Machine
Severity
Refer to
ISO
10816-3;
this
machine
is
classified
in the
machine
group 2
;
fiexible
foundation,
the
machine
severity
is "Inadmissible"
(>7.1 mm/s
as the
above
data)
condition.
Analyze
for
The
vibration
high at
3A and 4
A and
they are
much
more
than the
other
points
as
called "Directional
Vibration".
Main
source
of these
vibrations
are only
the
synchronous
speed or
the fan
speed
17.5 Hz
(1050
rpm) as
the
spectrum
attached
figure
1. This
is the
effect
of "Resonacne
" on the
machine.
In order
to
confirm
the
Resonance
Phenomenon,
we have
preformed
"Bump
Test" on
the
machine
to find
out the
resonant
part and
found
that the
Nutural
frequency
of the
Pedestal
is 15.25
Hz as
the
spectrum
attachment
figure
2. This
Nutureal
frequency
is close
up the
main
source
at 3A
and 4A.
The
excitation
force at
17.5 Hz
is
higher
than the
Natural
frequency
at 15.25
only
2.25 Hz
or
14.75%
or the
Natural
frequency.
So the "Bump
Test"
result
is
confirmed
that
this is
the "Resonance
Phenomenon"
