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Help with calculating percent error

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    Help with calculating percent error

    If a current of 30 amps is measured with a 100 amp 3% ammeter, the maximum possible error in terms of actual error is:
    Im having problems calculating these types of questions, could someone help?

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    Percent Error reply

    For percent error on that device:

    100Amps X 3% = plus or minus 3 from 100 or a range of 97A to 103A when measuring 100A.

    If the error is +/- 3 amps then your 30Amps may be 27A to 33A.

    if the device is listed as a 3% tolerance over all measurement ranges then use 30A X 3% = plus or minus 0.9A or range of 29.1A to 30.9A

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    Quote Originally Posted by stuebes View Post
    For percent error on that device:

    100Amps X 3% = plus or minus 3 from 100 or a range of 97A to 103A when measuring 100A.

    If the error is +/- 3 amps then your 30Amps may be 27A to 33A.

    if the device is listed as a 3% tolerance over all measurement ranges then use 30A X 3% = plus or minus 0.9A or range of 29.1A to 30.9A
    The correct way is this. 30/3=10

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    Percentage error calculation

    What am I missing if I keep coming up with 3.9%?

    If 4000 was the specified value, and 3850 was the measured value, what is the percent error?

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  11. patelnipul5 is offline Junior Member Pro Subscriber
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    Percentage error

    Please see below for percentage error calculation.

    Step 1: Calculate the error (Subtract one value from the other)
    Step 2: Divide the error by the specified value (we get a decimal number)
    Step 3: Convert that to a percentage (by multiplying by 100 and adding a % sign)

    % error =((Specified value-Measured value)/ Specified value )X 100 %

    = ((4000-3850)/ 4000) X 100 %

    = 0.0375 X 100 %
    = 3.75%

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    Quote Originally Posted by Flashman View Post
    What am I missing if I keep coming up with 3.9%?

    If 4000 was the specified value, and 3850 was the measured value, what is the percent error?
    I always do
    [expected (specified) - Calculated (Measured)] / expected (specified)

    this will give you a decimal, which can be converted into a percentage by multiplying by 100

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  15. simmonmw71 is offline Junior Member Pro Subscriber
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    Quote Originally Posted by Mmfz85 View Post
    The correct way is this. 30/3=10
    The correct way is;
    2% of 100 is 2.
    2 is the maximum error.
    2/30 is 0.0667 which is 6.6%

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