TTR test on T type transformer with odd vector

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I am trying to get proper TTR test results but having issues with every method I try. I have tried the T-T lag 30 and T-T lead 30 along with random tries. Any help with figuring this out would be awesome!

Thanks in advance!

lp xfmr
lp xfmr1063Ă—458 31.9 KB

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I’m not to familiar with this particular type of transformer but this would be my first stab at it:

H1-H2 - X1-X0
H2-H3 - X2-X0
H3-H1 - X3-X0

H4-H5 - X1-X0
H5-H6 - X2-X0
H6-H4 - X3-X0

H7-H8 - X1-X0
H8-H9 - X2-X0
H9-H7 - X3-X0

I may be completely wrong on this lol. What kind of test kit are you using at what are your connections? Also would be good to know the exciting current.

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Hey Michael,

To get accurate TTR results with this T-type transformer, make sure you’re considering the following:

  1. Vector Group Check: Identify the vector group configuration of the transformer (e.g., Yd11, Dy1). This will determine the phase shift between HV and LV. The phase shift setting on your TTR meter needs to match the transformer’s configuration.

  2. Phase Shift Settings: Make sure your TTR meter is set for the correct phase shift (e.g., T-T lag 30 or lead 30). Mismatched settings can throw off your readings.

  3. Connections: Double-check all connection points on both HV and LV sides. Any wrong connections can lead to erroneous results. Stick to the manufacturer’s recommendations for connecting to each winding.

  4. Polarity Consistency: Keep consistent polarity across all measurements. Any mismatch in polarity between HV and LV can skew your results.

  5. Neutral Handling: If the transformer’s neutral (X0) isn’t supposed to be connected during the test (as per the diagram), make sure it’s left unconnected. Connecting it can impact your readings.

  6. Instrument Calibration: If you’re still getting odd results, verify that your TTR tester is properly calibrated. Sometimes the issue could be with the instrument itself.

Hopefully, this helps you get the results you’re looking for!

Thanks!

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