Setra Systems Super Count Operator's Manual page 11

USING THE MINIMUM SAMPLE SIZE & ACCURACY FEATURE
Counting errors can be caused by non-uniformity in the parts being counted or by insufficient sample
weight. To reduce these errors your scale is designed with two special features. The minimum sample
size feature ensures the scale will calculate an average piece weight from a large enough sample
which is nearly equal to the average piece weight of the entire lot. This feature prevents an operator
from using a sample size which is too small and could be "biased", i.e., not truly representative of the
distribution of unequal parts in the lot to be counted. Setting the scale to require a larger minimum
sample will reduce the error which is introduced by non-uniformity.
The minimum accuracy feature ensures that total sample weight is heavy enough to keep counting
errors very small. The higher the degree of accuracy desired, the larger the total sample weight that
will be required. This means that even if the sample satisfies the minimum sample size requirement it
may still be too light to achieve the accuracy level selected and therefore the scale will request more
pieces.
Your scale has been preprogrammed at the factory with no minimum-sample requirement and a mini-
mum accuracy requirement of 95%. To change the minimum accuracy and/or a minimum sample size
setting refer to Appendix II, Setup Functions.
When the scale is set up to require a minimum sample size or certain degree of accuracy it may
display messages during the counting procedure. The steps are outlined below:
1. Press the zero key.
2. Press the sample size key.
3. The scale display will say "Add nnn PC", where nnn represents the programmed minimum
sample size.
The sample size requirement can be increased by pressing the sample size key repeatedly.
The predetermined sample size are: 10, 25, 50 and 100 pcs. This sequence of predetermined
sample sizes will repeat itself as the sample size key is pressed. A custom sample size may be
preset by using the minimum sample size setup feature. The scale will never request a sample
size less than the preset minimum sample size. (e.g. If the minimum sample size has been
preset at 12 pieces then the sample size key will display Add 12 PCs, Add 25 PCs, Add 50
PCs, Add 100 PCs, Add 12 PCs...etc. when pressed repeatedly.)
4. When you reach the desired sample size, place the requested number of pieces on the pan.
5. Press the count key.
6. Wait for the "OK" symbol, then read the display.
The scale may request that more pieces be added after the initial sampling if a minimum accu-
racy requirement has not been met.
If the minimum accuracy requirement has been met, the scale will display the correct number
of pieces and you can proceed to Step 10.
If fewer than the required number of pieces have been placed on the pan, the scale will ask you
to add pieces. In this case, perform Steps 7-11 below.
7. Add the exact number of pieces requested by the scale.
8. Press the count key.
TM
Setra Super Count Operator's Manual 11