JP3133090B2 - Insulation method for salient field winding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a salient pole field winding mainly used for a rotor of a synchronous generator, and more particularly to a method of insulating an insulating coating layer around the field winding.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a conventional salient pole field winding (hatching is omitted). A dovetail portion 1B of a magnetic pole core 1 is connected to, for example, a rotor of a water turbine generator. Therefore, a large centrifugal force acts on the field winding 2 wound around the magnetic pole core 1. Therefore, the field winding 2 uses a bare conductor band as its coil conductor 2A, and winds this plural times in the form of a track in the edgewise direction (wide direction) to form a mica sheet as the inter-turn insulation 4. , Glass cloth, aramid paper, or the like, is adhered to the bare conductive band with an adhesive to insulate the turns from one another, and the obtained field winding 2 is placed in the H-shaped recess of the magnetic pole core 1 with a core insulation 5. And, it is mounted with the end insulation 3 interposed, and is fixed to the concave portion of the pole iron core 1 in a state where a tightening load is applied between the coil conductors of the field winding 2. An insulating material having high mechanical strength such as an epoxy glass laminate, a polyester glass laminate, or a laminate of mica sheet is used for the core insulation 5 and the end insulation 3 for electrically insulating the field winding 2 and the pole core 1. Therefore, a strong salient pole winding capable of withstanding severe centrifugal force, mechanical vibration, and thermal stress due to heat cycle can be obtained.

[0003]

On the other hand, the outer peripheral side of the field winding 2 protrudes from the outer peripheral surface of the magnetic pole core 1, the end insulation 3, and the inter-turn insulation 4 by about several tens of mm to form cooling fins. Forming
The field winding is configured to be forcibly cooled when the rotor rotates. Therefore, a better cooling effect can be obtained if the bare conducting band is exposed in the field winding, but dust in the rotating air adheres to the surface of the field winding or the operation is stopped. When the temperature of the field winding decreases, dew condensation may occur on the surface of the field winding, and the end surfaces of the end insulation 3 and the turn-to-turn insulation 4 are covered with wet dust. In particular, the leakage current to the pole core 1 increases, and eventually a situation occurs which may lead to a ground fault in the field winding or a short circuit between turns.

In order to avoid such a situation, a varnish containing a synthetic resin as a main component is applied to the surface of the field winding 2 over the outer peripheral surface of the magnetic pole core, dried by heating and dried. No. 7 is formed to prevent an increase in leakage current due to surface contamination of the field winding. However, since the conventional varnish contains an organic solvent, pinholes are liable to be generated in the film due to the scattering of the solvent in the drying step,
Not only is it difficult to obtain sufficient moisture resistance, but to reduce pinholes, it is necessary to increase the drying time to suppress rapid evaporation of the solvent, or to increase the number of times of recoating to increase the film thickness. There is a problem that a large number of processing steps and processing time are required for forming the insulating coating layer 7.

Further, for example, it is expected that the use of an epoxy-based solventless resin varnish can form an insulating coating layer 7 having less pinholes and excellent moisture resistance. Bis (epichlorohydrin.
(Bisphenol A type) epoxy resin has a high viscosity and cannot be used as a coating material as it is, so it is necessary to reduce the viscosity by adding epoxide or various organic solvents which are reactive diluents. There is a drawback that the cross-link density of the product is lowered to lower the properties of the epoxy resin cured product, especially the moisture resistance, and the addition of an organic solvent causes the same disadvantages as in the synthetic resin varnish described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for insulating a salient-pole field winding in which an insulating coating layer having excellent moisture resistance can be easily formed by a labor-saving processing method.

[0007]

According to the present invention, there is provided a field winding comprising a plurality of windings of a bare conductor band edgewise, and an inter-turn insulation interposed between the windings. A salient pole field winding in which a winding is insulated and supported in a recess of a magnetic pole core having a cross-sectional shape close to an H shape, and an outer peripheral portion of the field winding including an outer peripheral surface of the magnetic pole core is covered with an insulating coating film. In, after heating the salient pole field winding and the magnetic pole core supporting the same to a predetermined temperature at which the gelation of the solventless resin varnish to be applied is promoted, vinylcyclohexenedioxite or the like is used as the solventless resin varnish. Solvent-free resin resin mainly composed of epoxy resin having a viscosity of about 360 to 1500 cpc, such as cycloaliphatic epoxy resin, bisphenol F type epoxy resin, or glycidyl ether resin such as trimethylolpropane triglycidyl ether. A varnish is applied, and then the applied film is heat-cured to form an insulating coating film.

Further, after the salient pole winding and the magnetic pole core supporting the salient pole winding are heated to a predetermined temperature, a curing accelerator is first applied, and then a cycloaliphatic epoxy resin such as vinylcyclohexenedioxite; Viscosity of bisphenol F type epoxy resin or glycidyl ether resin such as trimethylolpropane triglycidyl ether is 36.
A solventless resin varnish mainly composed of an epoxy resin of about 0 to 1500 cps is applied, and then the applied film is heat-cured to form an insulating coating layer.

Further, the viscosity of a cyclic aliphatic epoxy resin such as vinylcyclohexenedionoxide, a bisphenol F epoxy resin, or a glycidyl ether resin such as trimethylolpropane triglycidyl ether is about 360 to 1500 cps. And a step of previously performing a surface roughening treatment on the application surface of a solventless resin varnish mainly composed of an epoxy resin.

[0010]

The structure of the present invention is that, among epoxy resins, cycloaliphatic epoxy resins such as vinylcyclohexenedionoxide, bisphenol F epoxy resins, and glycidyl ethers such as trimethylolpropane triglycidyl ether. Telluric resin has a viscosity of about 360 to 1500 cps without adding a solvent. It was obtained by paying attention to the fact that it is considerably lower than that of the screw type and can be used as a solventless resin varnish. That is, after heating the salient pole field winding to a predetermined temperature, the epoxy resin-based solventless resin varnish is applied, and then the applied film is heated and cured to form an insulating coating layer. The solvent-free resin varnish can be easily applied to the applied coating surface, and the gelation of the solvent-free resin varnish is promoted, so that a relatively thick coating film can be formed by a single coating operation without dripping of the varnish. Further, in the heat curing step, since there is no solvent, defects such as pinholes are hardly generated, and an insulating coating layer having excellent moisture resistance can be obtained. In addition, if the coating surface is configured to be roughened in advance, an insulating coating layer having excellent durability by being firmly fixed to the field winding can be obtained.

Further, if the solvent-free resin varnish is applied after applying the curing accelerator to the heated field winding, the gelation of the resin starts from the inside of the applied solvent-free resin varnish. Since the flow of the varnish is restrained, a thick and uniform insulating coating layer can be formed, and the coating surface is roughened in advance, so that it can be firmly attached to the field winding. An insulating coating layer having high durability can be obtained by being fixed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a sectional view of a salient pole field winding according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a portion A in FIG. And a duplicate description will be omitted. In the figure, the solvent-free resin varnish used is any of a cycloaliphatic epoxy resin such as vinylcyclohexenedionoxide, a bisphenol F epoxy resin, and a glycidyl ether resin such as trimethylolpropane triglycidyl ether. Or
To this, an inorganic powder such as quartz powder, alumina, or pigment is added as a filler at a ratio of 30 to 50 with respect to a resin weight of 100, and an amine-based or acid-anhydride-based curing agent is added to a necessary amount determined by an epoxy equivalent. About 90% of the solution was used.

The field winding 2 and the magnetic pole core 1 supporting the field winding 2 are heated to about 60 to 70 ° C. in advance.
The solventless resin varnish is applied from the surface of the zigzag field winding 2 to the outer peripheral surface of the magnetic pole core 1. At this time, the solvent-free resin varnish temporarily decreases in viscosity in the process of being applied to the heated salient-pole field winding, thereby facilitating the application operation and gelling in about several minutes. The varnish is prevented from falling off, and the insulating coating layer 17 having a thickness of about 0.15 to 0.2 mm is formed by a single coating operation by performing the heat curing treatment immediately, as shown in FIG. It is formed while maintaining a uniform thickness along the surface. In the conventional insulating treatment method using a synthetic resin-based varnish, two coats are required when an insulating coating layer 7 having a thickness of about 0.15 mm is to be formed. According to this method, an insulating coating layer having a thickness greater than this can be formed with a single application, and the heat-curing process can be shortened.
The man-hour for the insulation treatment can be greatly reduced, and the insulation treatment time can be reduced to about one third of the conventional case.

Furthermore, if the surface of the bare conductive band of the field winding 2 forming the insulating coating layer 17 and the outer peripheral surface of the pole core 2 are roughened in advance using an acid or an abrasive,
The insulating coating layer 17 is firmly fixed to the salient-pole field windings to increase the mechanical stability against centrifugal force and vibration, and also occurs due to the temperature change of the salient-pole field windings and the difference in thermal expansion of each part. Since the stability against thermal stress is also increased, a highly reliable insulating coating layer can be formed.

Further, on the surface of the heated salient pole field winding,
First, apply a curing accelerator, and then configure the insulation treatment method to apply an epoxy-based solventless resin varnish on it,
As the gel time of solventless resin varnish can be further reduced,
An insulating coating layer having a thickness of 20 to 30% thicker can be formed in one coating operation, and a salient pole field winding having an insulating coating layer with more excellent moisture resistance can be obtained. Furthermore, if it is configured to apply a hardening accelerator to the surface of the salient pole field winding subjected to the surface roughening treatment,
Since the adhesiveness to the salient pole field winding is further improved, a salient pole field winding having a more durable insulating coating layer can be obtained.

Table 1 shows the moisture resistance of the insulating coating layer using the epoxy-based solventless resin varnish according to the embodiment of the present invention in comparison with that of the insulating coating layer using the conventional synthetic resin varnish. It is a characteristic table. It shows insulation resistance in a dry atmosphere (temperature of 20 ° C., humidity of 40%) and a wet atmosphere (temperature of 40 ° C.).
C, humidity 90%). In the table, in the conventional example using a synthetic resin varnish, the resistance value in a wet atmosphere is lower by four orders of magnitude than that in a dry atmosphere, and many defects such as pinholes are present in the insulating coating layer 7. It shows that the moisture resistance performance is low. On the other hand, in the embodiment using the epoxy-based solventless resin varnish, the decrease in insulation resistance in a humid atmosphere is less than one digit, and the resistance value is higher than the insulation resistance value in a conventional dry atmosphere. This indicates that the insulating coating layer used in the insulating treatment method according to the example has few defects such as pinholes and has excellent moisture resistance.

[0017]

[Table 1]

[0018]

As described above, the present invention provides a cycloaliphatic epoxy resin such as vinylcyclohexenedionoxide, a bisphenol F epoxy resin, or a glycidyl ether resin such as trimethylolpropane triglycidyl ether. Using a solventless resin varnish mainly composed of an epoxy resin having a viscosity of about 360 to 1500 cps, heating the salient pole field winding to a predetermined temperature and then applying the epoxy resin solventless varnish. Thereafter, the coating film was heated and cured to form an insulating coating layer. As a result, even if the viscosity of the solvent-free resin varnish is somewhat high, it can be easily applied because the temperature of the application surface is high, and the gelation of the solvent-free resin varnish is promoted, so that the varnish is relatively thick without dripping. The film layer can be formed by a single coating operation, and there is an advantage that the insulating processing operation can be greatly reduced in labor and time as compared with the conventional insulating processing method using a synthetic resin varnish. Further, in the heat curing step, since there is no solvent, defects such as pinholes do not easily occur, and an insulating coating layer having extremely excellent moisture resistance, in which insulation resistance hardly decreases even in a humid atmosphere, can be formed. Therefore, troubles such as ground fault accidents of the field winding caused by low moisture resistance performance by the conventional insulation treatment method are eliminated, and salient pole field winding having an insulating coating layer excellent in long-term insulation reliability. Can be provided economically and advantageously.

Further, if a configuration is adopted in which a solvent-free resin varnish is applied after applying a hardening accelerator to the heated field winding, gelling of the resin starts from the inside of the applied solvent-free resin varnish. Since the flow of the varnish is restrained, an insulating coating layer that is thicker than before and has excellent moisture resistance can be saved,
The advantage that the insulating film can be formed by a time-saving insulating method can be obtained. Furthermore, by pre-roughening the coating surface, it is firmly fixed to the field winding, and has high durability against centrifugal force, vibration and thermal stress acting on the salient pole field winding. The advantage that a film layer can be formed is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a salient pole field winding according to an embodiment of the present invention;

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a sectional view showing a conventional salient pole field winding.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 magnetic pole core 2 field winding 2 A coil conductor (bare conductor band) 3 end insulation 4 turn insulation 5 core insulation 7 insulating coating layer 17 insulating coating layer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 15/00

Claims (3)

(57) [Claims] A field winding formed by winding a bare conductive band a plurality of times in an edgewise manner, with inter-turn insulation interposed between each winding, is provided within a recess of a magnetic pole iron core having a cross section close to an H shape. Insulated supported,
In the salient pole field winding in which the outer peripheral portion of the field winding including the outer peripheral surface of the pole core is covered with the insulating coating film, the salient pole field winding and the pole core supporting the same are coated with a solventless solvent. After heating to a predetermined temperature at which the gelation of the resin varnish is promoted, a cyclic aliphatic epoxy resin such as vinylcyclohexenedioxite, a bisphenol F epoxy resin, or a trimethylolpropane triglycidyl ether or the like is used as a solvent-free resin varnish. A salient pole characterized by applying an epoxy resin-based solvent-free resin varnish with a viscosity of about 360 to 1500 cpc, such as glycidyl ether resin, and then thermally curing the applied film to form an insulating coating film. Field winding insulation method. 2. A method for heating a salient pole winding and a magnetic pole core supporting the salient pole winding to a predetermined temperature, first applying a curing accelerator, and then applying a cycloaliphatic epoxy resin such as vinylcyclohexenedioxite; The viscosity of bisphenol F epoxy resin or glycidyl ether resin such as trimethylolpropane triglycidyl ether is 360 to 1
The salient pole field winding according to claim 1, wherein a solventless resin varnish mainly composed of an epoxy resin of about 500 cps is applied, and then the applied film is heat-cured to form an insulating coating layer. Wire insulation method. 3. A method for insulating a salient pole field winding according to claim 1, further comprising a step of preliminarily roughening the surface to be coated with the epoxy resin-based solventless resin varnish. .