DC Motor Starter Fried? - Page 3
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  1. #41
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    No but there is no need to have it filtered, and at a 20+ amp draw it would be a huge filter caps, with one hell of inrush amps, you would need 200 amp didoes to hold the current, so I would think no filter...Phil

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    You're probably right.

  3. #43
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    Quote Originally Posted by 9100 View Post
    A used blade is fine because you will be using the end that doesn't saw.

    Bill
    Perhaps I should have said doesn't saw in normal use. There is a small part on each end of the blade that doesn't touch the work so the teeth are new. Cut the blade back at an angle, eliminating the rounded end that will bump into things. Some blades do not have a wavy set on the ends, making the job that much easier.

    Bill

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    Using a ton of filtering to get peak voltage also messes up the incoming power because all the current is drawn at the very peak of the waveform.

    Most single phase drives are 0-180VDC output so that you can spread the current out easily. Higher voltages make me suspect it was intended for a three phase drive/rectifier as you get a minimum of 0.75x peak line-to-line value.

  5. #45
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    Got it - thanks.

    I got the starter box dismounted from the machine yesterday - something of a thrash - and will start cleaning when I get back with the engine hoist.

  6. #46
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    Quote Originally Posted by Phil in Montana View Post
    No but there is no need to have it filtered, and at a 20+ amp draw it would be a huge filter caps, with one hell of inrush amps, you would need 200 amp didoes to hold the current, so I would think no filter...Phil
    230 VDC motor is meant for 3-Phase rectified power use. Single-phase 230 VAC only holds-up 180 VDC when under design load.

    And yes, a filter is spec'ed by folks such as the motor makers. Reliance requires a ripple-filter for all RPM series motors wound for higher than 180 VDC.

    But no capacitors involved.

    Not unless you want to go practically "stealth"? If so, see Yaskawa/Magnetek "Quiet Elevator", an easily-scalable 10 HP reference circuit.

    Otherwise, the "ripple filter" is just a big fat lumped inductance AKA "choke".

    Do you NEED it? On three-phase source, maybe not.

    That depends on whether the machine-tool it is driving passes-on the "sound" so as to "watermark" a workpiece.

    If it never had one, it probably doesn't need one now... on 6-pulse 3-Phase power, anyway.

    Two-pulse single-phase is three times as rough, of course.



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