What does not make sense? Turning loads on and off at preset voltages? Take it this way, load which is always on (middle one) is neither resistive neither capacitive. Current wave is perfectly in phase, but the PF is very low, as low as 0.4. It peaks at 90 and 270 degrees but there is no draw if Vac is lover as 50 - 60V. Passive PFC front end is not very practical solution because there is no full wave rectifier so you have to go with large L and C directly on primaries. My working solution is what I call Load balancer. You insert loads which will work as a resistive load but only from lets say [0 - 60] AND [120 - 180] AND [180 to 240] AND [300 to 360] degrees. However, I had to do it with PIC controller, which is not very practical either. What I would like to achieve is slow acting, analogue solution.