Bently Nevada Velomitor Sensor Operation Manual page 26

Special installation instruction for 330530's cable (330533) and installation in
nuclear environments
This cable has the shield and drain wire connected at the sensor's connector.
The sensor should be correctly grounded on the machine and so this becomes
the primary shield grounding point inside containment. Our best practice says
that only one point should be used to connect to the cable's shield and so to keep
with this practice, an isolation capacitor needs to be installed, see diagram for our
recommendation.
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Figure 2-1. Recommendations for 330533 Cable Hook-up
Application Advisory: The capacitor is required to prevent ground
loops. If the case of the machine that the 330530 is mounted to is not
at the same voltage potential as the monitor's common, a current will
flow through the shield of the interconnect cable. This low level current
could cause false readings or trips. At high levels, this current could
destroy the monitor if the capacitor is not used.
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"B", black
"A", white
SHLD
Capacitor, 0.01uF to 0.05, minimum of 300 V
Feed-through Terminal Block, Outside Containment
Feed-through Terminal Block, Inside Containment
Velomitor® Sensor Connector
Typical Monitor
Wall of Containment
Section 2 - Maintenance
21