Multiple bearings in one housing
If there are several bearings in the same housing,
they are normally treated as a single bearing. In the
bearing arrangement for a vertical pump (4), it is not
possible to distinguish between the shock pulses from
the paired bearings in point 1.
There is also a risk for cross talk between point 1 and
point 2, which means that the shock pulses from the
bearing in worst condition are picked up in both points.
Check signal strength with the probe. Use one
measuring point only if readings are identical in both
points. This point (x) can be placed halfway between
points 1 and 2.
Installed transducer
On large electric motors (5), 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 (A) 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.
The bearing at the fan end (B) requires a permanent
transducer installation. 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.
1
X
2
4
A
B
5
A. Drive end
B. Fan end
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