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Large Dehumidifying Dryers Troubleshooting 49
Chapter 7: Troubleshooting
7-1 Introduction
The utmost in safety precautions should be observed at all times when working on or around
the machine and the electrical components. All normal trouble-shooting must be
accomplished with the power off, line fuses removed, and with the machine tagged as out of
service.
Before making haphazard substitutions and repairs when defective electrical components are
malfunctioning, we recommend that you check the associated circuitry and assemblies for
other defective devices. It is common to replace the obviously damaged component without
actually locating the real cause of the trouble. Such hasty substitutions will only destroy the
new component. Refer to wiring diagrams and schematics.
7-2 Basic Troubleshooting
Problem Possible Cause Corrective Action
Dirty Filters Clean or replace filters.
Desiccant beds contaminated by
material or plasticizer leaking
into the system.
Replace desiccant See page 46.
Blower fuse(s) blown. Fix problem and Replace fuse(s).
Overload tripped. Fix problem and reset the
overload.
Little or no air
coming from
process delivery
tube.
Blower fins filled with dust or
contaminants.
Remove blower side plate, clean
baffles, replace.
Suction in delivery
tube, pressure from
the return tube.
Phase is reversed on power drop
coming into the dryer.
Stop the Dryer.
If the dryer was connected to the
drying hopper, check to see if the
desiccant and process air heater
has been contaminated with resin.
If so, replace the desiccant and
remove any resin carry-over.
Otherwise, change the phase of
two legs of the three-phase power
drop. Never change the phase at
the motor starters unless only one
of the two blowers is rotating
improperly.
Process heaters are faulty.
Check for open or shorted heaters.
Replace if required. Check the
fuses.
Solid-state temperature controller
faulty.
Replace.
Loss or reduction of
process air
temperature.
Process temperature was adjusted
in error by plant personnel.
Make sure that plant personnel are
aware of the proper temperature
set point. A sign posted next to the
control would be helpful.