Grain Systems PNEG-1851 - Manual (Page 42)

Chapter 5: The Drying Modes
Figure 5-1 Breakdown of the control parameters and schemes in the continuous flow mode
Continuous Flow Based on Grain Temperature
Temperature-based control schemes in continuous flow use the grain temperature as their reference
parameter. As the grain temperature rises or drops, the unload speed automatically adjusts according to
the selected control scheme.
How It Works
Grain temperature is directly proportional to grain moisture. The unload rate changes to keep the grain
temperature constant, thus controlling the moisture output.
Let’s assume a grain temperature setpoint of 105°F. If the dryer reports a grain temperature reading of
110°F, the grain is five degrees higher than the target temperature. To correct this, the selected control
scheme automatically increases the unload speed, thereby reducing the length of time that the grain
spends in the grain columns. The opposite is also true. If the dryer reports a grain temperature reading of
100°F (five degrees below the setpoint), the unload speed automatically decreases.
The following three temperature-based control schemes are available in continuous flow mode:
• 1-speed
• 2-speed
• 5-speed
The 1-Speed Control Scheme
In the 1-speed control scheme, you enter the following parameters:
• The metering roll speed setpoint
• The grain temperature setpoint
As shown in the figure that follows, the metering rolls turn at the speed setpoint if the grain temperature is
equal to the grain temperature setpoint, and shut off if the grain temperature drops 1°F (0.56°C) below its
setpoint. See
Setting the 1-Speed Temperature Scheme in Continuous Flow, page 58 for details on how to
set up this control scheme.
42 PNEG-1851 Vision N2