Vous êtes sur la page 1sur 9



Service the generator twice yearly. Even if you're not using the generator, it needs to be
serviced. If you keep pushing off the maintenance, chances are your generator will not work

when needed.
Start by checking the overall condition of the generator. Look for corroded elements,
loose wires, stuck buttons, etc. Check for any loose connections and frayed wiring. Make sure
the area around the generator is clean, and if the generator has sucked in any dirt or leaves
make sure to clean out the area. Debris getting into an alternator is 1 way of destroying a
perfectly good generator!
Check the distilled water in the battery; top up if needed. Also check the battery's
voltage. It is generally best to replace your battery every 2-3 years.


Change the lubricant oil and filters Oil filters doesnt need to be done each 6 months;
rather this is an annual task whether or not the generator has been operated. Record the yearly
change in the record book so that you are reminded each time when it is due. Make sure that
the oil level is adequate and top up if needed. Air cooled machines should have their oil replaced
every 30-40 hours of run time. Liquid cooled machines should have their oil replaced every 100
hours of run time


Clean the spark plugs. It is generally best to just replace the spark plugs annually.


Check the bolts. Note that bolts on the generator will tend to loosen after reasonable
usage; this is usual wear and tear caused by the vibrations. Check the gasket head and piston
for solid condition; replace if worn or cracked.


Start up the generator regularly. If a generator is not used on a regular basis, it is recommended
that you fire it up at quarterly intervals to ensure that its workings run smoothly. At the very least, start it

after each six monthly maintenance, twice. First check is to see that it is starting OK, second check is to
ensure that it will keep starting OK.

Main components of a generator

The main components of an electric generator can be broadly classified as follows
(refer to illustration above):
(1) 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
A description of the main components of a generator is given below.
There are several factors that you need to keep in mind while assessing the engine
of your generator.
Type of Fuel Used Generator engines operate on a variety of fuels such as diesel,
gasoline. Smaller engines usually operate on gasoline while larger engines run on
(2) 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. Which
generates electricity.
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.
The following are the factors that you need to keep in mind while assessing the
alternator of a generator:
(a) Metal versus Plastic Housing An all-metal design ensures durability of the
alternator. Plastic housings get deformed with time and cause the moving parts of
the alternator to be exposed. This increases wear and tear and more importantly, is




(b) Ball Bearings versus Needle Bearings Ball bearings are preferred and last
(c) Brushless Design An alternator that does not use brushes requires less
maintenance and also produces cleaner power.

(3) Fuel System

The fuel tank usually has sufficient capacity to keep the generator operational for 6
to 8 hours on an average. In the case of small generator units, the fuel tank is a part
of the generators skid base or is mounted on top of the generator frame. For
commercial applications, it may be necessary to erect and install an external fuel
tank. Common features of the fuel system include the following:
(a) Pipe connection from fuel tank to engine The supply line directs fuel from
the tank to the engine and the return line directs fuel from the engine to the tank.
(b) Ventilation pipe for fuel tank The fuel tank has a ventilation pipe to prevent
the build-up of pressure or vacuum during refilling and drainage of the tank.
(c) Overflow connection from fuel tank to the drain pipe This is required so
that any overflow during refilling of the tank does not cause spillage of the liquid on



(d) Fuel pump This transfers fuel from the main storage tank to the injector
pump. The fuel pump can either be mechanical or electrically operated.
(e) Fuel Water Separator / Fuel Filter This separates water and foreign matter
from the liquid fuel to protect other components of the generator from corrosion and

(f) Fuel Injector This atomizes the liquid fuel and sprays the required amount of
fuel into the combustion chamber of the engine.

(4) Voltage Regulator

As the name implies, this component regulates the output voltage of the generator.

(1) Voltage Regulator: Conversion of AC Voltage to DC Current The voltage

regulator takes up a small portion of the generators output of AC voltage and
converts it into DC current. The voltage regulator then feeds this DC current to a set










(2) Exciter Windings: Conversion of DC Current to AC Current The exciter windings

now function similar to the primary stator windings and generate a small AC current.
The exciter windings are connected to units known as rotating rectifiers.

(3) Rotating Rectifiers: Conversion of AC Current to DC Current These rectify the

AC current generated by the exciter windings and convert it to DC current. This DC
current is fed to the rotor / armature to create an electromagnetic field in addition to
the rotating magnetic field of the rotor / armature.

(4) Rotor / Armature: Conversion of DC Current to AC Voltage The rotor / armature

now induces a larger AC voltage across the windings of the stator, which the
generator now produces as a larger output AC voltage.
This cycle continues till the generator begins to produce output voltage equivalent
to its full operating capacity. As the output of the generator increases, the voltage

regulator produces less DC current. Once the generator reaches full operating
capacity, the voltage regulator attains a state of equilibrium and produces just
enough DC current to maintain the generators output at full operating level.

(5) Cooling & Exhaust Systems

(a) Cooling System
Continuous usage of the generator causes its various components to get heated up.
It is essential to have a cooling and ventilation system to withdraw heat produced in
the process.
Raw/fresh water is sometimes used as a coolant for generators, but these are
mostly limited to specific situations like small generators in city applications or very
large units over 2250 kW and above. Hydrogen is sometimes used as a coolant for
the stator windings of large generator units since it is more efficient at absorbing
heat than other coolants. Hydrogen removes heat from the generator and transfers
it through a heat exchanger into a secondary cooling circuit that contains demineralized water as a coolant. This is why very large generators and small power
plants often have large cooling towers next to them.

For all other common

applications, both residential and industrial, a standard radiator and fan is mounted
on the generator and works as the primary cooling system.
It is essential to check the coolant levels of the generator on a daily basis. The
cooling system and raw water pump should be flushed after every 600 hours and
the heat exchanger should be cleaned after every 2,400 hours of generator
operation. The generator should be placed in an open and ventilated area that has
adequate supply of fresh air. The National Electric Code (NEC) mandates that a
minimum space of 3 feet should be allowed on all sides of the generator to ensure
free flow of cooling air.




Exhaust fumes emitted by a generator are just like exhaust from any other diesel or
gasonline engine and contain highly toxic chemicals that need to be properly
managed. Hence, it is essential to install an adequate exhaust system to dispose of
the exhaust gases. This point can not be emphasized enough as carbon monoxide
poisoning remains one of the most common causes for death in post hurricane
affected areas because people tend to not even think about it until its too late.
Exhaust pipes are usually made of cast iron, wrought iron, or steel. These need to
be freestanding and should not be supported by the engine of the generator.
Exhaust pipes are usually attached to the engine using flexible connectors to
minimize vibrations and prevent damage to the generators exhaust system. The
exhaust pipe terminates outdoors and leads away from doors, windows and other
openings to the house or building. You must ensure that the exhaust system of your
generator is not connected to that of any other equipment. You should also consult
the local city ordinances to determine whether your generator operation will need to
obtain an approval from the local authorities to ensure you are conforming to local
laws a protect against fines and other penalties.




Since the generator comprises moving parts in its engine, it requires lubrication to
ensure durability and smooth operations for a long period of time. The generators
engine is lubricated by oil stored in a pump. You should check the level of lubricating
oil every 8 hours of generator operation. You should also check for any leakages of
lubricant and change the lubricating oil every 500 hours of generator operation.




The start function of a generator is battery-operated. The battery charger keeps the
generator battery charged by supplying it with a precise float voltage. If the float
voltage is very low, the battery will remain undercharged. If the float voltage is very

high, it will shorten the life of the battery. Battery chargers are usually made of
stainless steel to prevent corrosion. They are also fully automatic and do not require
any adjustments to be made or any settings to be changed. The DC output voltage
of the battery charger is set at 2.33 Volts per cell, which is the precise float voltage
for lead acid batteries. The battery charger has an isolated DC voltage output that
does interfere with the normal functioning of the generator.




This is the user interface of the generator and contains provisions for electrical
outlets and controls. The following article provides further details regarding
the generator control panel. Different manufacturers have varied features to offer
in the control panels of their units. Some of these are mentioned below.
(a) Electric start and shut-down Auto start control panels automatically start your
generator during a power outage, monitor the generator while in operation, and









(b) Engine gauges Different gauges indicate important parameters such as oil
pressure, temperature of coolant, battery voltage, engine rotation speed, and
duration of operation. Constant measurement and monitoring of these parameters
enables built-in shut down of the generator when any of these cross their respective


(c) Generator gauges The control panel also has meters for the measurement of







(d) Other controls Phase selector switch, frequency switch, and engine control
switch (manual mode, auto mode) among others.





All generators, portable or stationary, have customized housings that provide a

structural base support. The frame also allows for the generated to be earthed for