transformer phase shift - how to measure with oscilloscope 3

[MRSSPOCK]

I know this might seem like a schoolboy level question, but I'm afraid I'm stuck.

If I have an unknown transformer and what to determine if there is a phase shift, how can I do it with my two channel scope, considering both channels use the common ground, and so by connecting two channels I am really creating a direct physical connection between the two otherwise isolated primary and secondary coils.

Thanks

I think I am going to be embarassed by the simple answer.

 

[MRSSPOCK]

@skogsgurra When I did the coil test, I was simply switching the coil on and off with an IGBT, so I guess my scope trace will be different to that if I had been feeding the coil a sine wave voltage like your one with the AC supply. I still haven't got a chance yet to repeat that test.

 

[MRSSPOCK]

So here is the screengrab from the actual coil test. The horizontal markers on the oscilloscope screengrab are set at 10ms apart, then aligned with the LTSPICE 10ms markers. I did stretch the image in the vertical direction, as the actual recorded current was only 1.8A