Grain Systems PNEG-526 - Manual (Page 22)

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Tower Dryer Operations & Service
IV. How the Controller Works
The controller continuously monitors the
moisture coming in and out of the dryer,
and the column grain temperature at the end
of the drying section. The control action is
mainly based on the dry sensor at the outlet
of the dryer. If the moisture coming out of
the dryer is not right at the target, the con-
troller will speed up or slow down the
unload device accordingly. The wet sensor
and the column grain temperature sensor are
intended to detect moisture spikes coming
into the dryer so that the moisture controller
can react ahead of time. For example, if the
wet sensor detects a jump of moisture
coming into the dryer, the controller will
start slowing down the unload speed right
away. However, the controller does not act
to the full scale immediately. Instead, it
slows down the dryer gradually so that the
grain currently in the dryer will not be
overdried too much.
In the first pass after the dryer started, the
controller does not have enough informa-
tion of the grain in the dryer. It controls the
dryer by using the manual speed setting as a
starting point. In other words, the manual
speed setting is most responsible for the
first pass of drying. Therefore, set the
manual unloading speed as close as it
should be for the grain currently in the dryer
before switching to AUTO control mode.
The manual speed setting does not have to
be adjusted after the controller is switched
into AUTO mode.
4. Check or change the target moisture
from the main screen.
Check upper/lower unloading limits and
change them if needed.
6. Press the “CONTROL MODE”
button from the moisture control set-up
screen and set the mode to AUTO. The
moisture controller will start adjusting the
unload rate between the upper and lower
limits of the unload speed to maintain the
moisture coming out of the dryer.
5. Press “MOIST CONTROL” to ac-
cess the moisture control set-up screen.
TRI-POINT MOISTURE CONTROLLER
The sensor should be calibrated 2-3 times a
day. At the same time check and clean the sensor
and sensor sampling box to make sure that there is
no debris blocking the grain flow around the
sensor.
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