Polyphase AC Induction Motor …

1 Properly installed and maintained Lincoln Electricpolyphase AC Induction motors operated within thenameplate ratings will run trouble-free for many and premature failures often indicate inputpower system troubles, poor or deteriorating mechanicalinstallations, or malfunctions in the driven , Motor troubleshooting involves the entiresystem, not just the AC Induction MotorTROUBLESHOOTING GUIDED5T Application DataTroubleshooting GuideWARNINGA llow only qualified personnel to perform troubleshootingand maintenance of motors. Be sure such techniciansobserve standard safety precautions including those in thisTroubleshooting Guide.

2 2 Steps for EffectiveTroubleshooting Determine answers for the following questions:a. What are the troubles and when did theyfirst occur?b. If new, did the installation ever run properly?How long?c. If an established installation, is the trouble new or has it been occurring for years?What changes, even if minor, occurred inin the operation or maintenance of theequipment before the trouble started?d. Do you have accurate meter readings ofcurrent and voltage for all three phases ofthe input circuit? Such readings are neededto correctly determine the cause of mostelectrical to Troubles and CuresSection 1: Motor VISIBLY BURNED OUTT rouble 1: Motor burned out Page 5 Section 2: STARTING TROUBLEST rouble 2: Motor won t start (No hum or heating) Page 6 Trouble 3: Motor won t start (Just hums and heats up) Page 6 Trouble 4: Overload relays trip during starting Page 6 Trouble 5: Motor starts but comes up to speed slowly Page 7 Section 3.

3 TROUBLES WHILE RUNNINGT rouble 6: Motor frame hot to the touch Page 7 Trouble 7: Motor overheats or overload relays trip Page 8 Trouble 8: Thru bolts feel hot Page 8 Trouble 9: Motor runs but appreciably below nameplate speed Page 9 Trouble 10: Excessive electrical noise or clatter under load Page 9 Section 4: EXCESSIVE NOISE OR VIBRATION,PHYSICAL DAMAGE, OR BAD BEARINGST rouble 11: Excessive vibration and/or mechanical noise Page 9 Trouble 12: Noisy bearings Page 10 Section 5: INPUT POWER AND INPUT CIRCUITTROUBLEST rouble 13: High input current in all three phases Page 12 Trouble 14: Unbalanced input current Page 12 Trouble 15: Excessive voltage drop Page 13 Troubles VS1-VS5: Page 14 Trouble BM1: Brake overheats Page 15 Trouble BM2: Coil has failed Page 16 Trouble BM3.

4 Brake is noisy during stopping Page 16 Section 1: Motor VISIBLY BURNED OUTS ection 2: TROUBLES WHILE STARTINGS ection 3: TROUBLES WHILE RUNNINGS ection 4: EXCESSIVE NOISE OR VIBRATION, PHYSICAL DAMAGE, OR BAD BEARINGSS ection 5: INPUT POWER AND INPUT CIRCUIT TROUBLESA pplication DataTroubleshooting GuideD5T Section 6: AC MOTORS USED WITH VARIABLE SPEED DRIVESWARNINGHIGH VOLTAGE can kill. Internal parts of the Motor may be atline potential even when it is not rotating. When troubleshooting requires thatmeasurements be taken with the inputpower on, the input power should be turnedon only when necessary and extreme cautionshould be taken to avoid electric shock.

5 Isolate your body from ground and donot touch electrically hot dry insulating gloves. Disconnect all input power to the drive andmotor before performing any 7: BRAKE MOTORS WARNINGMOVING PARTS can injure. Do not operate the Motor at speedsabove the Motor maximum safe speed. Operating the Motor above maximumsafe speed may cause parts to be ejectedresulting in bodily injury. All Motor driven components must bedesigned by the machine builder tooperate safely at the Motor maximumsafe speed listed on the a Motor fails to run properly when first installed, ALWAYS check the connection arrangement of the Motor leads and theinput power lines.

6 The connections must be made in conformance with either the across-the-line start diagrams on the motornameplate or the reduced voltage start diagrams available from the Motor manufacturer. If the connection arrangement iscorrect, proceed to identify the trouble using this Troubleshooting motors are suitable for full voltage or across-the-line start. See the Motor nameplate for proper connection standardLincoln Electric motors are also capable of PWS, YDS or both as indicated in the following RatingsVoltageConnectionLeadsPWSYDS56 - 256T1/2 - 25 230/460Y9 NoNo3600284T - 405T30 - 150 230/460 12 NoYes444T - 445T125 - 250 460 6 NoYes56 - 256T1/3 - 20 230/460Y9 NoNo1800284T - 405T25 - 125 230/460 12 NoYes444T - 445T125 - 250 460 12 YesYes447T - 449T250 - 300 460 6 NoYes56 - 256T1/2 - 10 230/460Y9 NoNo284T - 286T15 - 20 230/460 12 NoYes1200324T - 365T25 - 50 230/460 12 YesYes(lower voltage only)

7 404T - 405T60 - 75 230/460 12 NoYes444T - 445T100 - 150 460 12 YesYes900143T - 256T1/2 - 7-1/2 230/460Y9 NoNoNEW INSTALLATIONSD5T Application DataTroubleshooting Guide 4 REDUCED VOLTAGE START CONNECTION DIAGRAMSA pplication DataTroubleshooting GuideD5T HP _____ RPM _____ FRAME _____VOLTS _____ PHASE ____ HERTZ _____AMPS _____ TIME RATING _____CAN BE USED ON208V SYSTEM UP TO _____ AMPSMAY NOT MEET ALL NEMA PERFORMANCELIMITS ON 208V SYSTEMSERVICEMAXINS _____ FACTOR_____AMB _____OCNEMA CODE ____ NEMA DESIGN ____ TEMP RISE ____SERIAL_____TF_____THE LINCOLN ELECTRIC CO.

8 CLEVELAND, OHIO, 5 LE CODE:(Lincoln Electric Code)Completely describes the Motor forLincoln Electric. Have this numberready when talking with a 1: Motor VISIBLY BURNED OUTT rouble 1: Motor burned out(Indicated by burning odor or smoke before the Motor stopped, and/or bubbled or burned paint.)Cause 1a:Input power troubles, startingtroubles, troubles while running, or excessivenoise or vibration, physical damage to themotor, or bad 1a:Install a new Motor . ALWAYS determine the cause of the Motor s failure, starting with Section 5, pages 12 and 13,or the replacement Motor may also fail before it delivers a fulllife Application DataTroubleshooting GuideLOW VOLTAGE LINEHIGH VOLTAGE LINETEFC ENERGY EFFICIENTTOTALLY QUALIFIED AS ODP REPLACEMENTC onnection Diagrams:shown for across-the-line(full voltage) :Nominal winding voltagerating.

9 Power system voltage mustbe within 10%.Amps:Current draw perphase at the Motor s Factor:Continuousoverload capacity of Motor ;ie: 50 HP x = draw at service factorload would approximate theamps listed times Number:Uniquenumber identifies when themotor was Code:Indicates the Motor s startingKVA code letter which can be used to approximatestarting or locked rotor current draw which istypically 5 to 6 times the rated horsepower DATA IMPORTANT TO TROUBLESHOOTING 6 Trouble 2: Motor will not start(No hum or heating.)NOTE:Reset the overload relays, if tripped.

10 Read Causes 2a through 2e. Then try to restart the Motor , and look for theconditions 3: Motor will not start(Just hums and heats up.)NOTE: Immediately shut off the power to prevent a Motor burnout. The overload relays may 4: Overload relays trip during startingCause 3a:Input circuit single phased (Novoltage in one or two phases; could havebeen a temporary condition).Cause 3b: Motor was single phased asindicated by heat damage to one or twophases of the Motor windings. Cause 3c: Motor rotor, bearings, or driven load is 3a:Have a qualified technician check for the proper voltage inall three phases.