911.1 Hydro power plant: ...................................................................................................... 29

11.2 Diesel generators ......................................................................................................... 32

11.2.0The Prime Mover: Internal Combustion Engine ..................................................... 32

11.2.1The electrical generation component .................................................................... 32

11.2.2The Governor: AC Output Frequency and Regulation ........................................... 32

11.3 Voltage Regulation: ...................................................................................................... 32

11.4 Switchgears and Distribution: ...................................................................................... 32

12.0 CHAPTER SIX: TRANSFORMER SYSTEM ............................................................................ 33

13.0 PROBLEMS ENCOUNTERED DURING THE PERIOD ........................................................... 34

14.0 RECOMMENDATIONS ...................................................................................................... 36

15.0 CONCLUSION .................................................................................................................... 38

16.0 REFERENCE: ...................................................................................................................... 39

5.0 INTRODUCTIONFinlays group of companies was founded in the year 1750 by the late James Finlays.

As a wholly owned subsidiary of the Swire Group, the company has extensive tea and

horticultural interests in Kenya, South Africa, Sri Lanka and China, complemented by global


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trading, packaging and extraction activities. Its primary markets are in the UK, USA, Asia and

increasingly continental Europe.

Finlays is a well-respected global brand, with a 250+ year old heritage. It has

operations in many countries and in diversified markets and is well known across the tea

and horticulture industries. Over the years Finlays has played important roles in the

development of the tea industry in India, has pioneered instant tea research, development

and production. Recent expansion into flowers, fresh produce and rubber is in keeping with

its 250 years old tradition to continually expand by seeking opportunities which will benefit

shareholders, employees and stakeholders.

At Kericho, which is 2,000m above sea level, they produce 23 million Kgs of made tea

every year. It benefits from the deep rich loam soils which are high in organic content.

Combined with the ideal climate, it has the perfect environment for high yields of good

quality tea. There are approximately 1,500 different varieties of tea in the world, all

offering interesting and varied styles, taste and color. The character of tea, like wine, isinfluenced by the elevation of the garden, the soil, wind conditions and temperature and, of

course, the quality of the plucking. It is also self-sufficient in sustainable timber and power

(85% hydro-electric) and it employs nearly 12,000 people who live on the companys estates

where it provides for them, and their families, with housing, schooling and medical services.

This amounts to more than 11,000 houses, one 106 bed hospital, 25 medical dispensaries,

14 primary schools, 17 nursery schools and one secondary school.

Blending and packing tea and coffee is also an important element of their overall

offering. They take pride in achieving the highest service standards for their retail partners

in the United Kingdom out of their facility in South Elmsall, as well as the broader range ofinternational customers they serve out of their packaging plant in Colombo.


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6.0 CHAPTER ONE

6.1 TELEPHONE EXCHANGE SWITCH (PABX)

Telephone exchange or telephone switch is a system of electronic components that

connects telephone calls. A central office is the physical building used to house inside plantequipment including telephone switches, which make telephone callswork in the sense of

making connections and relaying the speech information.

In a normal analogue telephone line, it passes approximately 50 volts dc power. The

telephone presents an open circuit when it is on-hook.When a telephone user removes the

phone hook, the central communication panel detects the user has gone on an off hook

state. The pick-up has also a switch that when removed, it allows the 50 volt dc to flow

through the circuitry. In this mode the telephone is ready to receive any number from the

user. When pressing the dial buttons the sequence is interpreted by the telephone circuitry

and each pattern describes a certain frequency (DTMF- dial tone multi frequency) which

refers to a certain number in the telephone switch/exchange room.In the exchange room (private exchange) the lines to various offices within the

company are connected to a programmable command switch. This switch selects the line

required by the caller based on the incoming signal frequency. The lines to or that get out of

the company are multiplexed together using a voice card and then converted to light signal

by a transponder which are inserted to a fiber optic for transmission purposes to various

communication service providers.

Also, in the process of making a call the line voltage reduces due to the loading in the

process of conversation. The central office provided power for the telephone circuits.

6.2 Pre-digital automatic exchanges

A telephone switch is the brains of an automatic exchange. It is a device for routing calls

from one telephoneto another, generally as part of the public switched telephone network.

The local exchange automatically senses an off hook (tip) telephonecondition, provides dial

toneto that phone, receives the pulses or DTMFtones generated by the phone, and then

completes a connection to the called phone within the same exchange or to another distant

exchange.

The exchange then maintains the connection until a party hangs up, and the connection is

disconnected. This tracking of a connection's status is called supervision. Additional

features, such as billing equipment, may also be incorporated into the exchange.

6.3 Manual service exchangesWith manual service, the customer lifts the receiver off-hook

and asks the operatorto connect the call to a requested

number. Provided that the number is in the same central

office, the operator connects the call by plugging into the jack

on the switchboardcorresponding to the called customer's

line. If the call is to another central office, the operator plugs

into the trunk for the other office and asks the operator

answering (known as the "inward" operator) to connect the

call.

When the subscriber goes off-hook, the telephone puts a DCresistance short across the line. In manual service, this current


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flowing through the off-hook telephone flows through a relay coil actuating a buzzer and

lamp on the operator's switchboard. The buzzer and lamp would tell an operator the

subscriber was off-hook.

6.4 Main distribution frameThis is a signal distribution frame used to connect telephones to cables and subscriber

carrier equipment. It is a termination point within the private branch exchange equipment

and termination of companys loops are connected.

All cable pairs supplying services through the users telephone lines are terminated at the

MDF to equipment within local exchange e.g. repeaters and DSLAM. The MDF provides

flexibility in assigning facilities and has a higher capacity.

The kind of MDF is a large steel rack accessible from both sides. On one side termination

blocks are arranged horizontally at the front of rack shelves. Jumpers lie on the shelves and

go through an insulated steel hoop to run vertically to other termination blocks that are

arranged vertically.

6.5 Maintenance tasks

The daily routine tasks included fault trouble shooting and diagnosing of communication

line.

Checking and renewing of telephone joints. This was usually done on the drop

wires that shorted each other or shorted to stay wires.

Replacing of broken u sleeves.

Replacing of shorted communication fuses i.e. gas discharge fuses. This was

because of high lightning intensities that induced much current that burned the

wires.

Installing new extensions and configuring them on the central command lines.

Replacing new cards for radio signal generators. These are high power amplifiers

for radio communication with several service providers. They were damaged due

to un proper cooling scheme and wearing out.

Re-joining broken fiber optic cables. Some fiber optic cables that were not

properly suspended on the road were damaged by vehicles and thus needed

much attention because fiber optic is the major back bone of communication at

James Finlays.

Replacing new support timber poles.

6.6 VOIP (voice over internet protocol)

VoIP is the routing of voice conversation over the internet or any IP based network. It also

involves diffusion of voice traffic over internet-based networks. It also delivers services that

are cumbersome or costly to implement when using traditional PSTN.

The advantages of VoIP are;

More than one phone call can be transmitted on the same broad band phone line.

Hence facilitates addition of telephone lines to the company.

Features that are charged extra by telecommunication companies are simple with

VoIP technology.


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United communications are secured with VoIP technology, because it allows

integration with other services available on the internet such as video conversation

and messaging

To implement this, a VoIP gateway is used to convert telephony traffic into IP for

transmission over data network. There were two types of VoIP gateways:

1)

Analog unitsused to convert regular analogue lines to it.

2) Digital units digital units allow the connection of digital lines either one or more

lines.

Network connection application diagram of a NIPHX 128 communication platform

This is a modern generation PABX system which integrates internet and wireless functions.

It also provides many interfaces to connect analog phone sets, digital telephone sets,

multichannel recording devices etc. it also provides VoIP services for internet equipment.

6.7 Contents in the control panel

Master processor control card - It is the main control unit with a CPU, SDRAM

and flash memory to store system programs and databases. It also provides a

pulse code modulation clock, PCM switching network and PCM conference

interface to all 64 Kpbs voice channels of all interface cards. It is also used to

generate tones.

Slave processor card-it is a slave control unit used when MPC is completely

occupied or when it detects a fault in it.

Analogue line cards- the ALC contains codec in coding and decoding ADC and

DAC and its I/O ports offer controlling access to DSP and loop relays, message

led, caller id and read on/off hook state.

Central office trunk interface card- controls the input/output mapping,

processing sequence and interface with MPC. Also decode and code ADC &

DAC.

Primary rate interface - transceiving u-law/a-law conversion.


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Control module processor card- achieves host/slave switching.

6.8 Cisco phone network architecture

6.9 Description of componentsNetwork gateway

This is the access point for the subscribers, through which they connect to the broadband

network. When a connection is established between a network gateway and a CPE

(customer premise equipment) the subscriber can access the broadband service provided by

the network service provider or internet service provider (NSP/ISP). It establishes and

manages communication sessions. When a session is active the gateway aggregates traffic

from an access network and routes it to the network of a service provider.

The gateway router not only performs the routing function but also communicates with

authentication, authorization and accounting (AAA) server to perform session management

and billing functions.Network switch

It is used to connect computers, printers, telephones and servers within the company. It

serves as a controller enabling networked devices to talk to each other efficiently. It assists

in information sharing and allocating resources. Switches are used to create networks. Two

types of switches;

Unmanaged switchit is not designed to be configured.

Managed switchit gives greater flexibility because it can be configured. This gives

control over network traffic and who has access to the network.

In addition to the cisco network, an Ethernet cable is used to connect the old PABX. These

assist both networks to communicate together. The PABX is the old system of


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communication used within the company and hence there was no need to faze it out

completely and also the high expenses of installing cisco communication system. In the

PABX control panel a PRI card is used to establish connection/communication interface to

the cisco network.

The GSM gateway (router) and the switch communicate or can be linked together by a fiber

optic cable or an Ethernet data cable.

In the cisco network architecture, a data cable is used to interconnect the telephones,

where computers or pc console also obtains its network from there.


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7.0 CHAPTER TWO

7.1 Fiber optic transponder

It includes components for electrical signal processing and components for

transmission and reception of optical signals. Conventional optical transponders typically

receive electrical signals in parallel, serialize the information represented by these signals,and convert the serialized data into a light based signal and couple that signal to an

outbound optical fiber.

Similarly conventional optical transponders, typically receive a serialized light based data

stream, convert that data stream for an electrical equivalent, de-serialize that data and

provide the de-serialized electrical data i.e data inside a parallel format, to some plurality of

output terminals.

OEO means optical-to-electrical-to-optical. It is a kind of transponder. OEO converts

optical signals to electrical signal and then optical again. It enables for add-drop

functionality, in addition to simple optical reply or transponder.

In fiber optic communications, wavelength division multiplexing (WDM) is a technologywhich multiplexes a number of optical carrier signals onto a single optic fiber by using

different wavelengths (i.e colors) of laser light.

7.1.0 Block diagram of a transponder (optical)

Fiber optic is used within the company to as a communication medium within and outside

the companys premises. For instance in telecommunication, it is used to carry voice signals

and data because of its large bandwidth. Hence it eradicates a lot of hardcore wiring that

would have been used. An example includes its use in carrying telephone signals from the

exchange room to Saosa where, they are radiated to Telkom Kericho town via a radio

transmitter.


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8.0 CHAPTER THREE: ELECTRICAL INSTALLATIONS

8.1.CPW and CCW machines installation at Chomogonday factory

Weathering of a step done in tea manufacturing factories carried out to remove excess

amount of water from the leaves and stimulate temperate enzymatic oxidation. The leavesare arranged in weathering columns as soon as they are transported to the factory. At

Chomogonday factory a new weathering machine was being installed where I was part of

the electrical team send to oversee electrical activities at the site.

Some of the electrical tasks I participated in included:

Installation of electrical motors to the machines. These motors were used by

conveyor belts, and air fans

Mounting of brackets on the machines that were used to hold conduit pipes, cable

trays and some other electrical equipment such as limit switches.

Designing and mounting of cable trays. Installation of limit switches, temperature sensors and isolation sockets in the six

machines

Installation of control panels and power supply panels.

Running of electrical cables from the control panel and terminating them on the

motors, sensors and other electrical equipments.

Running of 75mm cable from the post supplying power to the factory to the main

circuit breaker panel.

Testing of each equipment and control panel.

8.1.1 Other installation and general maintenance

The basic symptoms of an electrical fault may be described when, there is a complete loss of

power, there is partial or localized loss of power, the installation is failing because of the

following:

a. an individual component is failing;

b. the whole plant or piece of equipment is failing;

c. the insulation resistance is low;

d. the overload or protective devices operate frequently

e. electromagnetic relays will not latch

8.1.2 Causes of electrical faultsThe fault in an electrical installation may be caused by:

i. negligencelack of proper care and attention;

ii. misusenot using the equipment properly or correctly;

iii. Abusedeliberate ill-treatment of the equipment.

8.2 WIRING CIRCUITS

8.2.1 Lighting circuits

For a domestic lighting circuit rated at 5 A, a maximum of 11 lighting outlets could be

connected to each circuit. In practice, it is usual to divide the fixed lighting outlets into two

or more circuits of seven or eight outlets each. In this way the whole installation is not


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plunged into darkness if one lighting circuit fuses. A 1.5mm cable is used either in a loop-in

or joint-box method of installation. The use of junction boxes with fixed brass terminals is

the method often adopted in domestic installations. The type of circuit used depends upon

the installation conditions and requirements. One light controlled by one switch is called

one-way switch control

One-way, two-way or intermediate switches can be obtained as plate switches for

wall mounting or ceiling mounted cord switches. Cord switches provide a convenient

method of control in bedrooms or bathrooms and for independently controlling an office

luminaire.

To convert an existing one-way switch control into a two-way switch control, a three-

core and earth cable is run from the existing switch position to the proposed second switch

position. The existing one-way switch is replaced by a two-way switch

8.2.2 Socket outlet circuits:

Socket outlets are obtained in 15A, 13A, 5A and 2 A ratings; each 13 A plug top contains

a cartridge fuse to give maximum potential protection to the flexible cord and theappliances which it serves. Socket outlets may be wired on a ringor radialcircuit.

i. Radial circuits

In a radial circuit each socket outlet is fed from the previous one. Live is connected to live,

neutral to neutral and earth to earth at each socket outlet. The number of permitted socket

outlets is unlimited but each radial circuit must not exceed the floor area stated.

ii. Ring circuits

Ring circuits are very similar to radial circuits in that each socket outlet is fed from the

previous one, but for ring circuits the last socket is wired back to the source of supply. Each

ring final circuit conductor must be looped into every socket outlet or joint box which forms

the ring and must be electrically continuous throughout its length. The number of permittedsocket outlets is unlimited but each ring circuit must not cover more than 100m2of floor

area.


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8.3 LIGHTNING ARRESTORS:

Its a metal rod mounted on top of a building electrically connected to the ground

through a wire to protect the building in the event of lightning. If lightning strikes the

building it will preferentially strike the rod, and be conducted harmlessly to ground through

the wire, instead of passing through the building, where it could start a fire or cause

electrocution. A lightning rod is a single component in a lightning protection system. In

addition to rods placed at regular intervals on the highest portions of a structure, a lightning

protection system typically includes a rooftop network of conductors, multiple conductive

paths from the roof to the ground, bonding connections to metallic objects within the

structure and a grounding network. The rooftop lightning rod is a metal strip or rod, usually

of copper or aluminum. Lightning protection systems are installed on structures, trees,

monuments, bridges or water vessels to protect from lightning damage. Individual lightning

rods are sometimes called finials,air terminalsor strike termination devices.

Diagram of a simple lightning rod system

A lightning arrester is placed where wires enter a structure, preventing damage to electronic

instruments within and ensuring the safety of individuals near them. Lightning arresters,

also called surge protectors, are devices that are connected between each electrical

conductor in a power and communications systems and the Earth. These provide a short

circuit to the ground that is interrupted by a non-conductor, over which lightning jumps. Its

purpose is to limit the rise in voltage when a communications or power line is struck by

lightning.


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8.4 SMOKE DETECTORS:

During my attachment period I had to install smoke detectors at various staff houses

and this assisted gain much knowledge about the device and how it works.

A smoke detector is a device that detects smoke, typically as an indicator of fire.

Commercial, industrial, and mass residential devices issue a signal to a fire alarm system,

while household detectors, known as smoke alarms, generally issue a local audible and/or

visual alarm from the detector itself.

Smoke detectors are typically housed in a disk-shaped plastic enclosure about 150

millimeters (6 in) in diameter and 25 millimeters (1 in) thick, but the shape can vary by

manufacturer or product line. Most smoke detectors work either by optical detection

(photoelectric) or by physical process (ionization), while others use both detection methods

to increase sensitivity to smoke.

Sensitive alarms can be used to detect, and thus deter, smoking in areas where it is

banned such as toilets and schools. Smoke detectors in large commercial, industrial, and

residential buildings are powered by a central fire alarm system, which is powered by the

building power with a battery backup. However, in many single family detached and smallermultiple family housings, a smoke alarm is often powered only by a single disposable

battery.

8.5 INTRODUCTION TO MOTORS

As a general rule, conversion of electrical power into mechanical power takes place

in the rotating part of an electrical motor. In DC motors, the electrical power is conducted

directly to the armature i.e. rotating part, through brushes and commentators. Hence in this

case a DC motor can be called a conduction motor. However, in AC motors, the rotor does

not receive electrical power by conduction but by induction in exactly the same way as the

secondary of a transformer receives power from the primary. That is why such motors are

known as induction motors. Of all the AC motors the poly-phase induction motor is the onewhich is extensively used for various kinds of industrial drives.


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The electric motor has played a leading role in the high productivity of modern

industry, and it is therefore directly responsible for the high standard of living being enjoyed

throughout the industrialized world. The induction motor has truly emerged as the prime

mover in industry, powering machine tools, pumps, fans, compressors, and a variety of

industrial equipments.

8.5.1 Electrical Characteristics and Connections

Voltage, frequency and phase of power supply should be consistent with the motor

nameplate rating. A motor will operate satisfactorily on voltage within 10% of nameplate

value, or frequency within 5%, or combined voltage and frequency variation not to exceed

10%.

8.5.2 Insulation Class

Insulation systems are rated by standard NEMA classifications According to maximum

allowable operating temperatures. They are as follows:

Class Maximum Allowed Temperature*

A 105C (221F)B 130C (266F)

F 155C (311F)

H 180C (356F)

* Motor temperature rise plus maximum ambient

Generally, replace a motor with one having an equal or higher insulation class. Replacement

with one of lower temperature rating could result in premature failure of the motor. Each

10C rise above these ratings can reduce the motors service life by one half.

8.5.3 Torque and Horsepower

Torque and horsepower are two very important characteristics that determine the

size of the motor for a particular application. Torque is the turning effort. For example,

suppose a grinding wheel with a crank arm one-foot long takes a force of one pound to turn

the wheel at steady rate. The torque required is one pound times one foot or one foot-

pound. If the crank is turned twice as fast, the torque remains the same. Regardless of how

fast the crank is turned, the torque is unchanged as long as the crank is turned at a steady

speed.

Horsepower takes into account how fast the crank is turned. Turning the crank more

rapidly takes more horsepower than turning the crank slowly. Horsepower is the rate of

doing work. By definition, one horsepower equals 33,000 foot-pounds per minute. In other

words, to lift a 33,000-pound load one foot in one minute would require one horsepower.

The discussion so far has only involved torque at a steady speed. More effort is

required to start a load than to keep it going. An AC induction motor is built to supply the

extra torque needed to overcome the inertia of starting a load.

8.5.4 Motor troubleshooting techniques

The general way we used to troubleshoot a motor that had failed was:

Initial inspection- Spend a few minutes with the user and get as much history as you

can on the failed motor. Find out if anyone else recently attempted repairs or modifications.

If so, what did they do and when? Turn the shaft to determine if it rotates freely (a normal

motor should rotate freely). Listen carefully for unusual noises (such as scraping), smell forburned insulation, and feel for excess heat.


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Resistances of line and load circuit to ground- Manually engage the starter and

measure the resistance through its contacts. You should read 0.09 ohms or less. Disengage

the starter and inspect the contacts closely. A mega ohm meter would be applied to ground

test line and load circuits at the starter. This will effectively identify the resistance to ground

of the starter, line circuits to disconnect and load lines to the motor and starter windings.

Generally, AC devices safely operate at not less than two mega ohms to ground, and DC

devices can safely operate at not less than one mega ohm to ground. But care should be

taken: before ground testing, by disconnecting any electronic control because they can be

destroyed by misapplied high-voltage test equipment. The resistance will depend on the

horsepower of the motor. For example, a 50-hp motor should ideally show 0.05-ohm

resistance. Measurements between phases should be roughly equivalent. Given a variety of

motors in use, specific engineering data may not be given for each one. However, the exact

measurement value is less important than the balance between phases. They should be

close to the identical readings.

Line to line check-it involve testing line to line, so that the operating voltage doesn't

have a path to ground. If an unreasonable voltage imbalance between any two phases isfound, that's a problem. A 5% voltage unbalance is normal and reasonable.

Motor junction box- at least by this point preliminary determination should have been

known of where the problem exists. So the motor lead junction box can be opened and

check the connections inside. Even if nothing is found wrong during the preliminary testing,

the motor connections should be checked many motor failures result from poorly

installed wire nuts or insufficiently insulated connections grounding inside the junction box

or shorting together.

If during testing, recorded low ground readings or open readings at the load side of

the starter, the next step is to test stator winding phase resistance and resistance to ground.

This will help to determine whether the discrepancy is in the motor or in the line circuit. Toconduct the tests, break the motor connection and first test in one direction and then in the

other supply. For the motor, test the stator winding resistance phase-to-phase and phase-

to-ground. If a phase-on-phase short is found, the motor needs evaluation for a rewind or

for replacement. If a phase-to-ground short is found, a motor shop may be able to do an in-

place repair for a large motor. However, rewinding or replacing is needed.

Final tests and procedure- Once corrected all identified problems and the motor is

installed and aligned, its almost done. Energize the motor and testthe controls and overall

system operation. While the motor is running, record the operating voltage and current,

check the balance, and verify that your measurements are within the nameplate

specifications. Listen for unusual noises, Smell for smoke or hot insulation, feel the motorfor excessive heat or vibration and Look for possible obstructions.

8.6 ADJUSTABLE SPEED DRIVE SYSTEMS

Commercial and industrial firms today use adjustable-speed drive (ASD) systems for a

variety of applications. Most common of these include standard pumps, fans, and blowers.

Newer applications include hoists and cranes, conveyors, machine tools, film lines,

extruders, and textile-fiber spinning machines.

Many applications have unique demands and characteristics. The combination of the

many types of drives available and the abundance of applications has made the selection of

the optimum drive for a given application a challenge.

New generation ASDs have evolved with advancements in solid-state electronics.


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ASDs are applied to ac motors regardless of motor horsepower or location within the

factory and can be used to drive almost all types of motorized equipment, from a small to

the largest. These drives help the industry reduce both energy consumption and operating

and maintenance costs while offering improved operating conditions by using new

generation electronic ASDs. The latest generation of ASDs allows ac induction motors to be

just as controllable and efficient as dc counterparts.

Variety of terms has been used to describe a system that permits a mechanical load

to be driven at user-selected speeds. These terms include, but are not limited to:

Variable-Speed Drive.

Variable-Frequency Drive.

Adjustable-Frequency Drive.

Adjustable-Speed Drive.

The term variable implies a change that may or may not be under the control of the

user. Adjustable is the preferred term since this refers to a change directly under control of

the user. The term frequency can only be applied to drives with an AC output, while the

term speed is preferred since this includes both ac and dc drives. Thus, the term most

commonly accepted is Adjustable-Speed Drive (ASD).

9.0 CHAPTER THREE: MOTOR REWINDING:

9.1Introduction

In the work shop the motors and transformers are serviced and even rewound incase the

windings are defective or short circuited.


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9.2Parts of a motor

Terminal box -box where motor terminations are made.

Fan for the cooling effect of the motor.

Motor base the support and stability of the motor.

Fan cover -protection of the fan.

Rotor -rotating part of the motor.

Bearing -reduces friction during rotation of the rotor.

Fins -increases surface area of the cooling.

Stator -provides housing for windings.

Name plate -gives motor details.

9.3 MOTOR REWINDING AND SERVICING

Electrical rewinding workshop standard operating procedures:

The rewinding workshop plays the role of servicing and repairing of motors and generators.Generally all electrical devices in factories are serviced within the factory by engineering and

factory based electricians while water pumps stations have all the motors serviced at the

electrical workshop. The standard operating procedures for the rewinding shop are as

follows:

1) When a motor fails at any user site (factory/ water pump stations) it is delivered to

the rewinding workshop.

2) On receipt of the motor, the rewinders check the job requisition details and open a

job card.

3) The motor is dismantled to check the nature of defect as outlined in the job

requisition.


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4) Once the nature of defect has been confirmed, the motor either goes into rewinding

workshop or undergoes some minor repairs.

5) Minor repairs would be replacement of bearings, replacement of terminal leads etc.

6) Motors confirmed to be having burnt windings are taken into rewinding shop for

stripping and preparation for rewinding. Before the windings are stripped all winding

details are taken and recorded. This include type of connection, pitch of coils,

number of turns per slot, size of wire and number of wires in hand. A drawing is also

made that describes the arrangement of the coils in the slots and the connection

that had been done by the manufacturer. An example of drawing made is as shown

below

7) The burnt windings are cut and removed and slots thoroughly cleaned.

8) The insulation papers are cut to suit the slots and inserted in all slots

9) The coils are made ensuring accurate counts of turns.

10)The coils are inserted into the slots ensuring no scratches occur on the winding

wires.

11)All the coil ends/overhanging are tapped with cotton tape ensuring even layout by

use of a mallet

12)All the wedges are inserted to ensure coils are safely locked in the slots.

13)All termination leads are prepared and carefully soldered and terminated on the

terminal block.14)The motor is assembled for test on no load to confirm that the windings are alright

15)The motor is disassembled for the stator/rotor to be varnished with Hymeg AD 12. It

is advisable to have the stator/rotor briefly warmed to ensure good varnish

penetration into the windings.

16)The stator is put into the oven for drying process which generally takes about 12

hours.

17)The motor is re assembled and tested; readings of voltage phase and line arrests are

recorded on no load.

18)Once the motor if fully assembled and tested, a delivery note is raised and attached

to the motor.


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19)The user department is advised to collect the repaired motor or the electrical motor

may be used to deliver several motors that have been repaired.

This concludes the motor rewinding process.

9.4 TERMS USED IN MOTOR REWINDING.

- Slots -total number of holes inside stator.

- Pitch -range of slots after one full set of turns is wound.

- Set -number of coils.

- Turns -one full wound of coil wire.

- WSYC -standard wire gauge wire used in rewinding.

9.5 MOTOR CONNECTION

Star connection

When the motor windings end terminals are shorted at one end.

Delta connection

When the motor winding are in series with each other.

9.6 VARIOUS TYPES OF MOTOR USED WITHIN THE COMPANY

9.6.1 Direct current motor

Dc motors were used to drive conveyor belts and screw conveyors. The major reason

of application is that that produce a high torque that is required to drive heavy amount of

tea on the conveyors. Another reason of application is the ease of operation and flexibility

to operate in their respective areas of application compared to ac motors. DC motors were

configured in many types and sizes, including brushless, servo, and gear motor types. A

motor consists of a rotor and a permanent magnetic field stator. The magnetic field is

maintained using either permanent magnets or electromagnetic windings.

Brushed DC motors have built-in commutation, meaning that as the motor rotates,

mechanical brushes automatically commutate coils on the rotor. Brushless DC motors use

an external power drive to allow commutation of the coils on the stator. Brush-type motors

are used when cost is a priority, while brushless motors are selected fulfill specific


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requirements, such as maintenance-free operation, high speeds and hazardous

environments where sparking could be dangerous.

One special feature that some of these dc motors had compared to other motors is

that it had compensating windings added in between the main winding. This windings

allows flexible operation including; forward direction moving, instant stopping and

reversing, emergency stopping and even assist increase the torque of the motor. Thus it

allows maximum operational clearance.

9.6.2 Ac motors

AC motors is a very wide class of motors, including single / multiphase, universal,

servo, induction, synchronous and gear motor types. The magnetic field, generated by AC

motors, is produced by an electromagnet powered by the same AC voltage as the motor

coil. The coils that produce the magnetic field are traditionally called the "field coils"

while the coils and the solid core that rotates is called the "armature." There are many

advantages in the use of ac motors aside from the wide availability of AC power.

Some types of AC motors do not use brushes or commutators. This eliminates many

problems of maintenance and wear, and also eliminates the problem of sparking. They are

also particularly well suited for constant-speed applications. This is because its speed is

determined by the frequency of the AC current applied to the motor terminals.

There are two distinct types of AC motors, synchronous and induction. A synchronous

motor consists of a series of three phase windings in the stator section. Since the current is

alternating, the motor will run smoothly only at the frequency of the alternating current.

Induction motors are the more common of the two motor types. They use alternating

electric current to induce alternating flux in the coils.Application of ac motors in the industry.

Used to drive the fun of the blower that was used in the weathering sections.

AC motors were widely applied in all water and coolant pumps.

Used to drive the cutting blade that was used for chopping tea leaves to small sizes.

9.6.3Hydraulic motors

Hydraulic motor is a common component in a larger hydraulic system. Hydraulic

motors convert hydraulic energy into mechanical energy. In industrial hydraulic systems,

pumps and motors are typically used in conjunction with proper valves and piping to form a

hydraulic powered transmission. Usually, a pump is connected via a carrier line to a motor,

which then draws fluid from a reservoir and forces it into the motor. The fluid forces the

movable components of the motor into motion, which in turn rotates the attached shaft.

The shaft which is mechanically linked to the work load supplies rotary mechanical motion.

Finally, the fluid is discharged at low pressure and transferred back to the pump.


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1. Drive shaft - via electric motor, hydraulic motor, belt and pulley etc.

2. Roller bearing - rigid support immersed in lubricating oil bath.3. Fixed-angle cam - translates rotary motion into linear to the hydraulic cells.

4. Hydraulic cells - displace diaphragms via pressurized oil.

5. Diaphragms - hydraulically balanced so that there are no stresses during flexing.

6. Inlet valve assemblies - allow liquid into pump chamber.

7. Outlet valve assemblies - allow liquid to flow into pressure discharge line.

8. Pressure regulating valve - controls outlet pressure and prevents pump overload.

Most hydraulic motors are fixed-displacement motors. Displacement is a motor

rating referring to the amount of flow that is required for a specified drive speed. Variable-

displacement piston motors are also utilized, but mostly in hydrostatic drives. Otherimportant ratings of a motor are torque and pressure. These ratings indicate how much load

a hydraulic motor is capable of handling. Hydraulic motors are entirely enclosed and self-

contained. These characteristics allow them to be submerged or operated in many hostile

environments.

Three types of hydraulic motors are gear, vane and piston-type motors. Each of these

types can be either unidirectional or reversible, although most motors used in mobile

equipment are the latter. In hydraulic gear motors, one of the two driven gears is attached

to the output shaft. Gear motors, which are the least expensive but the noisiest of the

hydraulic motors, have the ability to operate at high speeds; however, they are inefficient at

low speeds. In a hydraulically balanced vane motor, the vane on the inlet port side of the

motor is subject to full system pressure, while the chamber leading the vane is subject to

the much lower outlet pressure, forcing oil through the motor and, as a result, developing

torque.

Hydraulic vane motors are the most popular general-purpose motor, but they are

limited by their tolerance to high pressure systems and the higher percentage of slippage or

internal leakage relative to the lower total fluid flow at low speeds. Hydraulic piston pumps

can be either axial or radial and are generally the most expensive of the hydraulic motors.

They have advantages over the other motors, however, in that piston motors are far more

adaptable to high torque, low speed operation and higher system pressure applications.

Hydraulic motors provide solutions in applications involving infinite speed control,


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stalling under full torque, high power-to-weight ratio and small size. Their characteristics

make them useful in various parts of the industry.

9.6.4Servo motors

Servo motors are typically permanent magnet synchronous motors that often have

low torque-to-inertia ratios for high acceleration ratings. AC servomotors have an outputshaft that can be positioned by sending a coded signal to the motor drive. As the input to

the motor changes, the angular position of the output shaft changes as well. Generally, AC

servomotors are small but powerful for their size and easy to control. AC servo motors vary

by AC voltage and frequency.

AC servo motors are either single phase or three phases. Three phase power

contains three simultaneous sinusoidal or other alternating voltage patterns, typically 120

out of phase with each other. Higher power efficiency and smoothness of operation is

possible with three phase operation. Three phase power is most typically used in the

industry.

AC servo motors vary according to shaft speed, continuous current, continuoustorque, and continuous power output. The shaft speed is the no-load rotational speed of the

output shaft at a rated terminal voltage. The continuous current is the maximum rated

current that can be supplied to the motor windings without overheating. The continuous

torque is the output torque capability of the motor under constant running conditions. The

continuous output power is the mechanical power provided by the motor output. With

multi-speed AC servomotors, motor speed can be continuously adjusted or set at discrete

speeds within the operating range. With reversible AC servomotors, motors can be run in

both clockwise and counterclockwise directions with approximately the same operating

characteristics.

AC servo motors use integral encoders, integral resolvers, and integral tachometers forfeedback signals. Integral encoders contain attached encoders for angular position signals,

and may include absolute or incremental encoders and a number of different encoder signal

types. Integral resolvers contain an attached resolver to indicate the angular

position. Resolvers often rely on magnetic fields and are typically very robust; they are

sometimes specified for harsh environments. Integral tachometers produce an output

indicating rotational motor speeds.

9.7 Braking of motors


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Fig: - braking of an AC motor. Source: installation manual.

When a single phase is supplied to the circuit shown above the AC is rectified to DC.

This DC is supplied to a coil or an electromagnet and the electromagnet will form a

permanent magnet of a constant flux that is used to pull back the break shoe. When the

shoe is pulled back it releases the rotor of the motor and the rotor will start rotating.

When power is switched off, the electromagnet loses the magnetic energy that had

been created and will relieve the brake shoe. Through a spring arrangement the shoe will

fall back to its initial position and thus holds the rotating shaft through a brake lining. It is

noted that the single phase AC is supply is tapped from the terminals of the motor.

This arrangement is applied in crane motors that when the push button is released the

motor should stop instantly.


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10.0 CHAPTER FOUR: MOTOR STARTING TECHNIQUES

10.1 DIRECT ONLINE STARTING

Several methods are employed for starting induction motors because Induction

Motor draws more starting current during starting. To prevent damage to the windings due

to the high starting current flow, different types of starting methods are employed. Thesimplest form of motor starter for the induction motor is the direct On-Line starting. The

Direct On-Line Motor Starter (DOL) consist a MCCB or Circuit Breaker, Contactor and an

overload relay for protection. This method of DOL also assists in a way that if a motor is

using 3 phase power, it wont have a switch (3 phase switch) to control it. Therefore this

method is very important and provides an easier interface to the operator.

One advantage of the direct online starting is that the operator must be there to start

and stop the motors and in case electricity goes off when the motors are running when it

comes back the motors does not come on automatically until the operator presses the bush

buttons. These assist the motors in the case of over current in the line as electricity comes

back. Also this method saves a lot when there are a number of motors that have to bestarted by just a single press of a button.

Diagrammatically it can be represented as shown below.

R

Y

Control circuit

Hold (NO)

contact

A2

A1

Contactor coil

Start button (NO)

Overload (NC)

Stop button (NC)

Circuit breaker

Power circuit

Circuit breaker

Contactor

coil

Contactor

Overload relay

3 - Phase

motor

B

N


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The circuit above consists of the power circuit and the control circuit. The power

circuit consists of a circuit breaker to prevent the motor from over current in the line, a

contactor to make and break the motor when required to operate and an overload relay

that prevents overloading of the motor.

The control circuit consists of a stop bush button, that is usually a normally closed

contact to open the control circuit when pressed and a start button that is also a normally

open contact to close the control circuit when pressed. The start pushbutton as shown

above is interlocked with the normally open of the contactor so that when the start button

is pressed and released the motor will continue running until the stop button is pressed.

This is how the direct online operates. In a case where we have a motor that will be

operated in the forward and reverse directions then its circuit would be slightly different as

shown below.

It can be seen that in the forward and reverse direct online starting two contactors K1

and K2 are used. The contactor K2 is used to achieve the reverse direction by interchanging

any of the 2phases at the output of the contactor as shown above in the power circuit. Also

both the normally closed of the 2 contactors are interlocked together in the control circuit


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so that at no instance both contactors are operating at the same time because it will cause

a short in the power circuit.

DOL is Suitable for:

A direct on line starter can be used if the high inrush current of the motor does not

cause excessive voltage drop in the supply circuit. The maximum size of a motor allowed on

a direct on line starter may be limited by the supply utility for this reason. For example, a

utility may require rural customers to use reduced-voltage starters for motors larger than 10

kW. DOL starting is sometimes used to start small water pumps, compressors, fans and

conveyor belts.

10.2 STAR-DELTA CONNECTION IN AN ELECTRIC MOTOR (AC-STARTING)

When an induction motor is started directly online, it takes a starting current 6(six)

times that of the full load current. For large motors the high current causes voltage drop in

the power lines which may trip other motors within the same line. Finlays restricts the

rating of a motor which can be started in the star delta sequence. So to reduce the starting

current of a motor, the voltage across the motor need to be reduced. This can be done bystar delta connection, use of an auto transformer or incorporate a resistor when starting. So

for the star delta connection the motor windings are connected in star during starting and

delta when the motor starts running. By doing so, the starting current and torque are

reduced by 2.5 times of starting current.


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As can be shown above in the circuit there are 3 contactors involved in operation

namely; main, star and delta contactors. The star and delta work in coordination such that

when the circuit is energized from the control circuit, the star contactor comes on first

before the delta contactor. In a greater detail, as the start PB is pressed, the main contactor

comes on and also the timer comes on. So the control wire goes through the main contactor

and then to the timer. From the timer the control wire is split in such a way that one goes

through the normally closed and the other goes through the normally open contacts in the

timer.

The wire from the NC of the timer will pass through the NC contact of the delta

contactor and then to the coil of the star contactor while the wire from the NO of the timer

will pass through the NC of the star contactor and then to the coil of the delta contactor. So

when the circuit is energized, the power will flow from the NC of the timer to the NC of

delta contactor (just to check whether the delta contactor is energized) then to energize the

star contactor coil. After a time set to the timer i.e. 3 seconds it will shift the contact from

NC to NO and thus it cuts out the power from the NC contact to the NO contact. By doing so

the star contactor will be de-energized and the delta contactor will be energized throughthe same process. One thing of importance here is the interconnection of the NC contacts to


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only allow one contactor to be in operation at a time. So the motor will run on the star

contactor for 3 seconds and then switch to delta contactor. And this is how the star delta

starting of an AC motor is achieved.


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11.0 CHAPTER FIVE: GENERATORS AND TRANSFORMERS

11.1 Hydro power plant:

James Finlays Kenya limited has five factories within Kericho tea zone. Due to

greatest demand of power to be used in the factories and the need to have a cheaper cost

of running the factories, it has been economical for the management to have their ownpower supply through their own generating plant one of them being Masabet section which

generates more KW. The factory has 6 major power plants namely:

Masabet- 2 HEP generators producing 1060 KW

Dimbolil- 2 HEP generators producing 300KW

Zaosa- 2 HEP generators producing 360 KW

Kaproret- 2 HEP generators producing 120 KW

Chemamul- 2 HEP generators producing 300KW

Total HEP- 2230 KW or 2.23MW

Central power house -1 Perkins generator 1800kw

-2 CAT generators 1600KWKitumbe power house- 2 diesel Genset 1600KW

Changana power house- 2 diesel Genset 1000KW

Kymulot power house- 1 diesel Genset 500KW

Total diesel power- 6000KW or 6MW

However, under normal operation, only hydro-electric power is connected to the

grid thus supplying up to 2MW. Also under normal operations within the company all tea

factories, flower farms and estates consume or needs up to 5.5MW. So the extra 3.5mw is

supplied by the Kenya power. But when Kenya power line is off, then the diesel generators

are started and so allow production to be continuous.

For a generator to be connected to the companys grid it has to be synchronizedfirst. Also when Kenya power line goes off, almost all hydro generators fall out of the grid

because there is too much load to be driven compared to the power being generated and

thus, they are shut down.

Synchronization is the process of matching the speed and frequency of a generator

or other source to a running network. An AC generator cannot deliver power to an electrical

grid unless it is running at same frequency as the network. If two segments of a grid are

disconnected, they cannot exchange ac power again until they are brought back into exact

synchronization. The conditions to be met before the synchronization takes place are, the

source generator or sub network must have equal line voltage, frequency, phase sequence,

phase angle and waveform to that of the system to which is being synchronized.The process of synchronization involves bringing the generator to approximate

synchronous speed by supplying more energy to its shaft i.e increasing the amount of water

to the turbine or increasing the fuel rack setting on a diesel engine. The field of the

generator is energized and the voltage at the terminals of the generator is observed and

compared with the system voltage.


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FIG: syncroscope controls and monitoring

When a generator is synchronized, the frequency of the system will change

depending on the load and average characteristics of all generating units connected to the

grid. Large changes in the system frequency can cause the generator to fall out of

synchronism with the system. Protective devices on the generator will operate todisconnect it automatically.

Fig. HEP power plant.


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Description of operations at the power plant from the dam to the transmission anddistribution channel

From the dam the water flows through closed conduits and is directed to the surge

tank whose purpose is to control the pressure of water entering the penstock. From the

surge tank to the power house the water head is 20M just before the penstock enters the

power house it is made to further divide into two conduits each which leads water to each

turbine in the power house.

In the power house the water enters directly to the enclosed turbines which have

pocket like plates which are made to rotate when hit by the incoming water at a greater

pressure and thus rotary motion is realized. The turbine is connected to the AC generators

using a shaft. Another connection on the shaft is the flywheel. This flywheel makes it

possible to achieve well regulated revolutions of the shaft hence a controlled rotation of the

generators without vibrations.

From the generators the connections of the generated e.m.f is made via cables to

the panel. This is where synchronization is done. The panel contains meters that check the

amount of generated power among other essentials like the power factor and the reactive

power. It also contains relays which are used to detect any problem in the whole system and

they then convey the detected fault to the power control which triples thereafter. An

operating technician can thus rectify the problem himself or do as has been instructed by

the engineer. It is at the panel where excitation can be controlled to realize a higher power

factor and also in cases of breakdown the generators are switched off from there using the

isolators.

The generated e.m.f is then stepped up to 33KV for transmission to the central

power house then distributed to different factories.


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Fig: - Simplified diagram of AC electricity distribution from generation stations to consumers

Distribution networks are typically of two types, radial or interconnected. A radial

network leaves the station and passes through the network area with no normal connection

to any other supply. This is typical of long rural lines with isolated load areas. An

interconnected network is generally found in more urban areas and will have multiple

connections to other points of supply. These points of connection are normally open but

allow various configurations by the operating utility by closing and opening switches.

Operation of these switches may be by remote control from a control center or by a

lineman. The benefit of the interconnected model is that in the event of a fault or required

maintenance a small area of network can be isolated and the remainder kept on supply.

Within these networks there may be a mix of overhead line construction utilizing

traditional utility poles and wires and, increasingly, underground construction with cables

and indoor or cabinet substations. However, underground distribution is significantly more

expensive than overhead construction. In part to reduce this cost, underground power lines

are sometimes co-located with other utility lines in what are called common utility ducts.

Distribution feeders emanating from a substation are generally controlled by a circuit

breaker which will open when a fault is detected. Automatic circuit recloses may be installed

to further segregate the feeder thus minimizing the impact of faults.

Long feeders experience voltage drop requiring capacitors or voltage regulators to be

installed.

Characteristics of the supply given to customers are generally mandated by contract

between the supplier and customer. Variables of the supply include:

AC or DC - Virtually all public electricity supplies are AC today. Users of large

amounts of DC power such as some electric railways, telephone exchanges and

industrial processes such as aluminium smelting usually either operate their own or

have adjacent dedicated generating equipment, or use rectifiers to derive DC from

the public AC supply Voltage including tolerance (usually +10 or -15%)


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Frequency, commonly 50 or 60 Hz, 16.6 Hz for some railways and, in a few older

industrial and mining locations, 25 Hz.

Phase configuration (single phase, polyphase including two-phase and three phase)

Maximum demand (usually measured as the largest amount of power delivered

within a 15 or 30 minute period during a billing period)

Load factor, expressed as a ratio of average load to peak load over a period of time.

Load factor indicates the degree of effective utilization of equipment (and capital

investment) of distribution line or system.

Power factor of connected load

Earthing arrangements - TT, TN-S, TN-C-S or TN-C

Prospective short circuit current

Maximum level and frequency of occurrence of transients

Advantages of hydroelectricity:

It is more economical due to elimination of fuel costs.

Carbon dioxide emissions are reduced because there is no burning of fossil fuels.

The reservoir can be used for other activities such as sporting activities, irrigation

etc.

Disadvantages

Ecosystem damage and loss of land as a result of creation of the reservoir.

Siltation can fill a reservoir and reduce its capacity to control floods along with

causing additional horizontal pressure on the upstream portion of the dam.

Flow shortage will correlate with the amount of energy produced by the dam.

11.2 Diesel generators

A diesel generator is the combination of a diesel engine with an alternator to

generate electric energy. Diesel generating sets are used in places without connection to the

power gridor as emergency power-supply if the grid fails. Small portable diesel generators

that range from about 1 kVA to 10 kVA may be used as power supplies on construction sites,or as auxiliary power for mobile homes. The companys generators used as a back-up power

supply mainly during mains power failures. It utilizes energy supplied by diesel engines rated

at several KW at 1800r.p.m. speed, to drive an alternator. Its usually automatically

connected to the network with the aid of a change over breakers and start-up batteries.


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A standby generator system is composed of two basic subsystems:

1. The generator, which is made up of the prime mover, the alternator, and the

governor.

2. The distribution system, which is made up of the Automatic Transfer Switch (ATS)

and associated switchgear and distribution.

11.2.0The Prime Mover: Internal Combustion Engine

Internal combustion engine converts its fuel source into mechanical motion through

its internal moving parts. As outside air mixes with the fuel inside the engine these moving

parts ignite the air and fuel mixture to create a controlled internal combustion within the

cylinders. Although there are numerous variations of the internal combustion engine, the

most commonly used for standby generator systems is the 4to 16 valve engine. It is referred

to as a 4-stroke because of the four stages that occur in the combustion cycle. These stagesinclude intake of the air and fuel mixture, compression of that mixture, combustion, and

exhaust. When referring to generators the engine is generally referred as the prime mover.

11.2.1The electrical generation component

The function of the alternator is to convert mechanical energy from the prime mover

into alternating current. This is similar to the alternator in an automobile, however in an

automobile it is usually driven by a belt, whereas in a generator it is driven by the main drive

shaft of the prime mover. A very basic alternator can be made from a loop of metal wire and

a magnet. Electricity is produced when the loop of wire is moved through the magnetic field

produced by the positive and negative poles of the magnet. Alternatively the magnetic field

could move while the wire remains stationary. An alternator of this type would obviously

produce a very small amount of electricity but is based on the same electrical principles as

large alternators used in generators. Through the years, certain characteristics of alternator

components have been improved to increase the efficiency, capacity and reliability of the

alternator.

11.2.2The Governor: AC Output Frequency and Regulation

The governor maintains constant revolution of the prime mover under a variety of

conditions by adjusting the fuel that feeds the prime mover. A stable AC frequency is

required that is directly proportional to the accuracy and response time of the governor.

This item is a key component in determining the AC output power quality.


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11.3 Voltage Regulation:

A voltage regulator is basically used to control the voltage produced at the output of

the alternator. The operation of the voltage regulator is vital to critical loads dependent on

computer grade power. The goal is to configure a system with an appropriate response time

to minimize sags and surges that occur as the load changes. Another issue to be aware of is

the behavior of the regulator when subjected to non-linear loads such as older switch-mode

power supplies. Non-linear loads draw current in a manner that is inconsistent with the

voltage waveform, while resistive loads (like a light bulb) draw current in synch with the

voltage waveform. Non-linear loads can interact negatively with a generator system thereby

jeopardizing the availability of the critical load during standby operation.

11.4 Switchgears and Distribution:

This involves the automatic systems that monitor the utility source and initiate

engine starting and transfer of the load to generator as soon as it is available and stable.

This includes re-transfer of the load to utility when normal conditions are restored.

Typically, all these functions are incorporated into a system known as an Automatic TransferSwitch (ATS) and syncroscope. Other common features include automatic generator test

scheduling and a very important cool-down cycle for the generator after the utility is

restored.

12.0 CHAPTER SIX: TRANSFORMER SYSTEMA transformer is a static piece of apparatus by means of which electric power in one

circuit is transformed into electric power of the same frequency in one circuit. It can lower


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The chilly environment Finlays made me experience Colds during morning hours;

hence adapting was indeed a challenge

The supervisory duties were sometimes overwhelming given that i was made to

supervise seasonal employees doing menial duties

Working at the manufacturing floor was very tedious and hence required close

monitoring in case of a breakdown. Working on the steam area with very high

temperatures really exposed me to great dangers

Despite all those challenges listed above the industrial attachment 1 was a

success; vast knowledge and experience was instilled on me.

14.0 RECOMMENDATIONSDue to the problems encountered I would recommend that the company should look

for possible solutions such as to aid in hastening of works especially on the transmission

lines they should buy machines that can help them in lifting the poles rather than employing


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42

a lot of man power. They should also try to automate the cutting of insulation materials

used in insulating the slots and this will help them to speed up their motor rewinding. The

company should also train their workers on how to handle new people within their

company especially the attaches as they are there to learn more about the practical part.

Also the transport logistics should be reduced because in case of breakdown in

industries then it would be a problem to the engineering staff to attend to it immediately.


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ECE/0569/09

43

15.0 CONCLUSIONThe attachment period really helped me put my theoretical knowledge to the

practical part and I enjoyed my time at the company and wish to get back next time with

more knowledge in order to aid in improved services within the company and ensure they

offer the best to their customers.

The weak point was mainly at the computer science section because I had little time

there and not interacting well with the person I was attached to.

The strong points was at the telephone exchange and motor rewinding section as I was

really helped and gained more than expected not also forgetting the power house where I

had to really apply my theoretical knowledge to practice.

Generally, my objectives for the attachment were successfully met and I thank the entire

James Finlay Limited fraternity very much. I owe my success to them.


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ECE/0569/09

16.0 REFERENCE:Notes noted during the attachment period

Internet (James Finlays web site)B.L Theraja

Wikipdia

mutaiattachment-1

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