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  1. #1
    Join Date
    Mar 2009
    Posts
    32

    Cool Electrocraft PMDC servo ID ? Plz !

    Hello all !

    I need help !

    I put my hands on a Used but in good condition Electrocraft PMDC servo motor from Al the Man ... well Now I want to power it up !

    I have eyeballed this product ! from KB ! and was wondering if it could do the trick ??

    Here is my Servo ID Plate !
    it very plain !!! and any help Id this motor would be welcome...

    as I need to find the HP this baby can deliver !

    it comes with a Tach ! so I guess this will feed Speed feedback to the speed controler ? I'm new to this ! but I'm willing to play !!!

    I found an Info sheet from Electrocraft Legacy Catalogue and was wondering if it could be the one for my Motor ? it's for a G700 series


    Let me know !!!

    Norm

    out !

  2. #2
    Join Date
    Feb 2007
    Posts
    4553

    Norm,

    Why not ask Al? He knows these like the back of his hand.

    Jeff...
    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.

  3. #3
    Join Date
    Dec 2003
    Posts
    24221
    I think I mentioned this has a terminal voltage of around 60vdc, IIRC.
    I found this out by empirical test.
    The KB should run it OK, but you will have to restrict it from max output, put a resistor in series with the pot or method used to control the speed in order it does not over speed on full 90vdc, I would not run it over 2500~3000 rpm to be on the safe side.
    Unfortunately I believe the plate info is OEM part numbers which makes it difficult to pin down exact specs.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  4. #4
    Join Date
    Mar 2009
    Posts
    5
    I am trying to get a print for you for this motor. I think Al is right that this motor is designed to run at only 60VDC. It will run with a 90VDC drive but it will eventually pit the commutator on the armature.

    I'll let you know what I come up with.

    Email me with any questions

    Rob Kerber
    VP/GM Motion
    ElectroCraft
    [email protected]

  5. #5
    Join Date
    Mar 2009
    Posts
    32
    Thanks Guys....

    So... I am not too far off on my Driver selection...

    I'll try to find one... near 70 or 80V and look for Big Resistors....


    And another question ! Under Electrical Data in the Catalogue image...
    under A and B what is the meaning of those letters ?

    for each variant.... has 2 columns A + B ?
    and the Tachometers... Do I have to do a Imperial Measurement on the output of the tach...or can I measure the impedance ! and Gestimate ?

    and I'll try not to fry the motor...

    Al would not be impress ! :argue:

    (flame2)

    and thank you for looking for that Data Sheet for this Motor....

    Take care ALL ~

    Norm

    OUT !

  6. #6
    Join Date
    Dec 2003
    Posts
    24221
    The Tach output is a generated DC voltage proportional to rpm, usually indicated in v/1000rpm.
    You can easily measure this at a given speed.
    Don't put any resistors in series with the motor, the one I indicated would go in series on the high end of a control potentiometer for example.
    Also there are quite a few A-M-C servo controllers on ebay that can be run in the velocity mode for spindles.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  7. #7
    Join Date
    Mar 2009
    Posts
    32
    Thank you AL !

    I see your point ! about the Tach ! and about the Resistor... on the Pot !

    what about the Horse Power Resistor... ??? on that KB Drive ?

    They come in all Flavours...

    the A M C drivers... well !!! are out of my League ! 300$ ouchie !

    I don't need anything fancy !!! but controlabe via Mach 3 !!! with analogue ref. voltage from the Tach as a Spindle Speed Control Accel and Decel !

    are Breaking Resistors required ? or a controlled Decel time good enough ?


    Sorry for the Many questions but I don't want to Burn anything...

    ie. when the Servo is Free spining... and feeding EMF back into my board !

    so much to learn so little time !!!


    Norm

    out !:drowning:

  8. #8
    Join Date
    Dec 2003
    Posts
    24221
    I would go with a 1/2hp value to begin with. The worst case scenario is you would go into current limiting earlier, but I don't think that will happen.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

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