Manual

4WFBS120, 4WFBS350, 4WFBS1K 4 Wire Full Bridge Terminal Input Modules (TIM)
Subtracting the unstrained (zero) result from the strained result gives
V
r
:
gD
g
ggD
gg
unstrainedstrained
r
RR
R
RRR
RR
Vin
Vout
Vin
Vout
V
+
−
Δ++
Δ
+
=
⎟
⎠
⎞
⎜
⎝
⎛
−
⎟
⎠
⎞
⎜
⎝
⎛
=
4.5.4
()()
gDggD
gD
RRRRR
RR
+×Δ++
Δ×
=
The terminal input module is selected so that R
D
= R
g
; Substituting R
g
for R
D
:
38
V
RR
RR R
RR
R
R
RR
r
gg
gg
ggg
g
gg
=
RR RR
gg
g gg
⋅
++ ⋅ +
=
Δ
⋅
+
Δ
=
+
Δ
Δ Δ Δ () 242()4
2
4.5.5
Solving for strain:
(
)
grgg
RVRR
Δ
=
Δ
+
24
g
RR
rgrg
VRV
Δ
=
Δ
+
24
VRRVR
rggrg
=
Δ
−
24
Δ
(
)
rgrg
VRVR 214
−
Δ
=
4
12
V
V
R
R
r
r
g
g
−
=
Δ
4.5.6
Strain is calculated by dividing equation 4.5.6 by the gage factor. The units are
converted to microstrain by multiplying by 10
6
uS/S.
()
με =
⋅
−
=
⋅
410
12
10
6
6
V
GF V
R
GF R
r
r
g
g
Δ
4.5.7