JPS62152345A - Corona shield layer of rotary electric machine - Google Patents

Abstract

PURPOSE:To prevent impregnated resin from flowing out when it is heated for setting, by providing a liquid-impermeable film layer within a SiC tape- winding range. CONSTITUTION:A 1/2 SiC tapes of cloth reinforced with thermosetting resin in which SiC particles are mixed, are lap-wound in the partially overlapping form on a low-resistance corona shield layer 3 provided on the linear portion surface of the stator coil 7 extended internally and some what externally of the iron core to provide a layer 4, on which 1/2 polyester film tapes are further lap-wound within the SiC tape-winding range to provide a layer 6. After that, these layers are impregnated with resin as they are integral with the insulating layer 2, and then heated and set to form a corona shield layer. In this manner, it will be possible to increase a creeping corona discharge starting voltage in the corona shield portion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a corona shield layer applied to a coil of a high voltage rotating electric machine.

[Technical background of the invention and its problems]

In recent years, in single-rotation electric machines, there has been a trend toward higher voltage stator windings in order to increase the capacity of a single machine. Accordingly, it is necessary to improve electric field relaxation means for suppressing creeping corona discharge at the ends of stator windings.

As shown in Fig. 2, a conventional general corona shield layer (2) is a low-resistance corona shield layer (2) provided on the surface of an insulating layer (2) of a stator coil (ω) that extends slightly from the inside of the core (not shown) to the outside. 3) and are provided in a partially overlapping manner. The conventional corona shield layer ■ is made by wrapping mica tape as an insulating layer ■ on the coil conductor, and then wrapping it around a reinforcing cloth.
It is made by coating a thermosetting resin mixed with C (silicon carbide) particles.1SIC tape is wrapped around both ends of the straight part of the coil, and the entire coil is impregnated with the impregnating resin and thermally cured to create insulation. Integrate with layer ■.

A reaction accelerator (catalyst) is usually incorporated into the mica tape so that the impregnating resin has a long shelf life and a short curing time after being impregnated. When the impregnated resin permeates into the mica tape, it integrates with the catalyst and accelerates the curing reaction.

On the other hand, when an impregnating resin is placed alone at a high temperature, its viscosity decreases before it begins to harden.

Therefore, when curing the resin impregnated into the insulating layer (2), the resin tends to easily flow out from the insulating layer (2).

However, since the above-mentioned catalyst is mixed in the mica tape, one reaction is promoted, and the resin viscosity rapidly increases, so that the system prevents the resin from flowing out.

However, since the corona shield layer does not contain a catalyst in the SiC tape, there are no gaps or creases between the tape overlaps caused by overlapping the SiC tape.
There was a possibility that the impregnated resin would flow out from areas with low resin retention and remain as voids after curing. When the voltage applied to these voids increases, discharge occurs, which not only shortens the life of the insulation, but also triggers a creeping discharge on the surface of the corona shield layer (a), reducing the corona shielding effect. lower. The effect of such voids is more serious the closer the coil conductor is to the overlapping portion with the low-resistance corona shield layer (2), where the potential difference between the coil conductor and the corona shield layer (A) becomes particularly large.

[Purpose of the invention]

The present invention has been made in view of such circumstances.

The purpose is to provide a corona shield layer that is less likely to cause discharge in the corona shield area even when high voltage is applied, such as during withstanding voltage tests, and is effective even for stator windings with high rated voltages. be.

[Summary of the invention]

In the present invention, a low-resistance corona shield layer is provided on the surface of the coil straight part insulating layer that extends slightly inside and outside the iron core, and as a corona shield layer connected to this low-resistance corona shield layer, a conventional SiC A liquid-impermeable film layer is provided in the area where the SiC tape is wound to prevent the impregnated resin from flowing out during curing and heating.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIG.

The corona shield layer is made of SiC tape, which is made by coating reinforcing cloth with thermosetting resin mixed with SiC particles.

A low-resistance corona shield layer ■ is provided on the straight part surface of the stator coil ■ that extends inside the core and slightly outside. , Layer (2) is provided in the SiC tape winding range by wrapping polyester film tape (for example, Lumirror Tape Nitoshi trade name) in 1/2 overlap.

Thereafter, it is impregnated with an impregnating resin while being integrated with the insulating layer (1), and is heated and cured to form a corona shield layer.

Next, the effect will be explained.

The reason for the formation of voids between the corona shield layer) and the insulating layer is that the impregnated resin is removed during curing due to the gaps and creases between the tape overlaps caused by overlapping the SiC tape as shown in Figure 2. It was supposed to leak out.

In this example, as shown in FIG. 1, the surface of the SIC tape layer (A) is covered with a liquid-impermeable polyester film layer (2), so that the impregnated resin can be prevented from flowing out during curing. Since the polyester film shrinks slightly at the temperature during curing, the effect of preventing the impregnated resin from flowing out is even higher.

In order to verify the effects of the present invention, the creeping visible corona discharge inception voltage was measured using a coil with an insulation thickness of 4.5+ nm.
Approximately 30% improvement was seen compared to the conventional corona shield layer.

〔Effect of the invention〕

As explained above, according to the present invention, the creeping corona discharge starting voltage of the corona shield portion can be increased by using almost the same work procedure as the conventional method, so that a corona shield layer that can be applied to windings with a high rated voltage is provided. be able to.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the corona shield layer of the present invention, and FIG. 2 is a sectional view showing a conventional corona shield layer. 1... Coil conductor 2... Insulating layer 3... Low resistance corona shield layer 4... SiC tape overlapping layer 5... Space 6...
・Film tape overlapping layer 1o...Coil agent Patent attorney Nori Chika Yudo Hirofumi Mitsumata

Claims (1)

[Claims] In a corona shield layer of a rotating electric machine, which is provided continuously to a low-resistance corona shield layer provided on the surface of an insulating layer of a coil straight section extending from the inside of the iron core to the outside, silicon carbide particles are added to the reinforcing cloth. A corona shield for a rotating electric machine, characterized in that a SiC tape coated with a thermosetting resin mixed with is layered, and a liquid-impermeable film layer is provided in the wound area of the SiC tape. layer.