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Electric Motor Running Temp ?????

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  • Electric Motor Running Temp ?????

    I've been wondering about the operating temp of the hydraulic pump motor on my KO surface grinder for quite some time.
    I think it runs pretty hot but not sure if it's normal or not. It's a 220 volt 3 phase motor, I think it's 1/3 HP, made by GE.
    I run it off a VFD. All the motor does is run the hydraulic pump for the table, in my opinion it's a bit undersized for the job but I didn't design the machine. After about 20 - 30 min. of running the motor will reach about 158 degrees. It varies a few degrees across the housing but that is the hottest point I've indicated. The ends, sides or bearing housing what ever you want to call them run at about 90 degrees, not bad. The motor tags does say 40c amb.
    Any thoughts?????

    JL.........................

  • #2
    just do the math

    Originally posted by JoeLee View Post
    I've been wondering about the operating temp of the hydraulic pump motor on my KO surface grinder for quite some time.
    I think it runs pretty hot but not sure if it's normal or not. It's a 220 volt 3 phase motor, I think it's 1/3 HP, made by GE.
    I run it off a VFD. All the motor does is run the hydraulic pump for the table, in my opinion it's a bit undersized for the job but I didn't design the machine. After about 20 - 30 min. of running the motor will reach about 158 degrees. It varies a few degrees across the housing but that is the hottest point I've indicated. The ends, sides or bearing housing what ever you want to call them run at about 90 degrees, not bad. The motor tags does say 40c amb.
    Any thoughts?????

    JL.........................

    The 40C figure is temperature RAISE over ambient.

    Add 40 C to your room temp of say 20C you have 60 C That is too hot to put your hand on for more than a moment

    Clean the motor case or put a small fan to blow air over the motor if it troubles you. I bet the insulation in the motor is good for MUCH higher temps than that.

    I start to worry when motors start to smell hot ;-)

    ps the motor bearings are held in "End Bells"

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    • #3
      OK, thanks, when I checked the temp in C it read as 70. Still sounds like 10 higher than it should be. Shop temp or amb. is about 67 deg F.

      End bells................ that's what I was thinking of.

      JL..............................

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      • #4
        Are you running the VFD at 60hz (or name plate freq)

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        • #5
          THIS is a hot motor

          .

          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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          • #6
            Originally posted by CalM View Post
            Are you running the VFD at 60hz (or name plate freq)
            Yes I am........... The grinder motor runs cool.

            John, that's a real hot motor. I would wrap coils around it and preheat your hot water.

            JL..................

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            • #7
              I had the same concern about the motor on my mill a while back so I did some research and measured the operating temperature.
              It turned out that it felt quite hot but was well within the normal operating temp. for that motor.
              I just had another look at the info.
              Surface temperature of continuously operating general purpose electric motor will easily be 80°C (176°F) and can be as high as 100° (212°F)
              Depending on the temperature rating of the insulation on the windings they can go even higher.
              Last edited by Cuttings; 10-08-2013, 05:02 PM. Reason: spelling error
              Larry - west coast of Canada

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              • #8
                I also have a KOLee 7-18 and it runs about the same
                like you worried about it at first but dont any more been working for 40 + years now. it is a 1960 something model and mine is 110 volt 3/4 HP on pump and 110 volt 1 HP on spindle . Some times I run with the door to the HYG.open. But dont think it helps just more noise.
                Every Mans Work Is A Portrait of Him Self
                http://sites.google.com/site/machinistsite/TWO-BUDDIES
                http://s178.photobucket.com/user/lan...?sort=3&page=1

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                • #9
                  I understand that most motors are rated to run hot to the touch and be OK.
                  I don't like it though. If I had a hot one on a machine I use long enough to
                  get that hot, I would put a 4" computer fan on it. Not necessary, but I
                  sleep better.

                  --Doozer
                  DZER

                  Comment


                  • #10
                    Cooler is always better. ALL organic-based insulation, varnish, paper, plastic, whatever..... it all degrades with heat. Eventually it will actually char, despite never being nearly hot enough to char quickly.

                    That said, even basic motors are rated at a max temp of 115C inside. That likely equates to about 95 to 100C on the exterior, which is a temp you would *notice* if you touched it. The usual "hot spot" allowance is 10C from measurable exterior to inside hot spot, and the measurable exterior is essentially anything you can see from outside (even the outside of windings).
                    1601

                    Keep eye on ball.
                    Hashim Khan

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                    • #11
                      Originally posted by J Tiers View Post
                      Cooler is always better. ALL organic-based insulation, varnish, paper, plastic, whatever..... it all degrades with heat. Eventually it will actually char, despite never being nearly hot enough to char quickly.

                      That said, even basic motors are rated at a max temp of 115C inside. That likely equates to about 95 to 100C on the exterior, which is a temp you would *notice* if you touched it. The usual "hot spot" allowance is 10C from measurable exterior to inside hot spot, and the measurable exterior is essentially anything you can see from outside (even the outside of windings).
                      Well that's good to know, kind of reassuring. The KO S-718 grinder is mid 60's as lane mentioned, only mine is the 3 phase version with 1/3 HP for the hydraulics, lane said his is 3/4 HP single phase and he mentioned it runs hot also. I won't worry about as it's been running since the 60's.

                      JL......................

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                      • #12
                        Do the motor bearing have grease fittings?
                        I seen many a motors with the end bells
                        slap ass full of nasty grease. That would
                        not allow air flow and make it run hot for
                        sure. Might maybe take it apart and clean
                        the insides out with mineral spirits, being
                        so many years that old.

                        --Doozer
                        DZER

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                        • #13
                          Try lowering the carrier frequency on your VFD.
                          Paul Compton
                          www.morini-mania.co.uk
                          http://www.youtube.com/user/EVguru

                          Comment


                          • #14
                            The motor has oil caps, it doesn't have ball bearings either and everything is clean.

                            If I lower the VFD freq. the motor just runs slower. Since it's designed for 60 Hz. I thought it would be best to run it at that freq. Running the motor slower would probably cause it to run even hotter as I feel that 1/3 HP is undersized for the job.

                            JL.........................

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                            • #15
                              The "carrier" isn't the set output frequency, it is the PWM frequency. Usually you can choose from a series such as 4 kHz, 8 kHz, or 16 kHz.... some use other sets of frequencies.

                              It does NOT AFFECT the motor speed. It usually does not affect motor heating as much as it does VFD heating, but it could make a difference.
                              1601

                              Keep eye on ball.
                              Hashim Khan

                              Comment

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