JPS61174706A - Gas insulation transformer - Google Patents

Abstract

PURPOSE:To contrive the improvement of long term cooling reliability easily grasping the flow of a refrigerant in each cooling panel by installing a flow meter for measuring the flow rate in each of plural cooling panels installed in a cooling circulative system. CONSTITUTION:Each insulation pipe 12 at the flow-in side of each cooling panel 6a-6d of a transformer is extended externally from a tank 13, a flow meter 20 is installed on the way of the pipe 12 outside of the tank 13, connected to the flow measurement section, the display section or the recording section through the contact 21 provided in the flow meter 20, the maintenance operation such as a flow rate adjustment is carried out and the improvement of long term reliability is contrived.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a gas insulated transformer having a foil winding with a built-in cooling panel. Concerning gas insulated transformers with improved efficiency.

[Technical Background of the Invention 1 Foil-wound transformers have a good winding space factor and can be made smaller and lighter, so they have already been used as small-capacity transformers with relatively low voltages of several KV or several hundred KVA. It has been put into practical use in containers. In recent years, in view of its excellent advantages, research has been conducted to expand its application to higher voltage and larger capacity transformers, 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 3,
A so-called heat pipe type foil-wound transformer has a cooling panel built into the winding, and a refrigerant with excellent insulation properties is fed into this cooling panel, and the heat generated from winding loss is cooled using the latent heat of evaporation of the refrigerant. The vessel is powerful.

That is, this foil-wound 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 refrigeration panel 6, fluorocarbon R-
A refrigerant such as 113 or Fluorinert FC75 is sealed in the refrigerant, which is circulated by the pump 7, and the heat generated within the winding is absorbed by the latent heat of evaporation of the refrigerant, and the vapor is cooled and condensed through the cooling water pipe in the condenser 8. 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.

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 vibrator 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 the tank 13.
This is ensured by an insulating gas such as SF6 gas sealed inside.

The conventional foil-wound transformer described above is generally called a separate foil-wound transformer because the cooling system in which the refrigerant circulates and the insulating gas of the winding are completely separated, but the heat pipe type foil-wound transformer is generally called a separate foil-wound transformer. In addition to this type of winding transformer, there is a spray set that mixes an insulating medium and a refrigerant in a tank and sprays the refrigerant onto the windings.

[Problems with Background Art] By the way, in the various foil-wound transformers as described above, the low-voltage winding 4 and the high-voltage winding 5 are formed by overlapping and winding the thin metal sheet 2 and the insulating sheet 3. This 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, a pump forces refrigerant into the cooling panel built into the windings, and when manufacturing the transformer, internal head loss and pump discharge pressure are taken into account to determine the cooling temperature. The refrigerant flow rate is set to match the design location. However, due to long-term operation of transformers over several decades, it is possible that the refrigerant may deteriorate or decompose, or that foreign matter may be mixed in or generated, or that the refrigerant may leak, resulting in changes in the viscosity of the refrigerant or foreign matter entering the flow path. This may occur and cause the flow characteristics to change from the initial set values. In such a case, the flow of refrigerant within the built-in cooling panel changes, but in conventional transformers there is no means to control the flow of refrigerant. Therefore, as a result of the above-mentioned flow changes being left unattended, the temperature distribution within the windings and core will be disturbed, and in some cases, thermal deterioration of insulating materials will partially progress, resulting in a shortened lifespan. In extreme cases, this has become a major problem, as there is even the possibility of thermal exhaustion leading to a serious accident.

[Objective of the Invention 1 The present invention was proposed in order to eliminate the drawbacks of the prior art as described above, and its purpose is to facilitate the flow of refrigerant in each cooling panel built into the winding. It is an object of the present invention to provide a gas insulated transformer that can improve long-term cooling reliability by making it possible to understand the

[Summary of the Invention 1 The gas insulated transformer of the present invention is configured such that a flow rate measuring device for measuring the flow rate is provided for each cooling panel provided in a plurality of cooling circulation systems. At,
This allows the flow of refrigerant within each cooling panel to be easily grasped. By linking this device to a recording or control system, cooling reliability can be improved.

[Embodiments of the Invention] Examples of the present invention as described above will be described with reference to FIGS. 1 and 2. Note that the same parts as those in the conventional example described above are given the same reference numerals, and the description thereof will be omitted.

In the embodiment shown in FIG. 1, each cooling panel 6a to 6
Each of the insulating vibes 12 on the inflow side of d extends to the outside of the tank 13, and a flow rate measuring device 20 is attached to the middle of each insulating vibe 12 on the inflow side outside the tank 1. It is connected to various display sections, recording sections, flow rate control sections, etc. (not shown) via electrical contacts 21 provided therein. Furthermore, with this configuration, the entire length of the liquid guiding pipe 11 is also disposed outside the tank 13.

Further, in one embodiment shown in FIG. 2, the flow rate measuring device is arranged inside the tank 13, and each display device 20
Only the electrical contact 21 of the tank 13 is pulled out to the outside of the tank 13, and the flow rate is measured through this electrical contact 21! The a position 20 is connected to various display parts, recording parts, outflow side parts, etc.

In each of the embodiments having such a configuration, the flow rate of the refrigerant flowing into each of the cooling panels 6a to 6d built into the windings can be measured outside the transformer. refrigerant deterioration as a result of overload operation;
Even if the flow rate changes due to contamination of impurities or leakage of refrigerant,
This can be detected immediately, and the presence or absence of the above inside the tank 13 can be ascertained. In each embodiment, since each flow rate measurement device 20 is connected to various display sections, recording sections, or flow rate control sections, maintenance work such as flow rate adjustment can be performed, and therefore cooling reliability can be improved. can be significantly improved. In addition, in the case of the embodiment shown in FIG. 1, since the flow rate measuring bag M20 is provided outside the tank 13, this device 20 itself can be provided with display, recording, or flow rate control functions.
In such a case, the electrical contact 21 is not necessarily required.

Note that the present invention is not limited to the above-mentioned embodiments; for example, the flow rate measuring device may be installed on the outflow side of the cooling panel, and the same effect can be obtained in this case as well. can get.

Furthermore, in the explanation of the present invention as described above, the method of measuring the refrigerant flow rate in the cooling panel built into the winding was mainly explained, but this method also applies to the cooling panel built into the iron core. The invention can be applied.

Furthermore, the present invention is not limited to transformers having foil windings, but is equally applicable to disc-shaped, cylindrical, or outer iron transformer windings.

[Effects of the Invention] As explained above, according to the present invention, by simply improving the configuration by installing a flow rate measuring device in the middle of the cooling system, the immersed gas can be improved in the long-term cooling reliability. We can provide isolation transformers.

[Brief explanation of the drawing]

1 and 2 are sectional views showing different embodiments of the gas insulated transformer according to the present invention, and FIG. 3 is a sectional view showing an example of a conventional gas insulated transformer. DESCRIPTION OF SYMBOLS 1... Leg 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, 20... Flow rate measuring device, 21... Electrical contact. Figure 1 Figure 2 Figure 3

Claims (4)

[Claims] (1) In a gas insulated transformer that consists of a metal sheet and an insulating sheet wrapped around an iron core and a plurality of cooling panels inside which a refrigerant flows, the flow rate of the refrigerant is determined for each cooling panel. A gas insulated transformer characterized in that it is equipped with a flow rate measuring device that measures the flow rate. (2) The gas insulated transformer according to claim 1, wherein the flow rate measuring device has an electrical contact. (3) The gas insulated transformer according to claim 2, wherein both the flow rate measuring device and the electrical contact are arranged outside the tank. (4) The gas insulated transformer according to claim 2, wherein the flow rate measuring device is disposed inside the tank and its electrical contacts are disposed outside the tank.