AEC AD Series Operation And Installation Manual page 64

Problem
Loss or reduction in drying
capacity. (cont'd.)
PLC Regeneration Bed LED
indicators both off.
PLC Regeneration Heater
Left/Right output indicators both
off.
Material in drying hopper cakes,
or meltdown occurs.
Poor dew point performance.
Page 64
Possible cause
Airflow valve sticking or failing to
shift.
Blower fins filled with dust or
contaminants.
Insufficient power to PLC
(Power LED is off).
Faulty PLC (PLC Power light is
on, Run light is off, and/or Error
light is on).
Regenerating bed cooldown.
Blower Input indicator is off.
Process air in high-temperature
condition.
Insufficient power to PLC
(Power light is off).
Faulty PLC (PLC Power light is
on, Run light is off, and/or Error
light is on).
Process temperature set too
high due to operator error.
High temperature alarm not set
properly.
Process set point is out of
acceptable range.
Function set for degrees Celsius
(ºC), set point at degrees
Fahrenheit (ºF).
Process thermocouple not in
airflow.
Burned out regeneration heater.
Contaminated or worn out
desiccant.
Leaking process air hoses.
Dryer operates beyond its
capacity.
Bad dew point sensor.
Corrective action
Check for proper operation of
valve actuators. Repair or
replace if necessary.
Remove blower side plate, clean
baffles, replace.
Replace filter elements.
Check power supply and power
wiring to PLC.
Replace PLC.
None.
Verify that blower contactor is
on. Check input wiring to PLC.
None.
Check power supply and power
wiring to PLC.
Replace PLC.
Check resin manufacturer's data
sheet for proper drying
temperature. Make sure plant
personnel are aware of the
correct process temperature set
point.
Reset high temperature alarm.
Restore temperature controller
to factory pre-sets.
Verify correct Celsius or
Fahrenheit settings.
Verify that the thermocouple is
properly installed in the inlet
tube.
Repair or replace.
Replace.
Repair or replace.
Check dryer and drying hopper
sizing.
Replace.
AD Series Dehumidifying Dryers