standards and guidelines for communication sites - Radio And ...

STANDARDS AND GUIDELINES FOR COMMUNICATION SITES GENERATOR OUTPUT AND DERATING CONSIDERATIONS
6.9.1 GENERATOR PLACEMENT
All generators shall have an adequate supply of fresh air to ensure proper operation and extend life. Air
is required for safe and efficient combustion as well as to cool the engine and generator. The type of
engine cooling is determined by the capacity of the generator. Most generators above 7.5 kW utilize
water-cooled engines; generators below 7.5 kW typically use air-cooled engines. The rate of airflow
required for cooling is specified by the manufacturer. Manufacturer's guidelines shall be followed to
ensure proper operation.
NOTE: The type of fuel used for a generator dictates the elevation of the fuel tank relative to the generator. A
liquid-fuel generator (diesel or gasoline) will require that the fuel tank be upgrade from the generator
fuel inlet such that the generator remains primed. Conversely, because gases rise, an LPG or natural-gas
powered generator shall be placed upgrade from the fuel source outlet port.
6.9.1.1 GENERATORS LOCATED INDOORS
If the generator is to be located inside a separate structure or within the site building, the following
requirements shall be met:
• Personnel safety and vulnerability of the generator to damage shall be considered, especially if the
generator is to be installed without a protective housing. Moving engine parts and the exhaust
system may be exposed, which could pose a hazard. Guards or shields shall be installed on exposed
engine parts that could pose a safety hazard to personnel.
• The generator shall be located in an area accessible only by authorized personnel.
• Provide adequate spacing for service to the generator in accordance with NFPA 70-2005 and state
and local codes (or equivalent). Generally, a minimum spacing of 914 mm (3 ft.) on three sides is
acceptable.
• Manufacturer's specifications shall be followed to ensure proper ventilation, fuel supply, and
engine exhaust.
• Properly sized air intake and exhaust ports shall be installed and maintained. The exhaust air from
the radiator area of the generator in most cases is ducted to the outside.
• A louver or shutter should be installed on the exterior of the duct to close off the duct when the
generator is not running. The shutter should open automatically when the generator begins
operating
• A motorized louver or shutter should be installed on the air intake to close off the duct when not in
use. The shutter should open automatically when the generator begins operating.
• The concrete foundation for the generator should be separate from that of the general structure. An
inset sub-foundation set within a well in the overall foundation will help isolate transmitted
vibration and noise emanating from the generator.
• Ensure that there is an adequate fresh air supply. Should the fresh air supply not be adequate, air
will be drawn through doors, or possibly through existing vent pipes, causing a down draft of these
vents. This could draw undesirable or potentially harmful fumes or gases back into the room or
building. This could be a major concern in manned buildings. Check local codes for
recommendations and guidance in this area.
• Fuel supply lines shall be no smaller in diameter or of greater length than that specified by the
manufacturer. These lines should be routed and installed such that they are protected from potential
damage.
68P81089E50-B 9/1/05 6-37