Abstract: A tubular core (6) for a controllable inductor with a main winding (1) surrounding the core and a control winding (7) passing substantially axially through the core. The core (6) is capable of receiving a magnetic flux from the main winding (1) running substantially axially therethrough and having a plurality of core rings (8) stacked co-axially on top of each other and connected to a rigid unit. The core rings (8) are connected to each other forming a walled construction. The core (6) also has an inner envelope (18) with an outer cross-section that is substantially equal to the inner cross-section of the core ring walled construction. The walled construction has joints (16) between the core rings (8) in an axial direction which are overlapped by a part of the envelope (18).

Abstract: A controllable inductor including at least one tubular core (10), a main winding (5) surrounding the core and a control winding (11) running substantially axially through said core and returning substantially axially outside thereof between said core and said main winding. The control winding is divided into a plurality of separate part control windings (12). The cross section of the part control windings is formed in a way that at least some adjacent part control windings inside the core are separated by means of a spacing (20, 26), which is at least partly defined by substantially parallel surfaces (16, 17) of these part control windings.