Volts / Turns - Transformer winding question

[made2hack]

Hey,

So as per my previous topic post regarding a 1kVA transformer I'm rewiring, I have some issues with the primary and secondary winding.

As per Ludens Transformers & Coils, I should be using roughly 412 - 495 turns per 220V. 412 volts assuming 1.2 Tesla and 495 assuming 1 Tesla. Since I don't know the quality of the lamination, I will assume the crappier 1 Tesla coefficient. I used the calculation as follows: 220V / 4.44 / 0.002m2 / 50Hz / 1T (or 1.2 T).

When I look at the primary and attempt to estimate the number of turns, I get approximately 620 - 660 turns. There are around 70 turns per layer, 8 layers (560) + around 60 turns on the last layer. This would indicate around 620 turns / 220 V (or close to 3 Turns / 1 Volt).

When I wound 9 turns to form a secondary, I was getting roughly 2.6V on the secondary, which seems to uphold the 3 Turns / Volt theory. However, I only assembled the E Core, without really clamping it down too hard. Thus, lots of vibration. Could this loose me 1-2 Volts? Should I use the calculation of 2 - 2.5 Turns / Volt and not the apparent 3 - 3.5 turns / volt?

I don't want to wind all my secondaries and then find out I messed up.

[made2hack]

OK,

So I redid the test today, same 9 turns on the secondary but this time I bolted the EI core and significantly reduced the vibration. I am now getting a relatively stable 4.2V on the secondary.

Or, as the math suggests, 2.2 turns / volt.