KERN PBJ-N, Service Manual

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PBJ_N-SH-e-1810.docx 52
21
Performance Inspection
Performance inspections are to be conducted after at least 2 hours have passed since turning
on the power and “g” display (back-light turn on ), in a location where there is no air
movement, vibrations, or sudden temperature changes.
Fit the supplied windbreak set onto models capable of minimum readings of 0.001g.
21.1 Repeatability
- A mass close to the half of weighing capacity (a calibration weight is desirable) is loaded
and unloaded 5 times onto the center of the pan. The repeatability at zero and weighing
capacity is calculated.
R
x
= X
max
- X
min
: X
1
, X
2
･･･
X
5
R
y
= Y
max
- Y
min
: Y
1
, Y
2
･･･
Y
5
21.2 Corner load error
-
Prepare a weight as shown in “ table 1 ”.
-
Load the weight in turn on center of the pan “1” and positions ”2”,”3”,”4”,”5” located off
center of the pan and finally center “1” as shown in Fig.30, and take readings.
- Operation is normal if the difference between the value obtained in the position away
from the center and the value obtained in the center (the corner load error) is below the
specification value.
Example : ( Corner load error of “3” position) = (“3” value ) - ( average of ”1” values )
Fig. 30
21.3 Built-in weight calibration
- Calibrate the span using the built-in calibration weight.
- Load a calibration weight close to the weighing capacity and take a reading.
- Repeat steps 1) to 2) 2 times.
- Obtain the average error of the 2 measurements. ( error ) = ( average of reading values )-
( actual weight )
- Operation is normal if the error is less than the specification value.