Sterling manual STT40 / STT70

STT40 / STT70

Problem	Possible cause	Corrective action
	Process heaters are faulty.	Check for open heaters. Replace
		if required.
	Solid-state temperature	Replace.
Loss or reduction of process air	controller faulty.
		Make sure that plant personnel
temperature.
	Process temperature was	are aware of the proper
	adjusted in error by plant	temperature set point. Post an
	personnel.	appropriate sign next to the
		controller.
	Process heaters are faulty.	Replace.
	Desiccant beds are	Replace desiccant.
	contaminated.
		Drying systems are designed for
	Material being dried differs	the material which was
		originally specified. Different
	from material specified at the
		materials may need a longer
	time of purchase.
Loss or reduction in drying		residence time or a different
		drying temperature.
capacity.
	Break in flex hose to/from	Inspect for air leaks; replace as
	drying hopper.	needed.
	Airflow valve sticking or failing	Check for proper operation of
		valve actuators. Repair or
	to shift.
		replace if necessary.
	Blower fins filled with dust or	Remove blower side plate,
		clean baffles, replace.
	contaminants.
		Replace filter elements.
	Insufficient power to PLC	Check power supply and power
PLC Regeneration Bed LED	(Power LED is off).	wiring to PLC.
	Faulty PLC (PLC Power light is
indicators both off.		Replace PLC.
	on, Run light is off, and/or Error
	light is on).
	Regenerating bed cooldown.	None.
	Blower Input indicator is off.	Verify that blower contactor is
		on. Check input wiring to PLC.
PLC Regeneration Heater	Process air in high-temperature	None.
	condition.
Left/Right output indicators both
	Insufficient power to PLC	Check power supply and power
off.	(Power light is off).	wiring to PLC.
	Faulty PLC (PLC Power light is	Replace PLC.
	on, Run light is off, and/or Error
	light is on).

Troubleshooting 9-2