Sterling SDA AP-1 specifications Introduction, Basic Troubleshooting

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
Little or no air	Dirty Filters	Clean or replace filters.
coming from	Desiccant beds contaminated by	Replace desiccant
process delivery	material or plasticizer leaking
tube.	into the system. See Sec. 6-6.
	Blower fuse(s) blown.	Fix problem and Replace fuse(s).
	Overload tripped.	Fix problem and reset the
		overload.
	Wrong motor rotation.	Turn off power. Reverse
		incoming power.
	Blower fins filled with dust or	Remove blower side plate, clean
	contaminants.	baffles, replace.
Suction in delivery	Phase is reversed on power drop	Stop the Dryer.
tube, pressure from	coming into the dryer.	If the dryer was connected to the
the return tube.		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.
Loss or reduction of	Process heaters are faulty.	Check for open or shorted heaters.
process air		Replace if required. Check the
temperature.		fuses.
	Solid-state temperature controller	Replace.
	faulty.
	Process temperature was adjusted	Make sure that plant personnel are
	in error by plant personnel.	aware of the proper temperature
		set point. A sign posted next to the
		control would be helpful.

Large Dehumidifying Dryers Troubleshooting 64