Windings 'A', 'B' and 'C' have 20 turns each and are wound on the same iron core as shown, along with winding 'X' which has 2 turns. The figure shows the sense (clockwise/anti-clockwise) of each of the windings only and does not reflect the exact number of turns. If windings 'A', 'B' and 'C' are supplied with balanced 3-phase voltages at 50 Hz and there is no core saturation, the no-load RMS voltage (in V, rounded off to 2 decimal places) across winding 'X' is ______.
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A single square window-type iron core (one closed magnetic loop), drawn shaded. Windings A (upper) and B (lower) are on the left limb and drawn identically: each has two rightward chevrons inside the window and one leftward chevron outside the limb. Winding C is on the bottom limb, with two upward loops inside the window and one downward loop below the core. Winding X is on the right limb, with two leftward chevrons inside the window and one rightward chevron outside, and two open leads marked X. On the left are three ideal sinusoidal sources, each with its '+' terminal on the right: 230∠0° V, 230∠−120° V and 230∠120° V. The '+' terminal of each source goes to one end of A, B and C respectively. The other ends of the three windings go to a common return line, joined to a left-hand bus that connects the other terminals of all three sources. So each winding is connected directly across its own source.