Moving the slider [math]\varphi_e[/math] load impedance power factor is changed. You can easily appreciate the difference between VOLTAGE VARIATION (difference between the length of the phasor [math]V_1[/math] (primary supply voltage) and the length of the phasor [math]V_{12}[/math] (secondary voltage referred to primary)) and the VOLTAGE (or IMPEDANCE) DROP [math]\Delta V_{Z12cc}[/math] corresponding to the voltage drop on the short circuit impedance [math]Z_{1cc}[/math].[br]Plase note the colour change of the segment related to the voltage variation when [math]V_{12}>V_1[/math]. Note also the difference between [math]\varphi_e[/math] (phase displacement between [math]\overline{I}_{12}[/math] and [math]\overline{V}_{12}[/math]) and [math]\varphi_{12}[/math] (phase displacement between [math]\overline{I}_{12}[/math] and [math]\overline{V}_{1}[/math]).[br]The angle colour changing passing from lagging to leading phase displacement.