This shunt tool is only applicable when the shunt scaling mode is selected. Calculation of the equivalent strain sets the Physical span value.
The equivalent strain value is calculated from the bridge resistance, shunt resistance, shunt polarity, strain gage factor and bridge factor. When any of these values are changed, the equivalent strain value and Physical span are no longer valid and must be recalculated.
Following is the formula for computing this in μm/m (microstrain) units if the shunt polarity is Up scale. If the shunt polarity is Down scale, multiply by -1.0.
ES = 4.0e+06 * (Rb/(2 * Rb + 4 * Rs)) / (GF * BF) , where:
Rb = Bridge resistance
Rs = Shunt resistance
GF = Strain gage factor (default is 2.0)
BF = Bridge factor (default is 1.0)
ES = Equivalent strain