1 quarter bridge strain with 3 wire element wiring, No 1, Datalogger a cti ve g auge – Campbell Scientific 4WFBS120, 4WFBS350, 4WFBS1K 4 Wire Full Bridge Terminal Input Modules User Manual
Page 11
4WFBS120, 4WFBS350, 4WFBS1K 4 Wire Full Bridge Terminal Input Modules (TIM)
4.1.1 Quarter Bridge Strain with 3 Wire Element Wiring
Figure 4.1-2 illustrates the wiring of the strain gage to the 4WFBS module and
the wiring of the module to the datalogger. It is important that the gage be
wired as shown, and that the leads to the L and G terminals be the same length,
diameter, and wire type. It is preferable to use a twisted pair for these two
wires so that they will undergo the same temperature and electromagnetic field
variations. With this configuration, changes in wire resistance due to
temperature occur equally in both arms of the bridge with negligible effect on
the output from the bridge.
Datalogger
A
cti
ve G
auge
or G
AG
L
H
VX or EX
4WFBSXXX TIM
R
2
=1
K
Ω
R
1
=1
K
Ω
R
D
Shunt Receptacle
Shunt Receptacle
FIGURE 4.1-2. 3-wire ¼ bridge strain wiring
4.1.1.1 Quarter Bridge Strain with 3 Wire Element Wiring using a multiplexer
When using a mechanical relay multiplexer such as the AM16/32B, the
4WFBS module should normally be placed on the face of the multiplexer
similar as shown in Figure 4.1-3.
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
2
3
4
5
ODD
EVEN
13
4X16
2X32
21
22
23
24
25
N
O
1
H
L
G
AM16/32B Relay Multiplexer
4WFBS
2
3
COM
7
11
12
13
RE
S
CL
K
GN
D
12
V
CR800
CR850
G
12 V
G
C1–C4
C1–C4
CR10X
CR1000
CR3000
G
12 V
G
C1–C8
C1–C8
CR23X
CR5000
12 V
G
C1–C8
C1–C8
21X
+12 V
EXCIT 1–4
C1–C6
CR7
12 V
EXCITATION
725 Card
Control
CR10X
AG
E1–E3
1L
1H
CR23X
EX1–EX4
1L
1H
CR1000
EX1–EX3 or
VX1–VX3
1L
1H
CR3000
CR5000
VX1–VX4
1L
1H
21X
EXCITATION
1–4
1L
1H
CR7
SWITCHED
ANALOG OUT
1L
1H
CR800
CR850
EX1–EX2 or
VX10VX2
1L
1H
Cable Shield
FIGURE 4.1-3. 3-wire ¼ bridge strain with multiplexer wiring
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