Moisture Probe Calibration & Repairs

Specifications to confirm the correct moisture input values:

Setting the Cgain value - One 10 foot probe Cgain=46; Two 10 foot probes Cgain = 92, any reduced length is Pro Rated from above values, i.e. 8 foot probe Cgain = .8*46 = 36.8. These value should not be altered. To calibrate the moisture probe for the correct moisture input we work with an Empty Bin. Read the scan result (Present Value Number) for the bin under consideration. The formula to calibrate the input is (Present Value # - Cgain) = Coffset. This is repeated for each bin. Reading the Log Value will yield an empty bin reading of 1.00. "JAM" and "Calc" buttons can aid in this process.

Diagnosis of moisture input reading errors. If Present Value # reading deviate from the initial empty bin settings (i.e the Log Value deviates from 1.0 ± .1 ) then you should look to the hardware involved. Each component part of the Moisture rod and coax cable contributes an amount of dead or offset capacitance and by this you can often pinpoint the problem. The best method I can offer is an example. Lets presume the majority of Present Value reading are about 190 to 200 which would represent a single moisture rod input with 10 foot of coax. How is this 200 value made up from the parts and what does it tell us.  The contribution estimates are:  Rod = 45,  10 foot coax 135,  Union = 6.5,  12" Box Coax = 17.   So in my example if I have a moisture graph problem and I read PV = 155 for that bin I would conclude the disconnect is where the coax connects to the rod. If the PV reads 17 or 23 I suspect the Union.                       If PV reads 0.0 I would look at the connection on the circuit card. Of course this presumes your first look at the problem would be for screen input error such as no Hybrid selected. Also, if the Bin has been loaded with corn and the input problem exists you can select "Faulty M% Probe" in the Start Status Window until the hardware can be fixed.

For those bins with more than one moisture rod the total dead capacitance will be comprised of multiple coaxes and rods and therefore this must taken into account with less definitive diagnosis.