May 152011
 

Preventive maintenance of Diesel Generator

Because of the durability of diesel engines, most maintenance is preventive in nature. Preventive diesel engine maintenance consists of the following operations:

• General inspection
• Lubrication service
• Cooling system service
• Fuel system service
• Servicing and testing starting batteries
• Regular engine exercise

CHARTGeneral inspection

When the generator set is running, operators need to be alert for mechanical problems that could create unsafe or hazardous conditions. Following are several areas that should be inspected frequently to maintain safe and reliable operation.

• Exhaust system: With the generator set operating, inspect the entire exhaust system including the exhaust manifold, muffler and exhaust pipe. Check for leaks at all connections, welds, gaskets and joints, and make sure that the exhaust pipes are not heating surrounding areas excessively. Repair any leaks immediately.

• Fuel system: With the generator set operating, inspect the fuel supply lines, return lines, filters and fittings for cracks or abrasions. Make sure the lines are not rubbing against anything that could cause an eventual breakage. Repair any leaks or alter line routing to eliminate wear immediately.

• DC electrical system: Check the terminals on the starting batteries for clean and tight connections. Loose or corroded connections create resistance which can hinder starting.

• Engine: Monitor fluid levels, oil pressure and coolant temperatures frequently. Most engine problems give an early warning. Look and listen for changes in engine performance, sound, or appearance that will indicate that service or repair is needed. Be alert for misfires, vibration, excessive exhaust smoke, loss of power or increases in oil or fuel consumption.

Lubrication service

Check the engine oil level when the engine is shut down at the interval specified in CHART. For accurate readings on the engine’s dipstick, shut off the engine and wait approximately 10 minutes to allow the oil in the upper portions of the engine to drain back into the crankcase. Follow the engine manufacturer’s recommendations for API oil classification and oil viscosity. Keep the oil level as near as possible to the “full” mark on the dipstick by adding the same quality and brand of oil.

Change the oil and filter at the intervals recommended in CHART. Check with the engine manufacturer for procedures for draining the oil and replacing the oil filter. Used oil and filters must be disposed of properly to avoid environmental damage or liability.

Cooling system service

Check the coolant level during shutdown periods at the interval specified in CHART. Remove the radiator cap after allowing the engine to cool and, if necessary, add coolant until the level is about 3/4-inch below the radiator cap lower sealing surface. Heavy duty diesel engines require a balanced coolant mixture of water, antifreeze and coolant additives. Use a coolant solution as recommended by the engine manufacturer. Inspect the exterior of the radiator for obstructions and remove all dirt or foreign material with a soft brush or cloth. Use care to avoid damaging the fins. If available, use low pressure compressed air or a stream of water in the opposite direction of normal air flow to clean the radiator. Check the operation of the coolant heater by verifying that hot coolant is being discharged from the outlet hose.

Fuel system service

Diesel fuel is subject to contamination and deterioration over time, and one reason for regular generator set exercise is to use up stored fuel over the course of a year before it degrades. In additional to other fuel system service recommended by the engine manufacturer, the fuel filters should be drained at the interval indicated in CHART. Water vapor accumulates and condenses in the fuel tank and must also be periodically drained from the tank along with any sediment present.

The charge-air piping and hoses should be inspected daily for leaks, holes, cracks or loose connections. Tighten the hose clamps as necessary. Also, inspect the charge-air cooler for dirt and debris that may be blocking the fins. Check for cracks, holes or other damage.

The engine air intake components should be checked at the interval indicated in CHART. The frequency of cleaning or replacing air cleaner filter elements is primarily determined by the conditions in which the generator set operates. Air cleaners typically contain a paper cartridge filter element which can be cleaned and reused if not damaged. Starting batteries Weak or undercharged starting batteries are the most common cause of standby power system failures. Even when kept fully charged and maintained, lead-acid starting batteries are subject to deterioration over time and must be periodically replaced when they no longer hold a proper charge. Only a regular schedule of inspection and testing under load can prevent generator starting problems. See CHART for the recommended inspection interval for the batteries and charging system.

Testing batteries: Merely checking the output voltage of the batteries is not indicative of their ability to deliver adequate starting power. As batteries age, their internal resistance to current flow goes up, and the only accurate measure of terminal voltage must be done under load.

• Cleaning batteries: Keep the batteries clean by wiping them with a damp cloth whenever dirt appears excessive. If corrosion is present around the terminals, remove the battery cables and wash the terminals with a solution of baking soda and water (1/4-pound baking soda to one quart of water).
Be careful to prevent the solution from entering the battery cells, and flush the batteries with clean water when done. After replacing the connections, coat the terminals with a light application of petroleum jelly.

• Checking specific gravity: Use a battery hydrometer to check the specific gravity of the electrolyte in each battery cell. A fully charged battery will have a specific gravity of 1.260. Charge the battery if the specific gravity reading is below1.215.

• Checking electrolyte level: Check the level of the electrolyte in the batteries at least every 200 hours of operation. If low, fill the battery cells to the bottom of the filler neck with distilled water.

Generator set exercise

Generator sets on continuous standby must be able to go from a cold start to being fully operational in a matter of seconds. This can impose a severe burden on engine parts. However, regular exercising keeps engine parts lubricated, prevents oxidation of electrical contacts, uses up fuel before it deteriorates, and, in general, helps provide reliable engine starting. Exercise the generator set at least once a month for a minimum of 30 minutes loaded to no less than one-third of the nameplate rating. Periods of no-load operation should be held to a minimum, because unburned fuel tends to accumulate in the exhaust system. If connecting to the normal load is not convenient for test purposes, the best engine performance and longevity will be obtained by connecting it to a load bank of at least one-third the nameplate rating.

Conclusion

Preventive maintenance of diesel generators plays a critical role in maximizing reliability, minimizing repairs and reducing long term costs. By following generally recognized diesel maintenance procedures and specific manufacturer recommendations for your application, you’ll be assured that your standby power system will start and run when you need it most.

Mar 082011
 

Diesel Generator Maintenance –  Minor  

The following Diesel Generator maintenance procedures must be followed to ensure a good performance of the equipment and extension of its lifetime.

Diesel Generator maintenanceCLEANING

  • Frame, vents, screens and fan cover must be kept clean,
  • Free of dust, dirt and oil.
  • Soft brush or clean cotton rags should be used to clean the generators.
  • Remove non-abrasive dust from the fan
  • Cover and any accumulated grime from the fan and cooling fins (frame). Oil or damp impregnated
  • All unused space dust-free.

 

LUBRICATING SYSTEM

  • Take oil sample and report findings – optional
  • Check engine oil for leaks
  • Check hydraulic governor oil level, if fitted
  • Check operation of lubricating oil heater, if fitted
  • Record oil pressure – P.S.I R.P.M.

FUEL SYSTEM

  • Drain sediment from fuel tank
  • Check fuel tank breather
  • Check fuel system and unions for leaks
  • Check operation of engine governor and stop controls
  • Check fuel level, inform Owner/Manager if low

COOLING SYSTEM

  • Check coolant level and antifreeze content and top up if necessary
  • Check for coolant leaks
  • Check condition of hoses and clips
  • Check condition of fan belts and adjust or renew, if required
  • Check and lubricate fan hubs and idlers
  • Check condition of radiator
  • Check operation of block and radiator heaters
  • Check operation of ventilation automatic louvers, if fitted
  • Record engine cooling system temperatures

AIR INTAKE SYSTEM

  • Change air filter element
  • Clean and check air cleaner and piping for damage
  • Check turbocharger operation and condition
  • Check inlet manifold and gaskets
  • Check and tighten turbocharger outlet hose clips

EXHAUST SYSTEM

  • Tighten Manifold nuts and cap screws
  • Tighten turbocharger mounting nuts
  • Check for leaks and signs of blowing
  • Check condition of silencer and piping
  • Drain moisture trap in exhaust pipe

ENGINE ELECTRICAL SYSTEM

  • Check battery electrolyte level and specific gravity, top up if necessary
  • Check condition of charging system
  • Record charging rate – amps
  • Check operation of charging system

CONTROL PANEL AND INSTRUMENTS

  • Check warning lights for operations, replace if necessary
  • Check operation of gauges and instruments
  • Check operation of switches

GENERAL MAINTENANCE

  • Check engine mounting bolts
  • Check engine anti-vibration mountings
  • Check operation of engine governor
  • Check engine vibration dampers
  • Lubricate all engine linkages
  • Keep generator plant room in a clean and tidy condition
Feb 272011
 

The following procedures and checklists to be carried out during a major service include:

Diesel Generator Maintenance – Major

LUBRICATING SYSTEM

Diesel Generator

  • Change engine lubricating oil
  • Change engine lubricating oil filter
  • Change engine lubricating oil bypass filter, if fitted
  • Check engine oil for leaks
  • Check hydraulic governor oil level, if fitted
  • Record oil pressure – P.S.I R.P.M.
FUEL SYSTEM
  • Drain sediment from fuel tank
  • Check fuel tank breather
  • Clean out water and sediment trap
  • Change fuel filters
  • Check fuel system pipes and unions for leaks
  • Check operation of engine governor and stop controls
  • Check operation of fuel system priming pump
  • Check fuel level, inform Owner/Manager if low
COOLING SYSTEM
  • Check coolant level and antifreeze content and top up if necessary
  • Check coolant inhibitor
  • Change coolant filter, if hours occurred
  • Check for coolant leaks
  • Check condition of hoses and clips
  • Check condition of fan belts and adjust or renew, if required
  • Check water pump and lubricate
  • Check and lubricate fan hubs and idlers
  • Check condition of radiator
  • Clean radiator fins
  • Check condition of radiator ducting and trunking
  • Check operation of block and radiator heaters
  • Check operation of ventilation automatic louvers, if fitted
  • Record engine cooling system temperatures
AIR INTAKE SYSTEM
  • Change air filter element, if necessary
  • Clean and check air cleaner and piping for damage
  • Check turbocharger operation and condition
  • Check inlet manifold and gaskets
  • Check and tighten turbocharger outlet hose clips
EXHAUST SYSTEM
  • Tighten Manifold nuts and cap screws
  • Tighten turbocharger mounting nuts
  • Check for leaks and signs of blowing
  • Check condition of silencer and piping
  • Drain moisture trap in exhaust pipe
ENGINE ELECTRICAL SYSTEM
  • Check battery electrolyte level and specific gravity, top up if necessary
  • Check condition of charging system
  • Record charging rate – amps
  • Check operation of starting system
  • Check condition of wire and connectors
ALTERNATOR
  • Check bearings and lubricate
  • Check communicators or slip rings
  • Examine brush gear
  • Check alternator to engine alignment
  • Check alternator to engine coupling

Diesel GenratorGENERAL MAINTENANCE

  • Check engine mounting bolts
  • Check engine anti-vibration mountings
  • Check operation of engine governor
  • Check and adjust engine valve clearance, if hours occurred
  • Check and clean engine crankcase, breather
  • Check engine vibration dampers
  • Lubricate all engine linkages
  • Keep generator plant room in a clean and tidy condition
Feb 122011
 

Diesel Generator

An electric generator is a device that converts mechanical energy obtained from an external source into electrical energy as the output.

Diesel Engine + Alternator = Diesel Generator

Main components of a Diesel Generator

The main components of an electric Diesel generator can be broadly classified as follows (refer to illustration above):

Diesel Generator(1) Diesel Engine
(2) Alternator
(3) Fuel System
(4) Voltage Regulator
(5) Cooling and Exhaust Systems
(6) Lubrication System
(7) Battery Charger
(8) Control Panel
(9) Main Assembly / Frame

Diesel Engine

The diesel engine is a type of internal combustion engine, more specifically, a compression ignition engine, in which the fuel is ignited by the high temperature of compressed gas, rather than a separate source of energy (such as a spark plug).

 

How diesel engines work.

 

 

 

When gas is compressed its temperature rises. A diesel engine exploits this property in order to ignite the fuel. Air is drawn into the cylinder of a diesel engine, and compressed by the rising piston. This happens at a much higher compression rate than in a spark-ignition engine. At the top of the piston stroke diesel fuel is injected into the combustion chamber at high pressure through an atomizing nozzle. It mixes with the hot, pressurized air. The resulting mixture ignites and burns very rapidly. This contained explosion causes the gas in the chamber to expand, driving the piston down with considerable force, and creating power in a vertical direction.

The connecting rod transmits this motion to the crankshaft which is forced to turn, delivering rotary power at the output end of the crankshaft. ‘Scavenging’ – pushing the exhausted gas-charge out of the cylinder and drawing in a fresh draught of air – is done through ports or valves.

A vital component of any diesel engine system is the governor, which limits the speed of the engine by controlling the rate of fuel delivery.

Alternator

The alternator, also known as the ‘genhead’, is the part of the generator that produces the electrical output from the mechanical input supplied by the engine. It contains an assembly of stationary and moving parts encased in a housing. The components work together to cause relative movement between the magnetic and electric fields, which in turn generates electricity.

 

Alternator

 

 

 

 

Diesel-Alternator

(a) Stator – This is the stationary component. It contains a set of electrical conductors wound in coils over an iron core.

(b) Rotor / Armature – This is the moving component that produces a rotating magnetic field in any one of the following three ways:

(i) By induction – These are known as brushless alternators and are usually used in large   generators.

(ii) By permanent magnets – This is common in small alternator units.

(iii) By using an exciter – An exciter is a small source of direct current (DC) that energizes the rotor through an assembly of conducting slip rings and brushes.

The rotor generates a moving magnetic field around the stator, which induces a voltage difference between the windings of the stator. This produces the alternating current (AC) output of the generator.