Great Plains NTA3007 Operator Manual - Manual (Page 97)

Great Plains Manufacturing, Inc. Table of Contents Index Adjustments 93
2012-07-02 Table of Contents Index 166-371M
21. Wipe all the material off the flanges around the
meter doors and capture that material in the
calibration bag.
22. Accurately weigh the calibration bag plus material. If
you have a digital scale, and set a “tare” on the
scale, the reading is the sample net weight, so skip
step 23.
23. Subtract the empty container weight to determine
the application rate for
1 ⁄
10
hectare (or
1 ⁄
10
acre).
24. Press the Stop softkey on the monitor
and enter the sample net weight (SampleWeight).
The monitor responds with a Calibration Constant.
Push the Save softkey to accept this
value.
25. If the sample was based on
1 ⁄
10
hectare
(or
1 ⁄
10
acre), multiply the sample size by 10 to
determine application rate per hectare (or acre) at
the current variable rate gearbox setting.
If the calibrated rate matches the target rate, skip to
step 31. Otherwise…
26. Subtract the calibrated rate per hectare (or acre)
from the target rate to determine a correction
difference.
27. Refer to the seed rate chart for gearbox setting
values for the target rate.
Manual Seeding Example; Net Weight (step 23):
Metric U.S. Customary
TotalWeight is: 23.26 kg gross
bag + sample 22.76 lbs. gross
bag + sample
BagWeight is: 1.52 kg 3.36 lbs.
SampleWeight is: 23.26 - 1.52
= 21.74 kg 22.76 - 3.36
= 19.4
SampleWeight TotalWeight BagWeight – =
If the calibrated rate turns out to match the desired
target rate, record the material details and final
Calibration Constant for future reference.
Manual Seeding Example - Calibrated Rate
Metric U.S. Customary
CalibratedRate = 21.74 x 10
= 217.4 kg/ha
19.4 x 10
= 194.0 lbs./ac
This is 8% higher than our target rate. However,
because the gearbox actuator effect is not linear, we
cannot simply adjust the control arm by 4.8%. CalibratedRate SampleWeight
10 ×
=
Correction Difference (Seeding Example)
Metric U.S. Customary
TargetRate = 200 kg/ha 178.4 lbs/ac
RateDifference = 200 - 217
= -17 kg
178.4 - 194.0
= -15.5 lbs
The calibration run metered too
much.
You must lower the gearbox setting
to compensate.
RateDifference T etR arg ate CalibratedRate – =
TargetRate
Example:
Initial Variable
Rate Gearbox
Setting: 62
158.5 177.6 58 78684
163.7 183.5 59 78794
169.0 189.4 60 78916
174.3 195.4 61 79050
179.6 201.3 62 79197