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Technical data are subject to change without notice.
ISO 9001 certified. © Copyright SPM 1996-9. 71411.B
SPM Instrument AB • Box 4 • S-645 21 Strängnäs • Sweden
Tel +46 152 22500 • Fax +46 152 15075 • info@spminstrument.se • www.spminstrument.se
Fig. 19
Measuring Points, Examples
On large electric motors (fig. 18), the bearings are
often mounted in bushings which are welded or bolted
to the motor shields. Because of the damping in the
interface between the bushing and the shield, the
measuring point should be on the bushing.
The bearing bushing at the drive end is usually within
reach. A long adapter is installed at an angle to the
shield, so that there is enough space for connecting
the transducer (fig. 18A).
Installed Transducer
The bearing at the fan end requires a permanent
transducer installation (18B). The transducer is installed
in the bushing. The coaxial cable is run through a slit
in the fan cover to a measuring terminal on the stator
frame.
Check Installed Equipment
Incorrectly installed adapters, studs, or transducers
can cause a significant damping of the shock pulse
signal.
Check all installations. Make sure that mounting holes
are correctly countersunk and that the seat surfaces
of adapters have good contact with the material of
the bearing housings.
Any metallic machine part knocking or rubbing against
the adapter will produce a disturbance. This must be
avoided by making large clearance holes and using
soft, elastic sealing material.
Use high temperature cables and moisture proof equip-
ment where required, and protect installations against
damage. Studs and adapters should be fitted with
protecting caps.
Mark the Measuring Points
Measuring points for the probe transducer should be
clearly marked with SPM measuring point markers.
To get comparable readings, one must always use the
same measuring point.
Fig. 18
A
drive end
A
B
Disturbance
Correct installation
Faulty installation
B
fan end
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