CHAPTER ONE

1.0 INTRODUCTION

The electrical/maintenance section is the power house of the company. All

other section depends of it, either directly or indirectly. The major functions

carried out in this section are repairs of electrical equipments (grinding and

cutting machines, generator sets, welding machine compressors etc.) from site.

It’s also in charge of installing TV cables, telephone lines, repairing and fixing of

light fittings, construction of welding cables and building of electrical panels. On

rare occasions, the section is in charge of supervision of house wiring of the

company’s residential area.

This report is into two chapters, the first chapters outlines the importance and

aim of SIWES, it gives an over view of the company’s profile and a good

representation of the organizational structure of the management. The second

chapter describes the various industrial equipments, their mode of operation,

how there are troubleshot and repaired. Chapter three treats the procedures for

conduit wiring a with emphases on the working of the electrical lighting arrestors

and earth pit while the last is the conclusive chapter which highlights the skills I

acquired by virtue of my training, the challenges I encountered and possible

recommendations.

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1.1 OBJECTIVE OF SIWES

The student industrial work experience scheme (SIWES) is a federal

government policy, which is aimed at assisting students to obtain relevant

practical experience and skills in their course of study among other reasons; it

is an effort designed to bridge the gap between the theory and practical

aspect in various degree program. It also strengthens employer’s involvement

in educational process and also in preparing students for employment.

1.2 COMPANY’S PROFILE

Alcon Nigeria Limited was launched into Nigeria construction industry as

LED construction Nigeria Limited on the 10th of May 1982 and on the 30th

march 1984 it was re-named Alcon Nigeria Limit. It is located at plot 17 Trans-

Amadi industrial layouts, Portharcourt, Rivers state.

FIELDS OF ACTIVITIES

Alcon has track records of excellent project performance across abroad industry

spectrums either as a simple construction contractor or as a main contractor

responsible for turn key projects in the following fields.

Oil and gas upstream and mid stream prospects

Refining chemical and petrochemical

Power generation and distribution

Infrastructure

Civil works.

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I t is a full single source provider, a strategic partner ally for

Project management

Engineering procurement construction and installations

Operations and maintenance

Alcon is committed to executing its projects safely without compromising

quality in a timely manner and within stated budget.

SECTIONS

Electrical / maintenance section

Welding section

Iron bending/ panel beating section

Mechanical/automobile section

Carpentry section

Quality control department

Account department

Store department

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1.3 MANAGEMENT ORGANOGRAM

Chairman

Director

Deputy General Manager

Quality Mngr. Maintenance Mngr. Utility Mngr. Store Mngr. Acc Mngr. Admin Mngr. Marketing Mngr. Security Officer.

Senior officer Maintenance Engr. Utility Engr. Senior officer Acc. Officer Admin Officer Marketing Officer Asst. Officer

Officer Fore man Sub. Asst. Engr. Officer Cashier Asst. Admin Officer Officer Security Guards

Lab. Asst. Helper Workers Helper

Lab boy Workers Workers

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CHAPTER TWO

INDUSTRIAL ELECTRICAL EQUIPMENTS

They were some industrial electrical equipment I got acquainted with. The

machines are; welding machine, generator set (big), grinding and cutting

machine amongst many others.

2.0 WELDING MACHINE:

Welding machines are used to permanently connect metal piece with heat

generated from electrical energy. They are available in variety of sizes and

output voltage. Welding machines takes electrical current from a high-voltage

power source and coverts it into viable energy to fuse two materials together.

Some welding machine use a transformer to convert the high voltage current

from the wall outlet into a lower voltage current for outlet while other types

or welding machines uses a motor or combustion engine to convert electrical

energy into mechanical energy. An alternator or generator is then used to

convert this mechanical energy into a low current electrical output.

2.1 MAINTENANCE OF A WELDING MACHINE

I. The first thing to check when a welding machine is not working fine is if

the wire is feeding properly. A worn drive roller can affect the feed and

causes it to slip. When checking, look for debris and dirt on the liner.

This can also cause bird hesting. Sometimes troubling shooting welding

machine is as simple as cleaning it and allowing the wire feed freely.5

II. Look out for the tip near the wire exist inside the gun. A worn out tip

doesn’t allow the electricity to efficiently hit and this creates a lot more

work on the job. Burn back can cause a bad wire.

III. Inspect the ground clamp, when the part of the clamp is coated with

oxide, electrons can’t ready transfer. A bad ground clamp can cause a

lot of resistances and change the way current comes back to the

machine.

IV. Examine the welding cable for worn spots.

2.2 GENERATOR:

A big generator set used mostly in the company is the SA-200 Lincoln

generator. It comprises of two DC generators working in tandem. The first

generator is the exciter (the nose that sticks out the front of the machine. The

exciter is actually a 2kw DC generator that provides a DC current that is adjusted

to control the welder output. The exciter also provides an auxiliary 115 volts DC

for accessories.

The second generator is the welding generator. This generator produces a

regulated constant current output that produces the wonderful arc, that the

welder’s love. The fig below shows a typical Lincoln SA-200 generator set.

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Figure 1; Lincoln SA-200 generator set

2.2a EXCITER PARTS LOCATION AND DEFINITIONS.

The graphic below is a standard Lincoln SA-200 exciter with cap removed.

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Figure 2; lincoln SA- 200 exciter.

Facing the machine from the front the parts are named as follows:

1. The right hand brush holder is the positive spring loaded brush holder.

2. The left-handed brush holder is the negative spring loaded brush holder.

3. Behind the right brush holder is the right exciter coil.

4. Behind the left brush holder is the left exciter coil.

5. The exciter armature is held onto the armature shaft by nut secured by a

lock washer.

6. The brush springs the hold the brush in place.

2.2b HOW IT WORKS

The exciter coils and the poles pieces form electromagnets. When DC current

flows through the exciter coil, the magnetic fields produced by the exciter coils

are broken by the winding on the exciter armature producing approximate 115

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volts DC at full RPM. The faster the engine turns the more voltage the exciter

produces.

The system is a series wound compound generator, with an additional shunt coil

across the exciter armature. The fine current control (heat control) rheostat varies

the exciter voltage that is applied to the main stator shunt coils, the variable

control the output current (heat) of the arc.

2.3 TROUBLE SHOOTING THE EXCITER FIELD COILS

In fig c below, the wiring diagram, you will see that there are two halves of the

exciter circuits. The exciter generator produces 115 volts DC that is fed to the

auxiliary power outlet and to the main exciter shunt coils. This DC current is

varied by the fine current control rheostat (like a valve) then fed into the main

exciter shunts coils. This controls the strength of the magnetic field, which

controls the amount of welding current that is a variable .A fault in either circuit

or the machine will not weld if the failure is in the exciter shunt circuit the

generator can still produce power. This can be verified by checking the auxiliary

with a meter, light or a grinder if you can grind but not weld the exciter shunt coil

is faulty.

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Figure 3; the two halves of an exciter circuit.

2.3a HOW TO TROUBLE SHOOT THE MAIN EXCITER SHUNT COILS

I. Reach under the exciter armature and locate the black and blue leads, the

wire should be connected with a butt splice or bolted together. If they are

spliced or connected with bolt and nut, you must break this wire apart. It’s

only then will you be able to check the coils separately.

II. To check the exciter field coils, remove both exciter brush from their

holders and make sure they do not touch anything while making

measurement with the VOM on the lowest resistance scale you can use,

check resistance between the right brush lead to each to the separated

wire. If the wire is good, one wire will show resistance, the other will not,

this is normal. The resistance should be approximately 130-170 ohms. If

you get no resistance go to the next higher range (make sure you do not

touch the lead with your hand else you could be reading the resistance of

your body.)

III. The next thing to check is the resistance from each coil leads to the outside

terminal (it may have a red wire attached) of the fine current control

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rheostat. One of the wires will show continuity, between the lead and the

rheostat. Both measurements should be identical.

IV. If the measurement shows very high resistance or an “open coil” infinite

resistance, or a very low resistance(less than 100 ohms) the coil must be

replaced.

V. If the coils check out ok, then the exciter armature will be the next to be

suspected.

2.3b TROUBLE SHOOTING THE EXCITER ARMATURE

The defects to look out for when trouble shooting an armature includes:

1. Burnt or blacked commutator bar. Before further check, clean the

commutator with a commutator cleaning stone. It is not normal for

brushes to deposit enough carbon powder to contaminate the

commutator.

Note: that a properly maintained commutator should be the colour of a

used burnished penny.

2. Inspect the windings for any burnt insulation, broken wires, or damaged

commutator bars. Armatures have two problems. A winding that is

shorted to the armature shaft or broken (open) windings.

Note: if a bright green spark is seen when the unit is running. That is a

sign of a shorted (to ground) armature winding.

3. Check for an armature shorted to ground. With the VOM set to the

highest resistance range to check for a short to ground. This is done by 11

placing one lead to a clean spot on the armature shaft. With the other

lead check each commutator bar. If there is any resistance reading in

any of the cummutator then the armature needs to be replaced.

4. Sometime a high bar may occur. A high bar simply means that one of the

commutator bars has come loose and is sticking up. This makes the

brush jump and results to excessive sparking.

2.3c FLASHING THE FIELD

The exciter field coils are held in place with solid iron “pole piece”. The

special pieces of iron do more than just hold the exciter coils in place. They

retain a small amount of residual magnetism just a bit. They hold a small

amount of residual magnetism to provide “self-excitation” so the exciter

will start generating current from a dead start. The pole piece can lose their

magnetism as the unit sits idle for a long period to time and there is no easy

test to detect the loss.

When the exciter field coils, the brushes, and the exciter armature check

out, the only thing left to do is “flash the field”. This is normally done with a

12 volts car battery, not with standing in front of the machine in a trench

coat. This is how it is done:

1. Remove the exciter dust cover.

2. Connect jumper wires first to the battery then to the exciter brush

terminals.

3. Start the engine and makes sure it is running at its slow speed.

4. Connect the positive (+) lead to the right brush lead terminal.12

5. Touch the negative (-) lead, to the left brush lead terminal, you will

generate a strong spark. Hold the lead on the terminal for

approximately two seconds there will e strong spark the field poles

will be “flashed”.

Figure 4; shows parts of an exciter that is being flashed.

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The other machine that we repair and service at the work shop includes; grinding

and cutting machine. They are mostly used by the welders, carpenters, panel

beater and on rear occasion by electricians. They are used for cutting metals,

woods, smothering rough surface, cutting almond cables etc.

2.4 HOW TO TROUBLE SHOOT A GRINDING AND CUTTING MACHINE:

1. Check if the wire terminal at the plug of machine is still tightly

connected.

2. Check for continuity of the wire. This is done by placing the leads

of the VOM at the neutral and life components of the wire. If a

sound is heard from the VOM, then the wire is in good condition.

3. Check if the carbon brush at both sides of the machine located

beside the armature is worn off. If the brushes are worn off then

they should be changed or replaced.

4. If all the listed above have been checked and rectified and still the

machine doesn’t work at all, or if it does, it brings out offensive

odour, only then do we go further to check the armature.

On checking the armature, if it is covered with a black substance, it is burnt and

should be replaced or rewired.

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CHAPTER THREE

3.0 CONDUIT WIRING

It is an electric piping system used for protection and routing of electrical wiring.

It may be made up of metal, plastic, fiber or fired clay. The term conduit is

commonly used to describe any system that contains electrical conductor but it

has a more restrictive definition when used in wiring regulations.

Conduit wiring provides mechanical protection and electrical safety to persons

and property and provides convenient accessible ducts for the conductor. A well

designed conduit wiring system has adequate capacity for future expansion.

Varying number, types and size can be pulled into a conduit which simplifies the

designs and constructions compared to multiple runs of cable. Frequent wiring

changes are made simple and safer through the use of electrical conduit, as

existing conductors can be withdrawn, and new conductors installed with little or

no disruption along the path of the conduit. Some types of conduit are improved

for direct encasement in concrete. This commonly use in commercial building to

allow electrical and communication outlet to be installed in the middle of large

open areas.

Metal and plastic conduit can be bent in the jobsite to allow neat installation

without excessive number of manufactured fittings. This is particularly

advantageous when following irregular or curved building profile. Conduit wiring

is more expensive than other forms of electrical wiring. One major disadvantage

of the type of wiring is that it doesn’t dissipate heat as readily as those installed in

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open wiring. Therefore it is advised that the current capacity of each the

conductor be reduced.

3.1 TYPES OF CONDUIT WIRING

i. RIGID METAL CONDUCT (RMC)

It is a thick treaded tubing usually made of coated steel, stainless and aluminum.

It is the thickest and heaviest of all other type of conduit, and it can be use to run

wire under drive way, service feeder installation in extreme conditions.

Ii. GALVANIZING RIGID CONDUIT (GRC)

It is a galvanized tubing system. It common applications are in commercial and

industrial construction.

Iii. ELECTRICAL METALLIC TUBING (EMT)

It is sometimes called thin wall. It is commonly use instead of GRC as it is less

costly and much lighter, though it is damage easy.

Iv. FLEXIBLE METALLIC CONDUIT (FMC)

It is made through the coiling of a self-interlocked strip of aluminum or steel,

forming a hallow through which wire can be pulled. It is used mainly in dry areas

where it would be impractical to install any non-flexible conduit, yet where

metallic strength would be required. It doesn’t maintain any permanent bend.

Typical examples of where flexible conduit is applied are in water heaters, attic

vent etc.

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V. ALUMINUM CONDUIT

It is similar to galvanized steel conduit. It is a rigid conduit generally used in

commercial and industrial application (in food processing plants) where higher

resistance to corrosion is needed. Aluminum conduit cannot be directly

embedded in concrete since the metal will react with alkalis in the cement.

Vi. POLYVINLY CHLORIDE CONDUIT (PVC)

This is the most commonly used type of conduit because it is the lightest and

cheapest compared to other conduit materials. The thin-PVC are only burial and

exposed work.PVC resist moisture and any corrosive substance. Since PVC has a

higher thermal coefficient of expansion other types, it must be mounted so as to

allow for expansion and contraction for each run. Since it is not conductive it is

advised to always run green grounded (earthing) wire in the conduit for proper

grounding method at connection. One major reason why PVC is preferred in

conduit wiring is because it is insulated. The figure below show a typical example

of a PVC in a junction box.

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Figure 5; PVC conduit pipe.

3.2 FITTINGS FOR PVC CONDUIT WIRING.

* Box connectors; they join conduit to a junction boxes.

* Couplings; it connects two pieces of conduit bodies together.

* Condulets; they are used to provide access to wires placed within the conduit it

differ from a junction box which allows access for pulling wires and space for

splicing. Condulets are in various types, moisture rating and materials including

galvanized steel, aluminum and PVC. Some of the Condulets includes L-shaped

bodies, T-shaped bodies and –shaped bodies. The figure below show some fittings

for PVC wiring.

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3.3 PIPING FOR PVC CONDUIT WIRING

MATERIALS NEEDED; PVC pipe, bending spring, male brush PVC adhesive, Y-

way junction box, U-junction box, 4-way wire coupling, knockout boxes, nails

sledge hammer, claw hammer, wire strippers, hack saw, flat headed screw

drivers, files, PPE. Etc.

Piping is mostly done before plastering or decking, in cases where the piping is

done before plastering is done, then the walls have to be broken and holes

bored through which the pipes will pass. When passing a pipe through a

junction, the PVC pipe needs to be bent using a bending spring, also if the lent

of the pie will not reach to its destination, couplings and adhesive gums are

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used to extend the length. It is important to note that during pipe, outlet

boxes for switches, lightning sockets are connected.

3.4 WIRING FOR CONDUIT

This is done after the piping activity. Here the major tools used are; scaffold,

fishing tape, wires of various sizes depending on the circuit being wired. The

table below shows the sizes of cables used in some wiring units.

Table3.0

WIRING UNITS SIZES OF CABLES USED

Lightning points/ ceiling fans 2xI.5mm PVC single core cable

13Aswitch socket outlet 3x2.5mm PVC single core cable

15A switch socket outlet 3x4mm PVC single core cable

Air conditioners, water heaters ,

cooker control units

3x4mm PVC single core cable

3.5 SURFACE MOUNTING RACE WAY/ TRUNKING

This type of decorative conduit is designed to provide an aesthetically acceptable

passage for wiring without holding it inside or outside a wall. It is used were

additional wiring is required and were going through a wall will be difficult. A

conduit has an open face with removable cover secured to the surface and the

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wires are placed inside it. It is often used for telecommunication wiring such as

network cables. Aside from the fact that if the appearance may not be acceptable

to the observers, one of the major advantage is that it is easily be accessible for

future changes, thus enabling minimum effort upgrading.

3.5 LIGHTENING ARRESTORS AND EARTH PIT

Lightning rods are designed to give lightening a safe part to travel if it happens to

hit a house. The lightening rod takes the lightening along a part through the

ground where it is dispersed without harm to the building or its inhabitants.

Installation is carried out by connecting the upper layer to the down layer with

the connecting lead. The upper part consist of the following

Gold plated centered needle

Gold platted 45c bended flat needles

Gold plated 90c bended needles

Gold pated base ball

Positive conductor

Parabolic dish steel clamp.

The down layer include

Negative conductors

Copper plate

Plate connectors

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Connecting lead consists of 20mm/2m copper stripes. The copper stripes are

thoroughly insulated and concealed within a PVC pipe from upper layer to down

layer.

Pre-requisites for installation

GI pipr ¾

PVC pipe(1)

Earth pit

Charcoal

Bentonate powder

In the earthening system, the ground electrode provides physical connection to

the mass of the earth and negative conductor is used to deliver faulty current to

it. In the lightening protection, the role of the earthening system is to dissipate

the lightening current into the earth as quick as possible whilst minimizing the

ground potential rise and maximizing the potential fall off from the current

injection pit.

Bentonate powder and charcoal provides conductivity to the earth. It should

be noted that the cable should not be bent sharply to a ‘U’OR ‘V’ formation at any

point. The cable should run horizontally or downward to the ground. Coppers

should not be used along side with aluminum roofing.

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3.7 EARTHING PIT

Earthing resistance of an electrode is dependent on several factors including; Soil

resistance, Contact resistance of the electrode to the earth, Resistance of the rods

couplers and connection.

Items needed for the construction of earth pit

Rod material

Couplers

Driving equipments

Wires

Installation ground rods should be 10-12 foot long. The couplers should be used

to couple the rod together in such a way as to limit soil contact with the surface of

the additional rods. Only the first rod will maintain a soil contact. Mechanical

drivers are necessary to drive the rods deep into the ground; however, the rod

material coupler designed must be able to withstand the force necessary to drive

the rod into the sub-soils. To maintain full rod to soil contact a slurry mixture of

sodium betonite (naturally occurring clay) is injected into the coupler void as the

rods are installed. This provides conductive material between the rod surface and

the soil over the depth of the rod. Electrode depth of 30-60feet are more

effective and practical than that of 8-10 foot because resistance of a shallow

electrode will vary greatly as seasonal conditions changes. Due to the high earth

resistance, the typical shallow electrode is unable to maintain an electrical system

at earth potential during transient voltage conditions of lighting. While deep

installed electrodes provides stable resistance of less than 5 ohms.23

3.8 CONSTRUCTION OF AN EARTH PIT

Before an earth pit is constructed, the follow points must be taken into

consideration.

i. The location of the pit should be such where the soil has reasonable chances of

becoming moist. This is because low earth resistance is required to give effective

earthling protection to electrical fittings and a moist soil has such quality.

ii. If possible earth plates or pipes should be located near water tap, water drains,

or rain water pipes.

iii. Earth plates and earth wires must be of the same metal.

iv. Wood coal powder (charcoal) and salt must be filled in the earth pit around the

earth pipe or plate.

v. the position of the earth plate or pipe when fixed should be clear from all

building foundations.

vi. A masonry enclosure should be made over earth pit.

vii. Entrance, pavement and roads are definitely avoided for locating the earth pit.

vii. Inside the building, in addition to all electrical appliances, all switches boxes

etc. should be earthed too.

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CHAPTER FOUR

CONCLUSION

4.0 Skills Acquired

By virtue of this training I received, I have acquired the following skills

from my SIWES work place.

I got a firsthand knowledge of some electrical industrial equipment like the

grinding cutting machine, industrial generating set, electrical mobile panels,

circuit breakers, miller welding machines etc. Not only was I exposed to this

equipments, I learnt the principles with which they operate in.

I learnt the proper use of electrical tools such as the AVO meter, screw

drives, spanners, cutting machines etc.

I was privileged to attend a number of tool boxes, safety briefings. This

enlightened me a lot on the risks and hazards involved in the electrical

world

Ability to work effectively in a team and to communicate effectively with

others in related field. It also gave me the opportunity to learn about good

work ethics and good interpretation and communication skills.

My industrial training has positively contributed to my training as a future

electrical/electronic engineer. It helped me broaden my view on what is

expected of me as a prospect engineer.

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4.1 Problems encountered my SIWES.

1. One of the major problems I encountered was getting an ideal industrial

placement. Ideal the sense that the company suits with course of my study.

As a result of this, I was forced out of frustration to settle for something

close to what is needed(that is, going to company that does something

close or related to my course of study)

2. At the cause of my training, I was not closely supervised by neither

university nor industry based supervisor. I was not given project or research

to carry out and this slowed down my learning process.

4.2 Ways of improving the SIWES programs

1. The SIWES management should make provision for automatic

placement of students in related industries.

2. Institutions and SIWES management should provide effective

supervision of students during then period of industrial training

experience.

3. T he SIWES management should go through the federal government to

make sure all the industries are involved in providing effective industrial

training opportunities for students and also ensure that they are given

benefits.

4.3 Advice For Future Participants

1. Students should have in mind the main aim of the SIWES and offer

themselves better alternatives rather than settling for anything. Better

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alternatives in the sense that, instead of just working in any organization

for the sole purpose of getting money, they should enroll in institutions

that will impact more practical knowledge even if they have to pay for it.

2. They should also start their placement application on time, so that they

can be attached on time.

3. They should learn the art of getting involved by observing earnestly,

asking question, carrying out assignments and tasks judiciously, because

that is basically the only way they can acquire true knowledge.

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