JPS62281409A - Foil-wound transformer - Google Patents

Abstract

PURPOSE:To obtain a foil-wound transformer having good cooling characteristics by preventing evaporation of a cooling medium in a cooling system by applying a pressure of an insulating gas to the lowest pressure part of a cooling medium system. CONSTITUTION:In a cooling medium system of a foil-wound transformer, a cooling medium pipe 17 is connected to the vicinity of an entrance side of a pump 8 to introduce a cooling medium 7 and an insulating gas pipe 18 is connected to a part of a tank 13 to introduce an insulating gas 14, respectively into each chamber of a pressing container 15 having two chambers and a variable partition 16. The insulating gas 14 is enclosed in the tank 13 at 3 kg/cm<2> or more in order to increase usual dielectric strength, so that the cooling medium 7 in the pressing container 15 is applied the same pressure as the insulating gas 14. Accordingly, in a cooling system, even near an outlet of a cooling duct 6 where the temperature of a cooling medium becomes the maximum locally, the pressure is 3 kg/cm<2> or more, so that the cooling medium 7 does not boil even when the maximum temperature about 80 deg.C is attained. Therefore, evaporation of the cooling medium 7 does not occur in the cooling duct 6 and cooling is carried out by the liquid-state cooling medium 7 constantly.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Purpose of the Invention] (Field of Application in M Industry) The present invention provides a method for forming a foil-wound coil in which a foil-like conductor and an insulating sheet are overlapped and wound around an iron core. This invention relates to a foil-wound transformer with a built-in cooling duct.

(Prior Art) Foil-wound transformers have a good space factor for foil conductors, so they have the advantage of being smaller and lighter than conventional transformers using linear conductors. However, in order to apply it to higher-voltage, larger-capacity transformers, it is necessary to improve the cooling capacity of the coil and provide the coil with high insulation capacity. For this reason, a cooling duct is built into the coil of the foil-wound transformer so that it overlaps with the coil, and a refrigerant is fed into the cooling duct to directly cool the heat generated from the conductor.

This type of conventional foil-wound transformer has an iron core 1, as shown in Figure 2.
A foil-shaped conductor 2 and an insulating sheet 3 are layered and wound on the outside to form a foil-wound coil, and a low-voltage coil 4 and a high-voltage coil 5 are formed.
wind it. An annular cooling duct 6 is built into each of these coils so as to be overlapped with each other. This cooling duct 6 is formed with a thin space through which a refrigerant 7 such as Freon R113 or Fluorinert FC75 can flow. This refrigerant 7 is circulated by a pump 8 to a cooler 9 to remove heat from the foil-wound coil, and the heated refrigerant is cooled by 1° of cooling water in the cooler 9 or by air. This cooled refrigerant further flows through a refrigerant circulation circuit where it is sent into the cooling duct 6 by a pump 8. A plurality of cooling ducts 6 are provided inside the coil, and each cooling duct 6 has a liquid collecting pipe 11 so that the refrigerant can flow in and out in a concentrated manner on its soaking or outflow side.
It is connected to the.

Since this liquid collecting pipe 11 is made of metal such as stainless steel, the inflow and outflow passages of each cooling duct 6 are connected with an insulated pipe 12 to maintain insulation from the cooling duct 6, and the liquid collection pipe 11 is connected to the ground potential along with the tank 13. It becomes. The insulating pipe 12 is made flexible in order to absorb vibrations of the coil during energization and transportation. The potential of the cooling duct 6 is electrically coupled to the same potential as the foil-like conductor because it is wound inside the coil. The entire coil is insulated by an insulating gas 14 such as SF or gas sealed in a tank 13.

Note that in FIG. 2, the lead wire from the conductor and the bushing that leads it out to the outside of the tank are omitted. In addition, this type of foil-wound transformer is called a separate foil-wound transformer because the circulation circuit through which the refrigerant for cooling flows and the insulating medium 14 for insulation are completely separated. I'll decide. A known example of this method is US Pat. No. 4,039,990.

(Problem to be solved by the invention) In a conventional separate foil-wound transformer, a conservator 20 is installed near the cooler 9 (at the top of the transformer) in order to absorb the volume change caused by the temperature change of the refrigerant. The interior is divided into two chambers by a movable partition wall 16, air 212 is placed on one side, and refrigerant 7 is introduced into the other side to apply atmospheric pressure to the refrigerant 7. On the other hand, the pressure of the refrigerant system is distributed such that pressure loss occurs in the cooling duct 6 and the piping system, and is lowest at the inlet of the pump 8 and highest at the outlet of the pump 8. In the conventional example, the pressure is almost atmospheric near the outlet of the cooling duct 6, which has the largest pressure loss in the piping system.
Refrigerant, especially R113 with a close boiling point (boiling point 5 at atmospheric pressure)
4° C.), the temperature of the refrigerant reaches a maximum of about 80° C. near the exit of the cooling duct 6, so boiling occurs within the cooling duct 6. When boiling occurs in the cooling duct 6, liquid and vapor coexist inside the cooling duct 6, and the vapor makes it difficult to supply the liquid, resulting in a decrease in cooling efficiency.

The present invention was made in view of the above problems, and its purpose is to prevent evaporation of refrigerant within the cooling system by constantly applying insulating gas pressure to the lowest pressure part of the refrigerant system. The purpose is to obtain a foil-wound transformer with excellent cooling characteristics.

[Structure of the invention]

(Means for Solving the Problems) The foil-wound transformer of the present invention has a cooling duct built into the foil-wound coil through which a liquid refrigerant flows, and this is housed in a tank together with a pressurized insulating gas. A pipe connected to the pump inlet of this cooling system and a pipe connected to the tank draw the refrigerant and the insulating gas into both chambers sandwiching the partition wall inside the container, which has a movable partition wall. The same pressure as the insulating gas is applied to the refrigerant.

(Function) By doing this, the same pressure as the insulating gas is applied to the refrigerant, and therefore, in the cooling system, the pressure is high even near the exit of the cooling duct where the temperature of the refrigerant is locally highest. Therefore, even if the maximum temperature of the refrigerant becomes high, the refrigerant does not boil, and therefore evaporation of the refrigerant does not occur in the cooling duct, and cooling is always performed by the liquid refrigerant.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a foil-wound transformer according to the present invention. Note that the same parts as in FIG. 2 are given the same reference numerals, and detailed explanation thereof will be omitted. The foil-wrapped transformer according to the present invention differs from conventional examples in that in the refrigerant system, a refrigerant pipe 17 is connected near the inlet side of the pump 8 to feed the refrigerant 7, and an insulating gas pipe 18 is also connected to a part of the tank 13. The insulating gas 14 is guided into each chamber of a pressurized container 15 having a movable partition wall 16 and two chambers. As the movable partition wall 16, for example, a stainless steel bellows or a rubber wall is used.

Insulating gas 14 is usually 3 kg/a to increase dielectric strength.
It is sealed in the tank 13 at a pressure of 1 (gauge pressure) or more.

The same pressure as the insulating gas 14 is applied to the refrigerant 7 in the pressurized container 15 . Therefore, in the cooling system, even near the exit of the cooling duct 6, where the temperature of the refrigerant is locally highest, the pressure is over 3 kg/ad (gauge pressure), so the refrigerant 7 will not boil even if the maximum temperature reaches about 80°C. Therefore, evaporation of the refrigerant 7 does not occur in the cooling duct 6, and cooling is always performed with the liquid refrigerant 7. As a result, refrigerant 7
The cooling properties can also be significantly improved by increasing the local temperature.

〔Effect of the invention〕

As described above, according to the present invention, a cooling duct through which liquid refrigerant flows is built into the foil-wrapped coil, and this is housed in a tank together with pressurized insulating gas, and the cooling duct is installed at the pump inlet of the cooling system. The refrigerant and the insulating gas are respectively drawn into the two chambers sandwiching the partition wall in a container having a movable partition wall by the connected pipe and the pipe connected to the tank, and the refrigerant is brought to the same pressure as the insulating gas in the container. Since the evaporation of the refrigerant can be prevented, an efficient refrigerant flow can be obtained, and a foil-wound transformer with excellent cooling characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a foil-wound transformer according to the present invention, and FIG. 2 is a schematic diagram of a conventional foil-wound transformer. 7... Refrigerant 14... Insulating gas 15... Pressurized container 16... Movable bulkhead 17... Refrigerant pipe 18... Insulating gas pipe 20... Conservator 21... Air agent Patent attorney Shi Nori Chika Ken Yudo Hirofumi Mitsumata Figure 1 Figure 2

Claims (1)

[Claims] A refrigerant duct through which refrigerant flows is built into the foil-wound coil, which is made by stacking a foil conductor and an insulating sheet and wrapping it around an iron core.
In a foil-wrapped transformer in which this is housed in a tank together with a pressurized insulating gas, the refrigerant and insulating gas are transferred through a pipe connected to the pump inlet of the refrigerant system and a pipe connected to the tank, respectively. A foil-wound transformer characterized in that the refrigerant is drawn into both chambers sandwiching the partition wall in a container having a movable partition wall, so that the same pressure as the insulating gas is applied to the refrigerant inside the container.