how to use current transducer

Discussion in 'General Electronics Chat' started by thehaders, Mar 6, 2009.

  1. thehaders

    Thread Starter New Member

    Nov 14, 2008
    6
    0
    Hi all,

    I bought a current transducer for measuring the current that goes into my dc motor. I have the datasheet but not really sure how to use it. Can anyone help me please?

    The current range that I am measuring is 0-2A. The link is for the datasheet is below. The current transducer that I bought is HX 03-P/SP2. Any comment, typical application circuit, anything at all are welcomed.

    http://www.datasheetcatalog.org/datasheet/lem/HX15-P_SP2.pdf

    Thank you very much.
     
  2. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    Do not buy something unless you have a circuit for it. Even if the circuit is available it may not be suitable. I can find no application notes for this. Just the spec sheet. The part that you need to go on is:

    ns subject to change without notice.
    Terminal Pin Identification
    1.....0V
    2.....0V
    3.....+12V to +15V
    4.....Output
    5.....Primary input Current(+)
    6.....Primary input Current(-)

    and the note that: VOUT Output voltage @ ± I
    PN, RL
    = 2 kW, TA = 25°C VOE
    ±0.625 V
     
  3. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
  4. thehaders

    Thread Starter New Member

    Nov 14, 2008
    6
    0
    I noticed that. Does it mean it gives me output voltage which proportional to the current. Well, of course V=IR, but i was expecting it gives me value of current not the output voltage.

    Anyhow, do you have any suggestion of particular current sensor/current transducer that is easy and relatively simple to use. All I need is just the actual current from the dc motor so that I can feed that current into my PI controller and compare it with the reference current.

    Thank you very much.
     
  5. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    There are a lot of commercial SCR based DC drives that simply use high wattage resistors in the range of from 0.1 (1/10) to 0.5 (5/10) ohm to monitor motor current. These resistors would go in series with the motor load. One end would be tied to ground so the voltage developed would be ground referenced. They typically use an op amp to amplify the small voltage derveloped by the shunt to a more usable value. If you go to

    http://www.cmccontrols.com/dc_drives_downloads.asp
    and click on the PaceMaster 1&2 manual link, you can see a full schematic of a commercial drive and how they monitor motor current. The shunt is near the lower right of the schematic near the dotted line optional reversing relay. Hope this helps. If you really want to use the device you bought, it simply converts current to a proportional voltage via a hall device and internal amplifier. From what I see on the data sheet, there must be an internal 5V regulator since the output varies around Voe of +2.5v and will be either 0.625V above or below that point with 3A flowing through the sense terminals. That gives the ability to also sense direction of the motor by use of your PI controller. If you notice on the suggested document from my prior post, other models use bi-polar power sources and their outputs are also bi-polar to denote direction of current.
     
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