3 phase motor size comparison
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  1. #1
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    Default 3 phase motor size comparison

    Hi all, I was wondering if someone could make some sense of these motor sizes & outputs comparisons. They are both around the same vintage. Attached are photos of two 3Phase motors. I am intending to use one for a new RPC I am preparing to build. The smaller one weighs 67kg and is 10Kw with a 19.7Amp output and has a speed of 1455 rpm.

    The second motor weighs 115Kg and is 11Kw with a 20-22Amp output and has a speed of 1465 rpm. The size difference between these two motors is quite significant and the weight is 19kgs shy of double on the bigger one. Is it possible that the name plate is incorrect on one of them? For the minor gain in power (as on name plates), the physical size difference seems inperportionate to the output?

    any thoughts are welcome.
    Attached Thumbnails Attached Thumbnails img_8055.jpg   img_8053.jpg   img_8051.jpg   img_8049.jpg  

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    Lighter weight motor appears to be 132 frame size and heavier in 160 frame size. Depending on manufacturer and exact model that could account 20-30kg difference alone.
    If the heavy one is cast iron and light one aluminium frame that adds another 20-40kg to the difference. WAG from pics says that the heavy is cast iron and lightweight alu frame.

    Sometimes you match the frame size to existing mounting so you might end up with large frame without need to max out the available hp.

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    Thanks heaps for the explanation Mattij, that makes total sense

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    Use the motor that makes the least noise. If not then you will always ask yourself why I didn't do it.

  5. #5
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    Pretty much, physical motor size has very little to do with power. There are large 1 hp motors and small 10hp motors. When you get into liquid cooled motors they are truly tiny in size for their power.


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