AEC HE Mass Flow Series Drying hoppers - Manual (Page 27)

Page 26 HE
• CHE • BCHE Mass Flow Series Drying Hoppers
Process Heater Light
CHE and BCHE Models
This green indicator lights when the process air heater is on.
High Process Air Temperature Light
CHE and BCHE Models
This red indicator lights when the temperature at the process air thermocouple is outside the set
alarm value. The alarm mode and value are factory-set to track 25° above the process set point.
Therefore, the alarm value is set as a deviation from the process set point.
When the indicator lights, the alarm relay is energized and all the heaters turn off while the
blowers remain on. When the temperature at the process thermocouple returns to within the
acceptable range, the alarm output is de-energized and the heaters will turn on again
automatically. The alarm range can be altered.
5-2 Using the 1/4 DIN Temperature Controller
Some AEC/Whitlock drying hoppers use a 1/4 DIN microprocessor-based PID temperature
controller for maintaining process air temperature. The controller is a modular, self-contained
unit you can remove from the mounting housing. All parameters except for the process air set
point are factory set and adjusted; normally, no field adjustment to the internal controls is
necessary.
Figure 10
1/4 DIN Controller
AT
ºF
3 0 0
PV
3 0 0
SV
OUT SHIFT AT ALM1 ALM2
Mode key
Down key
Up key
AT (Auto-Tune) key
ALM1 (Alarm 1)
indicator
AT (Auto-Tune)
indicator
ALM2 (Alarm 2)
indicator
SV (Set Value)
display
PV (Process Value)
display
ºF (Fahrenheit) decal
OUT indicator
SHIFT indicator
Level key