Prior to calibrating the instrument perform the following calculations.
This will enable you to determine where the dip-switches should be
positioned for zero and span. Obtain the capacity and full scale
output of the transducer/s from the calibration certificates.
If required, convert them into the engineering units being used in
the system.
Use the above values in the following formulas to determine
the zero and span mV values.
Multiply the full scale mV/V output of the transducer/s by
the excitation voltage to obtain mV.
Example: 3.0 mV/V x 10 Vdc = 30 mV.
Zero (mV) = Z x O / C
Z = Tare weight (vessel, agitator, etc)
O = Full scale output in mV
C = Total capacity of the transducers.
Set the zero adjustment dip-switches so the calculated value is
within the minimum/maximum mV ranges given in Table 1 (page 9).
Span (mV) = S x O / C
S = Net weight (live or product weight)
O = Full scale output in mV
C = Total capacity of the transducers.
Set the span dip-switches so the calculated value is within the
minimum and maximum mV ranges given in Table 2 (page 10).
Sample calculation:
Three 1000 kg load cells, output = 3.0 mV/V
Tare weight = 500 kg.
Net weight = 2000 kg.
3.0 mV/V x 10 Vdc = 30 mV
Zero (mV) 500 kg x 30 mV / 3,000 kg = 5 mV
Table 1 dip-switch setting = Off, On, Off, Off (3.0 to 5.5 mV)
Span (mV) 2000 kg x 30 mV / 3,000 kg = 20 mV
Table 2 dip-switch setting = On, On, On, On (15.2 to 24.7 mV)
SECTION 2
CALIBRATION
7
