Magnetic core for an electromagnetic induction device, an electromagnetic induction device comprising the same, and a method of manufacturing a magnetic core

1. A magnetic core for an electromagnetic induction device, comprising:

a limb made of a first grain-oriented material, wherein the limb is a vertically aligned member of the magnetic core,

a yoke made of an amorphous material, wherein the yoke is a horizontally aligned member of the magnetic core, and

an auxiliary joint member made of a second grain-oriented material,

wherein the auxiliary joint member joints the limb and the yoke with the auxiliary joint member being between the limb and yoke such that the limb is not jointed directly to the yoke,

wherein a grain orientation of the limb is perpendicular to a grain orientation of the auxiliary joint member,

wherein a connection between the auxiliary joint member and the yoke is parallel with a central longitudinal axis of the limb, and

wherein the auxiliary joint member and the yoke are jointed by interleaving laminated plates of the yoke with laminated plates of the auxiliary joint member such that frictional forces hold the auxiliary joint member and the yoke together.

2. The magnetic core as claimed in claim 1 , wherein the auxiliary joint member consists of the second grain-oriented material.

3. The magnetic core as claimed in claim 1 , wherein the limb and the auxiliary joint member each comprises a plurality of laminated plates, wherein a joint between the auxiliary joint member and the limb is formed by the laminated plates of the auxiliary joint member being interleaved with the laminated plates of the limb.

4. The magnetic core as claimed in claim 1 , wherein the yoke and the auxiliary joint member each comprises a plurality of laminated plates, wherein a joint between the auxiliary joint member and the yoke is formed by the laminated plates of the auxiliary joint member being interleaved with the laminated plates of the yoke.

5. The magnetic core as claimed in claim 1 , wherein a joint between the auxiliary joint member and the limb is a mitre joint.

6. The magnetic core as claimed in claim 5 , wherein an angle of the mitre joint is 45°.

7. The magnetic core as claimed in claim 1 , wherein a joint between the auxiliary joint member and the yoke is a butt-lap joint.

8. The magnetic core as claimed in claim 1 , wherein the yoke has a larger cross-section than the limb.

9. An electromagnetic induction device comprising a magnetic core as claimed in claim 1 .

10. The electromagnetic induction device as claimed in claim 9 , wherein the electromagnetic induction device is a transformer or a reactor.

11. The electromagnetic induction device as claimed in claim 9 , wherein the electromagnetic induction device is a high voltage electromagnetic induction device.

12. A method of manufacturing a magnetic core of an electromagnetic induction device, wherein the method comprises:

jointing a limb made of grain-oriented material with an auxiliary joint member made of a grain-oriented material such that a grain-orientation of the limb is perpendicular to a grain-orientation of the auxiliary joint member, wherein the limb is a vertically aligned member of the magnetic core, and

jointing a yoke made of an amorphous material with the auxiliary joint member, wherein the auxiliary joint member is between the limb and yoke such that the limb is not jointed directly to the yoke, wherein the yoke is a horizontally aligned member of the magnetic core,

wherein a connection between the auxiliary joint member and the yoke is parallel with a central longitudinal axis of the limb, and

wherein the auxiliary joint member and the yoke are jointed by interleaving laminated plates of the yoke with laminated plates of the auxiliary joint member such that frictional forces hold the auxiliary joint member and the yoke together.

13. The method as claimed in claim 12 , wherein the limb, the yoke and the auxiliary joint member each comprises a plurality of laminated plates, wherein the jointing of the auxiliary joint member and the limb includes interleaving the laminated plates of the auxiliary joint member with the laminated plates of the limb, and wherein the jointing of the auxiliary joint member and the yoke includes interleaving the laminated plates of the auxiliary joint member with the laminated plates of the yoke.

14. The method as claimed in claim 12 , comprising performing an inclined cut of the auxiliary joint member with respect to its grain-orientation before the jointing, wherein the jointing of the limb and the auxiliary joint member forms a mitre joint.

15. The method as claimed in claim 12 , comprising performing a perpendicular cut of the auxiliary joint member with respect to its grain-orientation before the jointing, wherein the jointing of the auxiliary joint member and the yoke forms a butt-lap joint.