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You need to know a
few terms and have a basic understanding of the different types
of generator sets and their operating principles. We will
explain in simple terms.
You should have your
equipment installed by an expert. A knowledgeable person, who
knows the electric code, can do wiring and simple plumbing can
do the installation, but you will have to know what your doing.
Installation may require expert assistance and must adhere to
local codes and regulations, not only to obey the law but to
make sure you don't void your insurance by installing equipment
illegally or without permits. We recommend that you have a
contractor do your installation or, at the very least, have him
provide professional advice. It is up to you to make sure the
installation is done correctly.
For a list of
resources on this website and to skip to specific areas of
interest see:
Generator
Information.
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PORTABLE OR
STATIONARY? |
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Most homeowners
first think of portable generators rather then stationary
generators. If you want to haul a generator outside or put one
outside in a shed and plug in cords when there is a power
outage, it can be done. You will not necessarily save any money
doing it but if you have a use for the portable generator for
non-emergency times then it might be an alternative. It has been
our experience that it is more economical and less hassle to
purchase a stationary system and power the whole house or
business. Not only do you get more power for the dollar but your
family and/or employees don't have to do anything to have
emergency power. Do you want your wife, children or employees
hauling out equipment and plugging things in and starting up the
system, switching the transfer switch and having to refuel? At
some point all of this becomes ridiculous and costs you more in
staff time and potential liability then its worth.
Before you decide
read:
Generator Sizes and Types for Your Home or
Business
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STAND-BY OR PRIME? |
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The first determination you will
need to make is whether you will require stand-by or prime
power. Simply stated, prime power is required when you have no
other source of power or you are using the system as you prime
means of power. Any generator that is used everyday or on a
fixed schedule to provide power is considered a prime power
generator. Another word for prime is "continuous". If you need a
prime power generator, use the generators prime or continuous
rating as a guide.
A standby set is a backup to
normal utility power. Standby units are used only when your
utility power is not available and will not be used frequently.
Many stand by generators run at 3600 RPM and are not designed
for constant daily use. Another word for standby is "emergency".
If you need a standby power generator, use the generators
standby or emergency rating as a guide.
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GENERATOR PHASES |
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Generator sets
produce either single or three phase power. You should
use the type of power your panel provides. Residences and small
business generally use single phase. Three-phase power is used
for medium to large businesses especially where power is used
for motor starting and running. Three phase generators are set
up to produce 120/208 or 277/480 volts. Single-phase sets are
120 or 120/240. Use the low voltage to run domestic appliances
and the high voltage for your motors, heaters, stoves and
dryers. Your service panel is either single phase or three
phase, you don't need a three phase generator if your panel is
only single phase. Check with your electrician before you begin
your search. |
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GENERATOR
AMPERAGE |
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Your service panel
is a good place to start. Go and look at your service panel and
see what the amperage is. If the panel is 100 Amps that tells
you that your won't need more then 100 amps of power. As the
panel gets bigger so will your generator needs. It is possible
to install a generator to power only a small portion of your
service panel, if you install appropriate sub-panels to sort out
what will and will not be powered.
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FUEL: GAS OR
DIESEL?
See
also
What Generator Fuel is Best? |
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We recommend diesels
due to their longevity and lower operating costs. Today’s modern
diesels are quiet and normally require much less maintenance
than comparably sized gas (natural gas or propane) units. Fuel
costs per kW produced with diesels is normally thirty to fifty
percent less than gas units.
1800 rpm water
cooled diesel units operate on average 12,000 to 30,000 hours
before major maintenance is required.
1800 rpm water
cooled gas units normally operate 6,000 to 10,000 hours because
they are built on a lighter duty gasoline engine block. Gas
units burn hotter (higher BTU of the fuel) so you will see
generally see somewhat shorter lives than the diesel units
3600 rpm air-cooled
gas units are normally replaced – not overhauled
at 500 to 1500 hours. These are "stand-by" generators, not
intended to be run long hours or very often.
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OPERATING SPEED |
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Electric equipment
is designed to use power with a fixed frequency: 60 Hertz (Hz)
in the United States and Canada, 50 Hertz in Europe and
Australia. The frequency output of a generator depends on a
fixed engine speed. To produce 60 Hz electricity, most
engines operate at 1800 or 3600 RPM. Each has its advantages and
drawbacks. 1800 RPM, four pole sets are the most common and
least expensive in large generators. They offer the best balance
of noise, efficiency, cost and engine life. 3600 RPM, two pole
sets are smaller and lightweight, best suited for portable,
light-duty applications. 3600 RPM sets are considered "Standby
Generators" and can never be considered for prime power use.
In simple terms it’s
like operating your car at 90 mph, versus 45mph – at 45mph your
car will last longer, is quieter, less maintenance and longer
life. Most 3600 rpm units are twin cylinder air cooled
lawn mower engines, while the water cooled 1800 rpm units are
comparable to those found in forklift and tractor engines. The
bottom line is the 1800 rpm water cooled units will last longer,
offer less maintenance problems and be more fuel efficient. In
addition, 1800 RPM generators are designed to be rebuilt, 3600
RPM units are designed to replaced and are much lower in cost
(most of the time). Some 3600 RPM stationary units and most RV
and commercial power units can be rebuilt at least one or more
times but this process is not inexpensive.
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FEATURES & BENEFITS TO LOOK FOR |
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Engine block.
For long life
and quiet operation we recommend four cycle, liquid cooled,
industrial duty diesel engines. |
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Air or liquid
cooling.
Air-cooled engines require a tremendous amount of air and may
require ducting and they are somewhat noisier. Liquid cooling
offers quieter operation, more even temperature control and
therefore longer engine life. Modern air cooled engines are
suitable for many applications, especially short run, portable
or standby uses. |
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Intake Air.
All quality
generators have intake air filters with replaceable filter
elements. Today even small portables have replaceable air
cleaners. |
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Mufflers.
Most generator come equipped with an industrial grade muffler.
One good investment is a residential or critical muffler that is
much quieter and lasts longer. All enclosed generators should be
equipped with at least a residential and preferably a critical
muffler.
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Lubrication.
The lubrication system should have a full flow, spin-on oil
filter. Larger generators should have a filter bypass. Most
generators today have low oil alarms and shutdowns, make sure
the generator you select has this valuable feature, its simply a
must have protection.
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Major brand of
engine. We do not know why people would even consider an
inferior "scrap metal" unit or "off brand" engine, you will not
be able to obtain the necessary parts, service and support. Many
engines come with a box of spare parts including pistons, rings
and bearings because your going to need them all. Save yourself
some grief and buy a major brand of engine. If you buy a junk
engine, we wont service it and most other reputable dealers
won't either. |
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Electrical system
and circuit breakers.
Standard 12 volt
system should include at least the following: 1) Quality starter
motor and battery. Larger generators should include a charging
alternator with a solid state voltage regulator. 2) Larger
diesel units should come with a pre-heat switch and all
generators should have a start/stop switch. 3) Al generators
should have a safety shutdown system to protect the engine in
case of oil pressure loss, generator over-speed or over-crank
and high water (or operating) temperature. 4) System circuit
breaker to protect the generator. On small systems and portables
there should be a circuit breaker on each circuit.
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GENERATOR END |
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(The
part that makes the generator "generate" electricity.) |
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AC generator
should have a 4-pole revolving field. An automatic voltage
regulator will provide “clean” power. Normal utility power
is +/- 6% voltage regulation; most generators are even better
ranging from +/- 5% or .25 % and even better. Most modern
generators offer AVR – Automatic Voltage Regulation or some
other proprietary brand of voltage regulation and can be safely
used with modern electronics and computers. |
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Lifetime
lubricated bearing. Cheap generators are not
supplied with these bearings. They often require complete
disassembly every two or three years for bearing replacement.
Most modern power alternators, or generator ends, are provided
with industrial quality lifetime lubricated bearings |
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ENGINE ACCESSORIES AND CONTROLS |
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Upon determining the
generator size you will need, make a list of optional and
installation equipment you require. For noise abatement, we
recommend a residential (not industrial grade) muffler. A good
primary fuel filter/water separator is a must to protect your
engine's fuel system. Stand-by sets may require a block heater
to keep the coolant/water mix at an adequate temperature for
easier starting and less smoking on startup. |
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WHAT SIZE SET
WILL I NEED? |
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Sizing is the most
important step;
nothing is more critical in your choice of a generator. A set
that is too small won't last, will smoke and can do damage to
your electrical equipment. If it is too large, the engine will
carbon up, wet stack or “slobber” and this means excess fuel
consumption and early failure.
We recommend
that a generator set never run continuously with less than 40%
load - 50% to 75% is optimum.
Additional factors,
which may affect efficient operation of your generator, are high
altitude and high air temperature. These conditions will lower
generator output. You must take into account your elevation,
normal and extremes of temperature and other factors. Ask your
sales engineer for de-rating information. Allow three (3)
percent loss in efficiency for each 1000 feet above sea level
minimum. Check the manufactures specifications and use the
de-rating factor they specify. Nothing is worse than buying a
generator that is too small.
For more
information:
Understanding Loads & Sizing,
Calculations, Doing it Exactly,
Generator Sizing Procedures,
Wattage Guide
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MOTOR
STARTING LOADS |
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In addition to load
requirements, it is important to consider motor starting load.
We use the rule of thumb that starting a motor
requires up to three (3) times more wattage than running
loads. Selecting a generator, which is inadequate for your motor
starting needs, may make it difficult to start motors in air
conditioners, compressors or freezers. In addition, the starting
load causes voltage dips, which is why the lights dim when a
large motor is started. These voltage dips can be more than
annoying – voltage dips can ruin delicate electronic equipment
such as computers.
You must make sure you account for starting loads, if you cant
start the load you can't run it. For more information see:
Starting Load Examples,
Electric Motor Wattage Guide,
Motor Formulas. |
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MORE
INFORMATION ABOUT GENERATORS |
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Read these sections
about generators, you may find some useful information.
Delta & Wye Connections,
Electrical Unit Conversions (formulas),
Proper Generator Operation
and
Generator Safety. |
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GENERATOR INSTALLATION
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A detailed
installation guide will usually be provided with your generator.
Here are some important points to consider when you install your
generator. |
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We strongly
recommend that the installation be performed by a licensed
electrical or mechanical contractor. They have the tools, the
know-how and an understanding of regulations and local codes.
Their expertise will save you money in the long run. Should you
chose to perform the installation yourself, PLEASE do your
homework before tackling the job and obtain the proper permits
required by your local jurisdiction. While all GenSets have some
basic requirements, each brand and model has unique installation
requirements. Also, it is extremely important to have all
relative codebooks for reference and to adhere to strictly
adhere to the laws which were designed for your safety. Most
important of all, your system must be inspected before starting
to prevent fires and explosions from improper installation. |
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LOCATION |
Ensure the following
items are considered, read the manual for the generator.
- Air inlet
for combustion and engine cooling.
- Outlets for
exhaust and hot cooling air.
- Fuel,
battery and AC electrical connections.
- Remember to
monitor for carbon monoxide!
- Rigid, level
mounting platforms (many sets are already mounted on a steel
skid base).
- Open
accessibility for easy service.
- Isolation
from living space. Keep noise and exhaust away from occupied
areas.
- Space and
equipment to extinguish a fire. Minimize the possibility of
fire danger.
- Remember,
GenSets move on their vibration mounts. Allow clearance to
compensate and use flex-joints on all lines and connections.
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EXHAUST
SYSTEMS |
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The exhaust system
may need to be covered with insulated material to prevent fire
resulting from contact with combustible materials. We
recommend a heat blanket over exhaust outlets to reduce the heat
radiated from the exhaust and to ensure personal safety. Some
insulation materials are best left to professionals with the
proper equipment. Keep all piping away from combustible
materials including walls. A seamless, stainless steel flexible
joint must be used between the generator set and the exhaust
system to prevent metal fatigue. Do not
use the exhaust manifold to support the exhaust system because
the weight will cause manifold failure. Exhaust pipe hangers are
readily available and inexpensive. |
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FUEL SYSTEM |
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Extreme care should
be taken in designing and installing the fuel system to prevent
fire danger. Fuel lines should have as few connections as
possible and be routed to prevent damage. Keep lines away from
hot engine or exhaust components. The lines should be no smaller
than the inlet and outlet on the engine. Support fuel lines with
clamps, as needed, to help prevent metal fatigue from vibration.
The fuel tank should be level with or below the set to prevent
siphoning in the event of a line failure. Remember to check the
lift capacity of the engine fuel pump and stay within its
limits. If the set is higher than the tank, an auxiliary fuel
pump may be required. |
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To prevent water
ingestion, fuel should be drawn out of the top of the tank with
the pick-up extending to no more than two inches from the
bottom. Fuel storage tanks must have leakage protection and many
jurisdictions require spill basins. Above ground tanks are
recommended and cheaper but you must check your local codes
before installing a tank. The safest tanks are double walled
with alarms. These alarms are simple and well worth the
investment to avoid a possible fuel spill, and significant
clean-up costs. If the tank is mounted above the generator set,
use a fuel shut-off valve, so that you can work on the fuel
system without the fuel-siphoning out. It also allows you to
cut-off fuel flow in the event of line breakage.
A high quality,
fuel/water separator filter should be mounted as close to the
generator set as possible. Because of its explosive nature,
gasoline fuel systems have special requirements; see your tank
supplier for complete information.
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COMBUSTION
AND COOLING AIR |
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The generator set
requires air for combustion and cooling. A radiator and a
“pusher” engine fan cool the generator engine temperature.
Your car or truck will normally operate with a “puller” fan.
An internal fan cools the generator.
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OUTDOOR
MOUNTING |
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GenSets
that are housed in weather-protective enclosures are designed
for installation out-of-doors.
Typically a cement
pad is placed in a suitable location, out of sight but with easy
access for maintenance and fueling. The generator is
secured to the pad.
Choose a site close to the electric service and
fuel supply lines (natural gas, propane, or diesel). The image
below shows a typical natural gas installation. The main
distribution panel, transfer switch and sub-panels are inside
the building in this example, but more often the distribution
panel, sub-panels and transfer switch are outside.
You should make sure that 110v power is available at the
generator for battery charging.
The GenSet must be a minimum of 3 ft from
combustible material (NFPA 37). Leave at least 3 ft (or
more if the housing and instructions for your particular unit)
all around the GenSet enclosure for access to the inside (NEC
Art. 110-26a, Art. 110-26b). The GenSet must be at least 5
ft from any opening (window, door, vent, etc.) in a wall, and
the exhaust must not be able to accumulate in any occupied area.
See figure below.
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INDOOR
MOUNTING |
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We do
not recommend locating generator sets indoors in residential
applications and small commercial and industrial applications.
The primary reason to avoid indoor installation is safety.
Carbon monoxide gas is odorless, colorless and can accumulate in
closed spaces. You can walk into a room full of carbon monoxide
and be overcome. A gas leak in space attached to your home can
kill you and your family.
In
addition to safety, it costs more to install a GenSet indoors
than for the same GenSet provided with the factory weatherproof
housing. When a GenSet is installed indoors, the building must
be designed carefully to handle ventilation to remove heat and
any fumes due to fuel, exhaust, lubrication and starting
batteries. The radiator must be provided with a duct
adapter that interfaces properly with louvers on an outside wall
of the building. Adequate air intake flow must be
available not only for the radiator fan but also for cooling the
alternator. The engine exhaust piping and muffler must be
tight to prevent any leaks that would allow dangerous carbon
monoxide to accumulate inside the building.
Generally, the
room or space in which the generator operates, should not exceed
100 F. We recommend keeping it under 85 F if possible. Generator
installations require an intake of cool, clean air and an outlet
vent for hot air. Whenever possible the cool air should be drawn
over the alternator (or generator end) to help keep the
alternator cool. The size of the space affects the room
temperature (the smaller the space the generator runs in, the
higher the room temperature is likely to be), smaller spaces may
require ducting. The size of the generator and the outside air
temperature or climate must be considered. In an indoor
installation, increasing these vent sizes may cool the room down
to acceptable levels and ensure “positive” airflow. Positive
airflow is cool, clean air in and hot air out, as opposed to
circulating hot air inside the room. Generator cooling fans move
moisture as well as air. Moist air is corrosive to a GenSets
copper windings, so make sure air inlets are positioned to
minimize moisture intake.
Automatic fire suppression systems may also be required.
Check with your local fire codes. You should also contact
your fire insurance provider to determine if an indoor GenSet is
even permitted.
Installation engineered to meet all
the above requirements and all safety codes can still become a
hazard later. For an installation to remain safe, it has
to be regularly inspected and maintained to ensure that leaks or
other dangerous conditions do not develop with age or use.
Sites that do not have a knowledgeable maintenance staff trained
to support an indoor generator set should not install a unit
inside a building.
Another factor is the initial cost. It is impossible to
construct a building to house a GenSet at a cost as low as the
factory housing that can be ordered with the GenSet. And
even if the building already exists, the design expense and
costs to adapt it for a generator set installation usually will
exceed the enclosure cost available from the GenSet
manufacturer. For a small GenSet the cost of an open unit
with duct adaptor and exhaust pipe kit is as little as $600 less
than the same GenSet with the factory weather housing. The
additional costs for just the exhaust thimble and louvers exceed
that savings.
Please
read
Policy,
Warranties and Disclaimers.
You as the buyer and user of generators sold by GeneratorJoe
assume all risk and liability in connection with all equipment
purchased.
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AC
CONNECTIONS
Connecting the generator to your electrical distribution system
is a job for a qualified, licensed and bonded electrician who is
familiar with local building codes. Electricity is dangerous,
respect it.
TRANSFER
SWITCHES & SWITCHGEAR
All generator
systems require a circuit breaker and a distribution panel.
The circuit breaker protects the generator set from short
circuit and unbalanced electrical loads. The distribution panel
divides and routes the connected loads and includes circuit
breakers to protect these loads. Stand-by systems also require a
main circuit breaker between the utility source and the transfer
panel. The transfer panel switches power from the utility to the
GenSet and back so that both aren't on at the same time.
Residential, commercial and industrial generators are equipped
with auto-start to allow connection to auto-transfer switches.
Unless you have
no other electric service (utility power), you must install a
transfer switch. Normally the transfer switch must be the same
size as the service panel or a sub-panel off the service pane.
The transfer panel switches power from the utility to the GenSet
and back so that both aren't on at the same time. Auto-start,
auto-transfer systems are available and are relatively
inexpensive. We can help you determine what you need. For more
information about transfer switches and how they work see:
Small Transfer Switch Information
and for large switches see:
Transfer Switches.
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GeneratorJoe can help you determine what you will need, call us.
We
hope this information has been helpful. If you have additional
questions, contact your GeneratorJoe sales representative.
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