electrical engineer pupilage training

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NATIONAL POWER AUTHORITY

REPORT ON PUPILAGE TRAINING AT THE

GENERATION DEPARTMENT-KINGTOM POWER

STATION FROM 1ST SEPTEMBER TO 31ST DECEMBER

2010

AS PART FULFILMENT FOR THE CONFIRMATION TO

ENGINEER

SUBMITTED TO: GENERATION DEPARTMENT-

KINGTOM

PREPARED AND SUBMITTED BY: MOMODU MANSARAY



ELECTRICAL ENGINEER (PUPIL)

JAN.2011

BACKGROUND:

Generation Department:

The Generation Department is one of the key departments in the overall operations

of the National Power Authority. This Department has the responsibility of

Generating Electrical power to the entire capital city of Freetown and its immediate

environs .The Department is housed at the Kingtom power station.

The Kingtom Power Station:

The kingtom power station has served as the main generating point for electrical

power Generation to the Capital city of Freetown and its immediate environs. This

was achieved through the use of thermal generators since 1965 when it was official

opened to take over this function from the older power stations of Blackhall Road

and Falcon Bridge.

Presently Kingtom power station is on standby i.e. none of the thermal generators

are running. Unless for the two Thermal Generators rated 5 MW each which were

installed by the Japanese International cooperation agency (JICA) Known as Niigata

Machines .These generators are only run when there is dare need. E.g. drop in the

output capacity of the other sources of generation.

Electrical power generation is from the following sources other than these Niigata

machines housed at the kingtom power station:-

Independent power providers (IPP)

1 Global Trading Group (GTG) at Kingtom

2 Bumbuna Hydro Electric Corporation



Generation Departmental structure

Generation Manager

Operations

Confidential

Electrical Mechanical

Monitoring of

Generating

Recording

readings of Stores

Planning

General

Electrical

General

Mechanical

Cleaning of

Generating

Planning of

routing

Making report

on Units



1st -30th September

ELECTRICAL MAINTENANCE

Electrical maintenance section has the responsibility to ensure that all electrical and

electronics control and protective devices within the operations of generating

electrical energy up to the point of transmission are operative and functional.

These equipments and devices must operate to make or break contacts as and

when the situation desires for the proper operation, protection and control of the

system.

Periodic tests are carried out on instruments. E.g. protective and control devices

and also other equipments to ascertain their integrity. Some of these devices are

housed on the main control panel. Examples are;

Instantaneous earth fault relays

Instantaneous over current protection relays

Distance protection relays

Negative sequence protection relays

Directional relays

Differential relays

Over/under voltage protection relays

Neutral Displacement protection relays

Rotor earth fault

Field failure/negative phase sequence



This section is also responsible for all electrical installations and maintenance in the

Power Station. It carries out maintenance practices based on the following

demands.

• Schedule maintenance

• Corrective maintenance

• Routine maintenance

The overall objective is to maintain satisfactory performance of all electrical

components and systems of the engines.

Some of the activities of this section include:

• Install, test and commission all electrical control panels, switchgears and

other auxiliaries using the manufacturers’ diagrams

• Inspect/check panels for cable defects, burnt contactors, blown fuses and

repair/replace the affected accessory/equipment

• Install/inspect auxiliary pumps/motors, repair burnt motor windings and

address damage to pumps

• Check the automatic voltage regulator performance

• Inspect the alternator periodically with a view to carry out maintenance if the

engine had been out of operation for a long period

• Inspect/check exciter against voltage effect, resistance/temperature, test

alternator rotor/stator windings of the engine

• Carry out fault diagnosis and resolve those related faults using diagrams

• Check/service government functionaries standby generators

• Regular inspections/servicing of the system high tension panel andswitchgears and other electrically driven equipments (cranes)

• Carry out maintenance on the lighting/power system within the PowerStation

and staff quarters

• Any other electrical work that may be assigned to the section by the

Generation Manager



SWITCH GEAR ROOM

At the switch gear room the brand and type of switches are mainly the Yorkshire –

F6 switch gear. Their current rating is 630A and 1250A for feeder and generator

breaker and 2500A Bus-Bar rating. The other type found in the switch gear room is

the Merlin Gerlin type of fuses also rated at 630A.They are gas operated switch

gears and can be charged automatically or manually .Some are remotely operated

from the control room whilst others are manually operated down in the switch gear

room.

Though electrical power generation is now from different generating sources like

the GTG, Bumbuna and Niigata most the generated electrical power has to gothrough the 11 KV bus bar systems at the Kingtom power station. This is achieved

by means of synchronizations. I.e. voltage, Phase angle and frequency must match.

Also there are other supply points from the Bumbuna which does not pass through

the 11KV system arrangement at the kingtom power station. One such supply goes

straight from the 161KV transformer sited at the Bumbuna Freetown Site at

Kingtom to Congo Cross 2 through the JICA newly constructed overhead lines and

the other feed is known as Mandalay2

Though the following machines were not operational,

Sulzer 4&5;

Mirless 1 & 2;

Mitsubishi and

Caterpillars

Their alternator systems and the method of excitation is hereby explained below

ALTERNATOR SYSTEM

SULZER MACHINES:

Excitation by commutation- brush type alternator (magnetized by

flashing).

1. After rated speed (synchronous) is achieved, the field switch in the control

room is closed thereby closing the field breaker.



2. The field flashing unit (time lag delay off operation) that is incorporated in the

field breaker closes to energize the excitation stator windings (creating field)

3. The excitation rotor winding produces voltage that is sent through the

commutator (Pulsating switch) that rectifies the AC voltage to pulsation DC

voltage

4. The pulsating voltage then supply the main rotor coil through the field

breaker and slip rings (+ve & -ve)

5. The energized rotating rotor (current carrying conductor) develops fluxes that

cut into the main stator winding. A voltage is produced in the main stator

winding (11kV), since the flash circuit initiate the process, when about 40% of

output voltage is produced, the flash field circuit disengage through time lag

relay and then the AVR unit comes into operation to supply the excitation

voltage (receiving supply through the AVR transformer, 11Kv/50V)

6. Part of the 11kV is passed through a step down transformer (excitation

transformer) to produce 50V A.C (maximum output) that is now sent to the

AVR while the bulk of the power is sent to the main bus bar via 1250 Amps

circuit breaker

7. The supplied AC power to the exciter stator winding is now rectified as it

induces power into the exciter rotor winding through a commutator (pulse

switch that produces a pulsating voltage (+ve and –ve). In this way a DC

power is produced and sent into field breaker and the process continues on

and on. The AVR unit continues to monitor and stabilize the output voltage.

CATERPILLAR, MIRRLEES AND MITSUBISHI:

A self-excitation, brushless with permanent magnet alternator

1. As the rotor of the alternator starts rotating with synchronous speed the PMG

automatically energize the AVR to initiate the magnetizing process

2. The breaker of the AVR then make available the correct AC voltage for

excitation process

3. An auxiliary contact of the field breaker (interlock contactor system) is

closed; further energizing the exciter main stator coils by manually closing

the field switch on the control room panel

4. The exciter rotor then produces a three phase AC voltage that goes through

six diodes for rectification (three +ve and three –ve)



5. This rotating diode then rectifies the AC voltage into DC voltage that is

conducted into the main rotor field coils along a common shaft

6. The energized rotating rotor (current carrying conductor) develops fluxes that

cut into the main stator winding

7. A voltage (about 11kV) is produced in the main stator winding

8. Part of the 11kV is passed through a step down transformer (excitation

transformer) to produce 50V ac (maximum output) that is sent to the AVR

while the bulk of the power is sent to the main bus bar. The AVR isolate the

PMG from the system when about 40% of the output voltage is produced

The supplied AC power to the AVR then continues the excitation process

endlessly. Since Mirrlees 2 output voltage is 6.6kV, an inter bus transformer

(6.6kV/11kV) is installed between the AC output and the 11kV switchgear

room

EXCITATION SYSTEM

The exciter rotor is a three-phase AC with six leads (three to a +ve plate and three

to a –ve plate) for diode connection. The diodes are connected to form a full wavebridge rectifier. These rotating diodes are mounted on an alluminium heat sink.

A varistor (non-linear resistor) is connected across to DC terminals from the rectifier

to prevent surges generated in the main field coil (winding) from damaging the

diodes. The principle is also applicable to the Caterpillar, Mirrlees 2 (brushless

alternator) and Mitsubishi engines respectively. The Sulzer engine has a

commutator (instead of rotating diode) slip ring, variable resistor (instead of

varistor)

EXPERIENCE GAINED:

During the training I participated in the following electrical maintenance work.

• installation of a new YSF6 Cubicle switch gear



• repair work on the overhead crane in the power house

• the drain pit pump motor control system

• installation of an AVR on a 60KVA Gen. set

• refurbishment of one YSF6 cubicle switch gear

• Work and function test on the automatic transfer switch at President Lodge

after Lighting strike

1st-22nd October

MECHANICAL MAINTENANCE:

This section is responsible to work on all breakdown of machinery that is

mechanical. They either fabricate these parts by the use of the lathe machines

where necessary or put in requisition for the supply of the worn out parts to stores.

Where these parts are not available in the stores, then an order is placed with the

full knowledge of the Management of the generation department to the

Management of the authority

This section is now a shadow of it former status as the only machines which are now

operational are the Niigata machines which are very new ones and far fromdeveloping major mechanical problem as they are seldom used. Even if mechanical

faults may occurs these machines are still under the warranty period.

Maintenance methods and practices is the key to the proper functioning of this

section.

In the event of a less strategic maintenance work, skilled personnel undertake such

maintenance while highly strategic jobs require the services of expatriates or

consultants even though the bulk of the work is being carried out by local

personnel.

Basically, corrective and preventive maintenances were carried out at the Kingtom

Power Station.

Corrective maintenance

This is an unplanned maintenance as it is carried out on an emergency basis.

Corrective maintenance is subdivided into:



• Breakdown maintenance and

• Plant defect corrective maintenance

Preventive maintenance

This is a scheduled and planned maintenance.

Preventive maintenance is also subdivided into:

• Planned maintenance

• Routine maintenance

Breakdown maintenance is carried out without proper planning and hence a

predetermined downtime of the plant could not be determined. The unavailability of

readily needed spare parts to bring the plant into operation at the shortest possible

time could be a major constraint.

Plant defect corrective maintenance is carried out on the plant to arrest defects that

might not sometimes necessarily lead to the shutting down of the plant as it does

not have any performance reduction effect on it and pose no threat to its smooth

running. The execution of such maintenance job can be deferred to coincide with

the plant shutdown to reduce engine down time. If however the defect threatens

the smooth running of the engine, it is shut down to arrest the problem

immediately.

Planned maintenance jobs (major overhauls) are executed following a long term

planning of activities to be undertaken without the plant necessarily breaking down.

Such maintenance is guided by the recommendations of the manufacturer that

would include the necessary spares, maintenance activities, and duration for the

successful completion of the job. When necessary, the services of expatriates are

sought for which detailed report is submitted by the consulting firm at the end of

the job.

Routine maintenance practices rely on recommended set of job activities that

should be executed within a stipulated time frame set by the manufacturer. The

operational performance, the working environment and the hours run of the plantare taken into consideration and the time interval adjusted to suit the prevailing

circumstance. Samples of maintenance work order are also submitted to give a clue

on few of the maintenance activities carried out under this type of maintenance.

With this type of maintenance practice in place, breakdowns are minimized, engine

lifespan prolonged and operations cost reduced.



The Central workshop

The central workshop is an auxiliary arm of the Mechanical Maintenance section and

is headed by a Workshop Superintendent taking directives from the Senior

Maintenance Engineer.

Some of the activities carried out by the Mechanical Maintenance section include:

•• Inspecting and servicing of turbochargers, cylinder heads, injectors, pistons

•• Major overhauling of engines

•• Inspecting of water and fuel supply lines for leakages and carry out the

necessary repairs

•• Checking the status of the various pumps and motors

••

Inspecting and servicing of oil coolers

•• Replacing of defective fuel valves, relief valves and filters etc. etc.

During the period of my training there was not much going on at the kingtom power

station in terms of mechanical maintenance work as the station is on standby and

hence the mechanical maintenance section is therefore engaged in servicing out of

station machines sited at the following places:

• State Lodge

• Parliament

• VP lodge

• VP Office

• State House

This has now lead to massive transfer of staff from this section to other area within

the Authority

This section mostly works in conjunction with the electrical maintenance section for

all provincial stations that have Generators run by NPA.

EXPERIENCE GAINED:



As the maintenance work within the power station was low key we used the

opportunity to visit all out stations to ensure that the machines were properly cared

for by the Engine attendants and electricians deployed at the site

Checks carried out before these generators at the various stations were started

include:

• Coolant level

• Lubricating Oil Level

• Radiator and Alternator fan Guards properly secured

• Fan belts tension

• Look for other leakages

Other than going out of the kingtom power station my training with the Mechanical

maintenance also included taking me on a conducted tour of the setup of the fuel

pipe lines from the fuel storage tanks for MFO (marine fuel oil) unto the service tank

for all the Generators installed in the power station including the two Sulzers and

the Mirless machines. During this tour I was shown the following equipments and

items listed below and their functions

Transfer pumps, Regulating tank, Boiler, Purifiers,

Electric Heaters, Boaster pumps, Filters,

Service tanks, Compressor, Air bottle

ENGINES CHARACTERISTICS

SULZER ENGINE

•• Two-stroke

•• In-line block (8 cylinder)

•• Low speed (150 rpm )

•• Air and water cooled: water to a greater extent and air to a lesser extent

•• Air intake by scavenging

•• Has only intake and exhaust ports



•• Air starting

•• Designed to consume both heavy and light fuel

MITSUBISHI AND MIRRLEES ENGINES

•• Four-stroke

•• V-block (16 cylinders for Mitsubishi and 12 cylinders for Mirrlees )

•• Medium speed (750 rpm for Mitsubishi and 600 rpm for Mirrlees )

•• Only intake and exhaust valves present

•• Both air and water cooled: water to a greater extent and air to a lesser

extent. The air cooling is an added benefit from the scavenged air.

••

Air starting

•• Designed to consume both heavy and light fuel

CATERPILLAR ENGINE

•• Four-stroke

•• V-block with 16 cylinders

•• High speed (1500 rpm )

•• Electric starting ( with batteries )

•• Consume light fuel only

Working cycles

The working cycle of an engine may be four-stroke or two-stroke; and the enginemay be single-acting or double-acting. These cycles are mechanical sequences of

events for the functioning of the machine. The working cycle (induction,

compression, expansion, and exhaust) is basically the same on both two-stroke and

four-stroke engines but the individual phases take place at different times and at

different points on the engine.

Operating principle of the two stroke engine



The two-stroke engine needs no separate components to control the gas

flow. This is the main feature which distinguishes it from the four-stroke engine.

Gas flow is normally controlled by the piston and takes place through slots (ports) in

the cylinder wall.

In contrast to the four-stroke engine, the two-stroke engine needs onlyone complete crankshaft revolution to perform its working cycle.

In order to perform the complete operating cycle within a single crankshaft

revolution (two piston strokes) on the two-stroke engine, both the cylinder and the

crankcase must be used for the gas flow. The crankcase together with the lower

part of the cylinder and the piston acts as a pump and must therefore be pressure-

tight to atmosphere. Since there are three different kinds of duct entering the

cylinder on this kind of engine, it is referred to as a three-duct two-stroke engine.

The inlet duct leads to the crankcase. The exhaust duct leads to the exhaust

manifold. The transfer duct connects the crankcase to the cylinder. The ducts

terminate at slotted ports in the cylinder wall.

Piston moves up from BDC to TDC

Processes in crankcase

After the piston has closed the transfer port, a partial vacuum to a certain pressure

builds up in the crankcase as a result of the overall volume increasing. This is called

the pre-induction phase. When the piston exposes the inlet port, the actual inward

flow of fuel-air mixture for the next working cycle commences.

Processes in combustion chamber

After the piston has closed the exhaust port, it begins to compress the mixture,

which is ignited just before TDC is reached.

Piston moves down from TDC towards BDC

Processes in combustion chamber

During the working stroke, the pressure generated by the combustion gases moves

the piston down

Processes in crankcase

After the piston has closed the inlet port, pre-compression of the fuel-air mixture up

to a particular pressure commences

The gas transfer process (above and below the piston)



The gas transfer process takes place at the point when the next working cycle is

due to start. First of all, the top of the piston exposes the exhaust port, which is

slightly higher up the cylinder, so that the burnt gas is violently expelled from the

cylinder. After this, it exposes the transfer port, and the pre-compressed fuel-air

mixture from the crankcase scavenges the cylinder and expels the exhaust gas as it

enters.

When the piston has moved up far enough to cover the transfer port and the

exhaust port, the cylinder scavenging process is completed

The two-stroke engine uses an “open” gas flow principle.

This means that both the exhaust and transfer ports are open at the same time for

most of the duration of the gas transfer process.

Operating principle of the four-stroke diesel engine

Each working cycle (four working strokes) takes two revolutions of the crankshaft to

complete.

Stroke 1- induction: The piston moves and creates a partial vacuum in the

increasingly large cylinder space above it. This results in a suction effect when the

inlet valve is opened. Filtered fresh air is drawn in through the open inlet valve. This

air absorbs heat from the valves, piston and cylinder wall.

Stroke 2- compression: the valves are closed, and the piston moves up the

cylinder and compresses the air previously drawn in. The air is compressed in the

combustion chamber to a pressure of 30 to 55 bars and thereby heated to a

temperature of between 700 and 900°C. Towards the end of the compression

stroke, finely atomized fuel oil is injected.

Stroke 3- expansion (working stroke): the fuel injected towards the end of the

compression stroke vaporizes at the high temperature in the combustion chamber,

and mixes with the hot air. This mixture is capable of igniting itself. The resulting

combustion pressure forces the piston down.

Stroke 4-exhaust: the exhaust valve opens and he combustion gases are expelled

at high pressure to the exhaust system, or forced out by the piston

ENGINES OPERATING SYSTEMS

All the engines are characterized by the following operating systems:



• Cooling system; comprising of the tertiary cooling loop (sea water),

secondary cooling loop (fresh water)and primary cooling loop (fresh water)

• Air starting system; comprising of starting air, air bottles, intake and

exhaust systems

• Fuel system; comprising the heavy fuel oil, light fuel oil or both

• Lubricating system; comprising the system oil and sump oil

Cooling system

The purpose of the cooling system is to dissipate to the atmosphere the heat which

builds up in engine components such as pistons, cylinder block and cylinder head

and in the engine oil. The cooling system is necessary because the heat resistance

of the materials used in the engine and of the engine oil is limited. As a result someconsiderable percentage of the thermal energy obtained from the combustion

process is lost. Effective cooling permits higher engine performance as a result of

improved filling.

The cooling system at the power station can be divided into two:

• The Sulzer and Mirrlees engines use the same cooling system

• The Mitsubishi and Caterpillar engines use the radiator type cooling system

For the Sulzer and Mirrlees engines, water via electrically driven pumps fitted with

strainer baskets is drawn from the sea and then delivered to four Alfa Laval made

flat plates heat exchangers (seawater flat plate heat exchangers connected in

parallel) installed outside the power station. Heat exchanging between the seawater

and hot water coming from a fresh water heat exchanger via a collecting tank takes

place. The hot seawater after the exchange process discharges into the sea at the

opposite end. The seawater forms part of the tertiary cooling loop (open circuit) and

the hot fresh water coming from a pair of fresh water heat exchangers installed at

the basement of the power station (which are smaller in size as compared to the

ones installed outside the power station) via a hot water collecting tank/pit formpart of the secondary cooling loop. The hot fresh water that goes through the

seawater heat exchangers becomes hot as a result of heat exchanging with fresh

water that directly cools the engine components. This fresh water forms the primary

cooling loop and is in a closed circuit.



The Mitsubishi and Caterpillar engines have their own separate cooling system.

They operate on radiators. The lost heat is dissipated from the engine by means of

water, which is re-cooled in the radiator.

Some Components cooling

a) Cylinder Jacket and Turbocharger cooling:

A closed circuit with a header tank is used. Fresh water, suitably treated to

prevent scale formation and corrosion, is circulated by an electrically driven

pump and cooled in a heat exchanger.

Air vent cocks are fitted at the highest points of the system and these should

be connected by continually rising pipes of generous size to a common rising

pipe leading to the expansion tank.

b) Fuel-valve cooling:

A separate closed fresh-water cooling system is used for cooling the fuel

valves. It has an electrically driven pump, a heat exchanger, heater and an

overhead expansion tank. The fuel-valve casings are connected in parallel

with shut-off valves in each inlet and outlet line, which enable each valve to

be dismantled without draining the whole system. An inspection cock is fitted

to each outlet line from the fuel valves. The surface of the water in the

expansion tank should be examined regularly, and, if traces of fuel are thenseen by observing the water bled-off from the inspection cocks, the faulty

fuel valve can be located quickly.

c) Piston cooling:

An independent open fresh water cooling system is used for piston cooling.

An electrically-driven pump draws the fresh water from a collecting tank and

supplies it through a heat exchanger, to a manifold extending along the

engine under the first platform. The pistons are circulated in parallel and the

outlet from each is taken to a flow indicator, before joining-up in a manifold

leading to the collecting tank.



Air starting system

Air starting is almost universal for large engines (requiring a storage tank plus a

compressor). The compressed air is piped to the storage tank. At the power station,

all the base load engines require air for starting. The air is being produced from

electrically driven air compressors and is stored in steel air bottles fitted with airpressure gauges to indicate pressure level. The engine starting air pressure is

maintained at a minimum pressure of 20 bars. The steel air bottles are however

interlinked through pipe networks to allow for flexibility in the use of a compressor

for starting various engines. Other components include the charged air cooler,

turbocharger, etc.

Fuel system

The task of the fuel supply system is to deliver to the fuel injection system with

sufficient fuel in all operating conditions. The fuel system comprises of both light

and heavy fuel oil.

The light fuel oil (diesel) is stored in the main diesel storage tank from where it is

pumped into the day tanks of the different engines via a transfer pump. From the

day tanks, delivery into the injectors is made possible with the use of a booster unit.

This unit increases the fuel pressure delivered to the injectors and consists of

duplex fuel filters which could be switched over from one filter to the other during

running for the purposes of cleaning. A change over 3-way switch is provided to

regulate the type of fuel required.

The heavy fuel oil also has its main storage tank. It is the main fuel oil that is used

by the base load engines and it is highly viscous containing impurities like water,

metallic components etc. which need to be considerably minimized to reduce the

risk of them entering the fuel line thereby creating problems to the smooth

operation of the engine. The fuel is transferred onto the regulating tank via transfer

pumps 1 and 2. The heavy fuel oil is heated partly by steam from a heat recovery

boiler and partly by electric heaters to reduce its viscosity. It then flows into the

various separators/purifiers for the removal of impurities and metallic compounds

and then sent to the various engines daily service tanks. From the service tank, it is

transferred to the booster unit; the engines are supplied with fuel through the help

of the transfer and booster pump capable of increasing fuel pressure to anacceptable pressure and circulating enough fuel more than that consumed by the

engine. The surplus fuel flows back into the day tank. Owing to the difference in

mass density and the time taken in the day tanks, the rest of the water that

bypassed the separator settle at the bottom of the day tanks. For this, the day

tanks are provided with drain pipes to drain off the water periodically. All the

wasted fuel as a result of overflowing of the regulating tank, fuel pumps and pipe

leaks etc. is collected at the basement and then pumped to an oily water separator



tank for recycling. The fuel flow lines are wrapped with special lagging material to

help reduce heat loss along the flow lines to the environment. A diesel fired

auxiliary boiler is provided in the system to serve as a standby in case of a failure in

the engine’s heat recovery boiler as in the case with the two Sulzer engines.

Lubricating system

The main task of the lubricating system is to prevent friction between the moving

parts of the engine. This is done by supplying them with an adequate flow of

lubricating oil. This oil has the task of cooling engine components which cannot

dissipate their heat directly to the cooling system and the outside air. In addition,

the engine oil makes a seal between sliding-contact components (for instance

piston and cylinder wall), and cleans the interior of the engine by flushing out

deposits and combustion residues. The lubricating

oil system consists of lubricating oil pumps which are normally driven by electric

motors. The oil delivered by the pumps passes through filters and coolers,

circulated with sea-water, and then branches into a low-pressure and a medium-

pressure system. The pressure in the low-pressure system is regulated by a valve

and supplies lubricating oil to the main bearings, thrust bearing, camshaft,

camshaft drive wheels, fuel pumps, chain drive and the rotating shafts in the control

stand. It also provides oil for cooling the crosshead guides.

The medium-pressure system lubricates the crossheads, lower connecting-rod

bearings, and the slippers. It also provides oil for the control-oil system and for the

turbocharger lubrication, if main engine oil is used for this purpose.

The cylinder lubricating is independent of the rest of the lubricating system. Theamount of cylinder oil necessary for the engine depends mainly upon the type of oil

used, the quality of the fuel and the loading of the engine.



23rd -29th October

STORES

Every section within the generation department is important .The stores sectionperforms the function of receiving and issuing goods. Simple as it appears but it

entails much more. At the generation department stores operations are divided

amongst the various sections as follows:

Receiving and issuing of all Fuel oil and Lubricating oil store

Machine spare part store

Electrical components store

All other stores materials other than those mentioned above are requested from the

main stores at head office or the other stores at Blackhall Road and Falconbridge.



30th October -19th November

OPERATIONS SECTION:

This section is responsible for the day to day running of the engines in the

generating of electric power. The section consists of an Operation Manager, Shift

Charge officers, engine attendants, Switch Board attendants, Electricians/Fitters and

labourers. With the exception of the operations Manager the rest of the staff in the

operations section are placed into shifts. These shifts are classified as follows, early,

Late, Night and off shifts. The smooth running of the generating sets rests squarelyon the shoulders of this section.

During normal operations, the Shift Charge Engineer is the head of this unit and is

responsible for the operations of the PowerStation and all other relevant activities.

Each shift consists of the following personnel:

• Shift Charge Engineer

• Engine Attendants

• Switchboard Attendants

• Auxiliary plant Attendant

• Electrician

• Fitter

With the above setup the operations and minor maintenance on both electrical and

mechanical equipment are taken care of to maintain an acceptable level of power

supply reliability.

The Shift Charge Engineer

• Supervises the shift staff and ensures that all operational procedures are

closely adhered to

• Prepares and log in the shift logbook reports on consumption of fuel and

lubricants and the operations of the engines



The Engine Attendant

• Monitors the cooling water system (piston and cylinder water tanks)

• Monitors the fuel system (fuel valves, heavy fuel oil and diesel tanks) and the

heavy fuel oil and lubricating oil separators

• Ensures that all the developments that occur during the engine operation are

accurately logged on progress sheets

• Attends to all queries that might arise in the form of alarms during operation

especially when the system is automated.

The Switchboard Attendant

• Synchronizes the engines to the common bus bar and requests for the

engines to be loaded

• Monitor loading during engine operations

• Take readings on an hourly basis on active power (MW), reactive power

(Mvar), temperature (windings), frequency (Hz), power factor (cos φ ), voltage(kV) and current (Amps)

The Auxiliary Plant Attendant

• Monitors the main boiler, the exhaust boilers of all the engines and all other

steam related components

• Monitors the heavy fuel oil separator and the day tank

• Draining of the water from day tank by opening the valves

• Monitoring of the basement to avoid water flooding it

• Other duties as assigned to him by the Shift Charge Engineer

The Electrician/Fitter

• Handles reported minor defects without delay



OPERATIONAL PROCEDURES

The operational procedures of the engines include:

• Starting

• Synchronizing

What is Synchronization?

The process where one or more engines run on a common bus bar with a reference

engine under the same conditions of system voltage, frequency and phase angle or

rotation is known as synchronization.

Procedure for starting and synchronizing

The engine must not be started without first ensuring that the adjustment of the

fuel pumps, the Woodward governor, and the entire regulating linkage is in order.

Check the shut-off valves.

All tools used for the adjustment of the control system must be removed. Check the

regulating link for free and easy motion before starting the engine.

1. Check that the starting-air supply to the engine is opened, the turning gear is

disengaged and secured, the automatic starting-air stop valve is at position

AUTOMATIC and the speed adjusting lever is positioned so that a chargesufficient for starting is released.

2. Pull the starting lever to position STARTING and release it again as soon as

the cylinders fire correctly. The starting lever is pulled back to its resting

position by the return spring and the starting control elements are vented of

air.

3. The engine is now running on fuel. As soon as the engine is turning over

correctly, check the pressure on the pressure gauges and adjust the

pressures to the proper values, if necessary. Check the turbocharger speed.

4. Make a tour of inspection all over and all around the engine.

5. Observe temperatures; listen carefully for unwanted running sounds.

After service speed has been ordered:

1. Close the automatic starting air stop valve by hand. Open the vent cock

on the starting air distribution pipe.



2. Raise the engine speed slowly, particularly if the engine has been cold,

until the service speed is reached. The load indicator position for full load

must not be exceeded.

3. Adjust the temperatures.

4. Close field breaker (an excitation to the armature is created and thereby

creating an electric field) and check voltage and frequency and adjust to

meet reference values.

5. Switch the synchronizing mode switch either auto or manual.

6. Push the initialize button.

7. Adjust the selector to the engine needed to be synchronized.

8. Observe the synchronizing pointer as it moves anti-clockwise. When the

condition of synchronization is achieved, the synchronization permitindicator comes on and the generator breaker is closed (manual or auto).

The controlling officer is then requested to load the engine

9. Turn off the synchronization mode switch after synchronization.

In order to avoid losing the engine on reverse power:

1. Ensure that the loads are switch on quickly (base loads)

2. Ensure that the interconnector breakers in the switching rooms are

charged

3. Avoid switching on heavy and unshed interconnectors/feeders

4. Keep adjusting the governor and auto voltage switch until the voltage

and frequency are stable

Once all of the above have been achieved, then generation of electrical

energy in to the grid which was the main aim of the Generation Department

within the organization is thus achieved. The transmission and Distribution

of the generated electrical energy becomes the responsibility of another

very important department within the operations of the organization



Aux. Engine

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