JPH0586135B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention is a shaped coil in which an untreated insulating tape is wound around a wire bundle to form an insulating layer, and a surface corona prevention layer made of a semiconductive material and an end corona prevention layer made of a highly resistant material are applied thereon. are inserted into the stator core slots together with a sliding layer made of a semiconducting material and an interlayer made of an insulating material so as to form a two-layer winding, and held in the slots by a wedge made of an insulating material. The present invention relates to a rotating electric machine in which a stator winding is formed by interconnecting the coils, and then a thermosetting resin is impregnated and cured under vacuum pressure to form a ground insulating layer of the coil.
In this type of rotating electric machine, it is important that work management during formation of the ground insulation of the coil be easy and accurate, and that the ground insulation of the formed coil be highly reliable.

[Prior art and its problems]

In general, methods for impregnating an untreated stator coil with a resin for ground insulation in high-voltage rotating electric machines with a rated voltage of 3 kV or higher include a single coil impregnation method and a total impregnation method. In the former method, each coil is wound with untreated tape and inserted into a designated coil mold, impregnated with thermosetting epoxy resin under vacuum pressure, tightened with the mold, and then heated. After heating and curing in a curing furnace to form a ground insulating layer as a stator coil, it is removed from the mold and the surface of the insulating layer is finished. Furthermore, a surface corona prevention layer made of a semiconductive material is applied to the surface of the insulating layer. An end corona prevention layer made of a high-resistance material is applied to form an individual stator coil, which is inserted into a slot in a stator core, restrained with a suitable wedge, and connected to form a stator winding. Make it. On the other hand, in the latter full impregnation method, a coil wound with untreated tape is coated with the above-mentioned surface corona prevention layer and an external corona prevention layer, and a semiconductive material is applied to the slots of the stator core to prevent slipping and The coils are inserted together with an interlayer made of an insulating material and restrained by a wedge made of an insulating material, and the coils are connected to each other to form a stator winding. In the final step of binding the coil, a thermosetting epoxy resin is impregnated under vacuum pressure and cured by heating to form a ground insulation layer of the stator coil. As mentioned above, the former single-coil impregnation method involves forming a ground insulating layer on each individual coil and then inserting it into the slot of the stator core, which is a complicated process and increases the cost accordingly, whereas the latter method involves a total impregnation method. This method incorporates individual coils into the stator core to form the stator windings, and then forms the ground insulating layer at the final stage of the process, which has the advantage of simplifying the process and reducing the cost of the rotating electric machine accordingly. There is. On the other hand, when it comes to checking the insulation performance of the stator coil, in the case of a single coil impregnation method, it is natural to conduct an electrical non-destructive property test to check the dielectric loss tangent and the presence or absence of partial discharge before winding the coil around the stator core. If a defective coil is detected, only that coil needs to be repaired or a new one made, whereas in the case of the total impregnation method, the stator windings need to be insulated. The insulation performance of the coil must be confirmed at the final stage of completion, so even if a defective part of the insulation performance is discovered, the stator coil is fixed to the stator core, so the It is extremely difficult to remove the healthy parts of the insulation layer from the stator core without damaging them, and in the end the insulation of the stator windings will have to be completely re-insulated, which will require a great deal of effort and expense. There's a problem. In order to overcome the above problems, work and quality control in the manufacturing process of stator coils used in the full impregnation method play an important role. In this regard, in recent years, as a means of control in the resin impregnation process of the coil, it has generally been common practice to replace the amount of resin impregnated into the insulating layer of the coil with electrical capacitance and monitor the resin impregnation state. It is being said. However, in this case, the alternating current is
When the change in the capacitance measured at 1 kHz with respect to the resin impregnation time is displayed, it becomes as shown in the A curve (1500 kVA rotating electrical machine) and B curve (290 kVA) in FIG. In actual cases, the thickness of the ground insulation layer of the stator coil of a rotating electric machine, the stator core length,
Because the change characteristics of capacitance with respect to resin impregnation time differ for each rotating electrical machine depending on the number of coils composing the stator winding, etc., this type of measurement alone can determine the state of resin impregnation in the stator coils of all rotating electrical machines. It has to be said that it is difficult to uniformly manage this, and it is also known that it is almost impossible to detect extremely small resin impregnation defects with this type of measurement. Currently, it is necessary to judge based on experience whether the resin impregnation of the stator coil is complete. As a result, if you make a mistake in the above judgment, you will have to redo the entire insulation of the stator coil as described above, or in the worst case, it may lead to a serious accident of the rotating electric machine during actual operation, resulting in significant damage. do not have. On the other hand, regarding the curing of the insulating resin impregnated into the coil, the curing temperature and time are determined based on experimental results in the laboratory and actual experience in manufacturing rotating electric machines.
Temperature for rotating electric machine and 290kVA rotating electric machine
The relationship between the dielectric loss tangent and the applied voltage when heat curing is performed at 140°C for 6 hours is 9th.
As shown in the figure, there is a considerable difference between the A curve in the former case and the B curve in the latter case. In this case, in curve A for a 1500 kVA rotating electric machine, the value of the dielectric loss tangent becomes high at high applied voltages, and it is determined that the curing of the impregnated resin is insufficient. The reason for this is that the heat capacity of the stator core of a 1500kVA rotating electrical machine is large. However, if this rotating electrical machine were to be operated as is, the stator coil would move along the above curve as the temperature rises due to operation. The dielectric loss of the ground insulating layer also increases, which causes the temperature of the ground insulating layer to rise, and as the temperature of the ground insulating layer increases, the dielectric loss further increases, creating a vicious cycle that eventually leads to breakdown of the insulating layer. In this case, the 1500 kVA rotating electric machine has no choice but to repeat the heating and hardening process of the resin impregnated into the coil, as this will result in serious damage. Therefore, in order to prevent insufficient curing of the coil-impregnated resin, there has been a growing tendency to perform heat treatment under conditions where the heating temperature and heating time are excessive than necessary, and the energy for stretching and heating in the process is increased. An increase in the consumption of the rotating electric machine becomes unavoidable, which also causes an increase in the manufacturing cost of the rotating electric machine. As mentioned above, in rotating electric machines using the conventional total impregnation method, it is extremely difficult to uniformly control the impregnation conditions and heat curing conditions of the coil insulating resin depending on the capacity of each coil, and as a result, the stator coil There is a risk that the insulating layer may not be formed properly, and in some cases, there is a risk that serious damage may be caused.

[Purpose of the invention]

In the process of impregnating an untreated coil wound around a stator core with an insulating resin, the amount of the resin impregnated into the insulating layer is replaced by a change in capacitance, and the impregnation state is monitored. In view of the above-mentioned drawbacks associated with the conventional fully impregnated electric rotating machine, in which the ground insulation of the coil is formed by heating and hardening after completion of resin impregnation, the present invention provides insulation of the coil by simple means. The purpose of the present invention is to provide a fully impregnated rotating electrical machine that can achieve good ground insulation of the coil regardless of the size of the rotating electrical machine by directly controlling the impregnation state and heat curing of the insulating resin in the layer. do.

[Key points of the invention]

In order to achieve the above object, the present invention provides the above-mentioned rotating electric machine, wherein an open groove is formed in a part of a particular wedge in the length direction of a particular wedge of the coil restraining wedge inserted into the slot of the stator core. A tape having the same structure as the untreated insulating tape applied to the coil wound around the stator core is placed on an electrode made of a conductive or semiconductive material provided on the bottom surface of the stator core. a counter electrode of the electrode made of a semiconductive substance is provided above the monitor layer, and a means for preventing the appropriate insulating monitor layer from falling off is provided above the counter electrode. An insulation monitor wedge is inserted into the slot so that the drop-off prevention means is in contact with the surface corona prevention layer made of a semiconductive material that forms the surface of the untreated coil, and external measurement is performed on each of the electrodes and counter electrodes. The capacitance and dielectric loss tangent of the insulating layer can be measured from the outside during the process of impregnation and heat curing of the insulating resin of the stator coil by the full impregnation method. This makes it possible to manage each individual rotating electrical machine.

[Embodiments of the invention]

Next, details of the present invention will be explained based on embodiments shown in the drawings. In the insulation monitor wedge 1 for a rotating electric machine according to the present invention illustrated in FIG. A groove 15, preferably 10 to 20 mm wide and about 300 mm long, having a depth equal to the thickness of the raw insulation layer of the coil to be restrained in the stator core slot, is provided in the bottom surface of the groove 15. An electrode 2 made of a metallic conductive material such as copper, iron, or aluminum, or semiconductively treated glass cloth or polyester nonwoven fabric is disposed in the electrode 2 .
On top of the electrode 2 are the same constituent materials as those of the untreated insulating layer wound around the stator coil, namely glass cloth-backed laminated mica tape, polyester non-woven fabric-backed laminated mica tape, glass cloth-based peel-off mica tape, A similarly untreated insulating monitor layer 3 is provided, consisting of a polyester non-woven substrate peel-off mica tape or the like. Furthermore, on the insulating monitor layer 3, there is a counter electrode 12 corresponding to the electrode 2 made of glass cloth or polyester nonwoven fabric that has been subjected to semiconductive treatment so as not to impair the resin impregnation of the internal insulating monitor layer 3. established,
Furthermore, there is a drop-off prevention device for preventing the insulation monitor layer 3, electrode 2, and counter electrode 12 from falling off from the wedge 1 when the insulation monitor wedge 1 is inserted into the slot to suppress the stator coil. Apply layer 4. In this case, as with the counter electrode 12, glass cloth or polyester nonwoven fabric is used as the drop-off prevention layer 4 so as not to impair the resin impregnation of the insulation monitor layer 3, and the drop-off prevention layer 4 and the insulation monitor wedge 1 are The contacting surfaces are fixed to each other using an adhesive such as epoxy resin. Furthermore, in another embodiment shown in FIG. 2, an open groove 16 similar to that illustrated in FIG. , containing the counter electrode 12 and providing the anti-falling layer 4 thereon is the same as in the embodiment shown in FIG.
A sealing layer 5 made of an adhesive such as epoxy resin is formed on both end faces of the insulating monitor layer 3 so that when impregnating the insulating monitor layer 3 with resin, impregnation with the resin is effective from the stacking direction of the insulating monitor layer 3. It is. In a further embodiment illustrated in FIG.
1, but an open groove 17 is formed in one end face in the length direction of the wedge 21, and inside the open groove 17, the first embodiment, the second embodiment, etc.
An electrode 2, an insulated monitor layer 3, and a counter electrode 12 made of the same material as in the embodiment are housed, and a fall-off prevention layer 4 is provided thereon in the same manner. This type of insulation monitor wedge 17 allows the measurement lead wires 6a and 6b to be easily drawn out from the electrode 2 and the counter electrode 12, so it is convenient to use it mainly as a wedge at the end of the stator core. Furthermore, in another embodiment shown in FIG.
The wedge 31, which is made of the same material as the insulation monitor wedge illustrated in FIGS.
The insulated monitor layer 3 and the counter electrode 12 are housed and the falling-off prevention layer 4 is provided thereon, as in the case of the insulated monitor wedge 21 of the embodiment shown in FIG.
In this case, the mechanical strength of the insulation monitor wedge 31 is improved compared to the insulation monitor wedge of the embodiment shown in FIG. 1 or 2, and it is easier to drive it into the slot of the stator core to suppress the stator coil. Therefore, it is advantageous to use a plurality of wedges in series in the central portion of the stator core in the axial direction, which are driven into the slots. Next, Fig. 1 shows the case where the insulation monitor wedge 1, 11, 21, or 31 formed as described above is actually applied to the stator core slot. is as illustrated in FIG. That is, in the slot 19 of the stator core 14, an insulating layer 8 formed by winding an insulating tape around a wire bundle 7 is provided, and a stator coil 20 having a surface corona prevention layer 9 formed on the outside thereof is arranged vertically. A so-called two-layer stator winding is formed. In that case, the surface corona prevention layer 9 is electrically connected to the iron core 14 via a slide 10 made of semiconductive graphite paper or glass cloth, and between the two-layered stator coils 20. Interlayer 1 is made of phenol laminate or glass cloth laminate.
1 is intervening. As described above, the insulation monitor wedge 1 is inserted into the opening side of the slot 19 of the stator coil 20 that is housed in the slot 19 so as to restrain the coil 20.
The falling-off prevention layer 4 is in contact with the surface corona prevention layer 9 on the upper surface of the stator coil 20. By arranging the stator as described above, the insulation monitor layer 3 of the wedge 1 is impregnated with the insulation resin and heat-cured under exactly the same conditions as the insulation layer 8 of the stator coil 20 when applying full-impregnation insulation to the stator. It can be carried out.
Therefore, measurement lead wires 6a and 6b are connected to the electrodes 2 and 12 located before and after the insulated monitor layer 3, respectively.
By providing this, the capacitance and dielectric loss tangent of the insulation monitor layer 3 can be measured using an impedance analyzer or the like during the impregnation process of the stator coil 20, and the resin impregnation of the stator coil can be monitored based on the results. This makes it possible to control heat curing. As described above, by the measurement of the insulation monitor layer 3 and the impedance analyzer, a voltage of 6kV is detected.
The changes in capacitance during resin impregnation and the change in dielectric loss tangent during heat curing obtained for a 1500kVA rotating electrical machine and a 500kVA rotating electrical machine are shown in the 6th column, respectively.
The result will be as shown in FIG. 7 and FIG. In this case, the insulation monitor wedges in both rotating electric machines have the same insulation monitor layer and are both placed approximately at the center in the axial direction of the stator core, and the C curve in Figures 6 and 7 is 1500kVA rotation. The curve D shows the case of an electric machine, and the D curve shows the case of a 500kVA rotating electric machine. In FIG. 6, the change in capacitance of the 1500kVA rotating electric machine is slower than that of the 500kVA rotating electric machine, but the maximum value of the capacitance is the same. By applying a similar insulation monitor wedge even when the capacitance of rotating electric machines differs, the state of impregnation of the insulating resin into the coil can be uniformly compared based on the measured capacitance value. This can also be easily detected by calculation from the dimensions. On the other hand, in Figure 7, a 1500kVA rotating electrical machine and
In a 500kVA rotating electric machine, the change in dielectric loss tangent with respect to curing time is not uniform, but this is due to the heat capacity of the stator core. In any case, it is possible to clearly determine that the curing of the impregnated resin has been completed by determining the point in time when the minimum dielectric loss tangent is reached. Furthermore, in a rotating electrical machine equipped with this type of insulation monitor wedge, for example, the stator coil 20 shown in FIG.
By measuring the capacitance between the surface corona prevention layer 9 and the counter electrode 12, the gap between the coil 20 and the wedge 1 during operation of the rotating electric machine is detected, and the gap between the surface of the coil 20 and the stator is detected. It is used as a means to predict the slot discharge that occurs between the inner surface of the slot 19 of the iron core 14, and the insulation monitor wedge 1 is taken out after the rotating electric machine has been operated for a certain period of time, and the mechanical strength or thermal weight of the insulation monitor layer is measured. There is an advantage in that it is possible to prevent accidents that may occur in the rotating electrical machine by performing analysis and determining the deterioration of the insulation of the stator coil 20 itself. Although the application of the insulation monitor layer according to the present invention to a rotating electrical machine has been described above, it goes without saying that the same technical idea can be applied to other high voltage electrical equipment such as a molded transformer.

【Effect of the invention】

As explained above, the present invention involves winding an untreated insulating tape around a wire bundle to form an insulating layer, and on top of that, a surface corona prevention layer made of a semiconductive material and an end corona made of a highly resistive material. The molded coil with the prevention layer is inserted into the stator core slot along with a sliding layer made of a semiconductive material and an interlayer made of an insulating material so as to form a two-layer winding, and then inserted into the slot with a wedge made of an insulating material. In the rotating electrical machine, the stator winding is formed by connecting each of the coils, and then a thermosetting resin is impregnated and cured under vacuum pressure to form a ground insulating layer of the coil. On the electrode made of a conductive or semi-conductive material provided on the bottom of the groove formed in a part of the length of a particular wedge of the coil restraining wedge inserted into the slot of the iron core, forming an insulating monitor layer having the same composition as an untreated insulating tape applied to the coil wound around the stator core; and forming an insulating monitor layer having the same structure as a tape of the same quality as the untreated insulating tape applied to the coil wound around the stator core; An insulated monitor wedge is provided with a counter electrode to the electrode, and an insulated monitor wedge is provided with an appropriate means for preventing the insulating monitor layer from falling off on the upper side of the counter electrode. The electrode is inserted into the slot so as to be in contact with the surface corona prevention layer made of a substance, and lead wires for measurement from the outside can be connected to each of the electrodes and the counter electrode, thereby providing ground insulation using a total impregnation method. The process of impregnating and curing the insulating resin on the stator coil of the rotating electrical machine in which the stator coil of the rotating electrical machine is formed in layers can be monitored and determined by electrical measurement through the insulation monitor layer, regardless of the capacity of the rotating electrical machine. In addition, since it is possible to clearly determine the end time of impregnation and curing of the insulating resin, there is no need to rely solely on experience as in the past, and there is no need to worry about work management due to the consumption of extra processing time for safety reasons. This has the effect of eliminating delays and wasting energy and economically providing a rotating electric machine with high quality and high reliability.

[Brief explanation of the drawing]

1 to 4 are schematic cross-sectional views or schematic vertical sectional views, respectively, of an insulation monitor wedge related to the fully impregnated rotating electric machine of the present invention, and FIG. 5 is a schematic longitudinal sectional view of the insulation monitor wedge when the insulation monitor wedge of FIG. 6 and 7 are schematic longitudinal cross-sectional views showing the relationship to the coils in the stator slots, and FIGS. 6 and 7 respectively show the capacitance of the insulating layer versus the impregnation time of the insulating resin in the stator coil of the fully impregnated rotating electrical machine of the present invention. Figure 8 shows the characteristic curves showing the relationship between the relationship between the dielectric loss tangent of the insulating layer and the hardening time for rotating electric machines with different capacities.
Figure 9 shows the relationship between the capacitance of the insulating layer and the impregnation time of the insulating resin in the stator coil of a conventional fully impregnated rotating electric machine, and the relationship between the dielectric loss tangent and the applied voltage in rotating electric machines with different capacities. represents the characteristic curve shown. 1, 11, 21, 31...Insulation monitor wedge, 2
... Electrode, 3 ... Insulation monitor layer, 4 ... Fall-off prevention layer, 5
... Seal layer, 6a, 6b... Lead wire, 7... Wire bundle, 8... Insulating layer, 9... Surface corona prevention layer, 10...
Sliding, 12...Counter electrode, 13...Interlayer, 1
4... Stator core, 15, 16, 17, 18... Open groove of insulation monitor wedge, 19... Stator core slot, 20... Stator coil.

Claims (1)

[Claims] 1. A formed coil is formed by winding an untreated insulating tape around a wire bundle to form an insulating layer, and then applying a surface corona prevention layer made of a semiconductive material and an end corona prevention layer made of a high-resistance material thereon. The molded coils are inserted into the slots of the stator core together with a sliding layer made of a semiconductive material and an interlayer made of an insulating material so as to form a two-layer winding, and held in the slots by a wedge made of an insulating material. In a rotating electric machine, the coils are connected to each other to form a stator winding, and then a thermosetting resin is vacuum impregnated and cured to form a ground insulating layer of the coil, which is inserted into the slot of the stator core. The coil is wound around the stator core on an electrode made of a conductive or semi-conductive material provided on the bottom of an open groove formed in a part of the length of a particular wedge of the coil restraining wedge. forming an insulating monitor layer having the same composition as the untreated insulating tape applied to the coil, and providing a counter electrode to the electrode made of a semiconductive material on the upper side of the monitor layer; Further, an insulating monitor wedge is provided on the upper side of the counter electrode with an appropriate means for preventing the insulating monitor layer from falling off. A fully impregnated rotating electrical machine, characterized in that the layers are inserted into the slot so that they are in contact with each other, and lead wires for performing electrical measurements from the outside can be connected to each of the electrodes and counter electrodes. .