Check the following when the moisture sensor doesn’t read the proper grain moisture content:
- Wiring cable from moisture sensor to PLC unit may not have the shield grounded properly. Shield should be grounded at the high voltage cabinet but NOT at the sensor.
- VFD noise is creating a variable signal and wires from sensor need to be pulled out of wiring harness and run separately from voltage wires.
- Build-up on moisture sensor, clean off sensor.
- Sensor does not read proper temperature and cannot be adjusted to read proper temperature. The thermistor or thermocouple is damaged and sensor needs to be replaced.
When running in TruDry, why does my metering speed have a wide range, even though incoming grain only varies a few points?
- Verify the level auger delay timer is not set over 60 seconds. If it is not, try decreasing by 15 seconds.
- On the HMI, slect “Settings” on the toolbar. Then select “Operational Setpoints.” Raise the “Min Discharge Speed” and lower the “Max Discharge Speed.” Make small changes, maybe 5% at a time, and observe if the range in speed of the metering narrows up.
- Remove cover and check for moisture. Dry with a hair dryer.
- Check that electrical connections are solid.
- Check that full 12vdc is delivered to the sensor. Check between terminals 1 and 2 in the sensor.
- On the HMI, select “Settings” on the toolbar. Then select “Operational Setpoints”. Raise the “Min Discharge Speed” and lower the “Max Discharge Speed” a little. Make these changes in small increments to determine what will work best for you.
- Go to the “PLC I/O” on the HMI tool bar. Arrow to the right until you find the screen labeled “Moisture/Temperature Analog Inputs”. Observe the values under “15 sec”. Warm up the temperature probe and the value on the screen should change. Touch the sensor blade and the sensor box at the same time. After 15 seconds, that value should climb into the 20s or 30s. If one reading changes but not the other, chances are the sensor needs replacing. If neither temperature or moisture responds, check wiring connections, and 24 vdc delivered to the sensor before replacing the sensor.
- Consult with your MC dealer’s service department before replacing the sensor.
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