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Ampere - Watts - Volts

Discussion in 'Motor actuators and drivers' started by gigi, Mar 28, 2017.

  1. gigi

    gigi Active Member

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    Hallo,
    I 'm reading the selection guide of their dc worm drive geared box https://www.motiondynamics.com.au/1...ve-geared-motor-200w-21-256-rpm-7.5-45nm.html
    But I don't understand something.
    In this r selection guide they specify that motors are 200W . The 12V motors are 23A rated current and 24V motors ara 12A rated current
    Ampere = Watt/Volt correct?
    200W/12V=16,66A and not 23A
    so if the 23A is correct for 12V motors this should mean the motor have 276W and not 200W
    as 23Ax12V=276W

    What i do not understand?

    Attached Files:

  2. speedy

    speedy Well-Known Member

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    what you get from calculations is the operating current ...

    The term rated in any electrical equipment,whether its RATED VOLTAGE or RATED CURRENT means it is the maximum value of current,voltage or any other parameter beyond which the motor will not be operating according to its desired operation.
    Rated current is the capacity of the equipment it is designed to operate safely.
    The operating current is the actual current drawn while in operation.
    Beyond the rated value the motor may have some faults or damages in winding ...
    Also it is not acceptable to run the motor on the rated current for a long time ...
    • Informative Informative x 1
    Last edited: Mar 28, 2017
  3. gigi

    gigi Active Member

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    Hi speedy thanks for your reply.
    RATED CURRENT and NOMINAL CURRENT are the same thing?
    So please see the file i upload now. 12V 180W nominal current 23A - peak current 40A

    Attached Files:

  4. speedy

    speedy Well-Known Member

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    Yes ... The rated current (or nominal current) are the same ... and is the current the device is rated at for continuous service. The operating current is the current causing operation of the device in conventional time .

    [Peak (pk) is the maximum value, Startup current, Surge Current , Inrush current] are all the same ...

    Peak is more commonly used as it is either positive (pk+) or negative (pk-), that a waveform attains. Peak values can be expressed for voltage (the usual case), current , or power . Alternating current ( AC ) waveform reach peaks in two directions of polarity or current flow.
    download.png

    https://en.wikipedia.org/wiki/Inrush_current
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  5. gigi

    gigi Active Member

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    if Ampere = Watt/Volt
    Last question sorry...only to let me undertsand correctly.
    if Ampere = Watt/Volt ... a motor that have 180W/12V means that its current is 15A (180:12=15)
    The value that I obtain dividing Watts by Volts how can be defining? According to what you written it is not
    rated or nominal current. So how can it be defining?
    • Like Like x 1
  6. speedy

    speedy Well-Known Member

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    Normally manufacturers provide numbers and information that can't be easily measured or calculated like you did ...
    That's why you have two numbers now :cheers .

    Edit : They have provided the Watt and Voltage [then you can calculate the operating current] ... then provided the rated current [ where you should be aware of without actually damaging the motor ] ...
    You can also calculate the internal resistance if you need Voltage = R * I .
    That doesn't mean you can't go beyond RATED voltage or current limits for a few seconds then go back ... but that should be on rare occasions only .
    Last edited: Mar 28, 2017
  7. gigi

    gigi Active Member

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    but the current that I obtain dividing watts by volts what is? 200W/12V result 15A . What is 15A? rated or nominal current? probably no, as in the data sheet they specify that their motors 200W 12V have 23A rated current.
  8. speedy

    speedy Well-Known Member

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    IT IS THE OPERATING CURRENT
    ======================================

    I will give a direct example ... :D

    Assume that you are beyond the normal questions :D ... and testing my maximum RATED or NOMINAL patience right now ...
    How do you know ? or How much do you expect me can go with you before I give up ? unless I tell you BY DATASHEET my Rated patience is here ... other normal conversations that can normally be estimated is not written .

    https://www.google.com.eg/search?q=what is meant by nominal current or nominal voltage&source=lnms&sa=X&ved=0ahUKEwikwLry7PjSAhUL2xoKHenhBQUQ_AUIBSgA&biw=1280&bih=680&dpr=1
    Last edited: Mar 28, 2017
  9. adgun

    adgun Active Member

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    There is efficienty to . Motor delivers 200w and ask 23 amp rated