Step up transformers and amp draw

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    Default Step up transformers and amp draw

    I have a quick question about a a transformer and amp draw....

    220v into a 480v step up transformer does amp draw stay the same? Double? Or does it use half? I'm under the impression that it would use half if I understand correctly.....

    Machine says 91.2/45.6 amps but it has a step up transformer built into machine currently machine is running on a 200amp panel and I'm getting an identical machine... cam I use the same panel or do I need a secondary panel? Thanks ahead of time it is greatly appreciated....

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    Community Moderator Jim Dawson's Avatar
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    Default Re: Step up transformers and amp draw

    The wall panel sees the 91 amp draw @ 220V. So with 2 machines, you should be able to use the same panel.



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    Default Re: Step up transformers and amp draw

    Quote Originally Posted by rdnck68 View Post
    I have a quick question about a a transformer and amp draw....

    220v into a 480v step up transformer does amp draw stay the same? Double? Or does it use half? I'm under the impression that it would use half if I understand correctly.....
    As to the transformer, the secondary current rating is reduced in proportion to the increase in voltage. Per the transformer Kva rating.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
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    Default Re: Step up transformers and amp draw

    Quote Originally Posted by rdnck68 View Post
    I have a quick question about a a transformer and amp draw....

    220v into a 480v step up transformer does amp draw stay the same? Double? Or does it use half? I'm under the impression that it would use half if I understand correctly.....

    Machine says 91.2/45.6 amps but it has a step up transformer built into machine currently machine is running on a 200amp panel and I'm getting an identical machine... cam I use the same panel or do I need a secondary panel? Thanks ahead of time it is greatly appreciated....

    Sent from my SM-G930T using Tapatalk
    If your machine needs 91 rated amps at 480v then you are correct, if the Transformer can output 91amps or more @ 480v then the input supply will use Double the amps at 220v to supply your machine , so you would need another Panel, this is the same with any step up type of Transformer

    It actually it is a little more than double, if you only have 220v, if your voltage is 240v then it would be double

    Mactec54


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    Default Re: Step up transformers and amp draw

    Quote Originally Posted by mactec54 View Post
    If your machine needs 91 rated amps at 480v then you are correct, if the Transformer can output 91amps or more @ 480v then the input supply will use Double the amps at 220v to supply your machine , so you would need another Panel, this is the same with any step up type of Transformer

    It actually it is a little more than double, if you only have 220v, if your voltage is 240v then it would be double
    I say double but yes a little more than double.... I looked at tag on transformer(had to remove several machine panels to get to it) and it says 130amps at 220 under the secondary column ....so.... looks like I have to get another panel.... but thanks all who replied very helpful and very time efficient

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    Default Re: Step up transformers and amp draw

    Quote Originally Posted by rdnck68 View Post
    I say double but yes a little more than double.... I looked at tag on transformer(had to remove several machine panels to get to it) and it says 130amps at 220 under the secondary column ....so.... looks like I have to get another panel.... but thanks all who replied very helpful and very time efficient

    Sent from my SM-G930T using Tapatalk
    Here are tags for machine and transformer

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    Community Moderator Jim Dawson's Avatar
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    Default Re: Step up transformers and amp draw

    The transformer tag is just the maximum capacity of the transformer. It will only draw what the machine needs, 91.4 amps @ 240V, plus a small amount for heat losses. I'm pretty sure the machine draws a lot less than the nameplate. The full load rating assumes you start all the motors at once.



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    Default Re: Step up transformers and amp draw

    Quote Originally Posted by Jim Dawson View Post
    The transformer tag is just the maximum capacity of the transformer. It will only draw what the machine needs, 91.4 amps @ 240V, plus a small amount for heat losses. I'm pretty sure the machine draws a lot less than the nameplate. The full load rating assumes you start all the motors at once.
    This is a Lathe, CNC Lathe run up to max amps all the time, note the main spindle motor is rated for 114 Amps

    There seems to be some confusion with the Transformer where does the 480v come in to use, it appears, that the Transformer is only for the low voltage side of the machine, and the main spindle motor will be on it own controlled circuit and VFD

    Mactec54


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    Community Moderator Jim Dawson's Avatar
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    Default Re: Step up transformers and amp draw

    Quote Originally Posted by mactec54 View Post
    This is a Lathe, CNC Lathe run up to max amps all the time, note the main spindle motor is rated for 114 Amps

    There seems to be some confusion with the Transformer where does the 480v come in to use, it appears, that the Transformer is only for the low voltage side of the machine, and the main spindle motor will be on it own controlled circuit and VFD
    I could be wrong here, but I'm guessing that is locked rotor amps on the spindle. If that is max running amps, then that would mean a 50 HP motor. Not impossible, but that's a big lathe. That data tag does not really make much sense. It really says the max load is greater than the full load current, never seen that on a data tag before.



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    Default Re: Step up transformers and amp draw

    Quote Originally Posted by Jim Dawson View Post
    I could be wrong here, but I'm guessing that is locked rotor amps on the spindle. If that is max running amps, then that would mean a 50 HP motor. Not impossible, but that's a big lathe. That data tag does not really make much sense. It really says the max load is greater than the full load current, never seen that on a data tag before.
    That machine does not have anything like a 50Hp motor, they don't have a regular AC motor, depending on what option motor the machine has, it could have over 20Hp, they are a special spindle motor that run up to 5,000 RPM

    Mactec54


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    Default Re: Step up transformers and amp draw

    It's full load current, if all motors basically locked up at once. Per some codes, you do have the supply that full 41.9 amps at 480 in, or 91.4 at 220 in, not to say it would ever be an issue running it on a 75 amp 220 service. Too small a service, you do run the risk of popping spindle drives.

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