JPS63124738A - Rotor coil - Google Patents

Abstract

PURPOSE:To prevent the concentration of bending stresses due to the thermal expansion and contraction of a coil, by a method wherein solid bars, provided with a stepped part only at the outer diametral side of a coil end part and different shape sections reduced in the radial height thereof, are connected to integrate them. CONSTITUTION:Rotor coils 2, 1 are arranged at the end part except core slots through a shock absorbing member 12 for a coil holding ring 5 connected to an end duct 4 while binds 9, 10 are wound to support and fasten them. Further, a stepped part is arranged at only the outer diametral side so as to have the same width as a conductor in the slot and obtain the size of 80 % of a height having a range in which only the bind is arranged while solid bars 16, reduced in the size of the radial height thereof and provided with different sections, are brazed or welded to connect and integrate them at the center of the end of the slot of a rotor core 3 and the end of the bind 9 or the bind 10. According to this method, the concentration of bending stresses at a specified position on the coil end part may be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of a rotor coil for a five-rotation machine, and particularly to stress concentration in the insulation of the coil end of high voltage and large current used in AC excitation. The present invention relates to a structure of a coil end portion suitable for avoiding this and improving insulation reliability.

[Conventional technology]

In the conventional coil configuration of a wound rotor, the coil end portions inside the core slots and outside the slots are a combination of wire conductors with the same dimensions.

Utility Model Application No. 57-139250 and Utility Model Application No. 60-17764
As described in Publication No. 9, a bind wire for supporting and constraining the coil end is bent inward to minimize the slot depth so that the coil end outside the slot has a step. I made sure to have enough space to wind it.

However, due to the binding of the coil end, bending stress is generated in the coil near the slot exit.
At that time, no consideration was given to alleviating the stress concentration applied to the stepped portion of the coil end portion.

[Problem that the invention seeks to solve]

In the above conventional technology, when the cross section of the rotor coil becomes larger due to the increase in capacity and voltage of equipment, and high voltage insulation becomes necessary, the coil is damaged at the slot and end portions due to centrifugal force during operation. As the coil ends are supported and restrained by binding, the level of bending stress due to thermal expansion and contraction of the coil that occurs during starting and stopping becomes even higher, and the level difference at the coil ends increases. It has the disadvantage that it concentrates on the bent part, which significantly shortens the life of the insulation. Therefore, in order to compensate for this drawback, if we stop bending the coil end, the radial dimension occupied by the bind wire wound to support and constrain the coil end will be added to the depth of the slot, resulting in leakage reactance and excitation. This has the disadvantage that the capacity increases and the entire rotor becomes excessively large.

An object of the present invention is to prevent the slot depth dimension from increasing due to the radial dimension of the binding wire for supporting and restraining the coil end part subjected to high centrifugal force, and to provide a coil in which bending stress due to thermal expansion and contraction of the coil is not concentrated. The object of the present invention is to provide a high voltage, large current rotor coil having an end structure.

[Means for solving problems]

The above purpose is to install a solid bar with an irregular cross section in which the coil end is stepped only on the outer diameter side and the height in the radial direction is reduced, between the first rotor core slot end and the bind end that supports and restrains the coil end This is achieved by joining and integrating a plurality of wire conductors in the slot by brazing or welding.

[Effect]

When looking at the internal cross-section of the slot of the rotor coil, the space factor of the conductor through which the current flows is, for example, 80%, if the insulation of the strand conductor and the space required for Lebel dislocation are added. Therefore,
Even if the magnetic potential difference is not a problem, even if the solid bar has a cross-sectional area of 80%, the skin effect will be small for currents of 0 to 10 Hz at most, so it will change the performance, and the width of the solid bar will change. If the dimension is made to match the width dimension of the conductor in the slot, the radial height dimension becomes 80%, and 20% of the difference in space can be used for winding the bind wire. By setting this reducible radial dimension on the outer diameter side of the coil, that is, on the binding side, it becomes possible to create a uniform coil with a constant inner radius of the coil conductor both inside and outside the slot, which reduces thermal expansion and contraction and centrifugal force. The stress level at the coil end changes continuously due to the difference in displacement between the inside and outside of the slot, making it possible to avoid stress concentration.

Moreover, since a neutral point where the stress direction is reversed appears at the center between the slot end and the bind end, the stress at the junction between the solid bar and the plurality of wire conductors in the slot can be minimized.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The rotor coils 1 and 2 are installed in the slots of the rotor core 3 through the intermediate layer 8, and are connected to the wedge 6 through the filler 7.
It is supported and fixed. Regarding the end portion outside the core slot, the lower rotor coil 2 is arranged with a buffer material 12 interposed between the coil retaining ring 5 connected to the end duct 4, and a bind 9 is wound around the rotor coil 2 to support and restrain it. Furthermore, the upper rotor coil 1 is also supported and restrained by winding the bind 10 around it.

In addition, for binds 9 and 10, absolute fiJ151
1 is provided to also have the role of absorbing unevenness of adjacent coils and protect the coil insulating layer IC.

For example, the three-phase field coil of the wound rotor of a 300MVA, 400RPM class large capacity variable speed generator is exposed to a high centrifugal force of approximately 1000G at unconstrained speed, so the stator of a conventional generator of similar size At the end of the rotor coil, which has high voltage insulation and has a cross-sectional dimension similar to that of the coil, it is necessary to support and restrain the end portion of the rotor coil with multilayer winding binding.

Furthermore, the design requires that the bind be wound around the lower and upper rotor coil end portions, respectively.

For this rotor coil 1, the combined cross-sectional area of the WM insulated wire conductors 1a in the slots is 100% height 8
If it is 0 nm, the space factor of the part where the current passes is, for example,
It is 80%. Therefore, we added a step only on the outer diameter side of the coil end so that the width of the conductor in the slot is the same, and the height of only the bound area is 80%, which is 64 mm. A solid par 1b with a reduced dimension and irregular cross section is placed at the center of the slot end of the rotor core 3 and the end of the bind 9 or 10.

Join and integrate by brazing or welding. Further, the rotor coil 2 has the same dimensions as the rotor coil 1.

According to this embodiment, there is a space on the outer diameter side of the coil for winding a bind of 16I, which is 20% of the conductor height of the coil in the slot, at the coil end. Even when the dimensions of the coil are minimized, that is, the depth of the slot is minimized, it is possible to obtain a coil shape that does not cause stress concentration at a specific position of the coil end. Further, as a derivative, it is no longer necessary to perform a step-down bending process on the coil end portion, so that the finished dimensional accuracy of the coil end portion can be easily improved.

The same effect can be obtained by adopting the present invention even in machines with small centrifugal force where it is only necessary to wrap a bind around the upper rotor coil 1, or in cases where a retaining ring is used to support the coil end. It will be done.

〔Effect of the invention〕

According to the present invention, the space for winding the supporting and restraining bind of the rotor coil end can be manufactured so that the inner diameter side of the bottom surface of the coil end is on the same cylindrical surface as the slot, without affecting the slot depth. It is possible to prevent bending stress caused by thermal expansion and contraction of the coil and displacement difference due to centrifugal force between the inside of the slot and the end portion from concentrating on a specific position of the coil end portion.

[Brief explanation of the drawing]

The figure is a cross-sectional view showing the assembly of a rotor coil of a wound rotor according to an embodiment of the present invention. 1... Rotor coil, 2... Rotor coil, 3...
・Rotor core, 4...end duct.

Claims (1)

[Claims] 1. In a rotor coil formed by Lebel transposition of a plurality of strands in the slots of a wound rotor, steps are provided only on the outer diameter side outside the slots to reduce the height of the radial conductors. A rotor coil characterized by integrally bonding solid bars with irregular cross sections. 2. In claim 1, the solid bar with irregular cross section constituting the coil end portion is defined as:
A rotor coil characterized in that a plurality of wire conductors subjected to Lebel transposition are joined and integrated at the center of an end of a bind that supports and restrains an iron core slot end and the coil end.