butterfly capacitors are used in symmetrical tuned circuits, e.g. rf power amplifier stages in push-pull configuration or symmetrical antenna tuners where the rotor needs to be "cold", i.e. connected to rf (but not necessarily dc) ground potential. since the peak rf current normally flows from one stator to the other without going through wiper contacts, butterfly capacitors can handle large resonance rf currents, e.g. in magnetic loop antennas.