Easy Solutions to Common Tower Troubles

Trouble

Cause

Remedy

Motor will not start

Power is not available at motor terminals

A: Check power at starter. Correct any connections between the control apparatus and the motor.

B: Check starter contact and control circuits. Reset overloads, close contacts, reset tripped switches, or replace failed control switches.

Wrong Connection

Check motor and control connections against wiring diagrams.

Low Voltage

Check nameplate voltage against power supply. Check voltage at motor terminals.

Open circuit in motor winding

Check starter windings for open circuits.

Motor or fan drive is stuck

Disconnect motor from load and check motor and gear reducer for cause of problem.

Rotor is defective

Look for broken bars or rings

Fan Stack

Due to high winds fan stack has become oblong interfering with fan blades rotation.

Unusual Motor Noise

Motor running single-phase

Stop motor and attempt to start it. Motor will not start if single-phased. Check wiring, controls, and motor.

Motor leads connected incorrectly

Check motor connections against wiring diagram on motor.

Ball bearings

Check lubrication. Replace bad bearings.

Electrical imbalance

Check voltages and currents of all three lines, correct if required.

Air gap not uniform

Check and correct bracket bearings

Rotor unbalanced

Rebalance

Fan hitting guard

Reinstall or replace fan

Motor runs hot

Motor overload, low voltage or unbalanced voltage

Check voltage and current of all three lines against nameplate values.

Incorrect fan blade pitch

See Fan Service Manual

Wrong motor rpm

Check nameplate against power supply. Check rpm of motor and gear ratio.

Bearings over greased

Remove grease reliefs. Run motor up to speed to purge excess grease.

Rotor rubs stator bore

If this is not due to poor machining, replace worn bearings.

Wrong lubricant in bearings

Change to proper lubricant. See motor manufacturer’s instruction.

One phase open

Stop motor and attempt to start it. Motor will not start if single-phased. Check motor wiring controls and motors.

Poor ventilation

Clean motor and check ventilation openings. Allow ample ventilation.

Winding fault

Check with ohmmeter

Bent motor shaft

Straighten or replace shaft

Insufficient grease

Remove plugs and re-grease bearings

Deterioration of grease or foreign material in grease

Flush bearings and re-lubricate

Bearings damaged

Replace bearings

Motor does not come up to speed

Voltage too low at motor terminals because of line drop

Check transformer and setting of taps. Use higher voltage on transformer terminals or reduce loads. Increase wire size or reduce inertia.

Broken rotor bars

Look for cracks near the rings. A new rotor may be required. Have motor service person check motor.

Wrong rotation (motor)

Wrong sequence phases

Change any two of the three motor leads.

Gear reducer noise

Gear reducer bearings

If new, see if noise disappears after one week of operation. Drain, flush, and refill gear reducer. See Gear Reducer Service manual. If still noisy, replace bearings.

Gears

Correct tooth engagement. Replace badly worn gears. Replace gears with imperfect tooth spacing or form.

Unusual fan drive vibration

Loose bolts and cap screws

Tighten all bolts and cap screws on all mechanical equipment and supports.

Unbalanced drive shaft or worn couplings

Make sure motor and gear reducer shafts are in proper alignment and “match marks” properly matched. Repair or replace worn couplings. Rebalance drive shaft by adding or removing weights from balancing cap screws. See Drive Shaft manual.

Fan

Be sure blades have proper pitch and track. Make certain all blades are as far from the center of the fan as safety devices permit. All blades must be pitched the same. See Fan Service manual. Clean off deposit build-up on blades.

Worn gear reducer

Check fan and pinion shaft bearings end play. Replace bearings as necessary.

Unbalanced motor

Disconnect load and operate motor. If motor still vibrates, rebalance rotor.

Bent shaft

Check fan and pinion shafts with dial indicator. Replace if necessary.

Fan noise

Loose fan hub cover

Tighten hub cover fasteners.

Blade rubbing inside of fan cylinder

Adjust cylinder to provide blade tip clearance.

Loose bolts in blade clamps

Check and tighten if necessary.