JPS628928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of filling oil into a bushing pocket formed in an oil-tight manner so that insulating oil in the transformer case does not enter into the bushing mounting portion of the transformer case.

BACKGROUND ART Conventionally, when an existing transformer temporarily stops operating due to maintenance or inspection or an accident, a mobile transformer may be used as an emergency measure in place of the above-mentioned transformer. In this case, due to height restrictions, the high-voltage bushing of the mobile transformer was removed and moved to the site, where the high-voltage bushing was reassembled and the mobile transformer was operated. However, when reassembling a high-voltage bushing on-site, the base of the high-voltage bushing is usually stored in a bushing pocket provided at the bushing mounting part of the transformer case, and the bushing is fixed upright on the bushing mounting part.
Next, the inside of the bushing pocket was reduced to a predetermined pressure using a vacuum pump, and then the bushing was assembled by filling the bushing pocket with degassed insulating oil. In this case, there is no problem if there is a power source to drive the vacuum pump at the site, but if there is no power source, the pressure in the bushing pocket cannot be reduced. Since the only method is to fill the pocket, air bubbles remain on the surface of the insulating shield tube that forms the bushing pocket or on the surface of the bushing, and these air bubbles can cause harmful partial discharges when voltage is applied to the equipment. As a result, there was a risk of deterioration and damage to the insulating shield tube and bushing.

In view of the above-mentioned points, the present invention makes it possible to easily reduce the pressure inside the bushing pocket to the required pressure without using a vacuum pump on-site, and fill the bushing pocket part under the above-mentioned reduced pressure state with insulating oil. This provides a method for filling oil into a bushing pocket.Hereinafter, an example in which the present invention is applied to a mobile transformer will be described. 1 is a case of a mobile transformer, 2 is an upper part of one side of the case 1. 3 is a cover that is oil-tightly attached to the case 1; 4 is a bushing mounting hole that is opened in the part of the cover 3 located above the bushing mounting part 2; , 5 is a bottomed cylindrical insulation shielding tube formed of an insulating material such as synthetic resin into a substantially inverted conical shape, and as shown in FIG. It is inserted into the bushing mounting part 2 and the flange at the upper end is oil-tightly mounted on the cover 3 around the periphery of the mounting hole 4 via a gasket, so that it is suspended and held in the bushing mounting part 2. Reference numeral 6 denotes a mounting seat for a bushing attached to the cover 3 surrounding the periphery of the upper opening end of the insulating shielding tube 5, and 7 is a high-pressure bushing, the base of which is stored in the bushing pocket 8 inside the insulating shielding tube 5. By attaching the flange portion 9 to the mounting seat 6 via the gasket, the high-pressure bushing 7 is mounted upright on the bushing mounting portion 2. A lead wire 10 is led out from a transformer main body (not shown) housed in the case 1, and is oil-tightly attached to the bottom of the insulating shield cylinder 5. Reference numeral 11 denotes a bushing lead passing through the high-voltage bushing 7, one end of which is electrically connected to the lead wire 10 at the bottom of the insulation shielding cylinder 5.
The other end is removably connected to a live part (not shown) at the upper end of the high-voltage bushing 7. 12 is the mounting seat 6
A lubricant pipe is welded to one side of the lubricant so as to communicate with the inside of the bushing pocket 8, and a valve 13 is attached to the tip. 14 is a decompression tank that is removably connected to the oil supply pipe 12 via a connecting pipe 15, and its volume is equal to that of the bushing pocket portion 8.
It is larger than the volume of .

Reference numeral 16 indicates a valve of the decompression tank 14, and reference numeral 17 indicates an oil tank that is also removably connected to the oil supply pipe 12 via the connecting pipe 15. Stores degassed insulating oil. 18 is oil tank 1
7 is a valve, and 19 is an oil filler port of an oil tank 17.

When moving the mobile transformer, the high voltage bushing 7 is removed and shipped separately due to height restrictions, and the bushing mounting seat 6 is covered with a blind cover (not shown) to move the transformer.

Further, insulating oil is sealed inside the case 1 of the transformer, including inside the bushing mounting portion 2.

Next, to explain the case of filling insulating oil into the bushing pocket 8, first move the mobile transformer to the site, remove the blind cover from the mounting seat 6, and connect the lead wire 10 to the high voltage bushing 7. The bushing lead 11 to be connected is inserted, the base of the high-pressure bushing 7 is housed in the bushing pocket part 8, the flange part 9 is fixed to the mounting seat 6, and the high-pressure bushing 7 is attached to the bushing mounting part 2, Subsequently, the upper end of the bushing lead 11 is connected to the live part of the high-voltage bushing 7. After this, the decompression tank 1 whose interior was previously depressurized to the required pressure
4 is connected to the oil supply pipe 12 via the connecting pipe 15, and after the connection, the valves 13 and 16 are opened to suck the air inside the bushing pocket 8 into the decompression tank 14. Reduce the pressure to the required pressure. (At this time, it goes without saying that the pressure inside the pressure reducing tank 14 is reduced so that the pressure inside the bushing pocket 8 can be reduced to the required pressure.) After reducing the pressure in the bushing pocket 9, Close the valve 13 and open the decompression tank 1.
4 from the connecting pipe 15, and then, as shown in FIG. 2, connect the oil tank 17 containing degassed insulating oil to the connecting pipe 15,
At the same time, the oil filler port 19 of the oil tank 17 is opened by removing the lid, etc., and the insulating oil in the oil tank 17 is filled into the bushing pocket portion 8 via the connecting pipe 15 and the oil filler pipe 12. After filling with insulating oil, only the oil filler port 19 of the oil tank 17 is hermetically closed. As a result, the bushing pocket 8 can be filled with insulating oil under reduced pressure, and moreover, during filling with insulating oil, the base surface of the high-pressure bushing 7 and the surface of the insulating shielding cylinder 5 that are present in the oil can be filled. Even if air bubbles are generated, the inside of the butting pocket 8 has been previously reduced to a required pressure or less, so the air bubbles will not disappear and remain.
It is possible to maintain a good insulation condition on the surface of the bushing in oil and on the surface of the insulating shield cylinder 5. Further, since insulating oil remains in the oil tank 17, this oil tank 17 can serve as a conservator for the bushing pocket portion 8.

Incidentally, instead of connecting the decompression tank 14 and the oil tank 17 to the oil supply pipe 12 via the connecting pipe 15,
The present invention can also be extended by connecting the valves 16 and 18 of these tanks 14 and 17 to the valve 13 of the oil supply pipe 12 so that each tank 14 and 17 is directly connected to the oil supply pipe 12.

Furthermore, it goes without saying that the oil filling method of the present invention can be used for installing bushings in existing transformers as well as mobile transformers.

As described above, the present invention includes a lubricating pipe protruding from the mounting seat of a high-pressure bushing in communication with a bushing pocket formed in an oil-tight manner in the bushing mounting portion of a transformer case, Connect the pressure reduction tank whose internal pressure has been reduced to below the required pressure to reduce the pressure inside the bushing pocket to the required pressure, then connect an oil tank instead of the pressure reduction tank to the oil filling pipe and store it in this oil tank. The insulating oil is filled into the bushing pocket under reduced pressure, and the insulating oil is sealed in the bushing pocket.When reassembling the transformer bushing on site, the power supply for driving the vacuum pump is used. Even if there is no such thing, the present invention reduces the pressure inside the bushing pocket using a previously prepared vacuum tank whose interior is depressurized, and then fills the bushing pocket with insulating oil under reduced pressure. Therefore, no air bubbles are generated within the bushing pocket, and the presence of air bubbles will not cause deterioration or damage to the insulation of the bushing pocket when voltage is applied or to the base surface of the bushing immersed in oil. Not at all. Furthermore, since no power supply equipment is used when filling the bushing pocket with insulating oil, the filling operation can be carried out economically. Furthermore, after being filled with insulating oil, the oil tank containing the insulating oil can serve as a conservator for the bushing pocket.

[Brief explanation of the drawing]

1 and 2 are vertical cross-sectional views of the main parts of a transformer showing an embodiment of the present invention. FIG. 1 shows a state in which the pressure inside the bushing pocket is reduced, and FIG. This shows the state where the insulating oil is filled. 2: Bushing mounting part, 8: Bushing pocket part, 12: Lubrication pipe, 14: Decompression tank, 1
7: Oil tank.

Claims (1)

[Claims] 1. A lubrication pipe is provided in the bushing mounting portion of the transformer case, which communicates with the bushing pocket section that is oil-tightly partitioned from the inside of the case, protruding from the mounting seat of the high-pressure bushing. A pressure reduction tank is connected to reduce the pressure inside the bushing pocket, and after the pressure is reduced in the bushing pocket, an oil tank is connected to the oil supply pipe in place of the pressure reduction tank, and the insulating oil in this oil tank is supplied to the oil tank as described above. 1. A method for filling oil into a bushing pocket in a transformer, characterized in that the bushing pocket is filled with insulating oil under reduced pressure to enclose insulating oil in the bushing pocket.