Siemens TROUBLE, Operation, CORRECTION, POSSIBLE CAUSES, Trouble Shooting

Operation

Trouble Shooting

Between regular maintenance inspections, be alert for signs of motor trouble. Common symptoms are listed in the following table. Correct any trouble immediately and AVOID COSTLY REPAIR AND SHUT DOWN.

DANGER

Hazardous voltage.

Will cause death, serious injury, electrocution or property damage.

Disconnect all power before working on this equipment.

TROUBLE	POSSIBLE CAUSES	CORRECTION
Motor will not start.	Usually line trouble. Single phasing at	Check power source. DO NOT check with
	starter.	motor energized! Check overloads, controls
		and fuses. Check voltage and compare with
		nameplate rating.
	Under Voltage.	Check voltage at motor terminals. Compare to
		nameplate.
	Excessive Load.	Disconnect motor from load to see if it starts
		without load. Reduce load or replace motor
		with unit of greater capacity.
Excessive hum.	High Voltage.	Check input voltage. Check for proper
		connections.
	Unbalanced rotor.	Balance rotor.
	Excessive wear of sleeve bearings.	Replace bearings. Check to determine cause
		of wear and replace as necessary. Check
		alignment.
Regular clicking.	Foreign matter in air gap.	Remove foreign matter.
Rapid knocking.	Bad anti-friction bearing or dirt in lubricant.	Replace bearing, clean grease cavities and
		renew lubricant.
Vibration.	Misalignment in coupling or feet.	Realign motor and driven equipment.
	Accumulation of dirt on fan.	Clean motor.
	Vibration in driven machine.	Run motor disconnected from driven load and
		check for vibration. Eliminate source in driven
		equipment.
	System natural frequency (resonance).	Alter rigidity of base structure.
Vibration following motor	Rotor out of balance; balance weights of	Balance rotor.
repair.	fans shifted on rotor.
Motor overheating.	Overload.	Measure load and compare with nameplate
(Check with thermocouple		rating. Check for excessive friction in motor or
or by resistance method,		complete drive. Reduce load or replace motor
do not depend on touch).		with unit of greater capacity.
	Single phase.	Check current, all phases.
	Dirt in motor.	Check flow of air.
		Check filters, if so equipped.
		Clean motor.
	Unbalanced voltage.	Check voltage, all phases.
	Rotor rubbing on stator.	Check air gap. Repair motor as necessary.

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