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transducers at any angular position on the bearing cap or frame. Vertical and
horizontal directions are usually preferred for horizontally mounted machines. In
some cases it may be recommended to measure the vibration also in the axial
direction. When recording the results of the measurements, record the specific
locations and directions with the actual values.
Evaluation of RIC engine generating sets
The main excitation frequencies of the RIC engine (Reciprocating Internal
Combustion) are in the range of 2 Hz to 300 Hz. However, when considering the
overall generating set structure and components, a range of 2 Hz to 1000 Hz is
required to evaluate the vibration.
Experience has shown that with a standard design of generating set structure and
components, damage would not be expected if vibration levels remain below
value 1 (See Table 7-9. Vibration velocities below):
Table 7-9. Vibration velocities.
Engine speed/[rpm]:
1300 but <2000
>720 but <1300
If the vibration levels fall between values 1 and 2, assessment of the generating
set structure and components may be required along with an agreement between
the generating set manufacturer and the component supplier in order to ensure
reliable operation.
In some cases vibration levels can be above value 2 but only if individual special
designs of generating set structure and components are applied.
In all cases the generating set manufacturer remains responsible for the
compatibility of the generating set components (see ISO 8528-5:1993, 15.10).
Additional information
For more details about vibration measuring, see the following International
Standards where applicable:
•
ISO 2954 Mechanical vibration of rotating and reciprocating machinery -
Requirements for instruments for measuring vibration severity.
•
ISO 5348 Mechanical vibration and shock - Mechanical mounting of
accelerometers.
•
ISO
Measurements on rotating shafts and evaluation criteria.
•
ISO 8528 Reciprocating internal combustion engine driven alternating current
generating sets.
•
ISO 10816 Mechanical vibration - Evaluation of machine vibration by
measurements on non-rotating parts.
7.4.3 Temperature levels
The temperatures of the bearings, stator windings and cooling air should be
checked when the synchronous machine is running.
The bearings might not reach a stable temperature until after several (2-6) hours,
when running at full speed.
The stator winding temperature depends on the load of the machine. If full load
cannot be reached during or soon after commissioning, the present load and
temperature should be noted and included in the commissioning report.
Limit 1/[mm/s]:
7919
Mechanical
Page 45
Limit 2/[mm/s]:
20
28
18
22
vibration
of
non-reciprocating
machines
-
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