JPH0799726B2 - Gas insulated static induction - Google Patents

Description

TECHNICAL FIELD The present invention relates to a gas-insulated static induction machine of natural circulation and natural cooling type.

[Conventional technology]

Fig. 11 or Fig. 11 shows the arrangement of the bushing for external drawing in a conventional gas-insulated static induction machine with natural circulation and natural cooling.
As shown in FIG. 12, a bushing 6 is attached to the upper end face or the upper side face of a tank 1 in which a main body 2 is housed and a high pressure resistant gas 5 such as SF ₆ gas is sealed as an insulating and cooling medium in an internal space. Was there. This is because the internal wiring and the external cable can be easily routed like a general oil-filled transformer. However, the convection of the gas circulating in the tank 1 and the radiator 9 dissipates heat and cools the main body 2. In the case of a natural circulation natural cooling type gas-insulated static induction electric machine that performs the above, since the gas temperature becomes higher in the upper part of the tank during operation, the bushing 6 is installed above the tank 1 as shown in FIGS. 11 and 12. When installed, the bushing 6 is located in the hottest part of the static induction machine.

As another bushing arrangement example, in a boiling cooling type transformer,
As described in Japanese Utility Model Laid-Open No. 59-166426, it is better to arrange the bushings in the condensate, which has better insulation performance than the vapor of the insulation and cooling medium, between the bushings and between the bushing and the grounded portion. Since the distance can be shortened, there is a type with a bushing attached to the lower side of the tank in consideration of the space inside the tank.
As described in No. 60-57110, in order to match the lead wire withdrawal position from the coil and the height, a bushing storage pocket is provided in the center of the side surface of the tank, and a bushing is attached to the tip of the pocket.

However, in the example of the boiling cooling type transformer, the temperature difference between the upper and lower parts of the tank due to convection of the condensate with high thermal conductivity is relatively small at about 10 ° C, so even if the bushing is arranged at the lower part of the tank, The temperature of the part is not much different from the temperature of the hottest part of the transformer, and in the above oil-filled transformer example, the bushing installation position is close to the oil level, so the bushing is placed almost at the hottest part of the transformer. Will be there.

Therefore, in all of these conventional techniques, it is necessary to use, as the material of the bushing, a material having an allowable temperature of the same degree as that of the content body. In particular, the natural circulation natural cooling type gas-insulated static induction equipment usually uses Class E or higher as the heat-resistant classification of the main body for economic reasons, size and electrical performance, and to improve insulation. Since the enclosed gas pressure is as high as about 1 kg / cm ² in gauge pressure, the bushing has a high allowable operating temperature in consideration of sealing performance.
In addition, heat-resistant epoxy resin bushings with good dimensional accuracy were used.

[Problems to be solved by the invention]

As described above, in the conventional natural circulation natural cooling type gas-insulated static induction electric device, the bushing was attached to the upper part of the tank, which is the highest temperature part. It is necessary to use a heat resistant epoxy resin bushing that can withstand high temperature use at the same level as, and this heat resistant epoxy resin bushing has a high allowable temperature because it needs to improve crack resistance and thermal stability at high temperatures. Since an expensive heat-resistant epoxy resin is used as the material, not only is the price twice as high as the general type epoxy resin bushing made by JEC-211 (epoxy resin bushing), but it is also a resin for improving heat resistance and mechanical strength. The breakdown voltage is lowered due to the effect of the additive mixed in, and the size of the bushing is increased to compensate for the breakdown voltage.

Further, since the bushing mounting portion becomes hot, a heat-resistant material such as fluorine rubber is used for the sealing material 7 such as an O-ring interposed in the bushing mounting portion, or a heat resistant crosslinked polyethylene cable is used as an external cable connected to the bushing. It is necessary to use a heat-resistant cable such as the above, and in consideration of heat deterioration of the seal material, the seal material 7 of the bushing mounting portion is arranged in double to improve reliability, and the seal structure becomes complicated. Was there.

An object of the present invention is to use a material having an allowable temperature lower than that of the main body for an accessory for external drawer such as a bushing, to make it thermally and electrically stable and compact, and to provide gas insulation. The aim is to reduce the size of static induction electric appliances and improve their reliability and economy.

[Means for solving problems]

The above object is to provide a transformer main body having an iron core and a winding,
Natural circulation natural cooling type gas insulation equipped with a tank that stores the main body of the contents, an insulating cooling medium enclosed in this tank internal space, and a radiator that is connected to the side surface of the tank and into which the insulating cooling medium flows In the static induction machine, SF ₆ gas sealed as an insulating cooling medium and an external drawing bushing located below the tank are provided, and the lead wire is drawn out from the lower part of the winding and connected to the external drawing bushing. This can be achieved by setting the difference in gas temperature between the upper part of the tank and the lower part of the tank during operation to be larger than 15 ° C and keeping the gas temperature of the lower part of the tank below 90 ° C.

[Action]

In a gas-insulated static induction machine of natural circulation and natural cooling system, a gas temperature difference occurs between the upper part and the lower part of the tank during operation due to convection of gas in the tank. This temperature difference depends on the thermal characteristics of the gas, the shape of the windings, the performance of the cooling device, and many other factors, but the thermal conductivity of the gas is relatively small, so an oil-filled transformer or a boiling cooling type transformer is used. The temperature difference between the upper and lower parts of the tank tends to be larger than that of the above.

Normally, on the tank, the cooling design is made so as to suppress the difference in gas temperature below 10 to 15 ° C, but in the present invention,
On the contrary, the difference in the gas temperature above and below the tank is set to a relatively large value to lower the gas temperature below the tank below the normal level, and bushings are placed in this low temperature part (the winding cooling duct of the main body and the side of the tank). By narrowing the gas flow path such as the radiator to be connected to, or reducing the enclosed gas pressure, the difference in gas temperature above and below the tank becomes large). By doing so, it is possible to use, for the bushing, a material having a low allowable temperature corresponding to at least one class lower than the heat resistance of the content body. For example, as shown in the temperature distribution example in Fig. 2, when the heat resistance classification of the main body of the contents is set to Class E, and the gas temperature near the upper part of the tank h ₁ is set to 120 ° C, which is the allowable temperature for Class E insulation, When a cooling design is made so that the difference in gas temperature between the two is 40 ° C, the gas temperature near the bottom of the tank h ₂ is 80 ° C.
As the bushing, a general epoxy resin bushing (JEC-211) with a low allowable temperature (about 90 ° C) equivalent to type A insulation can be used.

Further, as the temperature of the bushing attachment portion decreases, it is possible to use a sealing material of the bushing attachment portion and an external cable connected to the bushing, which has a lower permissible temperature than the content body (corresponding to type A insulation).

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

The main body 2 of the static induction electric device consisting of the winding wire 3, the iron core 4, the winding support insulator 14, the iron core fastening member 16, the fastening metal member-iron core insulator 17 is housed in the tank 1, and the inner space of the tank 1 is A high pressure resistant gas 5 such as SF ₆ gas is enclosed as an insulating and cooling medium. A radiator 9 is attached to the side surface of the tank 1,
Through this, the gas in the tank 1 is circulated by convection. The external drawing bushing 6 is attached to the lower side surface of the tank 1 via a sealing material 7, and a lead wire 8 drawn from the lower part of the winding 3 is connected to one end of the bushing 6, and the other end of the bushing 6 is illustrated. No External cable is connected. Reference numeral 15 is a tap changer connected to the winding 3, and 18 is a supply / exhaust valve arranged in the lower portion of the tank 1.

FIG. 2 shows the temperature in the tank height direction when the cooling design is performed so that the gas temperature near the tank upper portion h ₁ is 120 ° C. and the gas temperature near the tank lower portion h ₂ is 80 ° C. in this embodiment. In the figure showing an example of distribution, in this case, a general epoxy resin bushing having an allowable temperature of about 90 ° C. can be used for the bushing 6 arranged at the bottom of the tank. The general epoxy resin bushing is much cheaper and more economical than the heat-resistant epoxy resin bushing used in the conventional gas-insulated static induction electric device. According to this embodiment, since the bushing 6 is used in a relatively low temperature range of 90 ° C. or lower, thermal and electrical stable performance can be obtained even with a general epoxy resin bushing having a relatively low allowable temperature, Since the accuracy is good, there is no problem in terms of sealing performance. Also, compared to heat-resistant epoxy resin bushings, the amount of additives mixed in the resin for improving heat resistance and mechanical strength may be small, so reduction in breakdown voltage due to additives can be avoided, and bushings can be made smaller, As a result, it is possible to reduce the size of the gas-insulated static induction generator.

Similar to the bushing, other conductive parts such as the tap changer 15 are also arranged at the lower part of the tank, so that the allowable temperature of the insulating material can be lowered and an inexpensive material such as a general type phenol resin laminated material can be used.

For the main body 2 of the contents, when the tank upper temperature is 120 ° C., it is necessary to adopt the class E insulation for the winding 3, but the winding support insulator 14, the clamp / inter-core insulator 17, and the winding For the material of the internal insulation structure such as the duct piece placed inside the wire, the upper and lower parts are divided into heat-resistant sections. For example, only the upper part uses the E class insulating material and the lower part uses the A class equivalent insulating material. The material cost can be reduced. If the heat resistance classification of the main body 2 is upgraded to Class B or Class H, and the temperature difference between the upper and lower tanks is further increased by lowering the enclosed gas pressure, the insulating structure placed at the bottom of the paper body will have an upper part. It is also possible to use a material that is two classes below the heat-resistant category of the insulating structure to be placed in.

As for the sealing material (gasket) of the parts to be attached to the tank, as in the case of the above-mentioned internal structure insulator, those arranged in the high temperature region of the upper part of the tank such as the upper connection part of the radiator 9 are equivalent to Class E insulation such as fluororubber. Although it is necessary to use a heat-resistant material, a sealant such as the lower connection portion of the radiator 9 originally placed in the low temperature region of the lower part of the tank, the supply / exhaust valve 18 or the bushing 6 arranged in the lower part of the tank according to the present invention. about,
Inexpensive general-purpose materials such as nitrile rubber having a relatively low allowable temperature can be used. Further, since the bushing 6 is arranged in the low temperature region of the lower portion of the tank, the progress of heat deterioration of the seal material 7 at the bushing mounting portion is delayed and the reliability can be improved. Therefore, the seal structure is also provided with a single O-ring. It will be good and the structure can be simplified.

3 to 10 show another embodiment of the present invention.

In the embodiment of FIG. 3, a horizontal cylindrical bushing storage pocket 12 is provided on the lower side surface of the tank 1, and a bushing 6 is attached to the tip of the storage pocket 12 so as to communicate with the lower portion of the tank. By adopting the structure with the bushing storage pocket, the gas temperature of the bushing mounting portion becomes lower than the gas temperature in the tank due to the radiation cooling of the pocket portion, and as a result, the temperature of the bushing mounting portion is lowered as compared with the embodiment of FIG. be able to.

In the embodiment shown in FIG. 4, a radiation fin 13 is added to the bushing storage pocket 12 in the embodiment shown in FIG. 3, and it has the effect of further reducing the temperature of the bushing mounting portion.

In the embodiment shown in FIG. 5, when the bushing 6 is mounted upward in the bushing storage pocket 12, heat insulation from the side surface of the tank is achieved by attaching the heat insulating material 20 to the inner wall portion of the bushing storage pocket 12 along the side surface of the tank 1. Suppresses the influence of conduction and keeps the gas temperature in the bushing storage pocket 12 in the tank 1.
It is aimed at approaching the temperature at the bottom of.

In the embodiment of FIG. 6, the bushing 6 is attached downward at a position lower than the bottom of the tank 1 of the bushing storage pocket 12, the bushing attachment portion is set to the lowest gas temperature portion, and the bushing 6 is inserted into the underfloor pit 21, Wiring work with the cable in the pit is easy.

The embodiment shown in FIG. 7 corresponds to the content main body 2 in the embodiment shown in FIG.
The height of the bushing 6 mounted on the lower side surface of the tank 1 is relatively lowered by raising the table 19 by the base 19, and this also has the effect of lowering the gas temperature of the bushing mounting portion.

In the embodiment shown in FIG. 8, in addition to the bushing 6 in the embodiment shown in FIG. 1, a relay bushing 10 is attached to the upper side surface of the tank 1 with a stay 22, and a relay cable is provided between the bushing 6 and the bushing 6.
This method has the advantage of facilitating the cable wiring work when the external cable is drawn from above the tank 1. The relay bushing 10 used here is
Inexpensive aerial bushings that do not require heat resistance or sealing properties may be used.

The embodiment shown in FIG. 9 has an L-shaped bushing storage pocket 12
Is mounted on the lower side surface of the tank 1 and the bushing 6 is arranged at the same height as the upper surface of the tank 1 to facilitate the wiring work of the external cable as in the embodiment of FIG. The temperature is kept almost the same as the gas temperature at the bottom of the tank.

In the embodiment shown in FIG. 10, the radiating fins 23 are provided in the space left by moving the bushing 6 which has been conventionally arranged on the upper portion of the tank to the lower portion of the tank according to the present invention. It is a generally known phenomenon that the heat radiation effect becomes higher at higher temperature parts.In particular, in a gas-insulated static induction electric generator, since the ratio of radiative cooling to the entire cooling effect is large, the heat radiation fin 23 should be provided at the upper part of the tank. As a result, there is an effect that the temperature difference between the upper and lower sides of the tank is compressed so that the temperature difference between the upper and lower sides of the tank does not become too large and the design becomes uneconomical.

〔The invention's effect〕

According to the present invention, since the external drawer bushing is arranged in the lower portion of the tank where the gas temperature is relatively low or the bushing storage pocket communicating with the lower portion of the tank during operation, even if the heat-resistant category of the main body of the content is E type, Does not require the use of expensive heat-resistant epoxy resin bushings that match the heat resistance classification of the main body as in the past, but uses inexpensive epoxy such as general epoxy resin bushings that have a lower allowable temperature than the main body and are equivalent to Class A insulation. It can be used, and because the amount of additives mixed in the resin can be small to improve heat resistance and mechanical strength, it is possible to avoid lowering the breakdown voltage due to the additives, and it is possible to downsize the bushing. As a result, cracks are less likely to occur, and thermal and electrical stability and durability of the bushing are improved. Furthermore, as the temperature of the bushing attachment portion decreases, an inexpensive material with a low allowable temperature can be used as the sealing material of the bushing attachment portion.
Gas-insulated static induction equipment, such as the simplified arrangement of the bushing attachment part as a double arrangement, and the use of a cross-linked polyethylene cable for general atmosphere instead of the heat-resistant cross-linked polyethylene cable that was conventionally used for the external cable connected to the bushing. Overall compactness, reliability and economic efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of an embodiment of the present invention, FIG. 2 is a diagram showing an example of temperature distribution in the tank height direction, and FIGS. 3 to 10 are side sectional views of another embodiment of the present invention. FIG. 11, FIG. 11 and FIG. 12 are side sectional views of a conventional example. 1: Tank, 2: Main body, 5: Gas, 6: Bushing for external drawer, 12: Bushing storage pocket.

Claims (1)

[Claims] 1. A transformer main body having an iron core and a winding,
A natural circulation natural cooling system including a tank that stores the main body of the contents, an insulating cooling medium that is enclosed in the internal space of the tank, and a radiator that is connected to the side surface of the tank and into which the insulating cooling medium flows. In a gas-insulated static induction machine, SF ₆ gas enclosed as the insulating cooling medium,
An external withdrawing bushing disposed below the tank is provided, and a lead wire is pulled out from the lower portion of the winding to be connected to the external withdrawing bushing, and a difference in gas temperature between the upper and lower portions of the tank during operation is provided. Is set to be higher than 15 ° C and the gas temperature in the lower part of the tank is set to 90 ° C or lower.