JPS6238941B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stator coil for a rotating electrical machine having a structure capable of optically detecting and diagnosing mechanical breakdown of an insulating layer.

In recent years, large-capacity, high-voltage rotating machines such as turbine generators, water turbine generators, and large induction generators have tended to adopt stator coils that use high-performance insulation structures such as epoxy resin in order to obtain higher reliability. strong.
For this reason, the capacity of a single unit tends to increase, and the mechanical stress to which the stator coil is subjected is becoming more severe than in the past. Therefore, the reliability of the insulating layer of the stator coil tends to be more influenced by mechanical deterioration such as cracking than by electrical deterioration, and it is necessary to establish a technology to accurately diagnose the mechanical internal damage state of the insulating layer. is desired.

Conventionally, methods for diagnosing the deterioration state of the insulating layer of a stator coil have mainly been based on electrical measurements such as alternating current tests, tandelta-voltage tests, direct current tests, and partial discharge measurements. Although these tests can diagnose the overall state of deterioration of the insulating layer as described below, they have the disadvantage that local mechanical internal damage cannot be detected. On the other hand, the electrical insulation strength of the insulating layer is
It is known that the presence of localized internal mechanical damage causes significant degradation, and accurate detection of this damage is extremely important for damage prevention maintenance of equipment. This will be explained in more detail.

FIG. 1 is a sectional view showing a stator coil of a conventional rotating electric machine. In the figure, a stator coil 1 includes a plurality of integrally molded wire conductors 2, a main insulation layer 3 surrounding the wire conductors 2, and a semiconductive paint applied to the outer surface of the outermost layer of the main insulation layer 3. It is formed from a semiconducting layer 4 having a structure.

In the insulation test of the main insulating layer 3 that is generally performed at present, an external voltage is applied between the wire conductor 2 and the semiconducting layer 4 to perform electrical measurements. Local mechanical stress may occur in the main insulating layer 3 due to thermal stress caused by temperature changes in the stator coil 1 when the rotating machine starts and stops operating, electromagnetic force applied during operation, external pressure applied during the manufacturing process, etc. If a crack occurs, it is necessary to detect this defect non-destructively from the outside.

In the conventional stator coil insulation test, the strand conductor 2
The electrical characteristics of the main insulating layer 3 are measured by applying a voltage between the electrodes of the semiconducting layer 4 and the semiconducting layer 4. Therefore, when the above-mentioned mechanical cracks occur locally, an electrical detection result is obtained in the form of a ratio of the volume of the cracked portion to the total volume of the main insulating layer 3. Therefore, when the conventional stator coil 1 is the largest coil, even if there is a local mechanical crack that significantly reduces the breakdown voltage, the volume ratio is small, so
A major drawback was that it was almost impossible to detect electrically.

This invention was made to eliminate the above-mentioned drawbacks, and a plurality of optical fibers, which are electrical insulators, are installed inside the main insulating layer of the stator coil between both ends of the main insulating layer in the longitudinal direction of the coil. Insert the light into the optical fibers at both ends of the main insulation layer.
Provides a stator coil for a rotating electrical machine that can diagnose cracks inside the main insulating layer by optically detecting breakage of photoconductive fibers due to cracks inside the main insulating layer by connecting a light receiving device. It is intended to.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a side view showing one embodiment of a stator coil of a rotating electric machine according to the present invention. FIG. 3 is a sectional view taken along the line - in FIG. 2. In FIGS. 2 and 3, the stator coil 1 includes a plurality of integrally molded wire conductors 2, a main insulating layer 3 surrounding the wire conductors 2, and a half-layer on the outer surface of the outermost layer of the main insulating layer 3. A semi-conductive layer 4 formed by applying a conductive paint, and a plurality of optical fibers 5 provided inside the main insulating layer 3 in the longitudinal direction of the stator coil between both ends of the main insulating layer 3. It consists of Light emitting device 6
is optically connected to one end of the optical fiber 5 exposed to the outside, and the light receiving device 7 is formed of, for example, a photodiode, and is optically connected to the other end of the optical fiber 5 exposed to the outside. That is, in this embodiment, ten optical fibers 5 surrounding the wire conductor 2 are embedded in the center of the main insulating layer 4 . Further, near both ends of the main insulating layer 3, both ends of the optical fiber 5 are exposed to the outside.

Next, an insulation test of the stator coil 1 according to the present invention will be explained. In a state where the stator coil 1 has no mechanical damage immediately after manufacturing, the main insulating layer 3
Since the optical fiber 5 embedded therein is not cut, both ends of the optical fiber 5 exposed from both ends of the main insulating layer 3 are optically connected. That is, when light is input from one end of the optical fiber 5 through the light emitting device 6,
This light is optically transmitted to the other end and is received by the light receiving device 7, thereby confirming that the optical fiber 5 is not cut.

Note that the optical fiber 5 used in the present invention includes all fibers that can conduct light using the dielectric constant distribution in the cross-sectional axial direction, which are called light guides, optical fibers, optical fibers, and the like. Since the optical fiber 5 is made of an inorganic insulator or a polymer material, it is a good electrical insulator. Therefore, even if the optical fiber 5 is directly embedded inside the main insulating layer 3, the original stator coil 1
has no effect on the insulation properties of the Furthermore, although both ends of the stator coil 1 are at a high potential during operation, due to the electrical insulation properties of the optical fiber 5, there is no risk that the light emitting device 6 and the light receiving device 7 will be exposed to high voltage.

Generally, the main insulating layer 3 currently in use is made by wrapping mica or heat-resistant polymer paper around the wire conductor 2 in the form of a tape or wrapper, and then impregnating it with a thermosetting resin, or by impregnating it with a thermosetting resin. It is manufactured by wrapping impregnated mica tape or latsupa around it and curing it with heat. Glass cloth or polymer nonwoven fabric is usually used as the backing material for tapes and wrappers, and forms a composite insulating structure integrated with thermosetting resin. Further, the optical fiber 5 used in the present invention is an inorganic insulator such as glass or a polymer insulator, and has the same insulating structure as the main insulating layer 3.
Therefore, when wrapping mica tape, Latuppa, etc.,
The optical fiber 5 is appropriately embedded, and then impregnated with a thermosetting resin to completely integrate the embedded optical fiber 5 with the structure of the main insulating layer 3. The mechanical strength of the optical fiber 5 is equivalent to the strength of the backing material constituting the main insulating layer 3, and the insulation properties are also equivalent, so the stator coil 1 of the present invention is different from that of the conventional stator coil 1.
It has exactly the same electrical and mechanical characteristics as compared to

In addition, the optical fiber 5 has the same mechanical strength as the insulating structure of the main insulating layer 3 around which it is embedded, and is integrated with the surrounding tissue. If a mechanical crack occurs, the optical fiber 5 in that part is also cut. Optical fiber 5
When the optical fiber 5 is mechanically cut, it is also optically cut, and even if light enters from one end of the optical fiber 5 exposed to the outside, the light will not be transmitted to the other end. Therefore, when an optical fiber 5 is optically cut by a crack A as shown in FIG. 2, it can be confirmed that the vicinity of the cut optical fiber 5 has been mechanically cut. Since the optical fiber 5 is integrated with the structure of the main insulating layer 3, the mechanical crack state of the structure of the main insulating layer 3 can be diagnosed by this measurement. By embedding a plurality of optical fibers 5 inside the main insulating layer 3 in this manner, the position of the mechanical crack in the cross-sectional direction and the size of the crack can be measured.

Note that in the above embodiment, in the main insulating layer 3,
Although all the optical fibers 5 are placed at the same depth from the outer periphery of the main insulating layer 3, by placing the optical fibers 5 at different positions in the depth direction, even more accurate cracking can be achieved. can be measured. Further, in the above embodiment, the optical fibers 5 are arranged evenly in the main insulating layer 3, but they may be arranged in a concentrated manner if necessary, and there are no restrictions on the arrangement of a plurality of optical fibers 5. It's not something you can make money from.

Note that the light emitting device 6 and the light receiving device 7, which are diagnostic devices, may be any device as long as it can be optically confirmed when the optical fiber 5 is not cut.

As described above, according to the present invention, a plurality of optical fibers are arranged in the longitudinal direction in the main insulating layer of a stator coil of a rotating electric machine, and the optical fibers are exposed at both ends of the main insulating layer. Since the position and size of mechanical cracks inside the main insulating layer can be easily and optically measured, this method has a great effect on improving the reliability of rotating electric machines and preventing accidents.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a stator coil of a conventional rotating electric machine. FIG. 2 is a side view showing one embodiment of a stator coil of a rotating electric machine according to the present invention.
FIG. 3 is a sectional view taken along the line - in FIG. 2. In the figures, the same parts in each figure are indicated by the same symbols, 1 is a stator coil, 2 is a wire conductor, 3 is a main insulating layer, 4 is a semiconducting layer, 5 is an optical fiber, 6 is a light emitting device, 7 is a light receiving device, and A is a crack.

Claims (1)

[Scope of Claims] 1 A wire conductor, a main insulating layer formed integrally by impregnating and curing an insulating structure such as a tape, an optical fiber, and a thermosetting resin around the wire conductor; , a diagnostic device for detecting mechanical cracks in the main insulating layer by inputting an optical signal from one end of the optical fiber and receiving the optical signal at the other end. stator coil. 2. A stator coil for a rotating electric machine according to claim 1, wherein a plurality of optical fibers are installed at approximately equal intervals along the cross-sectional circumferential direction of the wire conductor. 3. A stator coil for a rotating electric machine according to claim 1 or 2, wherein a plurality of optical fibers are installed at different positions in the thickness direction of the main insulating layer.