Short-circuit generator

1. A short-circuit generator which comprises a rotor and a stator located around an outer periphery of the rotor so as to enclose a rotor central axis thereof, said stator having stator slots in which windings are placed, and said stator slots each having a depth in a radial direction perpendicular to the rotor central axis whose ratio divided by a width of the stator slot in a direction perpendicular both to the radial direction and a direction of the rotor central axis, is less than three,

wherein the rotor comprises: a rotor core in which plural magnetic poles and plural rotor slots are formed; a field winding placed in each of the rotor slots; a metallic damper bar placed in each of the rotor slots on an outer periphery side of the field winding; and a metallic wedge placed in each of the rotor slots on an outer periphery side of the damper bar and connected to the damper bar; and

wherein a damper-bar height that is a height of the damper bar in the radial direction is less than a wedge height that is a height of the wedge in the radial direction, and

the rotor includes, each as one of the rotor slots, a rotor slot in which the wedge of a first material is placed, and a rotor slot in which the wedge of a second material that is lower in electric conductivity than the first material is placed.

2. The short-circuit generator of claim 1 , wherein the rotor slot in which the wedge of the first material is placed, is located nearest to one of the magnetic poles of the rotor core.

3. The short-circuit generator of claim 2 ,

wherein each of these wedges is divided into plural portions;

wherein the thus-divided wedge is placed in the rotor slot in the direction of the rotor central axis; and

wherein a portion of the divided wedge placed at its end in the direction of the rotor central axis, is formed of the first material.

4. The short-circuit generator of claim 2 ,

wherein each of these wedge is divided into plural portions;

wherein the thus-divided wedge is placed in the rotor slot in the direction of the rotor central axis; and

wherein, in the rotor slot in which the wedge of the second material is placed, a portion of the divided wedge placed at its end in the direction of the rotor central axis, is instead formed of the first material.

5. The short-circuit generator of claim 2 , wherein the rotor is provided with a metallic retaining ring which covers an end portion of the rotor core in the direction of the rotor central axis and an end portion of the wedge in the direction of the rotor central axis, and which is in contact with the end portion of the rotor core in the direction of the rotor central axis and the end portion of the wedge in the direction of the rotor central axis.

6. The short-circuit generator of claim 2 , wherein the first material is BeCu or CrCu.

7. The short-circuit generator of claim 1 ,

wherein each of these wedges is divided into plural portions;

wherein the thus-divided wedge is placed in the rotor slot in the direction of the rotor central axis; and

wherein a portion of the divided wedge placed at its end in the direction of the rotor central axis, is formed of the first material.

8. The short-circuit generator of claim 7 , wherein the rotor is provided with a metallic retaining ring which covers an end portion of the rotor core in the direction of the rotor central axis and an end portion of the wedge in the direction of the rotor central axis, and which is in contact with the end portion of the rotor core in the direction of the rotor central axis and the end portion of the wedge in the direction of the rotor central axis.

9. The short-circuit generator of claim 7 , wherein the first material is BeCu or CrCu.

10. The short-circuit generator of claim 1 ,

wherein each of these wedge is divided into plural portions;

wherein the thus-divided wedge is placed in the rotor slot in the direction of the rotor central axis; and

wherein, in the rotor slot in which the wedge of the second material is placed, a portion of the divided wedge placed at its end in the direction of the rotor central axis, is instead formed of the first material.

11. The short-circuit generator of claim 10 , wherein the rotor is provided with a metallic retaining ring which covers an end portion of the rotor core in the direction of the rotor central axis and an end portion of the wedge in the direction of the rotor central axis, and which is in contact with the end portion of the rotor core in the direction of the rotor central axis and the end portion of the wedge in the direction of the rotor central axis.

12. The short-circuit generator of claim 10 , wherein the first material is BeCu or CrCu.

13. The short-circuit generator of claim 10 , wherein the second material is a stainless steel.

14. The short-circuit generator of claim 1 , wherein the rotor is provided with a metallic retaining ring which covers an end portion of the rotor core in the direction of the rotor central axis and an end portion of the wedge in the direction of the rotor central axis, and which is in contact with the end portion of the rotor core in the direction of the rotor central axis and the end portion of the wedge in the direction of the rotor central axis.

15. The short-circuit generator of claim 14 , wherein the wedge is formed of BeCu, CrCu or a stainless steel.

16. The short-circuit generator of claim 1 , wherein the rotor is provided with a metallic retaining ring which covers an end portion of the rotor core in the direction of the rotor central axis and an end portion of the wedge in the direction of the rotor central axis, and which is in contact with the end portion of the rotor core in the direction of the rotor central axis and the end portion of the wedge in the direction of the rotor central axis.

17. The short-circuit generator of claim 1 , wherein the wedge is formed of BeCu, CrCu or a stainless steel.

18. The short-circuit generator of claim 1 , wherein the first material is BeCu or CrCu.

19. The short-circuit generator of claim 1 , wherein the second material is a stainless steel.