Neutral point of a generator

Abstract

An electrodynamic machine includes a housing and a rotor, as well as a neutral point, wherein the neutral point is located inside the housing and the neutral point ends are interconnected by means of shorting bridges, and the shorting bridges are designed such that the neutral point ends inside the generator housing are electrically isolated from each other.

Claims

1. An electrodynamic machine, comprising a rotatably mounted rotor and a stator arranged around the rotor and a housing arranged around the stator, wherein the stator has a stator winding having three windings, wherein the windings each have a terminal lead end and a neutral point end, wherein the neutral point ends are connected to one another via a short-circuiting link to form a neutral point, wherein the neutral point is within the housing, wherein the short-circuiting link is designed such that electrical isolation can take place between the neutral point ends, wherein the electrical isolation takes place by virtue of a movement of the short-circuiting link, wherein the short-circuiting link is movable from outside the housing, when the housing is closed.

2. The electrodynamic machine as claimed in claim 1, wherein the neutral point ends are passed via measurement leads outwards outside the housing via measurement points.

3. The electrodynamic machine as claimed in claim 2, wherein the electrical isolation takes place by virtue of the short-circuiting link being drawn in one direction.

4. The electrodynamic machine as claimed in claim 1, wherein an electrical connection between the neutral point ends takes place by virtue of pressing in the direction towards the neutral point ends.

5. The electrodynamic machine as claimed in one of claims 1, wherein the movement of the short-circuiting link takes place mechanically outside the housing.

6. The electrodynamic machine as claimed in claim 1, wherein the movement of the short-circuiting link takes place electrically within the housing.

7. The electrodynamic machine as claimed in claim 1, wherein the short-circuiting link is connected to a substantially nonmagnetic rod assembly, and the rod assembly is connected to an apparatus for raising and lowering.

8. The electrodynamic machine as claimed in claim 7, wherein the apparatus comprises a motor.

9. The electrodynamic machine as claimed in claim 1, wherein the neutral point ends are formed with measuring end-lead bushings outside the housing.

10. The electrodynamic machine as claimed in claim 9, wherein current transformers for measuring the individual phases of a neutral point are arranged.

11. The electrodynamic machine as claimed in claim 1, wherein the housing is gas-tight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the invention will be described below with reference to the drawing. Said drawing is intended to represent the exemplary embodiments in a manner which is not true to scale; instead the drawing, where useful for explanatory purposes, is in schematized and/or slightly distorted form. In respect of additions to the teaching shown directly in the drawing, reference is made to the relevant prior art. Specifically, in the drawing:

(2) FIG. 1 shows a perspective view of a generator in accordance with the prior art;

(3) FIG. 2 shows a schematic sectional view of a part according to the invention of a generator;

(4) FIG. 3 shows another perspective illustration of a part according to the invention of a generator.

DETAILED DESCRIPTION OF INVENTION

(5) FIG. 1 shows a perspective view of a generator 1 as an embodiment of an electrodynamic machine. Such electric generators produce electrical energy of between 10 megawatts and 1500 megawatts. An electric motor is, for example, a further embodiment of an electrodynamic machine 1.

(6) The generator comprises a housing 2 and a rotor 4 mounted rotatably about an axis of rotation 3 in the housing 2. The rotor 4 comprises windings (not illustrated in any further detail in FIG. 1), which are denoted by the lowercase letters u, v and w. In the region of the communal energy supply, the generators are generally formed with three windings. The windings u, v and w each comprise a terminal lead end 9 and a neutral point end 5. The terminal lead ends u, v and w are passed to the outside via end-lead bushings 8. The end-lead bushings 8 are in this case arranged on the housing 2 in a gas-tight manner and with high voltage strength. The letters x, y and z are selected for the end-lead bushings 8 with respect to the neutral point ends. In accordance with the prior art, the neutral point ends x, y and z are connected electrically to one another and a neutral point box (not illustrated) is arranged over this neutral point end thus formed.

(7) A stator end winding 6 (illustrated schematically) and a laminate stack 7 are shown in FIG. 2.

(8) The electrodynamic machine 1 thus formed comprises a rotatably mounted rotor 4 and a stator arranged around the rotor 4. The stator has a stator winding having three windings. The windings each have a terminal lead end 9 and a first neutral point end 10, a second neutral point end 11 and a third neutral point end 12. The first neutral point end 10 is connected electrically to the second neutral point end 11 via a short-circuiting link 13. The neutral point ends 10, 11 and12 are thus connected to one another to form a neutral point 5. This neutral point 5 is arranged within the housing 2. The short-circuiting link 13 is now designed in such a way that electrical isolation can take place between the neutral point ends 10, 11 and 12.

(9) For this purpose, the short-circuiting link 13 is designed to be movable in one direction 14. This direction is illustrated by the double arrow in FIG. 2. The short-circuiting link 13 is in this case moved from outside the housing. The housing 2 is in this case closed.

(10) A movement of the short-circuiting link 13 upwards results in the short-circuiting link 13 being drawn and thus in electrical isolation between the first neutral point end 10 and the second neutral point end 11.

(11) FIG. 3 shows an illustration rotated through 90 with respect to FIG. 2. A second short-circuiting link 15 connects the second neutral point end 11 to the third neutral point end 12.

(12) The same applies to the second short-circuiting link 15 as to the short-circuiting link 13. Drawing upwards in the direction 14 results in electrical isolation between the second neutral point end 11 and the third neutral point end 12.

(13) An electrical connection is possible again when the short-circuiting link 13 and the second short-circuiting link 15 are moved downwards in the direction 14, with the result that there is touching contact between the first neutral point and the second neutral point with the short-circuiting link Likewise, a movement of the second short-circuiting link 15 downwards in the direction 14 should also follow when an electrical connection is intended to be reinstated.

(14) The movement of the short-circuiting links 13 and 15 in this case takes place mechanically from outside the housing 2. It is likewise conceivable for the movement of the short-circuiting links 13, 15 to be capable of taking place electrically within the housing 2.

(15) The short-circuiting link 13 is connected to an apparatus 17 for raising and lowering by a nonmagnetic rod assembly 16.

(16) In order to now be able to perform measurements during servicing, measuring leads 18, 19 and 20 are passed out, which pass the neutral point ends 10, 11 and 12 electrically outwards outside the housing 2 via measurement points 21, 22 and 23.

(17) The measuring lead 18 connects the neutral point end 10 to the measurement point 21. The measuring lead 19 connects the neutral point end 11 to the measurement point 22. The measuring lead 20 connects the neutral point end 20 to the measurement point 23.

(18) The current transformers are therefore positioned internally. In order to be able to measure the individual phases after isolation of the neutral point ends 10, 11 and 12 by means of the short-circuiting links 13 and 15, the contact points of the individual connections of the neutral point are laid on the outside with the aid of measuring end-lead bushings. There, after galvanic isolation of the phase connections in the end-lead region of the generator, they can be used for the desired electrical measurements of the stator winding.