A
C
D
B
Figure 12.32:
Shunt calibration completion plug
-
in module
A
User quarter
-
bridge Completion
B
User half
-
bridge Completion
C
User shunt cal
D
JUMPER!
Remove when installing a half
-
bridge completion
12.4.5
Shielding and driven guard
When long cable runs are required, the excitation leads and signal leads are
generally separately twisted and shielded within the cable to minimize the
cross
-
coupling that would otherwise occur.
The high
-
performance signal conditioners offers the “driven guard” system
where the cable shield is connected only to the drive pin of the conditioner.
When connected like this, the shield is driven to a potential that is equal to the
common
-
mode voltage of the bridge. The driven shield or guard therefore
minimizes the potential difference between the internal conductors and the
shield, thereby reducing the amount and levels of partial discharges between
them. In all cases, the driven shield is terminated only at the driven guard
conditioner terminal. It is strongly advised to have the driven shield surrounded
by an outer shield that is terminated to ground preferably at the strain gauge
installation site as shown in Figure 12.33.
GEN3i
252
I3763-3.1 en HBM: public
