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Easy Solutions to Common Tower Troubles



Easy Solutions to Common Tower Troubles


As you are completing your occasional cooling tower checkup, you hear that noise again, something about your cooling tower doesn't sound right. What's that noise? How can you quickly diagnose the problem and find a solution? The below table will help you do just that!






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





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.





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.





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.


If you have an issue that cannot be fixed using these tips, Contact Cooling Tower Depot for professional guidance and assistance.

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