Current Sensor Question

Discussion in 'The Projects Forum' started by BramLabs, Apr 14, 2016.

  1. BramLabs

    Thread Starter Member

    Nov 21, 2013
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    Hello Sir,
    I want to ask, what current sensor work best for sensing 10 - 40 Amp ?
    Does ACS712 can handle sensing current about 10 - 40 Amp ?
    And if can, how about the voltage, let's just say i want to sense electrical motor that can drive voltage up to 36 V and 34 Amp (Generally, the motor only consume about around 20 V and current, let's just say 10 - 40 Amp, and it depends on the acceleration).

    I have read the datasheet but i didn't understand all of the information in it.
    What's the difference between the information below ?
    tes_1.PNG
    tes_2.PNG
    tes_3.PNG


    Thank you so much sir !
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    The devices have different sensitivities to scale them for different currents. The lower sensitivity is used for the higher currents.

    The -05 is no good for 40 amps where it will give a 7.4 volt output, which it cannot do with a 5v supply. Either of the other two should work.

    These parts have an internal isolation of over 2,000 volts. The way you wire this in will probably reduce that limit.
     
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  3. BramLabs

    Thread Starter Member

    Nov 21, 2013
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    Thank you sir for your reply.

    So how to choose the 'mode' of the configuration sir, if i want to use x05B or x20A or x30A ?
    Is that based on the current that we want to sense ?
    So, if i want to sense around 30A, it will give output 2.64 Volt ?
    And if i want to sense around 5A, it will give output 7.4 Volt but it needs supply more than 7.4 Volt ?

    So sir, what i'm understand is that, the more current i want to sense (in this example more than 5 amps or 20 amps) the lower sensitivity i get, BUT the lower current i want to sense (in this example, let's just say 5 amps or 20 amps, the higher sensitivity i get ?

    Thank you sir
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    That is what it is, higher currents need a lower sensitivity. It's a classic engineering compromise due here mainly to the constraint of a 5 volt max output.

    Whatever range you measure you need to keep the output below 5 volts. Now you do want to use the highest sensitivity you can to get the best measurement just avoiding the 5v limit.
     
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  5. BramLabs

    Thread Starter Member

    Nov 21, 2013
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    Oh i know sir now. I thought that this ACS712 have 3 mode configuration. But it have 3 different option of IC. 1 IC for sensing up to 5 amps, another is for 20 and the last is for sensing 30 Amp.
    I thought that in 1 IC, we can choose whether to sense 5 amps, or 20 amps or 30 amps.

    Thank you so much sir :)
     
  6. absf

    Senior Member

    Dec 29, 2010
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    I knew what you're thinking. When I looked at the datasheet of that chip, there is not such a pin called "MODE" or "SELECT". So I just want you to figure it out yourself.:D

    Allen
     
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  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    This chip comes in three versions.

    You choose the sensitivity by which version of the chip you purchase.
     
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  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    You said you wanted to measure 10-40A. None of those chips has a specified 'Optimised Accuracy Range' extending beyond 30A, so it's unclear what error you would get when measuring in the 30-40A range.
     
  9. BramLabs

    Thread Starter Member

    Nov 21, 2013
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    Do you have any recommendation sir for the current sensor that can sense up to 40 A ? I'm new and even never use current sensor before. Thank you sir ^^
     
  10. bertus

    Administrator

    Apr 5, 2008
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  11. BramLabs

    Thread Starter Member

    Nov 21, 2013
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