HP Generating Set - Manual (Page 5)

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4. GENERATING SET
MOUNTING
The generating set will be shipped assembled on a
rigid base that precisely aligns the alternator and
engine and needs merely to be set in place (on
vibration isolation pads for larger sets) and levelled.
See figure 4.1
4.1 Vibration Isolation
It is recommended that the generating set be
mounted on vibration isolation pads to prevent the
set from receiving or transmitting injurious or
objectionable vibrations. Rubber isolation pads are
used when small amounts of vibration transmission
is acceptable. Steel springs in combination with
rubber pads are used to combat both light and
heavy vibrations. On smaller generating sets, these
isolation pads should be located between the
coupled engine/alternator feet and the baseframe.
The baseframe is then securely attached to the
floor. On larger sets the coupled engine/alternator
should be rigidly connected to the baseframe with
vibration isolation between the baseframe and floor.
Other effects of engine vibration can be minimised
by providing flexible connections between the
engine and fuel lines, exhaust system, radiator air
discharge duct, conduit for control and power
cables and other externally connected support
systems.
4.2 Floor Loading
Floor loading depends on the total generating set
weight (including fuel and water) and the number
and size of isolator pads. With the baseframe
mounted directly on the floor, the floor loading is:
Floor Loading =
Total Generating Set Weight
Area of Skids
With vibration isolation between the baseframe and
the floor, if the load is equally distributed over all
isolators, the floor loading is:
Floor Loading =
Total Generating Set Weight
Pad Area x Number of Pads
Thus, floor loading can be reduced by increasing
the number of isolation pads.
If load is not equally distributed, the maximum floor
pressure occurs under the pad supporting the
greatest proportion of load (assuming all pads are
the same size):
Max Floor Pressure =
Load on Heaviest Loaded Pad
Pad Area
FIG 4.1 REDUCING VIBRATION TRANSMISSION