Synchro Stator Voltage Spreadsheet

Discussion in 'Electronics Resources' started by john-campbell, Feb 11, 2009.

  1. john-campbell

    Thread Starter Member

    Feb 10, 2009
    For the uninitiated, synchros are devices that transmit angular information from one place to another. Superficially they look like little motors. When the synchro transmitter rotates through a given angle the synchro receiver will rotate thru the same angle. There are many variations of these devices, as well as synchro-to-digital (S/D) and digital-to-synchro (D/s) converters. I have attached a spreadsheet which calculates the stator voltages for angles between zero and 359. Ultimately, I would like to develop the spreadsheet to show the calculated values when there are faults present; such as, reversed, open or shorted connections. Does anyone else have anything along these lines?
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Not to be too flippant, but that might not be totally valuable, at least for 3 phase synchros. When the connections are reversed, the receiver is 180 deg out. If open, the receiver just sits there. And a short either pops a fuse or causes smoke to appear.

    If you're worried about the accuracy of the S -> D or D -> S converter, the table you have should be adequate.
  3. KL7AJ

    AAC Fanatic!

    Nov 4, 2008

    I had a pair of synchros when I was a kid. I thought they were the coolest thing on the planet! My brother and I set up a "telegraph" between our bedrooms using synchros and a dial with the letters of the alphabet and a pointer. When you pointed one to an A, the other one tracked.

    We were easily entertained, I guess. :)

  4. john-campbell

    Thread Starter Member

    Feb 10, 2009
    Thanks for the replies. Some of the impetus behind the spreadsheet was simply a thought experiment to calculate the stator voltages when various troubles were present. I'm not sure where this might lead. Maybe nowhere.
    See attached excerpts from MIL-HDBK-225 which describes numerous possible faults.
  5. john-campbell

    Thread Starter Member

    Feb 10, 2009
    I'm guessing you're still easily entertained. With me it was a telegraph made out of a couple of cigar boxes.
  6. Philbilly

    New Member

    Aug 18, 2009
    I understand your thought experiment and have some of the same basic questions. My problem is the math equation for determining the angle of rotation when the Z leg is intentionally grounded (Going back twenty-five years, I believe this make the synchro a resolver).
    All of my plots in Excel produce 180 degrees of resolution, meaning the addition of the X and Y leg produce a sine wave which have two points at zero volts. Thus the encoder cannot distinguish between the 0 degree and 180 degrees.

    Suggestions are welcomed.
  7. Paul Snyderwine

    New Member

    Apr 12, 2011
    Thanks, john-campbell. This will be useful in explaining synchros to co-workers.

    I am interested in calculating the "line to neutral" components, so that I could set up four synchronized sources R2-R1, S1-N, S2-N, S3-N so that I can test a synchro receiver without using a TR or simulator.

    Can you point me to the required math? I do understand that all voltages are either in phase or "180-out", and that the math may be surprisingly simple.

    Again, thanks!