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Power supply help

Discussion in 'Power Electronics' started by drumsticksplinter, Dec 5, 2013.

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  1. drumsticksplinter

    drumsticksplinter

    17
    0
    Mar 28, 2010
    Hi Guys,

    I wonder if anyone might be able to lend a hand with helping me design a power supply for a CNC machine I'm retrofitting?

    Here's what I know:

    I have 3 x 140v DC servo motors each with a stall current of 35A, continuous approx. 6A.
    I have 2 x (1 more on order) DC servo drives with a maximum voltage and current of 160VDC, 35A. I have spoken with the manufacturer and they suggest that a linear power supply be used using a rectifier and capacitors. They recommend that for voltages over 100v, 2000uF per motor amps need to be used for smoothing.
    The machine I have already has a transformer with multiple taps, 1 being 140V. Reading up a little on another forum, the 140Vac once smoothed produces 212Vdc, which is more than the maximum my servo drives will allow :confused:

    As a backup plan I have an old 110V transformer, the type typically used for power tools etc, would that be more suitable??

    Any advice would be gratefully received. Oh and does anyone know where to buy cheap capacitors in the UK? those things are steeeeeeeeep!! :eek:

    Thanks,

    Adam.
     
  2. OLIVE2222

    OLIVE2222

    690
    25
    Oct 2, 2011
    Hi Adam,

    Does the transformer already in the machine have multiple primary tap too?
    For instance you maybe have to high output voltage because you supply it with 240 V Ac on a 220v Input. Also what are the secondary tabs voltages?

    Olivier
     
  3. drumsticksplinter

    drumsticksplinter

    17
    0
    Mar 28, 2010
    Hi Oliver,

    Thats a good point you raise, I have to check tomorrow, I can't remember in the primary and secondary taps without having another look. ;)

    Thanks,

    Adam.
     
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