Rotor end-bell for electric generators

1. A rotor end-bell configured for placement on an end of a rotor of an electric generator, wherein the rotor end-bell is at least partially comprised of fiber reinforced plastic, a portion of the rotor end-bell comprising fiber reinforced plastic being configured to surround and directly contact an end winding of the rotor, the portion of the rotor end-bell, which comprises fiber reinforced plastic, being configured to contact a portion of the radial thickness of the end winding of the rotor at an end of the end winding of the rotor,

wherein the rotor end-bell has a radially inner side, a spacer ring is configured and located to define a support surface between the rotor end-bell and a support for the rotor end-bell, the spacer ring has a single step to allow an outer side of the spacer ring to bear against an inner side of the portion of the rotor end-bell comprising fiber reinforced plastic, the single step of the spacer ring bearing against a double step of the inner side of the portion of the rotor end-bell comprising fiber reinforced plastic.

2. The rotor end-bell as claimed in claim 1 , wherein the plastic includes fibers that have at least one preferred direction in the end-bell which at least substantially comprises a circumferential direction of the rotor end-bell.

3. The rotor end-bell as claimed in claim 1 , wherein the plastic includes fibers and the fibers include carbon fibers.

4. The rotor end-bell as claimed in claim 1 , wherein the plastic includes fibers and the fibers include ceramic fibers.

5. The rotor end-bell as claimed in claim 4 , wherein the ceramic fibers are aluminum oxide fibers.

6. The rotor end-bell as claimed in claim 1 , wherein the plastic includes fibers and the fibers include boron fibers.

7. The rotor end-bell as claimed in claim 1 , wherein the plastic includes fibers that are embedded in a matrix comprising a resin.

8. The rotor-end bell as claimed in claim 7 , wherein the matrix comprises epoxy resin.

9. The rotor end-bell as claimed in claim 1 , wherein the spacer ring has a lower specific electrical resistance than the fiber reinforced plastic material of which the rotor end-bell is comprised.

10. The rotor end-bell as claimed in claim 9 , wherein the inner side of the spacer ring has a thread.

11. The rotor-end bell as claimed in claim 10 , wherein the thread is a conical thread.

12. The rotor end-bell as claimed in claim 9 , wherein the spacer ring is comprised of copper or of steel having a low alloying contribution.

13. The rotor end-bell as claimed in claim 1 , wherein the rotor end-bell is configured for producing a quarter turn connection around the end of the rotor of the electric generator on which the rotor end-bell is placed.

14. A rotor for an electric generator having at least one rotor end-bell as claimed in claim 1 disposed on the end of the rotor.

15. The rotor as claimed in claim 14 , wherein the rotor end-bell has been installed on the end of the rotor by the end-bell being previously cooled and subsequently shrunk onto the end of the rotor.

16. An electric generator with at least one rotor as claimed in claim 14 .

17. The electric generator of claim 16 , wherein the electric generator is a turbo generator.

18. A rotor end-bell configured for placement on an end of a rotor of an electric generator, wherein

the rotor end-bell is at least partially comprised of fiber reinforced plastic;

the rotor end-bell has a radially inner side, a spacer ring configured and located to define a support surface between the rotor end-bell and a support for the end-bell,

the spacer ring has a lower specific electrical resistance than the fiber reinforced plastic material of which the rotor end-bell is comprised; and

the spacer ring has an outer side, which bears against the fiber reinforced plastic of the rotor end-bell, and an intensely conductive layer between the outer side of the spacer ring and the rotor end-bell.

19. The rotor-end bell as claimed in claim 18 , wherein the intensely conductive layer is silver.

20. A rotor of an electric generator including a rotor end-bell, the rotor end-bell being configured for placement on an end of the rotor, wherein

the rotor end-bell is at least partially comprised of fiber reinforced plastic;

the rotor end-bell has a radially inner side, a spacer ring configured and located to define a support surface between the rotor end-bell and a support for the end-bell,

the spacer ring has a lower specific electrical resistance than the fiber reinforced plastic material of which the rotor end-bell is comprised;

the inner side of the spacer ring has a thread; and

a mating thread, matching the thread of the spacer ring, is located on support surfaces of teeth of the rotor.