Recommend a current sensor?

Discussion in 'General Electronics Chat' started by fastwalker, Aug 13, 2009.

  1. fastwalker

    Thread Starter Active Member

    Jun 24, 2009
    38
    0
    Hi All,

    For my project here I need to measure DC current going to a number of motors, max. would be about 10A each. The measured values will be sampled by a NI Labview setup. Can anyone recommend a fairly inexpensive hall
    effect or other type of sensor that I could use to measure the current going through the power wires?

    Thank you to any responders,
    FW
     
  2. AdrianN

    Active Member

    Apr 27, 2009
    97
    1
    What is the maximum voltage on the DC power lines?
     
  3. fastwalker

    Thread Starter Active Member

    Jun 24, 2009
    38
    0
    The pump I'm using takes 24V.
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,685
    900
    How about a resistor? Can't beat it for price.

    John
     
  5. peranders

    Well-Known Member

    May 21, 2007
    87
    0
    The are quite nice current sensors out there suitable for NI cans. You can use these google words "current sensor dc".
     
  6. AdrianN

    Active Member

    Apr 27, 2009
    97
    1
    You can use a 0.005 ohm resistor and a current shunt monitor like the INA214 family from TI. This family has a common-mode voltage of 26V.

    The INA214 family are differential amplifiers. You can read about a power supply current measurement and common-mode voltage, as well as errors, in this article:

    The Differential Amplifier Common-Mode Error – Part 2 - Power Supply Output Current Measurement with a Differential Amplifier

    Since the INA family has integrated matched resistors you don't need to be concerned about the common-mode errors.
     
  7. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    I second jpanhalt's suggestion of a shunt resistor. The only catch is that you need a differential input unless one side of the resistor is tied to ground. Use about a 1/2" long chunk of 16 gauge Nichrome wire and you can make your own 0.01 Ω resistor that drops 100 mV at 10 A (it will be dissipating 1 W at 10 A, so it's gonna be warm).
     
  8. AdrianN

    Active Member

    Apr 27, 2009
    97
    1
    The alternative is to buy one from Digikey ($0.5 ... $2).
     
  9. fastwalker

    Thread Starter Active Member

    Jun 24, 2009
    38
    0
    Thanks guys, excellent responses. I think I'll try using a simple shunt resistor.

    Thanks again,
    FW
     
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