JP2022152034A - oil-filled transformer - Google Patents

Abstract

To provide an oil-filled transformer that suppresses a difference in thermal deterioration of windings.SOLUTION: In the present invention, a winding is divided into upper and lower parts, and in addition to introducing insulating oil through the gap between them, and insulating paper with different heat resistance class is used properly for each part.SELECTED DRAWING: Figure 1

Description

The present invention relates to oil-filled transformers.

In the high-frequency transformer described in Patent Document 1, both the primary winding and the secondary winding are covered with Kapton tape, and the primary winding is on the inside and the secondary winding is on the outside. The primary winding is inserted inside the secondary winding, and a thick Nomex sheet is sandwiched between adjacent windings to maintain an insulation distance.

JP 2017-174958

Distribution transformer windings generate heat due to power loss, and the windings cool the heat by circulating insulating oil inside the tank. The insulating oil whose temperature rises becomes less dense and moves to the top, while the cooled insulating oil becomes more dense and moves to the bottom of the tank, is drawn into the windings, takes heat from the windings and moves to the top. . The windings have a heat distribution similar to the temperature distribution of the insulating oil circulating above and below.

In the series of cooling systems in the oil-immersed transformer described above, there is always a temperature difference between the upper and lower windings, and the upper windings are always operated at a higher temperature than the lower windings. Thermal deterioration occurs quickly. In addition, the inner winding (low voltage) has a smaller area in contact with the insulating oil than the outer winding (high voltage), and the temperature is high, so thermal deterioration occurs quickly.

Although Patent Document 1 considers maintaining the insulation distance between windings, it does not consider suppressing differences in thermal deterioration of windings in an oil-immersed transformer.

An object of the present invention is to provide an oil-filled transformer that suppresses differences in thermal deterioration of windings.

In the present invention, the winding is divided into upper and lower parts, and in addition to introducing insulating oil through the gap between them, insulating paper with different heat resistance class is used properly for each part.

ADVANTAGE OF THE INVENTION According to this invention, the oil-filled transformer which suppresses the difference of the thermal deterioration of winding can be implement|achieved.

FIG. 2 is an external view of the winding and core in Example 1; The external view of the winding|winding and iron core in a comparative example. 4A and 4B are views for explaining windings and insulating paper in Example 1. FIG. FIG. 8 is a diagram for explaining windings and insulating paper in Example 2; FIG. 11 is a diagram for explaining windings and insulating paper in Example 3;

An embodiment will be described below with reference to the drawings.

FIG. 1 is an oblique external view of a core-winding assembly having a core and windings in Example 1. FIG. The core consists of an outer core 1 and an inner core 2 . In this embodiment, the coil (winding) is composed of an upper winding 4 and a lower winding 5 . FIG. 2 is an oblique view of the core-winding assembly in the comparative example. In the comparative example, winding 3 is not divided into upper winding 4 and lower winding 5 .

Insulating oil and the core-winding assembly shown in FIG. 1 are accommodated inside the tank of the oil-filled transformer having a three-phase tripod structure to which this embodiment is applied. In FIG. 1, illustration of a tank and insulating oil is omitted.

In the core-winding assembly, three-phase (U-phase, V-phase, W-phase) coils (upper winding A line 4 and a lower winding 5) are provided. The coil is composed of a primary winding portion and a secondary winding portion.

In this embodiment, the winding 3 is divided in the height direction, and oil is introduced into the upper winding 4 through a gap (divided portion) formed between the upper winding 4 and the lower winding 5 to cool the oil. . However, the windings of the upper winding 4 and the lower winding 5 are electrically connected.

Insulating oil is allowed to enter the gap formed between the upper winding 4 and the lower winding 5 to cool the heat generated from the upper winding 4 . Therefore, compared with the configuration of FIG. 2 of the comparative example, the difference in thermal deterioration of the windings is suppressed.

3A and 3B are diagrams for explaining windings and insulating paper in Example 1. FIG. FIG. 3(a) is a diagram showing the arrangement of the insulating paper 6 in the lower winding 5 when the lower winding 5 is horizontally cut in FIG. FIG. 3(b) is a diagram showing the arrangement of the insulating paper 7 of the upper winding 4 when the upper winding 4 is horizontally cut in FIG.

In FIG. 3, the upper winding 4 with a higher temperature is wrapped with insulation paper 7 of a heat resistance class higher than that of the lower winding 5 so that the insulation paper 7 is arranged between the upper windings 4. .

According to the first embodiment, it is possible to suppress excessive thermal deterioration of only the upper winding whose temperature is high. In addition, by using high-cost insulating paper with a high heat resistance class only for the upper winding and not for the lower winding, the cost is suppressed and the difference in thermal deterioration of the winding is suppressed. In addition, by using insulating paper with a high heat resistance class for the upper winding, it is possible to reduce the cooling area of the cooling fins, etc., so the tank can be made smaller, thereby suppressing the difference in thermal deterioration of the winding. , the manufacturing cost of the oil-filled transformer can be suppressed, and a compact oil-filled transformer can be realized.

FIG. 4 is a diagram for explaining windings and insulating paper in Example 2. FIG. In FIG. 4, the windings consist of an inner winding 9 and an outer winding 8 which is the side facing the insulating oil on the outer peripheral side of the inner winding 9 .
The configuration of FIG. 4 may be the configuration of either the upper winding 4 or the lower winding 5 of FIG.

The outer winding 8 is a primary winding connected to the primary side, which is the high voltage side. The inner winding 9 is a secondary winding connected to the secondary side, which is the low voltage side.
Descriptions of the same items as in the first embodiment are omitted.

In the configuration of the first embodiment shown in FIG. 1, the inner winding 9 is surrounded by the outer winding 8 and has a small area in contact with the oil, so that heat tends to accumulate. The inner winding 9 is wound with insulation paper 7 having a higher grade of heat resistance class than the insulation paper 6 used for the outer winding 8 so that the insulation paper 7 is arranged between the inner windings 9. - 特許庁

In this embodiment, a fourth insulating paper 7 and a third insulating paper 6 are wound around the windings between the inner windings 9 and between the outer windings 8, respectively. The fourth insulating paper 7 arranged between the inner windings is insulating paper having a higher heat resistance class than the third insulating paper 6 .

In Patent Document 1, both the primary winding and the secondary winding are covered with Kapton tape, which has a higher heat resistance class than the Nomex sheet, and the primary winding is arranged inside and the secondary winding is arranged outside. Therefore, the configuration is different from the present embodiment, and in Patent Document 1, by placing a thick Nomex sheet between the primary winding and the secondary winding, a reliable insulation distance can be maintained. Patent document 1 does not suggest suppressing the difference in thermal deterioration of the windings 9 and 8 .

According to this embodiment, the difference in thermal deterioration between the inner winding 9 and the outer winding 8 can be suppressed.

FIG. 5 is a diagram for explaining windings and insulating paper in Example 3. FIG. FIG. 5(a) is a diagram showing the arrangement of the insulating paper 6 in the windings constituting the outer bipod (U-phase, W-phase) 10 in the oil-filled transformer of the three-phase tripod structure of FIG. FIG. 5(b) is a diagram showing the arrangement of the insulating paper 7 in the windings forming the monopod 11 (V phase) in FIG. Descriptions of the same items as in the first or second embodiment are omitted.

In the case of the tripod wound iron core, the centrally arranged monopod 11 has a smaller area in contact with the insulating oil than the outer bipod 10, and heat tends to accumulate more than the outer bipod 10. - 特許庁An insulating paper 7 (sixth insulating paper) having a higher heat resistance class than the insulating paper 6 (fifth insulating paper) in the bipod 10 is wound around the winding constituting the centrally arranged monopod 11, The insulating paper 7 is arranged between the windings forming the monopod 11. - 特許庁

For either the upper winding 4 or the lower winding 5, a heat resistance class of insulating paper suitable for the temperature is selected and placed between the windings.

According to the present embodiment, it is possible to suppress the difference in thermal deterioration between the windings on the outer two legs and the windings on the central one leg of the oil-filled transformer having a three-phase tripod structure.

In this embodiment, the windings of the oil-immersed transformer are divided into three in the height direction, each of the two divided windings is called a winding group, and the oil-immersed transformer consists of three winding groups. .
Oil is drawn into the winding through two gaps (divided parts) formed between the upper winding, the middle winding, and the lower winding to cool the winding. However, the upper winding, middle winding and lower winding are electrically connected. Descriptions of the same matters as those of the first to third embodiments are omitted.

In this embodiment, although illustration is omitted, the seventh insulating paper arranged in the first winding group that constitutes the upper winding is the second winding group that constitutes the middle winding or the lower winding. Insulating paper having a higher heat resistance class than the eighth insulating paper arranged in .

Depending on the temperature, the middle winding also uses insulating paper of a different heat resistance class from that of the upper winding 4 or the lower winding 5 . For the upper winding 4 or the lower winding 5, the heat resistance class of insulating paper suitable for the temperature is selected and arranged between the windings.

In this embodiment, the windings are arranged in three winding groups consisting of an upper winding, a middle winding, and a lower winding from top to bottom. There may be.

According to this embodiment, the windings of the oil-filled transformer are vertically divided into three or more winding groups. Compared to the first embodiment, the number of gaps for taking in oil arranged between the winding groups is increased, and the difference in cooling efficiency between the windings can be reduced, so that the difference in thermal deterioration of the windings can be suppressed. can be done.

1 outer core, 2 inner core, 3 winding, 4 upper winding, 5 lower winding, 6 insulating paper (heat-resistant class: low), 7 insulating paper (heat-resistant class: high), 8 ... Outer winding, 9 ... Inner winding, 10 ... Bipod (U leg winding, W leg winding), 11 ... One leg (V leg winding)

Claims (6)

An oil-immersed transformer containing an assembly of an iron core and windings in a tank and filled with insulating oil,
The winding is
An oil-immersed transformer having an upper winding and a lower winding. In the oil-filled transformer according to claim 1,
An oil-immersed transformer having a gap between the upper winding portion and the lower winding portion. In the oil-filled transformer according to claim 1,
a first insulating paper positioned between the upper windings and a second insulating paper positioned between the lower windings;
The oil-immersed transformer, wherein the first insulating paper is insulating paper having a higher heat resistance class than the second insulating paper. In the oil-filled transformer according to claim 1,
a third insulating paper positioned between the outer windings and a fourth insulating paper positioned between the inner windings;
The oil-filled transformer, wherein the fourth insulating paper is insulating paper having a higher heat resistance class than the third insulating paper. The configuration of the iron core of the oil-filled transformer according to claim 1 is
A tripod wound iron core,
a fifth insulating paper disposed between the windings forming the outer bipod of the tripod;
and a sixth insulating paper disposed between the windings constituting a central monopod of the tripod,
The oil-filled transformer, wherein the sixth insulating paper is insulating paper having a higher heat resistance class than the fifth insulating paper. In the oil-filled transformer according to claim 1,
The winding is
Consists of three or more winding groups from top to bottom,
The seventh insulating paper arranged in the first winding group on the upper side among the winding groups,
An oil-immersed transformer that is insulating paper having a higher heat resistance class than the eighth insulating paper arranged in the lower second winding group.

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