JPH0525369B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is a gas-insulated transformer equipped with a gas-insulated load tap changer, and in particular, a method for transferring gas contained in a compartment during inspection and repair of a change-over switch. This invention relates to a gas insulated transformer equipped with a gas supply/discharge device for storage and return.

[Conventional technology]

Gas-insulated transformers, which mainly use sulfur hexafluoride gas (abbreviated as SF ₆ gas) as an insulating medium and a cooling medium, have the feature of being nonflammable, and are not suitable for indoor or underground substations mainly from the standpoint of disaster prevention. The demand for installed transformers has been increasing rapidly in recent years, and the on-load tap changer that adjusts the output voltage of the transformer in response to increases and decreases in load is also a changeover switch room that is compartmentalized in the transformer main tank. A gas insulated type filled with SF ₆ gas is used.

Figure 2 is a side sectional view of the main parts of a gas insulated transformer with on-load tap changer.
A transformer body 2 consisting of a coil B and a winding 2A wound thereon, and a main body tank 1 containing 10A of SF ₆ gas have an insulator inserted into the main body tank 1 through the cover plate in an airtight manner. A switching switch chamber 5 is provided, which is defined by a tank 6, a cylindrical joint 7 projecting upward from the tank 6, and a lid 8 removably connected to the opening of the joint 7. to SF ₆ gas 10
A gas-insulated on-load tap changer 9 is formed by the changeover switch 3 housed together with the changeover switch 3 and the tap selector 4 supported below the insulation tank 6 via the airtight drive shaft 3A in the changeover switch 3. The switching contact and the tap winding of the winding 2A are electrically connected by a plurality of lead wires 4A. For switching the current of the switching switch 3,
A vacuum valve element is used to prevent the SF ₆ gas 10B from being decomposed by arcing caused by switching on and off the current.

In addition, 10A of SF ₆ gas as an insulating gas contained in the main body tank 1 is kept at room temperature (20℃) so that the gauge pressure does not exceed 2.0Kg/cm ² even at the maximum allowable temperature of the transformer, mainly from the viewpoint of safety. gauge pressure
It is suppressed to about 1.2Kg/cm ² , and the withstand voltage performance and cooling performance are maintained under this condition. Furthermore, the SF ₆ gas as an insulating gas contained in the switching switch chamber 5 is suppressed to an even lower gas pressure, about 0.4 kg/cm ² in gauge pressure, which is normally required to maintain the withstand voltage performance of a vacuum valve element. The difference in gas pressure between the two is maintained by an insulating tank 6 that partitions the two.

[Problem that the invention seeks to solve]

The switching switch 3 includes a vacuum valve element and its switching mechanism, and must be inspected periodically at a predetermined switching frequency or every period of use. This is done by lifting 3. Although SF ₆ gas itself is harmless to humans and animals, its specific gravity is about five times heavier than air, so if the contained SF ₆ gas 10B is released into the air, it is likely to accumulate on the floor, especially in indoor substations and For gas insulated transformers installed in underground substations, etc., there is a risk that the released SF ₆ gas will remain indoors, creating an atmosphere with a low oxygen concentration in the room, a so-called oxygen-deficient condition. Therefore, in order to eliminate these dangers and reuse the SF ₆ gas contained in the switching switch chamber 5, a gas switch is connected to the switching switch chamber 5 via a valve 13 and has an exhaust valve 15 on the discharge side. A recovery device 11 and a valve 14 on the discharge side of the gas recovery device 11.
An SF ₆ gas storage tank 12 connected via a
After compressing the SF ₆ gas 10B to a predetermined pressure and temporarily storing it in the storage tank 12, and introducing air into the switching switch chamber 5 to perform lifting inspection or maintenance of the switching switch, the above Storage tank 12 in reverse order
A device is known that is configured to allow the switching switch 3 to be inspected and repaired without releasing the contained SF ₆ gas 10B to the outside by returning the SF ₆ gas inside the switching switch chamber 5 to the switching switch chamber 5. However, in the device configured in this way, the storage tank 12 is required, and in order to prevent the internal pressure of the storage tank 12 from being reduced to below atmospheric pressure and air entering the tank, it is necessary to disable the storage tank 12. Even at times, it is necessary to maintain the internal pressure above atmospheric pressure, and the stored SF ₆ gas 10C is nearly twice as large as the recovered SF ₆ gas 10B. Therefore, if the maximum working pressure of the storage tank is to be kept below the gauge pressure of 2.0 kg/cm ² at the same time as that of the main tank 1, the tank will become larger and require a large installation space, and the maximum working pressure will not be as high as above. If the storage tank 12 is constructed to be smaller by increasing the pressure higher than the pressure of A problem arises in that the pressure of the compressor becomes high.

An object of the present invention is to obtain a compact, inexpensive, and space-saving device by eliminating a storage tank.

[Means for solving problems]

In order to solve the above problems, according to the present invention, a transformer main body and a main body tank containing an insulating gas at a predetermined pressure are inserted into the main body tank by airtightly penetrating the cover plate thereof. A vacuum pump and a compressor connected to the main body tank and the switching switch chamber via a valve, in which the switching switch chamber houses an insulating gas at a pressure lower than the predetermined pressure and a switching switch. a gas discharge section that compresses the insulating gas contained in the switching switch chamber and transfers it to the main body tank for temporary storage; A gas supply/discharge device comprising a gas supply section having a side pipe that bypasses the gas discharge section for returning the gas to the gas discharge section is provided.

[Effect]

In the above means, a gas supply/discharge device consisting of a gas discharge section consisting of a connected body of a vacuum pump and a compressor, and a gas supply section forming a bypass line for the gas supply/discharge device is connected to the main body tank of the gas insulated transformer via a valve; By connecting it to the switching switch room that contains insulating gas at a lower pressure than the main tank, when lifting and inspecting the switching switch stored in the switching switch room,
The insulating gas stored in the switching switch room is compressed by the gas discharge part and transferred to the main tank, and the main tank can also be used as a storage tank for temporary storage. This is significantly larger than that of the switching switch, and because the switching switch is inspected in a cold state with the transformer stopped, even if the contained gas in the switching switch room is temporarily stored, the maximum allowable capacity of the main tank is Since sufficient pressure margin is obtained, the storage tank can be omitted without affecting the function of the isolation transformer. In addition, when the inspection of the switching switch is completed and the operation of returning (supplying) the temporarily stored insulating gas to the evacuated switching switch room, the gas pressure in the main tank is always lower than that in the switching switch room. Since the gas pressure difference is high, it is possible to easily supply the gas by a gas supply section consisting of a bypass pipe using the differential pressure, and the gas supply/discharge device can be configured simply.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 is a side sectional view of the main parts of an embodiment of the present invention. In the figure, the gas pressure in tank 1 of the gas insulated transformer at 20℃ is 1.2Kg/cm ²
an insulating tank 6 containing 10A of SF ₆ gas as an insulating gas maintained at a certain positive pressure, and airtightly penetrating the lid plate of the main tank 1 to partition the inside of the main tank 1;
A switching switch chamber 5 consisting of a cylindrical joint 7 and a lid 8, a switching switch 3 using a vacuum valve element housed therein, and a switching switch 3 connected to the switching switch 3 via an airtight drive shaft 3A. A load tap changer 9 consisting of a tap selector 4 and a tap selector 4, which are
The withstand voltage of the switching switch 3 is maintained by the SF ₆ gas 10B as an insulating gas, which is sealed to maintain a positive pressure of about 0.4 kg/cm ² at ℃, and the tap selector 4 is connected to the main body. Tank 1 storage
Withstand voltage is maintained by SF ₆ gas 10A. The gas supply/discharge device 21 connects the main body tank 1 via a valve 22.
For example, the side walls of the main tank 1 are used to communicate with the switching switch chamber 5 via the valves 23. The gas discharge section 24 has a vacuum pump 25 and a compressor 26 connected to each other via a valve 32.
The suction side of the vacuum pump 25 communicates with the switching switch chamber 5 via the valve 31, piping 28, and valve 23, and the discharge side of the compressor 26 communicates with the switching switch chamber 5 via the valve 31, piping 28, and valve 23.
and communicates with the main body tank 1 via a valve 22.
Further, the gas supply section 27 is connected to a gas discharge section 24 which communicates with the pipes 28 and 29 via valves 34 and 33.
It is configured as a bypass circuit. 36 is an exhaust valve arranged on the discharge side of the vacuum pump 25.

In the device configured as described above, lifting and inspecting the switching switch 3 first involves checking the valves 34, 35, 3.
6 close valves 23, 31, 32, 33, and 22
The vacuum pump 25 and compressor 26 are simultaneously driven to reduce the gas pressure in the switching switch chamber 5 to, for example, several mmHg.
After pressurizing and transferring the contained SF ₆ gas 10B to the main tank 1 until the level has decreased to a certain level, the valve 22 is closed and the main tank 1 is also used as a storage tank, and the SF ₆ gas 10B is transferred to the main tank 1.
This is done by storing air at atmospheric pressure and introducing atmospheric pressure air into the switching switch chamber 5. In addition, after the inspection was completed, SF ₆ was temporarily stored in the main tank 1 in the switching switch room 5.
Gas supply operation to return gas is performed by closing the valves 22 and 32, opening all other valves, and driving only the vacuum pump 25 to close the switching switch chamber 5 and the gas supply/discharge device 21.
Exhaust the air inside. Next, valves 31, 32, 3
3 and 36 are closed, and valves 23, 34, 35 and 22 are opened to release an amount of gas equivalent to the contained gas 10B in the switching switch chamber 5 using the gas pressure of the main body tank.
After supplying SF ₆ gas to the switching switch chamber 5 via the gas supply 27, the valves 22 and 23 are closed. In this way, the main body tank 1 and the switching switch chamber 5 can be returned to their original gas pressure.

Contained gas 10 in the switching switch chamber 5 in the main tank 1
The internal pressure of main tank 1 will rise somewhat due to the role of storage tank B, but when the switching switch is lifted and inspected, the transformer has stopped operating and has cooled down to near room temperature. The pressure increase in the main tank is small, and the maximum allowable pressure is 2.0 Kg/cm ² because the amount of contained gas 10B stored is much smaller than the contained gas 10A in the main tank. (gauge pressure), the storage tank can be omitted without interfering with the function of the gas insulated transformer. In addition, the return work of SF ₆ gas from the main tank to the supply switch chamber can utilize the pressure difference between the two, which simplifies the configuration of the gas supply section and reduces the gas pressure in the switch switch chamber to 0.4
Kg/cm ² is low, and the pressure difference with the main tank is also small, so the gas discharge section can be configured compactly by combining a small vacuum pump and a low-pressure compressor. It can be used for objects and attached to their side walls,
The installation space can be significantly reduced compared to conventional devices that use storage tanks.

〔Effect of the invention〕

As described above, this invention communicates a gas supply/discharge device between the main body tank of a gas insulated transformer and the switching switch chamber via a valve, so that when the switching switch is lifted and inspected, the stored gas in the switching switch chamber is The main tank is also used as a storage tank for temporary storage. As a result, by taking advantage of the fact that the amount of gas contained in the switching switch room and the gas pressure are much smaller than that of the main tank, the storage tank required in conventional equipment can be omitted without affecting the function of the isolation transformer. By providing a storage tank, it is possible to provide a gas-insulated transformer with a tap changer on load, which eliminates installation space and economical disadvantages. In addition, gas can be returned (supplied) from the main tank to the switching switch chamber by utilizing the pressure difference between the two, which simplifies the gas supply section of the gas supply/discharge device and saves space. Since there is no need to increase the pressure of the storage tank, the gas discharge section consisting of a vacuum pump and a compressor can be constructed in a small size and at low cost. Therefore, it becomes possible to attach the gas supply/discharge device to the side wall of the main body tank using the main body tank as a supporting material, and it is possible to obtain the advantage that the space of the device can be further reduced.

[Brief explanation of drawings]

FIG. 1 is a piping diagram including a side sectional view of a transformer showing an embodiment of the present invention, and FIG. 2 is a side sectional view showing a conventional device. 1... Main tank, 2... Transformer main body, 3...
Switching switch, 4...Tap selector, 5...Switching switch room, 9...Gas insulated tap switch on load,
11...Gas recovery device, 12...Storage tank, 2
1... Gas supply and exhaust device, 24... Gas discharge section, 25
... Vacuum pump, 26 ... Compressor, 27 ... Gas supply section, 36 ... Exhaust valve, 10A ... Gas contained in the main tank, 10B ... Gas contained in the switching switch chamber.

Claims (1)

[Scope of Claims] 1. A transformer main body and a main body tank containing an insulating gas at a predetermined pressure, which is comprised of an insulating tank inserted into the main body tank through the cover plate of the transformer in an airtight manner, and the pressure is lower than the predetermined pressure. In a device equipped with a switching switch chamber containing pressurized insulating gas and a switching switch, the switching switch comprises a communication pipe equipped with a vacuum pump and a compressor that connects the main tank and the switching switch chamber via a valve. A gas discharge section that compresses the insulating gas stored in the switch chamber and transfers it to the main body tank for temporary storage, and a gas discharge section that returns the insulating gas temporarily stored in the main body tank to the switching switch chamber due to a pressure difference are bypassed. 1. A transformer with a gas insulated load tap changer, characterized in that it is provided with a gas supply/discharge device comprising a gas supply section having a side pipe. 2. In what is stated in claim 1,
A transformer with a gas insulated load tap changer, characterized in that the gas discharge part is provided with an exhaust valve on the discharge side of the vacuum pump, and the switching switch chamber is evacuated by independent operation of the vacuum pump. .