The point of a transformer is that primary and secondary see the same flux linkage...
... so the voltage across each turn of each winding is identical.
In theory it should be possible to compensate for the phase shift (assuming constant mains frequency) by putting a capacitor...
Quote from: MarkT on Jul 23, 2012, 06:28 pmThe point of a transformer is that primary and secondary see the same flux linkage...Only true for an ideal transformer. Real transformers suffer from flux leakage.Quote from: MarkT on Jul 23, 2012, 06:28 pm... so the voltage across each turn of each winding is identical. Even if we ignore flux leakage, that is only true for an ideal transformer. A real transformer has nonzero winding resistance and finite primary inductance [and nonzero leakage inductance cased by flux leakage]. Think of the winding resistance as a resistor in series with each winding of an ideal transformer, the primary inductance as an inductor in parallel with the primary of the ideal transformer, and the leakage inductance as an inductor in series with one or both of the windings. Even with no load on the secondary, the combination of primary inductance and primary winding resistance causes the secondary voltage to be phase-shifted with respect to the primary.
Standard silicon steel mains transformers have core relative-permeabilities in the thousands, and primary inductance impedance several orders of magnitude higher than the winding resistance (otherwise the primary would melt at full load) - the variation from ideal is tiny. I would be surprised if the phase shift of an unloaded mains transformer was more than the order of minutes of arc (milliradians). How ideal do you want?
the question was -loaded or unloaded for minimal phase shift
Guys, in trying to show how clever you are at electrical theory you are losing sight of the question. the question was -loaded or unloaded for minimal phase shift
The 1k resistor and 33pF cap are suggested by Analog for filtering purposes.
At mains frequencies this will do chuff all about filtering.