Abstract: Defects in a pipeline may be detected by an in-line inspection tool passing therethrough. However, as the tool travels through the pipeline, errors associated with certain onboard components may accumulate. These errors may reduce the accuracy with which the locations of detected defects can be determined. Accordingly, markers may be positioned at various locations along the pipeline. Each marker may include a radio receiver to receive signal transmitted by an in-line tool passing thereby and one or more magnetic flux detection systems that may detect a magnetic field emanating from the in-line tool. The radio receiver may include an antenna comprising two or more coils connected in series and positioned side-by-side. The flux detection system may include one or more flux concentrators to amplify the strength of the magnetic field.

Abstract: The present application relates to circuitry having a plurality of inductors, each inductor having a first end and a second end; and a switching arrangement connected to the first end and to the second end of each of the plurality of inductors for routing a current via the inductors; wherein the switching arrangement is arranged to at least one of selectably prevent current from flowing through a subset of the plurality of inductors and select a current flow direction through one of the inductors relative to a current flow direction through at least one other of the inductors so as to vary an effective inductance that the plurality of inductors represents to the current.

Abstract: The present application relates to circuitry having a plurality of inductors, each inductor having a first end and a second end; and a switching arrangement connected to the first end and to the second end of each of the plurality of inductors for routing a current via the inductors; wherein the switching arrangement is arranged to at least one of selectably prevent current from flowing through a subset of the plurality of inductors and select a current flow direction through one of the inductors relative to a current flow direction through at least one other of the inductors so as to vary an effective inductance that the plurality of inductors represents to the current.

Abstract: Two vertical, parallel, horizontally spaced signal coils are connected in series but in opposite phase across an a.c. source. Thus a buried conductor located centrally beneath the coils experiences an alternating magnetic field whose strength is due to the addition of the fields induced by the two coils. The field strength may be further enhanced by one or more of: providing a ferromagnetic flux diverter between the upper ends of the coils; placing a conductive nonmagnetic screen between them; connecting a tuning capacitor in parallel with the coils; or providing a tuning circuit having series-connected secondary coils which are flux-linked to respective signal coils and are in parallel with a capacitor. There may be a switch arrangement for switching the signal coils to in-phase connection, for use when they are oriented horizontally.

Abstract: A variable transformer, reactor having a core combining at least two complete core elements wiht a common yoke; primary winding divided into two independently fed sets of phase coils wound in opposite direction, arranged on symmetrical legs of core elements and separated by the common yoke; secondary winding with each phase coil divided into two wound in opposite direction portions carried by symmetrical core legs, adjacent to the primary coils and separated by common yoke. The secondary short-circuited reactor winding is reduced to at least one close loop member with loop portions separated by the common yoke. The single, polyphase apparatus has at least one primary coil per set that includes a controllable device in circuit relation therewith to enable control of one primary coil relative to the other, either in current magntidue or in current phase shift. The controllable device being either a silicon control rectifier, triac or transistor.

Abstract: A phase-shift transformer circuit providing advance or retard phase shift at any predetermined phase shift angle. The phase shift angle is determined by the ratio of the main and short windings of the transformer primary. Two links are used to provide advance or retard phase shift. One transformer winding is connected directly to a phase conductor of the three-phase power system. The remaining two transformer windings are connected to the remaining two phase conductors via the links. The links are movable such that in the advance configuration, the phase two conductor is connected to one of the transformer windings and the phase three conductor is connected to the other. In the retard phase-shift configuration, the links are moved so that the connections are reversed.