JPS62244114A - Foil-wound transformer - Google Patents

Abstract

PURPOSE:To improve reliability on cooling in case of overload by a method wherein common pipings are mounted to the fronts and rears of a plurality of pumps and an inlet for a cooler, the rating of the pumps is set to a cooling flow demand or more in a winding on the stationary time, a flow rate is adjusted by a bypass piping on normalcy, the bypass piping is closed on the abnormality of the pumps and overload and the same flow rate as the stationary time is fed in the winding. CONSTITUTION:Check valves 15, 15' are each fitted to a plurality of pumps 7, 7 ', and a bypass piping 17 is arranged between common pipings 14b, 14c. A valve 16 is set up to the bypass piping 17, and regulates a flow rate flowing through the bypass piping 17 while filling the roles of the closing of the bypass piping 17 on the abnormality of the pumps and on overload and the readjustment of the flow rate of the bypass and the like. A flow rate more than a flow demand or more in windings is circulated through the bypass piping 17 on normalcy at rating, and the valve 16 is closed or adjusted on the abnormal stop of the pumps or on overload and a refrigerant at necessary quantity flows through liquid-introducing pipes 11, thus preventing the damage of reliability on cooling even on overload even when the pumps get trouble.

Description

DETAILED DESCRIPTION OF THE INVENTION (Objective of the Invention) (Field of Industrial Application) The present invention relates to a technology for improving cooling reliability of a foil-wound transformer.

, (Prior art) Foil-wound transformers have a good winding space factor and can be made smaller and lighter, so they are already used as small-capacity transformers with relatively low voltages of several KV or several hundred KVA. It has been put into practical use. In recent years, in view of its excellent advantages, research has been conducted to expand its application to higher voltage, such as 275KV and 300MVA class transformers. The important issues are whether the winding can be made to withstand the radial mechanical force in the event of a short circuit accident. Although such high-voltage, large-capacity transformers have not yet been put into practical use, as shown in Figure 5,
A cooling panel is built into the winding, and a refrigerant with excellent insulating properties is fed into this cooling panel, and the heat generated from the winding loss is cooled using the latent heat of evaporation of the refrigerant. A transformer is likely.

That is, this BW transformer has metal sheets 2 on the legs 1 of the iron core.
A low-voltage winding 4 and a high-voltage winding 5, which are formed by overlapping and winding an insulating sheet 3, are wound, and a hollow cooling panel 6 is built into these windings.

In the thin gap in the hollow part of the cooling panel 6, Freon R-1
A refrigerant such as 13 or Fluorinert FC75 is sealed in the refrigerant, which is circulated by a pump 7, and the heat generated within the winding is absorbed by the refrigerant's latent heat of evaporation. ing. A cooling system is constructed in which the liquefied refrigerant is stored in a refrigerant tank 10 and further fed into the windings by a pump 7. Note that the cooling system generally has multiple configurations, and the common piping 14a,
Between 14c cooler io, io', pump 7.7
′ is attached to multiple numbers.

The liquid guide pipe 11 constituting the cooling system is made of metal such as stainless steel, and the liquid guide pipe 11 and the cooling panel 6 are connected via an insulating pipe 12 made of Teflon resin or the like. The liquid guide pipe 11 is also connected to the ground potential of the tank 13 and the like. On the other hand, since the cooling panel 6 is incorporated into the winding, it is electrically connected to the same potential as the adjacent winding.

Furthermore, the insulation inside the winding is provided by S sealed in the tank 13.
This is ensured by an insulating gas such as F6 gas.

(Problems to be Solved by the Invention) By the way, various foil-wound transformers such as those described above are constructed by overlapping and winding thin metal sheets 2 and insulating sheets 3 to form low-voltage windings 4 and high-voltage windings. 5, it has the advantage of increasing the winding space factor within the core window, but on the other hand, it has the following problems.

In other words, in Fig. 5, the capacity of the pumps 7 and 7' is the rated flow rate, so in the unlikely event that the pump fails or there is a problem such as a blockage in the cooling pipe, the winding cooling flow rate will decrease.
There was a risk of thermal damage to the winding insulation. A method of installing a backup pump for this purpose has also been adopted, but this is uneconomical as it also requires a backup cooler.

In addition, it has been desired to introduce a system that has poor overload tolerance and can change the flow rate depending on the load.

The present invention was made in view of the above-mentioned conventional problems, and it is possible to maintain a constant flow rate in the winding direction even when there is a malfunction in the cooling pump or cooling system, and it is possible to maintain the flow rate in the winding direction constant not only in the case of a malfunction but also in the case of overload. The purpose is to obtain a foil-wound transformer with improved reliability.

[Structure of the invention]

(Means and effects for solving the problem) In the present invention, a plurality of cooling panels, a plurality of coolers, and a pump are used, and common piping is provided at the inlet of the cooler and the outlet of the pump. , the pump rating is set higher than the required flow rate for cooling inside the windings during normal operation, the flow rate is adjusted using the bypass piping during normal operation, and when the pump is abnormal or overloaded, the bypass piping is closed and the same flow rate as during normal operation is supplied to the inside of the windings. It has been made possible.

(Example) Examples of the present invention are shown in FIGS. 1, 2, and 3. 1st
In the figure, a plurality of pumps 7, 7' each have a check valve 15.
．． 15' is attached to the common pipe 14b.

Bypass piping 17 is arranged between 14c. A valve 16 is attached to the bypass pipe 17 and the bypass pipe 1
In addition to regulating the flow rate flowing into the pump 7, the pump also plays the role of closing the bypass piping 17 and readjusting the bypass flow rate when the pump is abnormal or overloaded.

In FIG. 2, the bypass pipe 17 is connected to the common pipes 14c and 14.
It is placed between A and A.

FIG. 3 shows a state in which the bypass pipe 17 shown in FIG. 2 passes through the tank 13, and in particular cools the insulating medium 19 thereby.

In Fig. 1, a flow rate greater than the rated flow rate required in the winding is normally circulated through the bypass piping 17, and when the pump stops abnormally or is overloaded, the valve 16 is closed or adjusted. Since a required amount of refrigerant flows through the liquid guide pipe 11, cooling reliability will not be impaired even if the pump malfunctions or is overloaded. Moreover, according to such a system, cooling reliability can be improved without adding a new backup pump or backup cooler.

The same can be said about FIG. 2 as well. On the other hand, in the case shown in Figure 3, the bypass piping 17 is used effectively, and during normal operation, it also serves to cool the surrounding insulating medium 19, and when the pump is abnormal, priority is given to cooling the inside of the winding, which is a basic method. The operation and effect are exactly the same as in the case of FIG. Further, since pump abnormality and bypass control can be automatically driven by some kind of signal, cooling reliability is not degraded.

The present invention is not dependent on the type of insulating medium 19, and can be applied in exactly the same way whether it is cattail, oil, or other materials. In the present invention, in FIGS. 1 to 4, 1
Although the description has been made regarding the leg windings, the present invention can be similarly applied when there are multiple windings, and can be applied to single-phase, three-phase, single-tank, and multiple-tank cases.

Although the present invention requires a plurality of pumps and coolers, the number is not limited. In the present invention, the pump sound interval is set to be greater than the required flow rate in the winding, but of course, the same effect can be obtained even if one standby pump is installed in the common piping, as shown in FIG.

(Effects of the Invention) As explained above, according to the present invention, a conductor sheet and an insulating sheet are overlapped and wound around an iron core, a cooling panel is built inside, and the cooling panel is stored in a tank together with an insulating medium. In foil-wrapped transformers that flow refrigerant using pumps, common piping is installed before and after the multiple pumps and at the cooler inlet, and each pump piping is equipped with a check valve and a cooling panel bypass piping with a valve in the middle is installed. Since the above-mentioned structure is attached, it is possible to obtain a foil-wound transformer with improved cooling reliability.

[Brief explanation of drawings]

1, 2, and 3 are cross-sectional views showing different embodiments of the gas insulated transformer according to the present invention, FIG. 4 is another embodiment, and FIG. 5 is a cross-sectional view of a conventional gas insulated transformer. FIG. 1 is a sectional view showing an example. 1... Legs of iron core 2... Metal sheet 3...
・Insulating sheet 4...Low voltage winding 5...High voltage winding 6...Cooling panel 7...Pump
10...Cooler 11...Liquid guide pipe
12... Insulated pipe 13... Tank 1
4...Common piping 15--Check valve 16-
...Valve 17...Common piping 18...Spare pump 19...Insulating medium agent Patent attorney Rule Noriyuki Chika Yudo Hirofumi Mitsumata Figure 1 Figure 4 Figure 5

Claims (6)

[Claims] (1) A foil-wound transformer in which a conductor sheet and an insulating sheet are layered and wound around an iron core, a cooling panel is built inside, and the cooling panel is stored in a tank together with an insulating medium, and the refrigerant is flowed by multiple pumps. A foil-wrapped transformer characterized in that common piping is provided before and after a plurality of pumps and at the inlet of a cooler, and cooling panel bypass piping is installed in which each pump piping is provided with a check valve and a valve is provided in the middle. (2) The foil-wound transformer according to claim 1, wherein the bypass pipe is installed between the common pipes on both sides of the pump. (3) The foil-wound transformer according to claim 1, wherein the bypass pipe is installed between the common pipe at the cooler inlet and the common pipe at the pump outlet. (4) The foil-wound transformer according to claim 3, wherein the bypass piping is installed outside the tank. (5) The foil-wound transformer according to claim 3, wherein the bypass piping is installed inside the tank to cool the insulating medium. (6) The foil-wound transformer according to any one of claims 1 to 5, wherein the capacity of the pump is greater than or equal to the required flow rate at the rated internal winding of the transformer.