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  1. #16
    Join Date
    Oct 2011
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    Norwood-ish, Adelaide
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    Is/was the motor running at 50Hz?
    If via a VFD, it may be that the air flow is not enough (I think air flow is related to rpm2). Just thinking that if the air flow was not enough to blow the heat way, the housing would get toasty and then melt the fan, lessening air flow more (and repeat).

    Michael

  2. #17
    Join Date
    Sep 2012
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    North Yorkshire UK
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    Hi Guys,

    I've seen something similar where the fan securing screw allowed the fan to migrate down the shaft to sit on top of the motor case, the heat melting the no longer rotating fan. I've also seen this with a metal cast fan, sat on top of the motor case.

    Those class "F" insulation motors are usually category "CR" continuously rated with a max temperature spec on the rating plate.
    Best Regards:
    Baron J.

  3. #18
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
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    61
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    Motor running at what ever the house supply is, no VFD.

  4. #19
    Join Date
    Dec 2013
    Age
    53
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    945

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    Sounds strange, I'd put a new fan on it and keep a check on it often.
    Do you have a digital thermometer to check it? There only cheap on eBay.

    I sometimes get some weird noises when I start mine or when it's running, I dont think there the best quality motor, one day I'll get around to fitting the new VFD motor I bought, lol
    Using Tapatalk

  5. #20
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
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    Hello Dave, just waiting on a fan to arrive, not sure as to how long this issue had been present, noticed today that cast iron dust had settled on the surface of the melted remains of the fan and unable to remove it, so would appear that it possibly had been just sitting on top of motor for a while.
    No thermometer, but in past have just used my hand on the motor fins after prolonged use, normally hot.
    Tried the motor again this morning everything worked as normal with no unusual noises ( only ran for about 10 secs in for/Rev, test will be after the fan goes on.

  6. #21
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    Dec 2013
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    53
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    Hopefully it's like you said and just cracked and worked it's way off
    Using Tapatalk

  7. #22
    Join Date
    Jun 2007
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    sydney ( st marys )
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    New fan and hub fitted, motor seems okay at present.

  8. #23
    Join Date
    Nov 2007
    Location
    melbourne australia
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    2,507

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    Quote Originally Posted by pipeclay View Post
    The motor is 1.5kw, 240 volt vertical flange mount, the motor is 17 yrs old.
    Hi Peter,
    Sorry I'm late to the party. If it's a single phase motor, maybe the centrifugal start switch is fused closed and the start winding is continuously energised? I cooked my table saw motor that way. Ordinarily the start winding would eventually burn out, but perhaps a well made motor would just get very hot as yours obviously has.
    Chris

  9. #24
    Join Date
    Jun 2007
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    Hello Chris,
    I know very little about electrics but if that switch was locked on would I be able to get reverse?

  10. #25
    Join Date
    Nov 2007
    Location
    melbourne australia
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    2,507

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    I'm pretty sure you would. The reverse switch reverses the polarity of the start winding. The centrifugal switch disconnects the start winding when the motor is up to speed.

    Apparently a shorted capacitor can result in the motor overheating too.

    It would be worth taking it to a motor rewinder for a quick checkup.
    Chris

  11. #26
    Join Date
    Oct 2015
    Location
    melbourne
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    368

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    You should be able to hear the centrifugal switch open and close as the motor starts and stops.
    Not loud but should be distinct..

  12. #27
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    Not sure if I hear it starting but definitely when stopping.

  13. #28
    Join Date
    Sep 2012
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    North Yorkshire UK
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    Hi Guys,

    The centrifugal switch on the lathe is very quiet when starting up but makes a loud clunk when stopping. Compared to the one on my grinder which you can barely hear either way.
    Best Regards:
    Baron J.

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