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Mechanical
AlternatorEngine
Energy
Chemical
Energy ofFuel
Electrical
Energy
A Block Diagram -Engine Alternator
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An Installation
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When the fuel ignites in the combustionchamber, energy in the form of heat andgases is generated. The rapid expansionof hot gases creates pressure in thecombustion chamber which pushes thepiston away. The reciprocating motion ofthe piston is converted in to the circular
motion by the engine crankshaft, which isconnected to the piston by the connectingrod.
Principle of operation of
Engine
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ADMISSION STROKE
The piston draws fresh air into the
cylinder on its downward travel
through the open admission valve.With turbo charged engines the air is
first compressed by a blower and
admitted to the cylinder underincreased pressure.
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COMPRESSION STROKE
On its upward travel the pistoncompress the fresh air in the cylinder
with the valves closed. Thetemperature of the fresh air is thusincreased to exceed the ignitiontemperature of the fuel. Shortly
before the piston reaches the topdead centre, fuel is injected into thecombustion space.
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POWER STROKE
The fuel injected ignites in the hot air
and burns. The combustion causes a
high pressure which forces thepiston down. Resulting into
reciprocating movement of the shaft.
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EXHAUST STROKE
The piston moving upward forces the
exhaust gas through the open
exhaust valve into the exhaust pipe.When the exhaust stroke is
terminated the exhaust valve close
and the admission valve opens for anew operation cycle.
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SYSTEMS OF
AN ENGINE
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LUBRICATION SYSTEM
The moving parts of the dieselengine are lubricated for their
optimum operation by thislubrication system. A dipstick in theoil sump serves to check the oillevel. The lub oil level and the
lubrication oil pressure have to bechecked for satisfactory performanceand long life of the engine.
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FUEL SYSTEM
Depending on the position of the
fuel, the fuel is supplied to the
distributing pipe through fuel filtereither by natural head from an
elevated tank or by a fuel pump. Fuel
is supplied inside the cylinder byinjection nozzles.
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AIR EXHAUST SYSTEM
For the combustion of fuel sufficient
quantity of the filtered air is taken in
the combustion chamber. After thecombustion the exhaust gases are
taken away from the engine through
suitable ducting or piping. This isknown as air exhaust system.
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COOLING SYSTEM
Cooling System is essential for
cooling the engine body, and to act
as a heat exchanger for lubricatingoil. This can be either water-cooled
or air cooled.
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STARTING SYSTEM
The Diesel Engine can be equippedwith the starting system i.e. with
an electric starter with a pinion,which engages with the fly wheel ofthe engine. The power to the electricstarter is provided by means of a
battery which is kept in chargedcondition by means of a dynamo orelectric rectifier.
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ALTERNATOR
Alternator works on Faradays law ofElectromagnetic induction. There are tworequirements for the functioning of Alternator(1) Magnetic field& (2) Rotation. Magnetic fieldis produced by passing direct current throughthe field winding of the Alternator and rotationis achieved by means of coupling the alternator
from engine. The Automatic Voltage regulator(AVR) is provided in the alternator formaintaining the terminal voltage within theclose limits over wide operating condition.
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INDICATIONS OF A HEALTHY
ENGINE Good Compression:
The temperature of the induced air whenentrapped and compressed in the
combustion chamber is about 540 deg Cto 560 deg C.
Good Combustion:
Fuel is sprayed in atomized form to ensure
proper ignition of the fuel. Burningtemperature is about 1425 deg C.
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Clean exhaust:
The exhaust system is clean and
back pressure is with in permissiblelimits. The general condition of theEngine can be determined by the typeof smoke it emits. This can be said asThe pulse of the engine. Smokeshould be of brown colour (Barelyvisible haze). Any other colour of smokeindicates some problem in the engine.
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IMPORTANT MAINTENANCE CHECKS
FOR ENGINE ALTERNATOR SETDaily Check Engine oil level and leakage if any.
Check Radiator for water level and leakage if any.
Check fuel level.
Check that ventilation of the EA Room is proper.
Check oil pressure.
Check if lights and exhaust fan are working properly.
Check physically before start for loose connection/nut
bolt.
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Weekly
Check Air filter.
Check fan belt, and its tension
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Fortn ight ly Check Battery voltage, Terminals, Electrolyte
level (Top up if necessary) .
Check Specific Gravity of Electrolyte.
(After the above checks, start theEngine for No Load/Connected Load and testfor 10 m inutes the fo l lowing)
Check for any abnormal noise. Shut down theE/A immediately and cause be examined.
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Check frequency, out put voltage, colourof exhaust etc.
Record various readings in the logbook.
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Monthly Check for tightness of connections in
Engine and Control Panel.
Watering of earth pits and tightening ofconnections.
Check functioning of safety devices.
Check belt tensions.
Check battery charger.
Check for leakage of fuel line.
Check for leakage in exhaust pipes.
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Half Yearly
Cleaning of bus bars chambers and
tightening of nut bolts.
Checking of protective devices
Earth testing and Meggering.
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Yearly
Tighten all mounting, nut and bolt.
Clean and calibrate all injectors.
Check fuel pump calibration.
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