Alarms
• Shutdown (A#): The dryer has automatically shut down because it has detect-
ed a serious problem that could damage your material or dryer.
• Passive (P#): The dryer continues to operate, but warns of a problem that could
prevent correct drying of your material. If ignored, this problem could lead to a
condition that will shut down the dryer.
6-16 l Troubleshooting
Problem
A50 - Process Protection
Differential - If the difference
between the process tempera-
ture exiting the process heater
and the temperature of the air
entering the hopper is greater
than 175°F {97°C} for longer
than 180 seconds it shuts
down the dryer.
A51 & P29 - Process
Protection RTD Integrity –
If the process protection RTD
is faulty, it shuts down the
dryer.
Possible cause
The air lines between dryer and hopper
are restricted or loose.
The dryer is located too far away from
the hopper.
The process RTD is loose or has fallen
out.
The process blower is not running.
The process hose is not insulated.
There is a loose connection in the
wiring leading to the RTD.
The connection of the RTD plug on the
control board is loose.
The process protection RTD has failed.
The control board has failed.
Solution
Check for air flow blockages or loose
hoses between the outlet of the dryer and
the inlet of the hopper. Straighten any
crimps in the hoses. Tighten any loose
hoses.
The dryer and the hopper should not be
located more than 10 ft
{3.05 m} apart.
Check the process RTD and tighten if
needed.
Correct the cause of the non-functioning
blower.
Insulated hose is required for high
drying temperatures.
Check the RTD plug connections,
make necessary repairs.
Check the plug connection and tighten
if needed.
Replace the process protection RTD.
Replace the control board.
When supplied for central drying applications, these shutdown alarms are not available.
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