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Installation, operation and maintenance instruction
High voltage flameproof motors for explosive atmosphere
AMD Rg 355-400-450-500
Sleeve bearings maintenance
Shaft vibration
According to standard IEC 60034-14 (2003), it is
advisable to measure the shaft vibrations only on
machines with sleeve bearings; operating speed more
than 1200 rpm and power greater than 1000kW The
vibration limits are usually established by agreement
between manufacturer and user
In any case, for explosion-proof machines, shaft
vibration alarm and stopping values will be on average
less than the values for standard machines; this is due
to the smaller gap between the shaft and the flame
arrester seals
It is not possible to establish beforehand the vibration
alarm and stoppage values since these depend on the
type of machine, rotation speed, stiffness of rotor,
operating conditions, etc.
Useful reference guides for a monitoring program and
the methods to measure the shaft vibration are
contained in ISO 7919-3 and ISO 7919-1.
The shaft vibration is to be measured by means of "non
contact" probes place near the bearings.
Converting the vibration speed V
amplitude S (vibration on bearing housings only)
To afford comparison with the measured values, the
vibration amplitude S can be calculated as follows (on
the supposition that vibration is sinusoidal):
2
xV
s
f
= frequency of rotational speed (round/sec)
V
= vibration speed (mm/sec)
rms
S
= vibration amplitude 0-peak (mm)
to vibration
rms
2
V
rms
x
rms
~
, 0
225
x
2
x
f
A conversion nomograph with limit values is shown
below:
V
rms
f
Sheet No.
3AAM101043 E
Rev. C
01.2023
Page 4 of 4
Issued by: MOLM
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