JPS6319709A - High voltage insulating conductor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a coil for a high voltage rotating electric machine, a dry type static induction 41! Concerning the insulation structure of high-voltage insulated conductors such as coils of electric appliances.

[Prior art and its problems]

For high voltage insulated conductors exceeding 1/C3KV,
If there are voids such as peeling or residual air bubbles in the insulating layer surrounding the conductor, the electric field will concentrate in the voids with a small electric contact rate based on the principle of constant capacitance partial pressure, and partial discharge will occur in the voids. Therefore, it is desired that the insulating layer does not contain voids and is difficult to form voids due to thermal deterioration.

FIG. 6 is a cross-sectional view showing an example of a conventional technique, and shows an example of a cross-sectional structure of a stator coil of a high-voltage rotating electric machine. In the figure, 1 is a shaped conductor), and the corner has a radius r
A plurality of insulating coated strands 1A with chamfered edges,
The shaped conductor 1 is formed so as to be fixed and integrated with each other, and the outside of the shaped conductor 1 is surrounded by a main insulation layer 2 having a thickness of d. After winding multiple layers of sheets or tapes with peelable mica, laminated mica, etc. pasted onto a base material consisting of two main insulating layers, woven fabric, non-woven fabric, or heat-resistant film, around the coil conductor 1, polyester resin, epoxy A thermosetting resin such as resin is impregnated with vacuum pressure and cured with heat and pressure (vacuum pressure impregnation method) A, or the above-mentioned sheet material or tape is pre-impregnated with resin and semi-cured, and then wound around a coil conductor. Pressure forming at constant temperature (prepreg method)
Techniques have already been established for obtaining high-voltage insulated conductors that meet the desired performance requirements described above. Also, 3
is a ground conductive layer deposited on the outer peripheral surface of the main insulating layer 2.

FIG. 4 is an explanatory diagram showing a state in which the high voltage insulated conductor shown in FIG. 6 is housed in a slot of a rotating electric machine. By holding the conductive layer 3 at the ground potential via the iron core 5, it is possible to prevent partial discharge that would occur if there is a gap between the main insulating layer 2 and the iron core 5, and also to prevent the edge of the ground conductive layer 6 from occurring. A semiconductive electric field relaxation layer 4 is deposited on the edge of the ground conductive layer 63 to disperse electric field concentration at the end of the ground conductive layer 63 in the creeping direction of the bottom surface of the main insulating layer 2. The structure is also designed to prevent partial discharges from occurring.

As mentioned above, as a result of successive elimination of insulation defects, the thickness d of the main insulation Ni2 of the high voltage insulated conductor is gradually reduced,
Therefore, the average electric field Eo obtained by dividing the applied voltage V by the insulation thickness d
=V/d is increasing. However, when trying to increase the average electric field EO, the chamfer radius r
The local electric field concentration Em at the corners of the shaped conductor 1 has become a new problem, and countermeasures are required.

The electric field strength Em at the corner □ with the chamfer radius r is expressed by the following equation.

Figure 5 is a characteristic diagram showing the degree of concentration of the electric field at the corner of the conductor, where the vertical axis is the ratio T2m/Eo of the electric field Km at the corner and the average electric field Eo, and the horizontal axis is the chamfer radius r and the main insulation. Each is standardized by the ratio r/d to the thickness d. In the figure, r
= 0.6 rrtn, d = 5 cabinets,
An electric field Em equivalent to approximately 6.5 times the average electric field Eo is generated at the corner of the conductor 1 with radius r, and this portion becomes an insulation defect and the main insulation dimension dt - is reduced. This becomes a cause of hindering the increase in the space factor of the conductor. In addition, in order to keep the degree of concentration of the electric field constant, it is necessary to increase the chamfer radius r in proportion to the insulation thickness d. There is a drawback that it leads to a decrease in the space factor.

Furthermore, a method is known in which a semiconductive sheet or tape is wrapped around the outside of the coil conductor 1 to increase the chamfer radius r isometrically, but this leads to a significant decrease in the conductor space factor and There is a serious problem in which the main insulating layer is contaminated by conductive substances.

Furthermore, a method is known in which electric field concentration at the corners of the conductor is alleviated by providing a plurality of conductive layers in the main insulating layer and adjusting the capacitance between each conductive layer. This method not only causes new problems with the adhesion of the insulating layer, but also has the drawback of significantly increasing processing costs.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned situation, and it is possible to alleviate local electric field concentration at the corners of the conductor without reducing the conductor space factor or increasing the number of steps required for insulation processing.
The purpose of the present invention is to provide a high voltage insulated conductor that can be used in high electric fields.

[Key points of the invention]

The present invention provides an insulating coating layer of a wire made of an insulated rectangular conductor made of a high dielectric constant material, and a main insulating layer covering a shaped conductor made of an aggregate of a plurality of wires having a lower dielectric potential than the insulating coating layer. By configuring it to be made of an insulating material with a low ratio,
Based on the principle of capacitance partial pressure, the average electric field in the insulating layer caused by the voltage applied to a high-voltage insulated conductor is lower on the side of the main insulating layer, which has a lower relative permittivity. It is possible to reduce the local electric field concentration at the corners of the shaped conductor by reducing the average electric field in the insulating coating layer, and the insulation of the strands is reduced. By increasing the dielectric constant of the coating layer, the effect of reducing local electric field concentration at the corners of the rectangular conductor can be maximized without changing the shape of the conductor or the composition of the main insulation layer, and the insulation coating can be The durability of the electric field relaxation effect is increased by taking advantage of the fact that the layer does not peel off from the corners of the rectangular conductor.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 is a sectional view of a main part showing an embodiment of the present invention, and shows an example of application to a stator coil of a high-voltage rotating electric machine. In the figure, strands IA and IB constituting the shaped conductor 1
, 1C, ID, etc., each rectangular conductor 11 has a corner 11A rounded with a chamfer radius r, and the outer periphery of the rectangular conductor 11 is covered with an insulating coating layer 12 made of a high dielectric constant insulating tape. The outer periphery of the shaped conductor 1 is covered with a main insulating layer 2 and a ground conductive layer 6 (not shown) as in the prior art.

In the high voltage conductor configured as described above, the applied voltage is .
l, ratio 1! When the ratio is 'ts, the thickness of the main insulating layer 2 is d, and the dielectric constant is gl, the electric field strength Em□ at the surface of the corner 11A of the rectangular conductor 11 is expressed by the following equation. Also, the electric field strength Em in the conventional technology expressed by equation (1)
The ratio of the electric field strength Km expressed by equation (2) is (3)
It is expressed by the formula, gl〉ε,.

rl)r, that is, the dielectric constant ε of the main insulating layer, and by covering the conductor corner 11A with an insulating coating layer 12 having a larger dielectric constant ε1, Em17Km is 1: the electric field at the corner of the rectangular conductor 11 is smaller than 1. The intensity Eml is compared to Em in the conventional technology.
can be reduced compared to

High position 1 in the embodiment based on the above-mentioned principle! The specific structure of the insulation sheath layer will be explained. First, as a high dielectric constant adhesive resin, we used bisphenol type epoxy resin (manufactured by Chipa Co., Ltd.,
Cy 205) In the 100 m landscape area, boronic monomethylamine trifluoride (manufactured by Cenil Cerny Co., Ltd.,
BF#-400) A resin containing 5 parts of Mi was used as a paste resin, and 50 parts by weight of acetone was added to this to form a solution, and 15 parts of fine barium titanate powder with a particle size of 0106 μm was added to this solution. :11 parts were added and stirred and used. Next, a 0.1-thick glass cloth and a laminated mica sheet were laminated together using the high dielectric constant adhesive resin 809/-, and dried at room temperature for 60 minutes and at 120° C. for 20 minutes.

High tensile strength 1 with a thickness of 0.15m after semi-hardening treatment! I created a rate collection Mykacy If. The sheet was then cut into tapes with a width of 12I, with a corner radius of curvature r = 0.6ttn.

A rectangular copper wire with a cross-sectional dimension of 2×10+s was wound twice in a half overlap to produce a wire having an insulating coating layer of approximately 0.6 m in thickness. The dielectric constant ε1 of the insulating coating layer 12 of the obtained wires 1A, jB, etc. was about 8. A shaped conductor 1 is made by stacking the strands produced in this way in 10 layers, and this shaped conductor 1 is
A main insulation (fit 2) having a thickness of d=6 was formed by winding a composite mica tape (f) made of glass cloth base material around the outer periphery of the insulator, impregnating it with epoxy resin under vacuum pressure, and curing it by heating. The dielectric constant ε1 of the main insulating layer was approximately 4 as a result of measurement using another laminate sample. Therefore, according to equation (3), p Em
When l/Em is calculated, it is approximately 0.6.

Figure 2 is an AC breakdown voltage characteristic diagram of the insulated conductor of the example. In the figure, the conventional method is manufactured using the high dielectric constant adhesive resin of the example conductor described above with barium titanate fine powder removed. It is an insulated conductor. As is clear from the figure, the breakdown voltage of the insulated conductor of the example is 1.2 times that of the prior art, and the corner 11A of the rectangular conductor 11 is
(due to the effect of mitigating local electric field concentration by about 40% by covering with a high dielectric constant insulating coating layer having a thickness of about /10)
It has become clear that the current dielectric breakdown voltage can be improved by as much as 20%. Further, according to the present invention, local electric field concentration can be alleviated by an extremely simple method of adding ferroelectric fine powder such as barium titanate fine powder to the adhesive resin of the insulating coating layer of the wire, and therefore the conductor This has the advantage that the space factor does not decrease. By making the insulating coating layer of the strands high in permittivity in advance, it is possible to use the techniques cultivated in the prior art for forming the shaped conductor and the main insulating layer when producing the high voltage insulated conductor. A highly reliable insulated conductor can be obtained without increasing the number of insulation processing steps. Furthermore,
Since the capacitance between the strands of the shaped conductor increases, it is possible to absorb abnormal voltages such as surge voltages applied between turns of a high-voltage coil, and the insulation coating layer decreases due to thermal deterioration of the main insulation layer. Even if peeling occurs between the conductor and the main insulating layer, the high dielectric constant insulating coating layer tightly covers the electric field concentration area at the corner of the conductor and has the advantage of stably maintaining the electric field relaxation effect.

In addition, high invitation 1! In addition to barium titanate powder, magnesium titanate powder or zinc titanate powder may be used as the ferroelectric fine powder to be mixed in the adhesive resin. An adhesive resin with a high dielectric constant can be obtained even by adding . Also,
The present invention is not limited to shaping coils for high-voltage rotating electric appliances, but can also be applied to coil conductors of stationary dielectric appliances, etc. to obtain an electric field relaxing effect.

〔Effect of the invention〕

As described above, the present invention is configured such that the insulation coating layer of the wire constituting the shaped conductor covered with the main insulation layer is formed of a tape insulation layer having a dielectric constant higher than that of the main insulation layer. . As a result, it is possible to significantly alleviate the local electric field concentration at the corners of the rectangular conductor of strands), providing a high-voltage insulated conductor with excellent withstand voltage performance, and therefore capable of increasing electric fields and voltages. can do. In addition, Denka Takabo's insulating coating layer can be easily formed by using an adhesive resin containing fine ferroelectric powder. This method does not involve a decrease in the conductor space factor, which is required by conventional techniques such as covering the conductor with a thin film, and does not affect the formation of the main insulating layer. It can be formed at low cost and can contribute to increasing the voltage and capacity of high-voltage circuits and stationary induction appliances. In addition, by increasing the dielectric constant of the insulation coating layer of the strands, it is possible to absorb abnormal voltages such as surge voltages applied between the strands, and even if the main insulation layer deteriorates due to heat, the corners of the rectangular conductor are closely surrounded. However, since the effect of alleviating local electric field concentration can be stably maintained, a high voltage insulated conductor with high insulation reliability can be provided.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view of the main part showing an embodiment of the present invention, Fig.
The figure is a characteristic diagram showing the dielectric breakdown voltage improvement effect in the example, Figure 6 is a cross-sectional view of the main part showing the conventional technology, Figure 4 is a cross-sectional view of the main part showing the state of application to rotating electric machines, and Figure 5 is an α-field concentration characteristic diagram at a corner of a conductor. 1... Vertical conductor, 1A, 1B, 1C... Element wire,
2... Main insulating layer, 6... Ground conductive layer, 11... Rectangular conductor, 12... High dielectric constant insulating coating layer, 11A...
- Rectangular conductor corner, r... chamfer radius, d... main insulating layer. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1) A shaped conductor having a substantially rectangular cross section by fixing a plurality of wires made of insulated rectangular conductors to each other, and a shaped conductor formed to tightly surround this shaped conductor. 1. A high-voltage insulated conductor comprising a main insulating layer, the shaped conductor comprising a plurality of wires having an insulating coating layer having a higher dielectric constant than the main insulating layer. 2) A high voltage insulated conductor according to claim 1, wherein the insulating coating layer contains an adhesive resin blended with fine ferroelectric powder.