JP2547433B2 - Stationary induction - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a static induction electric device.

[Conventional technology]

From the viewpoint of disaster prevention in dense urban areas, there is an increasing demand for non-combustible large capacity transformers used in urban areas. Conventional large-capacity transformers use mineral oil as an insulating medium and a cooling medium, and it is feared that mineral oil may leak to the outside in the event of an accident and cause a disaster such as a fire. Therefore, at present, an insulating liquid having a high ignition temperature is used instead of mineral oil. Silicone liquid is one of such insulating liquids, which is excellent in electrical and chemical properties and is widely applied to small-capacity transformers for indoor use, but its kinematic viscosity is 50 cSt.
Since it is as large as (centistokes) and has a small cooling effect, it cannot be applied to a large capacity.

For this reason, the development of low-viscosity materials is being promoted (Reference: Insulation Material Research Society of the Institute of Electrical Engineers, Material EIM-79-58
As discussed in 4)), the lower the viscosity, the lower the flash point and the higher the burning rate.
It has not been put to practical use.

There is one that uses a perfluorocarbane liquid as an insulating liquid other than the silicone liquid. For example, as disclosed in JP-A-58-122710 and JP-A-59-150410, an insulating gas is filled in a tank so that a winding or a winding and a core as a heat source are not combustible. A semi-pool type gas-insulated transformer of an evaporative cooling type has been proposed, which is soaked in a refractory liquid and loses heat as latent heat when the liquid refrigerant is vaporized. The perfluorocarbon liquid has a low viscosity and is suitable for cooling.

By the way, published literature (1984 National Conference of the Institute of Electrical Engineers of Japan No.670)
And Japan Petroleum Institute Electric Insulating Oil Handbook P74 (Showa 62)
Year)), for example SF as insulating gas
_{When 6} gas is used, SF ₆ gas is very easy to dissolve in the perfluorocarbon liquid, and the amount of dissolution changes significantly depending on the temperature of the perfluorocarbon.
_{6 The} phenomenon that the gas pressure changes drastically occurs. A decrease in the gas pressure in the tank will lead to a decrease in the dielectric strength of the lead wires of the windings arranged in the gas space. As a countermeasure against such a case, for example, Japanese Patent Laid-Open No. 59-47718 discloses. As described above, it has been devised that the temperature of the refrigerant liquid is raised by the heating device to increase the gas pressure in the tank before the operation.

[Problems to be solved by the invention]

When one of the above-mentioned conventional silicone liquids is used, it is more difficult to flow than mineral oil because of its high viscosity. Therefore, in order to obtain the same cooling capacity as in the case of using mineral oil, it is necessary to increase the cross-sectional area of the flow path, and the size of the device is increased accordingly, which is a problem that is difficult to apply to a large capacity device. Since it is often installed underground or inside a building, it is necessary to make it highly flame-retardant as much as possible. However, when a silicone liquid begins to undergo thermal decomposition at about 200 ° C and is immediately overloaded or an accident occurs, There was a demand to further increase the flame retardance because it would reach that temperature.

On the other hand, when the perfluorocarbon liquid is used, it is superior to the silicone liquid in terms of cooling and nonflammability, but SF ₆
Since the gas absorption and the temperature change of the gas absorption are large, the gas pressure of SF ₆ gas may fluctuate greatly and the insulation strength of the lead wire exposed to the gas may be reduced. There was a problem that required a mechanism. Further, if the lead wire is dipped in the perfluorocarbon liquid in order to avoid such a problem, there is a problem that the cost of the perfluorocarbon liquid increases significantly because the price of the perfluorocarbon liquid is very high.

The present invention has been made in view of the above points, and it is possible to improve cooling performance, flame retardancy, maintain the insulation strength of lead wires, and reduce the amount of expensive low-viscosity highly flame-retardant insulating liquid used. It is an object of the present invention to provide a stationary induction electric machine.

[Means for solving problems]

The above-mentioned object is that the insulating medium is composed of one insulating liquid having a lower viscosity and a higher flame retardance than the other, and the other insulating liquid having a higher viscosity and a lower flame retardant than the other, and a low viscosity and a high flame retardance. Insulation liquid is placed between the iron core and windings and the tank to fill the insulating container that accommodates the iron core and windings, and is circulated through a cooler with a pump, and also has high viscosity and low flame retardant insulation. This is accomplished by filling the gap between the insulating container and the tank with liquid.

[Action]

Since the insulating liquid in the insulating container has a low viscosity, it flows easily even if the gap is narrow, and the flow rate is large and it cools well, so that the cooling performance is improved and the flow path of the insulating liquid in the winding or the iron core, so-called duct The height can be reduced and the winding and iron core do not become large. In addition, since the flame resistance is high, it can withstand even higher temperatures of the winding and the iron core, which are the main heat generation sources soaked, and the flame resistance of the entire static induction electric machine is improved.

Unlike the gas, the insulating liquid in the gap between the tank and the insulating container does not significantly change the dielectric strength due to the pressure, so that the insulation of the lead wire can be stably maintained. Also, since there is almost no heat generated between this tank and the insulating container and the temperature is low, it can withstand even low flame retardance sufficiently, and by that amount of expensive low viscosity insulating liquid with high flame retardance The amount used can be reduced and the cost increase can be suppressed.

〔Example〕

Hereinafter, the present invention will be described based on the illustrated embodiments.
FIG. 1 shows an embodiment of the present invention. As shown in the figure, the static induction electric generator 1 includes an iron core 2, a winding 3 wound around the iron core 2, the iron core 2 and the winding 3.
It is provided with a tank 4 for storing the above, an insulating medium filled in the tank 4, and a cooler 5 and a pump 6 arranged outside the tank 4. In the static induction device 1 configured as described above, in this embodiment, the insulating medium is one insulating liquid 7 having a lower viscosity than the other and a high flame retardance, and the other insulating liquid 7 is a high viscosity and a low flame retardant insulating liquid. 8, an insulating liquid 7 having low viscosity and high flame retardancy is provided between the iron core 2 and the winding 3 and the tank 4, and the iron core 2 and the winding 3 are housed in an insulating container 9. Insulation container 9 is filled with insulating liquid 8 having high viscosity and low flame retardancy, which is circulated through cooler 5 by pump 6.
Filled the gap between the tank and the tank 4. By doing so, the cooling performance and flame retardancy of the stationary induction machine 1 are improved,
The insulation strength of the lead wire 10 is maintained, and the amount of the expensive low-viscosity and highly flame-resistant insulating liquid 7 used is reduced, so that the cooling performance, the flame retardancy are improved, and the insulation strength of the lead wire 10 is maintained. It is possible to obtain the static induction electric device 1 capable of reducing the amount of the expensive insulating liquid 7 having low viscosity and high flame retardancy.

That is, the iron core 2 and the winding 3 wound around the iron core 2 are housed in an open insulating container 9, which is then housed in a tank 4. Lead wire penetrating the insulating container 9 from the center of the winding 3.
Pull out 10 and connect to bushing 11. The insulating container 9 is filled with the insulating liquid 7 having low viscosity and high flame retardancy, and the gap between the insulating container 9 and the tank 4 is filled with the insulating liquid 8 having high viscosity and low flame retardancy. In the gap between these liquid levels and the tank 4, gas
Fill 12 and pressurize the liquid surface. The cooler 5 and the pump 6 arranged outside the tank 4 are connected to the insulating container 9 by the pipe 13.

When the static induction generator 1 configured as described above is operated, a large amount of heat is generated as iron loss from the iron core 2 and copper loss from the winding 3, and the temperatures of the iron core 2 and the winding 3 rise. The heat is received by the insulating liquid 7 and circulated by the pump 6, so that the heat is guided to the cooler 5 and dissipated to the outside to cool the iron core 2 and the winding 3. At that time, it is not enough to take the heat from the surfaces of the iron core 2 and the winding wire 3, so that a large number of ducts (not shown) are provided inside the iron core 2 and the winding wire 3, and the insulating liquid 7 It is also cooled from the inside through. By the way, the cooling capacity is proportional to the amount of the insulating liquid 7 flowing through the duct. The flow rate of the insulating liquid 7 is proportional to the height of the duct and inversely proportional to the viscosity of the insulating liquid 7. Therefore, when a constant cooling capacity is obtained, the height of the duct can be reduced by using the insulating liquid 7 having a low viscosity as in this embodiment. For example, when a perfluorocarbon liquid is used, its kinematic viscosity is about 1 to 2 cSt, which is much smaller than mineral oil's 10 cSt and silicone liquid's 50 cSt. It can be reduced to about / 5, about half that of mineral oil, and the core 2 and the winding 3 can be miniaturized not only when silicone liquid is used but also when mineral oil is used. Therefore, it is possible to increase the capacity. When the static induction electric device 1 enters an overload operation state or a short-circuit accident occurs inside or outside, the iron core 2 and the winding 3 become extremely hot. In this respect, according to this embodiment, since the insulating liquid 7 having low viscosity and high flame retardancy is in contact with the iron core 2 and the winding 3, the temperature affected is high. For example, when a perfluorocarbon liquid is used, its thermal decomposition temperature is about 500 ° C,
Much higher than about ℃. That is, the temperature difference flame retardancy is improved. As the insulating liquid 7 having low viscosity and high flame retardance, perfluorocarbons, perchlorethylene and the like are suitable.

A high voltage is applied between the lead wire 10 and the tank 4.
The insulation between the lead wire 10 and the tank 4 mainly depends on the dielectric strength of the insulating liquid 8 having a high viscosity and a low flame retardancy interposed therebetween. By the way, if gas is used instead of the insulating liquid 8, the dielectric strength of the gas varies greatly depending on the pressure. In the case of the static induction generator targeted by the present invention, the temperature greatly changes depending on the load condition, and the gas pressure also largely changes accordingly. Therefore, in order to obtain a stable dielectric strength, an adjusting mechanism for keeping the pressure constant is necessary. In that respect, in the case of the insulating liquid 8 of the present embodiment, since the dielectric strength hardly changes due to the pressure, the pressure adjusting mechanism is unnecessary.

Further, there is almost no heat generation source outside the insulating container 9, and the temperature is low. Therefore, it is sufficient that the insulating liquid 8 has lower flame retardancy than the insulating liquid 7 inside the insulating container 9. By the way, those with low flame retardancy are generally cheaper than those with high flame retardancy. In this respect, according to this embodiment, the amount of expensive insulating liquid 7 used can be reduced to about 1/3. For example, when perfluorocarbon is used as the insulating liquid 7 and silicone liquid is used as the insulating liquid 8, the price of each is about 100 and 10 when mineral oil is 1, and compared with the case where all of them are made of the insulating liquid 7. It is possible to reduce the cost by about 50% by looking at only the insulating liquid and about 20% for the whole static induction electric device. As the insulating liquid 8, in addition to silicone liquid, polybutene No. 3 oil having a flash point of about 200 to 300 ° C. is suitable.

Many insulating liquids 7 have high flame retardancy, but have relatively low boiling points at normal pressure. Therefore, there are cases where bubbles are generated by being heated inside the winding wire 3 and the iron core 2. Bubbles are gases, have a lower dielectric strength than liquids, and tend to be weak points in insulation. Therefore, the liquid surface is pressurized with the gas 12 to prevent generation of bubbles. If pressure is applied with a gauge pressure of about ² kg / cm ² which is a pressure container that does not make Taku 4 a pressure vessel according to legal regulations, bubbles will not occur at a use temperature of about 100 ° C. Gas 12 has a small amount of dissolution in insulating liquids 7 and 8 N ₂
Gas is preferred. As a material for the insulating container 9, an epoxy having high mechanical strength, high flame retardancy, and high insulation performance
FRP is preferred.

As described above, according to the present embodiment, the height of the cooling duct in the winding or the iron core can be reduced to 1/5, and can be reduced to about 1/2 compared with mineral oil, and the winding and the iron core can be downsized, so that the capacity can be increased. Is possible. In addition, the flame resistance is improved to around 300 ° C, the insulation strength of the lead wire is stable, and the amount of expensive and highly flame-retardant insulating liquid used is 1 /
It can be reduced to about 3.

FIG. 2 shows another embodiment of the present invention. In this embodiment, the tank 4 is filled with the insulating liquid 8 having high viscosity and low flame retardancy, and further a part of the conservator 14 is filled. At the interface between the insulating liquid 7 and the insulating liquid 8 having low viscosity and high flame retardancy, a mixing prevention plate 15 having a specific gravity intermediate between these is floated. Connect the bottom of the tank 4 and the top of the insulating container 9 with a pipe 16,
The pump 6a was arranged in the middle.

The static induction electric device 1a thus constructed is
11 is at the top of the tank 4. According to this embodiment, since the lead wire 10 is not exposed to the gas space, the insulation of the lead wire 10 can be stably maintained. If the insulating liquid 7 is a perfluorocarbon and the insulating liquid 8 is a silicone liquid, the specific gravities of the two liquids are 1.8 and 1.0, respectively, and the two liquids differ greatly, and both liquids do not react chemically. Do not mix. However, when the liquid is circulated by the pump 6, the liquid surface may be wavy and may mix with each other, so that the mixing prevention plate 15 prevents contact between both liquids. Even in this case, although they are mixed little by little, they are separated immediately, and perfluorocarbon has a large specific gravity and therefore accumulates at the bottom of the tank 4. This is returned by the pump 6a through the pipe 16. As a material for the mixing prevention plate 15, an acrylic plate or the like having a specific gravity between those of both liquids is suitable.

FIG. 3 shows still another embodiment of the present invention.
In this embodiment, the insulating container 9 is provided with a lid and the upper part is a conservator.
Place 14a. Place the conservator 14 in the tank 4,
Insulating liquids 7 and 8 are added to a part of the conservators 14a and 14 respectively. These conservators 14, 14a are connected by a pipe 17.

The static induction electric device 1b configured in this way is effective when the insulating liquid 7 and the insulating liquid 8 have similar specific gravities, or when both liquids are easily mixed due to easy chemical reaction. Since it is partitioned by the container 9, it does not mix.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, the present invention improves cooling performance and flame retardancy, maintains the insulation strength of lead wires, and reduces the amount of expensive low-viscosity highly flame-retardant insulating liquid used. ，
It is possible to obtain a static induction electric device capable of improving flame retardancy, maintaining the insulation strength of lead wires, and reducing the amount of expensive low-viscosity highly flame-retardant insulating liquid used.

[Brief description of drawings]

1 to 3 are longitudinal side views showing different embodiments of the static induction electric device according to the present invention. 1, 1a, 1b …… static induction electric generator, 2 …… iron core, 3 …… winding,
4 ... Tank, 5 ... Cooler, 6 ... Pump, 7 ... Low viscosity and highly flame-retardant insulating liquid, 8 ... High viscosity and low flame-retardant insulating liquid, 9 ... Insulating container.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kiyoto Hiraishi 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Kokubun Factory, Hitachi, Ltd. (72) Inventor Keizaburo Kawashima 1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1 No. 1 In the Kokubun Plant of Hitachi, Ltd. (72) Inventor Etsuo Oe 4026 Kujicho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi Ltd.

Claims (3)

(57) [Claims] 1. An iron core, a winding wound around the iron core, a tank for housing the iron core and the winding, an insulating medium filled in the tank, and a cooling arranged outside the tank. In a static induction electric machine equipped with a heater and a pump, the insulating medium is composed of an insulating liquid, one of which has a lower viscosity and a higher flame retardancy than the other, and the other of which has an insulating liquid of a higher viscosity and a lower flame retardant. , The low-viscosity and highly flame-retardant insulating liquid is provided between the iron core and the winding and the tank to fill an insulating container that accommodates the iron core and the winding, and the pump cools the cooler. A static induction electric device characterized in that the gap between the insulating container and the tank is filled with the insulating liquid having high viscosity and low flame retardancy. 2. The static induction electric device according to claim 1, wherein the insulating liquid having a low viscosity and high flame retardancy is a perfluorocarbon liquid. 3. The static induction electric device according to claim 1, wherein the insulating liquid having high viscosity and low flame retardancy is a silicone liquid.