JPH11102829A - Winding drying method for induction electrical equipment - Google Patents

Abstract

(57) [Problem] To provide a method for drying a winding of an induction electric device, which can reduce deterioration of insulating paper during energization drying. SOLUTION: When drying a winding housed in an induction electric equipment case, the inside of the case is evacuated to a high vacuum of about 1 to 3 mmHg, and the average winding temperature of the winding is reduced to about 14 mm.
The current is dried at 5 ° C. and the maximum winding temperature is about 160 ° C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drying a winding of an induction electric device such as a transformer.

[0002]

2. Description of the Related Art FIG. 7 shows the internal structure of a pole transformer, which is a kind of inductive electric equipment. In this pole transformer, a secondary winding (low-voltage winding) 4 is provided by winding a strip conductor 3 or a rectangular conductor as shown in the figure around an outer periphery of an iron core 1 via an insulating paper 2. A primary winding (high-voltage winding) 6 is provided on the outer periphery of the secondary winding 4 via a main insulating layer 5. Although the internal structure of the primary winding 6 is not shown, it is configured by winding a wire having a circular cross section via insulating paper. On the outer periphery of the primary winding 6, a decorative winding layer 7 is provided.

[0003] A transformer case (equipment case) accommodating the transformer body 8 having such a structure is filled with insulating oil after drying the windings 4 and 5 of the transformer body 8.

As described above, each of the windings 4 and 5 of the transformer body 8 is dried by putting a single unit of each of the windings 4 and 5 before assembling the transformer body 8 into a batch drying furnace, and drying the windings 4 and 5. Drying was performed by heating from the outside, and after drying, the transformer main body 8 was assembled.

[0005] However, such a method for drying a winding has a problem that a batch drying furnace is required. Further, since the windings 4 and 5 are heated and dried from the outside, it takes a long time for drying, and the energy required for drying is also large.

Therefore, the transformer main body 8 is assembled without using a batch drying furnace, and the windings 4 and 5 are energized to generate heat by Joule heat.
5 has been proposed.

In the conventional energization drying method, the inside of the equipment case accommodating the transformer main body 8 is evacuated to about 7 to 10 mmHg,
After passing about 240% of the rated current through each of the windings 4 and 5, the average winding temperature of each of the windings 4 and 5 reaches about 120 ° C and the maximum winding temperature reaches about 140 ° C, and then about 80% of the rated current. Current drying was performed while maintaining the average winding temperature by applying current.

According to such a current drying method, the windings 4 and 5 can be heated and dried from the inside by utilizing the heat generated by the windings, and the drying is performed in a shorter time than in a conventional batch drying furnace. And the energy required for drying can be saved.

[0009]

However, in the conventional winding drying method, particularly when the secondary winding 4 is formed of the strip conductor 3, moisture is distributed in the radial direction of the secondary winding 4. Since it is blocked by the strip conductor 3 and cannot pass through, there is a problem that a considerable amount of time is required as shown in FIG.

In this energization drying, since the inside of each of the windings 4 and 5 becomes hot due to the application of a large current, the moisture contained in the insulating paper 2 is discharged, and the insulating paper 2 is hydrolyzed by high temperature and high humidity. There was a problem that deterioration of No. 2 progressed. If the insulation paper 2 deteriorates, the life of the windings 4 and 5 will be shortened, which is not preferable. In particular, when the winding 4 is composed of the strip conductors 3, the water vapor generated from the insulating paper 2 between the layers of the strip conductors 3 cannot pass through in a direction orthogonal to the plate surface of the strip conductors 3. There is a problem that the insulating paper 2 is significantly deteriorated, and the average degree of polymerization, which is a guide for the degree of deterioration of the insulating paper 2, is reduced to about 50% as compared with the initial value before drying.

It is an object of the present invention to provide a method for drying a winding of an induction electric machine, which can reduce the deterioration of insulating paper during energization drying.

Another object of the present invention is to provide a method for drying a winding of an induction electric machine which can increase the drying efficiency as compared with the conventional energization drying.

It is another object of the present invention to provide a method for drying a winding of an induction electric device, which can efficiently discharge moisture in the device case by a vacuum pump.

[0014]

SUMMARY OF THE INVENTION According to the present invention, when drying a winding housed in an induction electric equipment case, the windings are energized while the inside of the induction electric equipment case is evacuated, and the conductors of the windings are energized. To improve the method of drying a winding of an induction electric device, in which heat is generated to dry an insulating layer of the winding.

According to the present invention, the inside of the induction electrical equipment case is approximately 1
A high vacuum of about 3 mmHg is applied to dry the electric current.

As described above, when the inside of the induction electric device case is subjected to a higher vacuum than in the case of the conventional energization drying, the energization drying can be performed in a shorter time than in the case of the conventional energization drying. In addition, even with a winding made of a strip conductor, the drying process can be performed in a shorter time than in the case of conventional energization drying. Further, since the drying is performed in a short time, even if the heating temperature by the energization drying is set higher than that in the conventional energization drying, the energization drying can be completed in a time in which the deterioration of the insulating paper does not matter.

More specifically, the drying conditions of the present invention are as follows. In the present invention, the inside of the induction electric machine case is set to a high vacuum of about 1 to 3 mmHg, the average winding temperature of the winding is about 145 ° C. The temperature is set to about 160 ° C., and the electric current drying is performed.

When the energization heating temperature is increased as compared with the case of the conventional energization drying, the drying process can be performed in less than half of the conventional energization drying time.

The control including the electric current for performing the electric drying at the electric heating temperature is performed as follows.
That is, the inside of the induction electric equipment case is set to a high vacuum of about 1 to 3 mmHg, and an average winding temperature of about 145 ° C. and a maximum winding temperature of about 160
After reaching the temperature, the average winding temperature is maintained by conducting about 70% of the rated current, and the drying is conducted.

As described above, even if a current of about 240% of the same rated current as in the conventional energization drying is applied to the winding, heat is hard to escape to the outside of the winding because of the higher vacuum than in the conventional energization drying. Therefore, it is possible to perform the energization drying at an average winding temperature of about 145 ° C. and a maximum winding temperature of about 160 ° C., which are higher temperatures than in the conventional energization drying. In addition, since the vacuum is higher than in the case of conventional energization drying, the average winding temperature of about 145 ° C. can be maintained by energizing about 70% of the rated current lower than in the case of conventional energization drying, and the energization drying is performed efficiently. be able to.

In these cases, the evacuation in the induction electric equipment case is performed by connecting a first evacuation pump for performing evacuation in the induction electric equipment case to the first evacuation pump via a water trap. When the first vacuum pump is used to evacuate the induction electric equipment case, the temperature of the pump oil in the first vacuum pump is equal to or higher than the evaporation temperature of water. , And the water is trapped to reduce the temperature of the exhaust gas from the first vacuum pump to condense water to remove water, and the water in the water trap is exhausted by the second vacuum pump.

As described above, when the first vacuum pump is used to evacuate the case of the induction electric equipment, the temperature of the pump oil in the first vacuum pump is raised to a temperature equal to or higher than the evaporation temperature of water, and the first vacuum pump is evacuated. Is performed, the water taken in the pump oil of the first vacuum pump during the process of vacuum can be evaporated from the pump oil and guided to the water trap. When the exhaust gas from the first evacuation pump is guided into the water trap to lower the exhaust gas temperature, moisture in the exhaust gas can be condensed and efficiently removed.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 show a first example of an embodiment of a winding dryer for implementing a winding drying method for an induction electric machine according to the present invention, and FIG. FIG. 2 is a longitudinal sectional view showing a schematic configuration of a winding dryer, FIG. 2 is a longitudinal sectional view showing a schematic configuration of a vacuum evacuation device used in FIG. 1, and FIG.
It is a longitudinal cross-sectional view which shows the schematic structure of the 1st evacuation pump used by the evacuation apparatus of FIG.

In this winding dryer, the transformer body 8 having the structure as shown in FIG. 7 is hermetically accommodated in a transformer case (induction electric device case) 9. Outside the transformer case 9, a primary winding (high-voltage winding) 6 of the transformer body 8 is provided.
Power supply 10 for supplying power to the secondary winding (low-voltage winding) 4
And a vacuum gauge 12 for detecting the degree of vacuum in the transformer case 9. Vacuum gauge 1
2 is input to the control device 13, and the control device 1
3, the first and second power supplies 10 and 11 control the energization of the primary winding 6 and the secondary winding 4. The transformer case 9 has a first vacuum pump 14 for evacuating the inside of the transformer case 9 and a second vacuum pump 14 connected to the first vacuum pump 14 via a water trap 15.
And a vacuum pumping device 17 composed of a vacuum pump 16.

The first vacuum pump 14 is connected to the transformer case 9 by a pipe 18. The first vacuum pump 14 includes a vacuum pump body 19, an oil tank 20 connected to the discharge side of the vacuum pump body 19, the vacuum pump body 19 and the oil tank 2.
And the pump oil 21 housed in the pump 2.
The space between the second blade 23 and the pump casing 24 is sealed with an oil film. A ribbon heater 25 is wound around the outer periphery of the oil tank 20, so that the pump oil 21 is heated.

The water trap 15 is provided in the trap housing 2.
The trap housing 26 is connected to an upper portion of the oil tank 20 by a pipe 27. A heat exchange pipe 28 is disposed in the trap housing 26, and cooling water flows through the heat exchange pipe 28 to cool the inside of the trap housing 26. Trap housing 26
Is connected to a pipe 29 for discharging trapped water. The upper part of the trap housing 26 is a pipe 3
At 0, it is connected to the second vacuum pump 16.

In this winding drying device, the primary winding 6 and the secondary winding 4 are firstly separated from each other while the inside of the transformer case 9 is evacuated to a high vacuum of about 1 to 3 mmHg by the evacuation unit 17. Power supply 1
0 and the second power supply 11 are energized at about 300% of the rated current, and the primary winding 6 and the secondary winding 4 are heated by Joule heat so that the average winding temperature is about 145 ° C. After the maximum temperature reaches about 160 ° C., the current is dried at about 70% of the rated current while maintaining the average winding temperature. The control device 13 controls the current supplied to the primary winding 6 and the secondary winding 4 as described above.

The temperature control of the primary winding 6 and the secondary winding 4 is as follows.
The average winding resistance is obtained from the current flowing between the primary winding 6 and the secondary winding 4 and the voltage between the terminals of the primary winding 6 and the secondary winding 4,
This is performed by determining the average winding temperature by the equation (1).

Θ ₂ = (R ₂ / R ₁ ) (K ₁ + θ ₁ ) −K ₁ (1) where θ ₂ is a target temperature (° C.) of the primary winding 6 and the secondary winding 4. ₂ : winding resistance at target temperature (Ω) R ₁ : initial winding resistance (Ω) K ₁ : temperature coefficient of conductor between primary winding 6 and secondary winding 4 (copper: 234.5; Aluminum: 225.0) θ ₁ : initial winding temperature (° C.).

In the evacuation device 17, when the first evacuation pump 14 performs evacuation in the transformer case 9, the temperature of the pump oil 21 in the first evacuation pump 14 is changed to the evaporation temperature of water. Above, the vacuum is raised by heating by the ribbon heater 25, and the exhaust temperature from the first vacuum pump 14 is lowered by the water trap 15 by cooling by the heat exchange pipe 28 to cause dew condensation to remove water. The inside of the trap housing 26 of the water trap 15 is evacuated by the vacuum pump 16.

As described above, when the inside of the transformer case 9 is subjected to energization drying with a higher vacuum of about 1 to 3 mmHg than in the conventional case, the drying process can be performed in a shorter time than in the case of the conventional energization drying. In addition, even with the secondary winding 4 made of a strip conductor, the drying process can be performed in a shorter time than in the case of the conventional energization drying. Further, since the drying is performed in a short time, even if the heating temperature by the energized drying is set higher than that in the conventional energized drying, the energized drying can be completed in a time in which the deterioration of the insulating paper 2 shown in FIG.

In particular, the inside of the transformer case 9 is set to a high vacuum of about 1 to 3 mmHg, the average winding temperature of the primary winding 6 and the secondary winding 4 is set to about 145 ° C., and the maximum winding temperature is set to about 160 ° C. When the energization heating temperature is raised by performing the energization drying by heating in comparison with the case of the conventional energization drying, the drying process can be performed in half or less of the conventional energization drying time as described later.

In particular, the inside of the transformer case 9 is set to a high vacuum of about 1 to 3 mmHg, and the primary winding 6 and the secondary winding 4 are energized by about 300% of the rated current, so that the primary winding 6 and the secondary winding Line 4
Average winding temperature of about 145 ° C and maximum winding temperature of about 160
After reaching the temperature, the primary winding 6 and the secondary winding 4 are subjected to the same rated current as in the case of the conventional energizing drying when the energizing drying is performed while maintaining the average winding temperature by energizing about 70% of the rated current. Even when the current is applied at about 240% of the current, the heat is hard to escape to the outside of the winding because of the higher vacuum than in the case of the conventional energization drying. Current drying can be performed at an average winding temperature of about 160 ° C., which is the maximum winding temperature. In addition, since the vacuum is higher than in the case of conventional energization drying, the rated current of about 7
The average winding temperature of about 145 ° C. can be maintained by the 0% energization, and the energization drying can be performed efficiently.

When the first vacuum pump 14 evacuates the transformer case 9 during the current drying, the temperature of the pump oil 21 in the first vacuum pump 14 is reduced by the evaporation of water. When the temperature is raised to a temperature (100 ° C.) or higher and a vacuum is drawn, water taken in the pump oil 21 of the first vacuum pump 14 in the process of vacuum evaporates from the pump oil 21. To the water trap 15. When the exhaust gas from the first vacuum pump 14 is guided into the water trap 15 to lower the exhaust temperature, moisture in the exhaust gas can be dewed and removed efficiently. In addition, when the inside of the trap housing 26 is evacuated by the second evacuation pump 16, the pressure is reduced and moisture can be easily captured.

FIG. 4 shows the relationship between the required drying time and the drying temperature in each of the conventional batch drying A, the conventional energizing drying B, and the energizing drying C of the present invention. This data shows that the secondary winding (low-voltage winding) 4
This is the data in the case of consisting of

As is apparent from this figure, the conventional batch drying A had a maximum winding temperature of about 105 ° C. and required about 960 minutes for drying, whereas the conventional current drying B had a maximum winding temperature of about 14 ° C.
It is greatly improved to about 120 minutes at 0 ° C., and the maximum winding temperature is about 40 minutes at about 160 ° C. in the energization drying C of the present invention. It turns out that it can be terminated. The reason why the energization time can be reduced in this way is that the rise time to reach the maximum winding temperature is short and that the maximum winding temperature is higher than before.

FIG. 5 shows a secondary winding (referred to as an S winding) 4, a main insulating layer 5, and a conventional batch drying A, a conventional energizing drying B, and an energizing drying C of the present invention. It shows the water content (%) in the insulating paper of the primary winding (referred to as P winding) 6 and the decorative winding layer 7.

As is apparent from this figure, it was found that the average moisture content of each part of the transformer body 8 can be reduced to almost half of the average moisture content of the conventional electrification drying B according to the electrification drying C of the present invention.

FIG. 6 shows a secondary winding (referred to as an S winding) in each of the conventional energization drying B and the energization drying C of the present invention.
4, the inner layer portion of the primary winding 6 (called inside the P winding), the central layer portion of the primary winding 6 (called inside the P winding), the primary winding 6
3 shows the measurement results of the average degree of polymerization and the average degree of polymerization residual of the paper insulating layer in the outer layer portion (referred to as “outside of the P winding”).

As is clear from this figure, the current drying of the present invention has a maximum winding temperature of about 160 ° C. and the conventional maximum winding temperature of about 140 ° C. in the case of current drying. It was found that the degree of deterioration of the primary winding (P winding) 6 was almost the same as that of the conventional energization drying, but the degree of deterioration of the secondary winding (S winding) 4 was better than that of the conventional energization drying.

In the above example, the case where the present invention is applied to the energization drying of the winding of the transformer has been described. However, the present invention is not limited to this, and the same applies to the energization drying of the winding of the reactor and the like. It can be applied to

[0042]

According to the present invention, since the inside of the induction electric equipment case is made to have a high vacuum of about 1 to 3 mmHg, that is, a higher vacuum is applied than in the case of the conventional energization drying, the energization drying is performed. The drying process can be performed in a short time. Also,
Even with a winding made of a strip conductor, the drying treatment can be performed in a shorter time than in the case of conventional energization drying. Further, since the drying is performed in a short time, even if the heating temperature by the energization drying is set higher than that in the conventional energization drying, the energization drying can be completed in a time in which the deterioration of the insulating paper does not matter.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration in a first example of an embodiment of a winding dryer for performing a winding drying method for an induction electric device of the present invention.

FIG. 2 is a longitudinal sectional view showing a schematic configuration of a vacuum evacuation apparatus used in FIG.

FIG. 3 is a longitudinal sectional view showing a schematic configuration of a first vacuum pump used in the vacuum apparatus of FIG. 2;

FIG. 4 shows a conventional batch drying A, a conventional energization drying B,
FIG. 4 is a comparison diagram showing a relationship between a required drying time and a drying temperature in each case of the energization drying C of the present invention.

FIG. 5 shows a conventional batch drying A, a conventional energization drying B,
FIG. 5 is a comparative diagram showing the water content (%) in the insulating paper of the secondary winding, the main insulating layer, the primary winding, and the decorative winding layer in each case of the energization drying C of the present invention.

FIG. 6 shows paper insulation layers in the secondary winding, the inner layer portion of the primary winding, the central portion of the primary winding, and the outer layer portion of the primary winding in each of the conventional energization drying B and the energization drying C of the present invention. FIG. 3 is a comparison diagram showing the results of measurement of the average polymerization degree and the average polymerization degree residual rate of the sample.

FIG. 7 is a longitudinal sectional view showing a layer structure on one side of a winding main body in the pole transformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Iron core 2 Insulating paper 3 strip conductor 4 Secondary winding (low voltage winding) 5 Main insulating layer 6 Primary winding (high voltage winding) 7 Decorative winding layer 8 Transformer main body 9 Transformer case (induction electric equipment case) 10 First power supply 11 Second power supply 12 Vacuum gauge 13 Control device 14 First vacuum pump 15 Water trap 16 Second vacuum pump 17 Vacuum device 18 Piping 19 Vacuum pump main body 20 Oil tank 21 Pump oil 22 Rotor 23 Blade 24 Pump casing 25 Ribbon heater 26 Trap housing 27 Piping 28 Heat exchange pipe 29 Piping 30 Piping

Claims (4)

[Claims] When drying a winding housed in a case of an induction electrical equipment, the inside of the case is evacuated, and while the inside of the case is evacuated, the winding is energized to generate heat in the conductor of the winding, thereby insulating the winding. A method of drying a winding of an induction electric device for drying a layer, wherein the inside of the case is dried under a high vacuum of about 1 to 3 mmHg, and the current is dried. 2. When drying a winding housed in an induction electric equipment case, the inside of the case is evacuated, and while the inside of the case is evacuated, the winding is energized to generate heat in the conductor of the winding, thereby insulating the winding. In the method for drying a winding of an induction electric device for drying a layer, the inside of the case is evacuated to a high vacuum of about 1 to 3 mmHg, the average winding temperature of the winding is about 145 ° C, and the maximum winding temperature is about 16 ° C.
A winding drying method for induction electrical equipment, wherein the drying is performed at 0 ° C. by conducting electricity. 3. When drying the winding housed in the case of the induction electric equipment, the inside of the case is evacuated, and while the inside of the case is evacuated, the winding is energized to heat the conductor of the winding, thereby insulating the winding. In the method of drying a winding of an induction electric device for drying a layer, the inside of the case is evacuated to a high vacuum of about 1 to 3 mmHg, and the winding is energized by about 300% of a rated current. After reaching about 145 ° C. and the maximum winding temperature to about 160 ° C., and maintaining the average winding temperature by conducting about 70% of the rated current to perform energization drying. Line drying method. 4. The evacuation in the induction electric equipment case is connected to a first evacuation pump for performing evacuation in the induction electric equipment case and a water trap to the first evacuation pump. When the first vacuum pump is used to evacuate the induction electric equipment case, the temperature of the pump oil in the first vacuum pump is changed to the evaporation temperature of water. Raise the above and evacuate,
2. The water trap is used to reduce the temperature of the exhaust gas from the first vacuum pump to form dew condensation to remove moisture, and the second vacuum pump exhausts the water trap. 3. 4. The method for drying a winding of an induction electrical device according to claim 2, 2 or 3.