JPS61174707A - Gas insulation transformer - Google Patents

Abstract

PURPOSE:To contrive the improvement of the dielectric withstanding strength of a transformer removing the moisture in a tank effectively and to make the exchange of a moisture absorbent easy by controlling the circulation of an insulation gas to a gas drier provided outside according to the output of a moisture sensor provided within the tank. CONSTITUTION:When the insulation gas 22 within the tank 1 of a transformer contains much moisture, the solenoid valve of a drier 26 is opened by the output of a moisture sensor 23 and an insulation gas 22 is introduced in the drier 26 by a pump 27 for drying. If the output of the moisture sensor 23 is at a constant value or less, the solenoid valve is closed, the operation of the pump 27 is stopped and the concentration of the moisture is kept at constant. Accordingly, the reliability of insulation is improved. The exchange of a moisture absorbent in the drier 26 is carried out easily without stopping the operation of the transformer by closing the solenoid valve.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a gas insulated transformer, such as a foil-wound transformer, that uses an insulating gas such as SF6 gas as an insulating medium, and particularly relates to a The present invention relates to a gas insulated transformer that allows easy management of moisture in lines and insulating gas.

[Technical Precedence of the Invention W4] Foil-wound transformers have a good winding space factor and are characterized by being able to be made smaller and lighter. It has been put into practical use in transformers.

In recent years, in view of its excellent characteristics, research has been conducted to expand its application to higher voltage, larger capacity transformers, such as 275KV and 300MVA class transformers, but the key to this is how to improve cooling capacity and high insulation capacity. It all depends on whether the winding can have this. Such high-voltage, large-capacity foil-wound transformers have not yet been put into practical use, but as shown in Figure 2,
The foil has a cooling duct built into the winding, and a refrigerant with excellent insulating properties is fed into this cold part duct, and the heat generated from the winding loss is cooled using the latent heat of evaporation of the refrigerant. Winding transformers are promising.

That is, in this type of foil-wound transformer, a low-voltage winding 4 and a high-voltage winding 5, each made of a metal sheet 2 and an insulating sheet 3 wound over each other, are wound around a leg portion 1 of the core. A hollow cooling duct 6 is built into the line. cooling duct 6
Inside the thin hollow part of the fluorocarbon R-113,
It is filled with refrigerants such as 70Lina-1, Fe12, etc.
It is circulated by a pump 7, and the heat generated within the winding is removed by the latent heat of vaporization of the refrigerant, and the vapor is cooled and condensed through a cooling water pipe in a condenser 8 outside the tank.

A cooling system is constructed in which the liquefied refrigerant is stored in the refrigerant tank 10 and sent into the cooling duct 6 again by the pump 7 to cool the windings.

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 duct 6 are connected via an insulating vibrator 12 made of Teflon resin or the like.

Further, the liquid guide pipe 11 is connected to the ground potential of the tank 13, etc., while the cooling duct 6 is electrically connected to the same potential as the adjacent winding because it is built into the winding. ing.

Furthermore, insulation of each part of the winding is ensured by an insulating gas such as SFs gas sealed in the tank 13.

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. In addition to this, foil-wound transformers include a spray set that mixes insulating media and refrigerant in a tank and sprays the refrigerant onto the windings, and a container that stores the refrigerant in the tank. A pool type method in which the winding wire is immersed is known.

[Problems with the 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 constructed by overlapping and winding the thin metal sheet 2 and the insulating sheet 3. Although this increases the space factor within the core window, there are the following problems.

That is, it is inevitable that moisture in the air will adhere to all transformer structures, such as the insulation sheet 2 and the insulation vias 12, during winding of the transformer windings or other work. The influence of moisture on dielectric strength has been investigated in various ways, but the dielectric strength tends to decrease as moisture increases. Therefore, like oil-immersed transformers, gas-insulated transformers are also dried before assembly, but it is impossible to completely remove moisture. In particular, in the foil-wound transformer as described above, since the winding is constructed by winding the wide metal sheet 2 and the insulating sheet 3, it is necessary to completely remove moisture from the center of the winding. I couldn't.

As a method for removing moisture in a tank, it has been known in the past to insert a moisture absorbent into the tank of a gas-insulated current transformer or the like. However, the method of using such a moisture absorbent has the following problems and is not suitable for gas insulated transformers including foil-wound transformers.

■ Because transformers have large windings, it takes a large amount of moisture absorbent to completely absorb the remaining moisture, and if you insert it into the tank, you will need a large tank and waste it. This requires a lot of space and the transformer becomes larger.

■ If a moisture absorbent is inserted into the tank, it cannot be easily replaced after the moisture absorbent has absorbed moisture.

■ Especially in foil-wound transformers, when a load current flows, the transformer windings self-heat and dry due to the current, resulting in an increase in moisture in the gas after operation, and a moisture absorbent that absorbs that moisture. However, the tank is gas-tightly sealed, and in order to replace the moisture absorbent, the operating transformer must be stopped, and various problems occur during power operation. There's a problem.

[Object of the Invention] The present invention was proposed to solve the above-mentioned problems, and its purpose is to effectively remove moisture inside the tank and improve the dielectric strength of the transformer. It is an object of the present invention to provide a gas insulated transformer in which the moisture absorbent can be easily replaced without stopping the operation of the transformer.

[Summary of the Invention] The gas insulated transformer of the present invention includes a moisture sensor for detecting moisture in an insulating gas inside a tank, and a part of an insulating gas circulation system provided outside the tank by the moisture sensor. A controlled gas dryer is installed, and insulating gas is circulated to the gas dryer side according to the output of the moisture sensor inside the tank, and the moisture in the gas is removed by the moisture absorbent, and the absorbent is replaced. At times, the circulation of insulating gas to the gas drying device is stopped so that the moisture absorbent inside the drying device can be replaced.

[Embodiment 1 of the Invention Hereinafter, an embodiment of the present invention will be specifically described with reference to FIG. 1. Note that the same parts as those of the conventional transformer shown in FIG. 2 are given the same reference numerals, and the description thereof will be omitted.

In FIG. 1, reference numeral 21 denotes a winding formed by overlapping an insulating sheet and a metal sheet, and is sealed in the tank 13 together with an insulating gas 22. A moisture sensor 23 is provided within the tank 13 and can detect the amount of moisture in the insulating gas as an electrical signal, for example. A cooling device 24 and a pump 25 are connected to the outside of the tank 13 for cooling the insulating gas 22 heated by the winding 21 . Further, a gas drying device 26 for drying insulating gas is connected together with a pump 27 in parallel with this cooling device 24 . A moisture absorbent such as silica gel is enclosed in the drying device 26 so that it can be replaced. A solenoid valve 28a, a solenoid valve 28a, and a
28b, 29a, and 29b are provided. These solenoid valves 28a, 28b and 29a, 29b are controlled by a detector 30 that is activated by the output of the moisture sensor 23. is small, the solenoid valves 28a and 29a on the cooling device 24 side open, and the drying device 26
The solenoid valves 28b and 29b on the side are controlled to close, and when there is a lot of moisture in the insulating gas and the output of the moisture sensor 23 is large, the solenoid valves are controlled to open and close in reverse. Moreover, this detector 30 detects the cooling system @ 2 at the same time as the opening and closing of the solenoid valve.
4 and the pumps 25 and 27 connected to the drying device 26. When the output of the moisture sensor 23 is small, the pump 25 on the cooling device side is operated, and when the output is large, the pump 25 on the drying device side is operated. 27. Furthermore, this detector 30 is connected to an alarm device and a display device that issue an alarm based on the output of the moisture sensor 23.

The effects of the gas insulated transformer of this embodiment having the above configuration are as follows.

■ When there is a lot of moisture in the insulating gas, the output of the moisture sensor 23 opens the solenoid valve on the drying device 26 side, and the pump 27 is operated to guide the insulating gas to the drying device 26 side and absorb the internal moisture absorbent. Can be dried on contact. Furthermore, when the output of the moisture sensor 23 is below a certain value, the electromagnetic valve is closed and the operation of the pump 27 can be stopped, so that the insulating gas is not led to the drying device 26, and therefore the moisture in the gas is Since the concentration is always kept at a constant value, a transformer with excellent insulation reliability can be obtained.

(2) During steady state, the pump 27 on the gas drying device 26 side is stopped, so a transformer with low auxiliary equipment loss and high energy-saving effect can be obtained.

■ Even if the moisture absorbent in the drying device 26 absorbs moisture, by closing the solenoid valve and disconnecting the drying device from the gas circulation system, the moisture absorbent can be removed without stopping the operation of the transformer. can be exchanged.

■ When the pump 27 connected to the drying device 26 is activated and the solenoid valves 28b and 29b are opened, the insulating gas introduced into the drying device is cooled by the drying device 26, which is at a lower temperature than the inside of the transformer tank. will be done. That is, the drying device 26 of this embodiment also functions as an insulating gas cooling device. Therefore, if the cooling efficiency of the cooling device 24 and the drying device 26 are made equal, even if one of the devices breaks down, it can be easily replaced, and a highly reliable transformer can be obtained.

Note that the present invention is not limited to the above-mentioned embodiments, but also includes other embodiments as follows.

(2) Although some of the piping for the drying device and the cooling device are shared in the illustrated embodiment, they may be provided independently.

(2) The insulating gas circulation system provided with the drying device does not necessarily need to be provided in parallel with the cooling system, and may be provided in series with the cooling system, or may be provided independently regardless of the presence of the cooling system.

■ The operation of the drying equipment using a moisture sensor can be controlled automatically according to the output of the sensor, or the output of the sensor can be used to activate an alarm or display, and then the operation of the drying equipment can be stopped manually. You may do so.

[Effects of the Invention] As described above, according to the present invention, a drying device is provided in a part of the insulating gas circulation system in a transformer tank, and this drying device is controlled by a moisture sensor in the transformer tank. The configuration makes it possible to maintain the moisture in the transformer tank at a constant level, thereby achieving an improvement in the dielectric strength of the transformer, and replacing the moisture absorbent used in the drying device when the transformer is no longer in operation. This has the effect of providing a highly reliable gas insulated transformer.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a gas insulated transformer of the present invention, and FIG. 2 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 duct, 7...Pump, 8...Condenser, 9
... Cooling water pipe, 10 ... Refrigerant tank, 11 ... Liquid guide pipe, 12 ... Insulating vibe, 13 ... Transformer tank, 21 ... Winding wire, 22 ... Insulating gas, 23...Moisture sensor, 24...Cooling device, 25...Pump, 2
6... Drying device, 27... Pump, 28a, 28b
, 29a, 29b... Solenoid valve, 30 Fig. 1 Fig. 2

Claims (1)

[Claims] A coil and an iron core are built into the tank, and SF is used as an insulating medium.
In a gas insulated transformer filled with an insulating gas such as _6 gas, a moisture sensor for detecting moisture in the insulating gas is installed inside the tank, and the moisture sensor is installed in a part of the insulating gas circulation system outside the tank. A gas insulated transformer characterized by being provided with a gas drying device controlled by.