Omega Products OM-CP-Bridge120 Installation Manual
650-467-8671
OM-CP-Bridge120
Bridge/Strain Gauge
Data Logger
GageFactor
R
R
ainsmi
000,000,1
)(crostr
×
∆
=µε
µε397
1.2
000,000,1
120
1.0
=
×
OM-CP-Bridge120
Product Notes
The OM-CP- Bridge120 data logger is designed to interface with and measure strain gauges and load
cells. The device provides an excitation voltage of 2.5V’s and is available in the following millivolt input
ranges: ±10mV, ±25mV, ±100mV, ±1000mV. The Bridge120 features a
sampling rate of up to 20Hz.
LEDs
Once started, the LED will flash at the selected reading rate to indicate the device is running.
Wheatstone Bridge Configuration
If it is desired to make strain gage measurements with better signal integrity and not requiring
matching the thermal expansion coefficient to the material, then a Wheatstone Bridge configuration
ought to be considered. While there are several versions of the Wheatstone Bridge, the least complex
configuration that has these desirable qualities is the One-half bridge.
ONE-HALF WHEATSTONE BRIDGE
Note 1: The two strain gages need to bend in the opposite direction when stressed. Under this arrangement, the non-linear error
is nulled out and temperature coefficients between the sensors and the material do not have to match.
Note 2: The tolerance of the 120Ω resistors and the “matched” values of the strain gages affect the “null”
reading which theoretically ought to be 0V. It is recommended to use 1% or better resistors and identical strain gages.
EXAMPLE:
A common unit of strain gage measurement is microstrains (μ). Microstrain is mathematically
expressed as such: Where R/R is the ratio between the change in strain gage resistance (under stress)
and the nominal strain gage resistance. The Gage Factor (GF) is specified by the manufacturer or
vendor of the particular gage. Typically, GF values are 2 to 4.5 for metal and 50 to 200 for
semiconductor strain gages. A 120Ω strain gage measures, under stress, 120.1Ω. The GF is 2,1.
Convert to microstrains:
Loading...