Spider DSA User’s Manual
216
However, there is great advantage in making both gages of a half bridge sensitive
to the primary strain. As shown below, the gages must be installed in
“complimentary” locations so that one of them experiences compression while the
other is in tension (and vice versa). When used in this fashion, the channel
sensitivity is increases to GF V
in
/2 microvolt-per-microstrain and the non-linear
term is cancelled out.
Figure x12: Using two active gages
Full Bridge Connections
A full bridge connection utilizes four strain gages and Spider inputs EXC+, EXC-,
IN+ and IN-, wired as shown below. This is the most sensitive installation. The
full bridge provides a channel sensitivity of GF V
in
μV-per-μstrain, temperature
compensation and perfect linearity. Of course, all four of its gages must be active.
Figure X13: Full Bridge connections
The full bridge utilizes four strain gauges and requires four wires from the Spider-80SG to
the bridge. There are three types of full bridges:
Type 1 orients the sensitive axis of all four gages in the primary strain direction.
This type of bridge is very sensitive (GF V
in
μV/microstrain) to bending strain and
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