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Thread: Shunt calibration / zero amp point set

  1. #1

    Shunt calibration / zero amp point set

    First time poster, long time lurker.

    I have an AFS sensor (P/N 44105, I believe) that is being fed into an AF-5500 on pins 24/25 of the DB37 connector. I'm trying to comply with this instruction from the installation manual "The Amps transducer (Hall or Shunt) will need to have the zero amp point set."

    Is there a procedure for that? How do I set other set points to allow it to scale? Can I use the VPX to do that or do I need an ammeter across the shunt (or similar).

    Thanks in advance,
    -Ed

  2. #2
    Advanced Flight Systems Shawn McGinnis's Avatar
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    The zero point is when no current is flowing. If your shunt is installed inline with the alternators output (the standard location) then it should be zero when the alternator field is grounded.

    To perform the zero, use the Shift Adjust to change the value in the upper right corner to 0.0. e.g: If it reads -0.4 then apply a 0.4 shift. Pressing SAVE should apply the new value. One trick is to first apply a 0.0 shift so you have less math.
    Shawn McGinnis

    Advanced Flight Systems
    support@advanced-flight-systems.com

  3. #3
    Thanks Shawn. How about setting the AD_VALUES? My AFS-5500 was pre-configured by my kit manufacturer for my engine - it has two set points - one at 0.0 (AD 2514) and one at 5.0 (AD 2614). Are those plausible/correct for the 44105 shunt?

  4. #4
    Advanced Flight Systems Shawn McGinnis's Avatar
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    Sounds accurate, is it not working? What's the present AD_VALUE and measured current?
    Shawn McGinnis

    Advanced Flight Systems
    support@advanced-flight-systems.com

  5. #5
    It seems to be working fine, although I was occasionally seeing 1-second spikes to 35 amps from a Rotax 914 with an 18 amp alternator. Trying to make sure it isn't a measurement error. I will check the measured current on the shunt verses what my VPX is showing as a sanity check.

  6. #6
    Advanced Flight Systems Shawn McGinnis's Avatar
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    If you continue to have spikes you could try using twisted wires or even shielded twisted wires on the sense leads going back to the EMS.
    Shawn McGinnis

    Advanced Flight Systems
    support@advanced-flight-systems.com

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