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  1. #1
    Join Date
    Sep 2010
    Location
    Port Sorell, Tasmania
    Posts
    592

    Default 3 phase motor braking options

    Am in the process of doing up an old table saw that has a 5hp 3 phase motor. The saw has a mechanical brake to slow the blade that will require some work and money to get it operating. This has me wondering what electric brake options there are that can be retrofitted. Have seen some DC injection units but these are relatively expensive. A VFD would do the job but it seems an overkill to have all that functionality simply for braking (and a soft start). Any suggestions appreciated.

    Tony
    You can't use up creativity. The more you use, the more you have. ~Oscar Wilde

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  3. #2
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    27,741

    Default

    I installed a VFD and brake on a 2HP radial arm saw at the mens shed.
    This thread discussed the instal and there are some photos later on in that thread.
    VFD install summaries
    It was not a cheap solution the 2HP Powtran VFD and the Brake cost about $280 - the brake resistor only cost about $7.
    A 5HP VFD will set you back more.
    At the time shipping was a killer as the Brake and the VFD had to come from two different sources so separate shipping.

    If you go this route then beware - not all VFD have the circuitry to handle a brake resistor and this may have to be back fitted.
    The Powtran VFDs with the brake circuits included have the suffix (Z) added onto the model numbers and cost about $5 more than the non braking models.

    If you have a really good guard on a TS then I don't really see the need for a brake in a home workshop environment.
    How long does it take to spin down?

    For my BS I made a mechanical disc brake and this works a treat.
    BobLs bandsaw brake
    A couple of years later I put a VFD on that BS but the mechanical brake works so well I won't be adding a VFD brake

  4. #3
    Join Date
    Sep 2008
    Location
    Petone, NZ
    Age
    68
    Posts
    2,807

    Default

    Quote Originally Posted by tony_A View Post
    Am in the process of doing up an old table saw...
    That's a very humble description for what I assume is a lovely Wadkin PP sliding table dimension saw...

    Sorry Tony, I have no experience with electric brakes (except on a train).

    Cheers, Vann.
    Gatherer of rusty planes tools...
    Proud member of the Wadkin Blockhead Club .

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