Specifications
PR 5220 Operating Manual Commissioning
Sartorius 39
5.4.7 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 CAvr is calculated as follows:
Ran
1
+ ... +
Ra2
1
+
Ra1
1
Ran
Cn
+ ... +
Ra2
C2
+
Ra1
C1
= CAvr
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 (nominalcapacity cell load
[mV/V Cy sensitivit cell loadcapacity 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 5.4.9) 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 5.4.11), and calibration is completed
by pressing
(see Chapter 5.4.12).