Fairbanks X SERIES PR 5220 ETHERNET TRANSMITTER - Manual (Page 40)

Section 5: Commissioning
05/11 41 51209 Revision 2
5.4.13 Calibration with mV/V Value
The scale can be calibrated without weights. During input of the load cell mV/V value, the
acceleration of gravity at the place of installation can be taken into account. The STAR load cell
data is based on the acceleration of gravity effective at Hamburg, Germany: 9.81379 m/s².
Calculation of the average load cell sensitivity:
With D1 specification load cells, the use of sensitivity C given in the data sheet is sufficient.
The average load cell sensitivity C
Avr
is calculated as follows:
Ran
1
+ ... +
Ra2
1
+
Ra1
1
Ran
Cn
+ ... +
Ra2
C2
+
Ra1
C1
= C Avr
The formula is simplified when the output resistance Ra for the load cells is almost equal:
C
n
1
= C Avr
∑
Span: Calculation of the equivalent input voltage in mV/V
Span indicates the equivalent input voltage in mV/V related to the maximum capacity (Max) of the
scale. It is calculated as follows:
cells) load of number * load (nominal capacity cell load
[mV/V C y sensitivit cell load capacity maximum
= [mV/V] SPAN
Avr ] *
Dead load: Calculation of the equivalent input voltage in mV/V
The input voltage in mV/V equivalent to the dead load can be calculated by using the dead load
rather than the maximum capacity in the formula specified above.
Normally, calculation of the dead load (scale without load/empty hopper) is not necessary.
Subsequent dead load correction (as described in Chapter 5.4.15) can be used for later re-
determination of the dead load, when the scale/hopper is empty.
Example: Load cell(s) with rated output of 2mV/V at nominal load of 2000 kg, dead load 500 kg,
load cell supply voltage 12 VDC
The calibration dialog provides an overview of all settings:
WP A/Calibration
Max 1000 d 1000 kg
Scale interval 1000 d 1 kg
Deadload at 500.00 kg 0.500000
Max at 1000.00 kg 1.000000
Calibrated at 1000.00 kg 1.000000
Sensitivity 2500.00 12.000000
After selecting [mV/V], the values for the Max and for the dead load (if necessary) can be entered.
The next step is calculation of the test value with [Test] (see Chapter 5.4.17), and calibration is
completed by pressing
(see Chapter 5.4.18).