55
The Load Cell and Input Sensitivity
The Load Cell and Input Sensitivity
The Load Cell and Input Sensitivity
The Load Cell and Input Sensitivity
The relationship between load cell and input sensitivity (
X
) for the FC-
i
scales is:
q
Example
Load Cell Capacity
100kg
“
A
”
Rated Output
3mV/V
“
B
”
Min., Division of Display
0.01kg
“
D
”
q
When a single Load Cell is used,
the following formula should apply:
q
System design will be satisfactory if “
X
” is
greater than 0.5µV. In the example above
Capacity and Resolution
Capacity and Resolution
Capacity and Resolution
Capacity and Resolution
q
The resolution of the remote scale is automatically determined during the calibration
procedure. The following is to enable you to calculate the resolution for a given capacity.
1. Decide the capacity value and assign it to “Ws”. Maximum 5 digits.
2. Get the maximum count “Ns” for the capacity. Ignore the decimal point and add “0” to
Ws until it is 5 digits.
3. Calculate: d’=Ns/10,000.
4. Decide the minimum division “d”.
d’=1
à
d=1
2
≥
d’>1
à
d=2
5
≥
d’>2
à
d=5
d’>5
à
d=10 This should be changed to d=1, dividing Ns by 10.
5. Now “Ns x d” and the resolution 1/No = d/Ns can be determined.
Step
Parameters
Example 1
Example 2
Example 3
1
Ws
200kg
30.0kg
600kg
2
Ns
20,000
30,000
60,000
3
d’
2
3
6
4
d
2 (=0.02kg)
5 (=0.005kg)
10 (=0.1kg)
Ns x d
20,000 x 2
30,000 x 5
6,000 x 1
5
1/No (=d/Ns)
1/10,000
1/6,000
1/6,000
6. Calculate the voltage sensitivity “Es”.
Es = (As-Ao) x 5,000 x 1/No (µV) [5,000 means excitation voltage 5V]
Ao: Load cell output at zero point (mV/V)
As: Load cell output at full capacity (mV/V)
7. Check the voltage sensitivity “Es”.
Es
≥
0.5µV
à
Calculated “Ns x d” is fixed. In example 3 in the step 5, a 600kg x
0.1kg scale will be obtained.
Es<0.5µV
à
Change “d” for new resolution 1/No.
d=1
à
2
d=2
à
5
d=5
à
10
à
1 (dividing “Ns” by 10)
In example 1,
the new d=5: 1/No=d/Ns=5/20,000=1/4,000 (200kg x 0.05kg)
In example 2,
the new d=1 and Ns=3,000: 1/No=d/Ns=1/3,000 (30kg x 0.01kg)
Using the new 1/No, go to step 6 and repeat it until Es
≥
0.5µV in step 7.
5,000 x
B
x
D
A
“
X
”=
µ
V
“
X
” = 1.5µV.
Summary of Contents for FC-50Ki
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