PASCO PS-2200 Load Cell, 100 N - Manual (Page 2)

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L o a d C e l l , 1 0 0 N PS-2200
2
Figure 2: A load cell combined with two #2 beams is the same length
as a #4 beam
Use thumbscrews to attach two beams to a load cell as shown in
Figure 2.
When using load cells, assemble your structure with the screws
loose. This will simplify the analysis by ensuring that the mem-
bers experience only tension and compression without moments.
Plug the mini-DIN connector at the end of the load cell cable into
a port on the Load Cell Amplifier (PS-2198). See the instructions
that came with the load cell amplifier for details about how to
connect the load cell amplifier to an interface or datalogger and
collect data.
Example: Bridge with Load Cells
Figure 3: Bridge with load cells
The bridge shown in Figure 3 incorporates six load cells to mea-
sure the tension or compression in various members. A hanging
mass is used to apply load. The mass is adjusted so that the com-
pression in one of the legs is 1.0 N. Compression is registered as
a positive value and tension as a negative value.
If the screws are loose, the theoretical analysis of the bridge can
be carried out by assuming that the net force at each node is zero.
Thus, the vertical component of compression in the left-most
diagonal member must be 1 N (to oppose the force applied by the
leg). The horizontal component must also be 1 N since the mem-
ber is at a 45° angle. The predicted resultant force is:
The actual measured force confirms the theory.
Calibration of Load Cells
Load cells are factory calibrated; however, you can recalibrate
them in software or on the datalogger. See the documentation for
your software or datalogger for instructions.
When calibrating a load cell, it is necessary to apply a known
load. Assemble the fixture shown in Figure 4 to support the load
cell. Hold or clamp the fixture at the edge of a table and hang a
mass from it as shown.
Note that the hanging mass applies tension to the load cell; there-
fore the known force that you enter into the software or datalog-
ger should be a negative value. For example, if the mass is 1.0 kg,
the applied force is -9.8 N.
Figure 4: Calibration fixture
Specifications
1.0 N ( )
2
1.0 N ( )
2
+ 1.4 N =
Range -100 N to +100 N
Dimensions 5.3 cm by 5.8 cm by 2.0 cm
Length of cable 120 cm
Mass approximately 100 g