ABB AMD Rg 355 Installation, Operation And Maintenance Instructions page 71

Installation, operation and maintenance instructions

High voltage flameproof motors for explosive atmosphere
AMD Rg 355-400-450-500
Rolling bearings maintenance and checking
The values are valid for:

Vibrations originating from the machine itself.

Machines on rigid foundations. Rigid foundations
definition in conformity with ISO standard 10816:
"For a rigid foundation the system natural
frequency is higher than the rotation speed
frequency".
The values are not applicable (usually) for:

Alternative compressor drives.

Machines on foundations with low system natural
vibration frequency (machines + foundations), i.e.
 0.25 x rotation speed frequency
For these machines, it is opportune that the values are
agreed between the manufacturer and the customer at
the time of ordering.
Vibrations detected on the bearing housings
The decisive quantity is the actual vibration velocity
measured on the bearing housing. The position of the
measuring point is defined on the basis of ISO
Standard 10816.
The recommended values to set the protection devices
activation controlled by the detectors (or according to
decisions made based on manual measurement) are
the following:
Sheet No.
3AAM101040 E
Rev. B
Page 3 of 11
ALARM V = 4.5 mm/s
rms
BLOCK V = 7.1 mm/s
rms
NOTE: The above values are, in fact, lower than the
limits recommended by ISO Standard 10816. The
restriction of the allowed levels is due to the
particular design solutions of the Ex db motors flame
arresters, that have a very small gap between the
motor fixed part and the rotating shaft.
Converting of vibration velocity V
amplitude S
In order to have a comparison with the measured
values, the vibration amplitude S can be calculated as
follows (supposing that vibration is sinusoidal):
2 xV V
2
 
S rms x
 
2 x
f= rotation frequency in revs per second
V = vibration speed (mm/sec)
rms
S= vibration amplitude from 0 to peak (mm)
A conversion monograph is given below.
01.2023
to vibration
ms
V
rms ~ , 0 225 x rms
f f
Issued by: MOLM