These chokes are made without a magnetic core and therefore have no core losses.

The circular arrangement of the coil greatly reduces the leakage flux compared to a cylindrical coil. Mechanical fixing of the coil gives the structure good mechanical damping properties.

Five-arm chokes are compact three-phase chokes with additional arms that allow asymmetries. The external arms absorb the residual fluxes and produce higher common-mode inductivity.

These products are suitable for voltage transformations over a wide range of frequencies. Besides ferrite, other materials such as amorphous-metal laminations, powder, or special silicon laminations are used for the cores.