Transformer phase / no phase marking

[sorenb]

Had a few transformers from ToroIDY with two 115V primarys I needed to serialize, unfortunately no markings of the phase.

Hook'ed up one of the secondaries to a function generator, and serialized the two primaries.
Having two free leads and two connected leads (CT)
Measured the voltage V1 from CT to one lead, and V2 from CT to second lead.
Finally measured the voltage V3 from lead to lead.
If V1 + V2 = V3, then the two windings are in phase.
If V1+V2  ≠ V3, the the two windings are out of phase.

Are there an easier way of determine the phase of transformer windings?

[kevin gilmore]

Hook the 2 primaries in series, and test the output.  If it's wired correctly you get voltage, if you get virtually zero, they are wired out of phase. It won't hurt the transformer.  

Don't do this for parallel windings

[luvdunhill]

http://www.diyaudio.com/forums/power-supplies/275477-little-tester-determine-transformer-phasedots-no-scope-signal-generator.html

[samsie]

I used a 9v battery and a multi-meter.  connect the 9v battery to the primary temporarily and see the fluctuated secondary output voltage to be positive or negative.  then you know which way to go.

 I have not tried the  KG methods but it appears to be very convenient. 

[Craig Sawyers]

The other thing to work out is which end of the primary winding is next to the secondaries.  You really want the hot or live input to be next to the core, and the neutral or low input next to the secondary.  It will of course be perfectly OK the other way round, but makes-borne noise coupling via the interwinding capacitance much easier.

As far as I know there is no straightforward way of figuring that out.

[Pars]

So I have this ILP 49783R, 160VA 2x24-26Vac xfrmr. No markings. Single primary, both leads white. From the descriptions I have read online (which jive with what I saw lighting this thing up and ohming), yel-red is one secondary and blue-black is the other. They state that yel-black is 48-52Vac (I would assume with the other leads connected together. So can I assume something like the following drawing, and that the phase dots would be either yellow and blue, or red and black? And don't laugh too hard at my crude drawing

[luvdunhill]

Seems reasonable. Are you wanting to run the secondaries in parallel?

[Pars]

No, was going to use them on a dual GRLV just for testing (with a variac to put it down to 20Vac). I'll buy an Antec 50VA for actual use. I also am going to buy one of Mark's phase dot kits from him just for the hell of it.