Mechanical

Alternator Engine Energy

Chemical

Energy of Fuel

Electrical

Energy

A Block Diagram -Engine Alternator

An Installation

• When the fuel ignites in the combustion chamber, energy in the form of heat and gases is generated. The rapid expansion of hot gases creates pressure in the combustion chamber which pushes the piston away. The reciprocating motion of the piston is converted in to the circular motion by the engine crankshaft, which is connected to the piston by the connecting rod.

Principle of operation of Engine

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 under increased pressure.

COMPRESSION STROKE

• On its upward travel the piston compress the fresh air in the cylinder with the valves closed. The temperature of the fresh air is thus increased to exceed the ignition temperature(540- C) of the fuel. Shortly before the piston reaches the top dead centre, fuel is injected into the combustion space.

POWER STROKE

• The fuel injected ignites in the hot air and burns. The combustion causes a high pressure which forces the piston downward. Resulting into reciprocating movement of the shaft.

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 a new operation cycle.

SYSTEMS OF AN ENGINE

LUBRICATION SYSTEM

• The moving parts of the diesel engine are lubricated for their optimum operation by this lubrication system. A dipstick in the oil sump serves to check the oil level. The lub oil level and the lubrication oil pressure have to be checked for satisfactory performance and long life of the engine.

FUEL SYSTEM

• Depending on the position of the fuel, the fuel is supplied to the distributing pipe through fuel filter either by natural head from an elevated tank or by a fuel pump. Fuel is supplied inside the cylinder by injection nozzles.

AIR EXHAUST SYSTEM

• For the combustion of fuel sufficient quantity of the filtered air is taken in the combustion chamber. After the combustion the exhaust gases are taken away from the engine through suitable ducting or piping. This is known as air exhaust system.

COOLING SYSTEM

• Cooling System is essential for cooling the engine body, and to act as a heat exchanger for lubricating oil. This can be either water-cooled or air –cooled.

STARTING SYSTEM

• The Diesel Engine can be equipped with the starting system i.e. with an electric starter with a pinion, which engages with the fly wheel of the engine. The power to the electric starter is provided by means of a battery which is kept in charged condition by means of a dynamo or electric rectifier.

ALTERNATOR

• Alternator works on Faraday’s law of Electromagnetic induction. There are two requirements for the functioning of Alternator– (1) Magnetic field & (2) Rotation. Magnetic field is produced by passing direct current through the field winding of the Alternator and rotation is achieved by means of coupling the alternator from engine. The Automatic Voltage regulator (AVR) is provided in the alternator for maintaining the terminal voltage within the close limits over wide operating condition.

INDICATIONS OF A HEALTHY ENGINE

• Good Compression: The temperature of the induced air when

entrapped and compressed in the combustion chamber is about 540 deg C to 560 deg C.

• Good Combustion: Fuel is sprayed in atomized form to ensure

proper ignition of the fuel. Burning temperature is about 1425 deg C.

INDICATIONS OF A HEALTHY ENGINE

• Clean exhaust: The exhaust system is clean and

back pressure is with in permissible limits. The general condition of the Engine can be determined by the type of smoke it emits. This can be said as “The pulse of the engine”. Smoke should be of brown colour (Barely visible haze). Any other colour of smoke indicates some problem in the engine.

IMPORTANT MAINTENANCE CHECKS FOR ENGINE ALTERNATOR SET

Daily • 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.

MAINTENANCE CHECKS

Weekly

• Check Air filter.

• Check fan belt, and its tension

MAINTENANCE CHECKS

Fortnightly• Check Battery voltage, Terminals, Electrolyte

level (Top up if necessary) . • Check Specific Gravity of Electrolyte.• (After the above checks, start the

Engine for No Load/Connected Load and test for 10 minutes the following)

• Check for any abnormal noise. Shut down the E/A immediately and cause be examined.

MAINTENANCE CHECKS

• Check frequency, out put voltage, colour of exhaust etc.

• Record various readings in the logbook.

MAINTENANCE CHECKS

Monthly • Check for tightness of connections in

Engine and Control Panel.• Watering of earth pits and tightening of

connections.• Check functioning of safety devices.• Check belt tensions.• Check battery charger.• Check for leakage of fuel line.• Check for leakage in exhaust pipes.

MAINTENANCE CHECKS

Half Yearly

• Cleaning of bus bars chambers and tightening of nut bolts.

• Checking of protective devices

• Earth testing and Meggering.

MAINTENANCE CHECKS

Yearly

• Tighten all mounting, nut and bolt.

• Clean and calibrate all injectors.

• Check fuel pump calibration.

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