Iv. how the controller works – Grain Systems PNEG-526 User Manual

Page 22

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.