SCADA Transducer

Discussion in 'Wireless & RF Design' started by bejoyengineer, Mar 29, 2009.

  1. bejoyengineer

    Thread Starter New Member

    Mar 26, 2009
    In SCADA, the analog output value of a transducer for a tap changing indication gave me a fluctuated value at the output of the transducer. The more we increase the taps of the transformer.. the more the transducer output value fluctuates and thereby not displaying the actual value in SCADA. What is it that could be the reason and how can I solve this issue. The transducer calibration used is 0-21 tap positions = 0 -1 mA
    ++++++++++++++++++++ Relay +++++++++++++++++++++++
  2. hgmjr

    Retired Moderator

    Jan 28, 2005
    For those unfamiliar with the term:

    SCADA stands for Supervisory Control And Data Acquisition.

  3. wr8y

    Active Member

    Sep 16, 2008
    I have implemented only one SCADA system, it was a 21 site system to monitor fresh and sewer water flow for a utility in Michigan. The customer's meters output was a 4 to 20 mA loop (4 mA meant no flow, 20 mA meant full flow, and any current below 4 mA indicated a metering failure - that is, an alarm.)

    Now, the 4 to 20 mA loop was DC - but you keep referring to transformers. Are you using an AC loop or are you talking about the power supply for the transducer?
  4. leftyretro

    Active Member

    Nov 25, 2008
    We really need a more detailed description of the tap change transducer. Tap changers in large industrial transformers were usually a mechancal switching device that changes the turns ratio of the transformer by switcing between different wire taps on a transformer winding to make small output voltage changes to adjust for additions or deletions in load(s) powered by the transformer.

    I assume your tap change transducer is some kind of mechanical motion detector/follower that converts mechanical travel to a variable DC current. If it is loop powered by the SCADA I/O equipment it most likely has a internal fixed voltage regulator and some kind of variable resistance element (like a pot) that mechaniclly connects to the tap changing hardware. If so you might have a bad regulator, bad cap or other internal component problem in the transducer. If you could provide a spec sheet or link for the specific transducer we might be able to help further.

  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    If the taps change the aplitude of what the transducer is reading, and the level varies erratically at any amplitude, then either what is being measured is erratic, or the transducer is faulty.