JPS6316890B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for injecting insulating oil into a bushing pocket formed within a bushing mounting portion of a transformer case and separated from the inside of the case.

BACKGROUND ART Conventionally, a mobile transformer is sometimes used as an emergency instead of the above-mentioned transformer during maintenance and inspection of a transformer installed in a substation or in the event of an accident. In this case, when moving a mobile transformer, due to height restrictions, the high-voltage bushing was removed from the case, moved to the place of use, and reassembled on-site for use. However, when reassembling a high-pressure bushing on-site, the base of the high-pressure bushing is normally stored in the bushing pocket provided at the bushing mounting part of the case, the bushing is attached to the bushing mounting part, and then the bushing is inserted into the bushing pocket. The interior of the bushing was depressurized using a vacuum pump using the oil fill hole, and after the pressure was reduced, degassed insulating oil was injected into the bushing pocket to assemble the high-pressure bushing. In this case, if there is a power source to drive the vacuum pump at the site when injecting the insulating oil, there will be no problem, but if there is no driving power source, it will not be possible to reduce the pressure inside the bushing pocket, and therefore the insulating oil will be injected. Since the only method is to inject into the bushing pocket under normal pressure, air bubbles remain on the inner wall surface of the bushing pocket and the base surface of the high-pressure bushing submerged in oil. When the inner wall of the bushing pocket or the base of the high-voltage bushing is deteriorated and damaged over many years due to harmful partial discharge caused by the application of voltage, or when high voltage such as lightning shock voltage penetrates. There was a risk of dielectric breakdown occurring.

The present invention eliminates the above-mentioned drawbacks, and even when insulating oil is injected under normal pressure conditions without special pressure reduction inside the bushing pocket, almost no air bubbles are generated in the oil. This invention provides a method for injecting insulating oil into a bushing pocket that can significantly suppress partial discharge caused by the presence of air bubbles in a bushing. 1 is a case of a mobile transformer; 2 is a bushing mounting portion formed by integrally bulging the upper part of one side of the case 1 to the outside; 3 is a cover attached to the case 1 in an oil-tight manner;
4 is a mounting hole opened in a portion of the cover 3 located above the bushing mounting portion 2; 5 is a bottomed cylindrical insulation shield formed of an insulating material such as synthetic resin into an approximately inverted conical shape; As shown in FIG. 2, the tube 5 is constructed by inserting the lower end into the case 1 through the mounting hole 4 and fixing the flange at the upper end in an oil-tight manner via a gasket on the outside of the mounting hole 4. , is vertically installed inside the case 1. 6 is a mounting seat that surrounds the upper open end of the insulating shield cylinder 5 and is attached to the cover 3;
Reference numeral 7 denotes a high-pressure bushing, and its base 7a is housed in a bushing pocket 8 in the insulating shield cylinder 5, and the flange 9 is mounted on the mounting seat 6 via a gasket. 2. Can be installed upright. 10 is a lead wire led out from the inside of the transformer (not shown) in the case 1, and is attached to the bottom of the insulation shielding tube 5;
Reference numeral 1 denotes a bushing lead that passes through the high-voltage bushing 7, and one end thereof is connected to a lead wire 10 and an insulating shielding tube 5.
The other end is removably connected to a live part at the upper end of the high-voltage bushing 7.
12 is a conservator mounted on the cover 3 via a frame 13 at a position above the mounting seat 6 so as to communicate with the inside of the case 1; 14 is a conservator mounted on one side of the mounting seat 6 in the bushing pocket 8; This oiling pipe 14 is connected to the conservator 12 via an oiling valve 15 and an oil conduit 16, and the inside of the bushing pocket 8 is connected to the oiling pipe 14 and the oil pipe 14. It is filled with degassed insulating oil supplied from conservator 12 via conduit 16. As shown in FIG. 3, in the oil supply pipe 14, a small diameter bottleneck 14a is formed at a position close to the oil supply valve 15 side with a required length, and the outlet side thereof is opened in the shape of a taper. There is. This is because the conservator 12 is installed above the bushing pocket part 8, so the insulating oil flows out forcefully from the opening 6a of the mounting seat 6 into the bushing pocket part 8 due to the head pressure of the insulating oil. This is to prevent the insulating oil from flowing forcefully from the bottleneck 14a into the butting pocket 8 due to its water head pressure.
4a itself is formed in such a position that even if the insulating oil is vigorously jetted out from the bottleneck 14a, the jetting tip will be in front of the opening 6a of the mounting seat 6, and the outlet side of the bottleneck 14a is opened in the shape of a bulge. In addition to suppressing the amount of insulating oil leaked, this also reduces the amount of insulating oil.
It is designed so that it can flow into the bushing pocket portion 8 from the opening 6a of the mounting seat 6 while running along the wall surface of the mounting seat 6. 17 is the butching pocket part 8
The insulating oil flowing into the bushing pocket 8 from the opening 6a of the mounting seat 6 is an oil reservoir formed on the inner cover 3 between the upper end periphery of the insulation shielding cylinder 5 and the wall surface of the mounting seat 6. The insulating oil that once flows down to this oil storage portion 17 and overflows from this oil storage portion 16 flows into the insulating shield cylinder 5. Reference numeral 18 denotes an exhaust valve mounted on the upper surface of the mounting seat 6 so as to communicate with the inside of the bushing pocket 8.

When moving the mobile transformer, only the high-voltage bushing 7 is sent separately due to height restrictions, and a blind cover (not shown) is attached to the hole for inserting the base 7a of the bushing in the mounting seat 6.

Next, to explain the case of injecting insulating oil into the bushing pocket 8, after moving the mobile transformer to the site of use, remove the blind cover (not shown) from the mounting seat 6, and insert the bushing into the high voltage bushing 7. The base 7a of the lead 11 is inserted into the bushing pocket 8, and then the flange 9 is inserted.
is fixed to the mounting seat 6, the high-pressure bushing 7 is attached to the bushing mounting part 2, and the bushing lead 1 is attached to the bushing lead 1.
1 is connected to the live part of the high voltage bushing 7. Next, when the exhaust valve 18 and the oil supply valve 15 are opened, insulating oil flows from the conservator 12 into the bushing pocket 8 via the oil conduit 16 and the oil supply pipe 14, and at the same time, the insulating oil flows from the exhaust valve 18 into the bushing pocket 8. The air in the chamber 8 is naturally discharged as the insulating oil flows in. At this time, that is, when the insulating oil flows into the bushing pocket 8, the oil supply pipe 1
The amount of insulating oil that flows out is suppressed by the attrition 14a of No. 4, and the insulating oil is vigorously jetted out from the attrition 14a toward the opening 6a of the mounting seat 6 due to the water head pressure. Opening 6 of seat 6
The dimension L up to a is set to such a length that the insulating oil itself will not flow forcefully from the opening 6a of the mounting seat 6 into the bushing pocket 8 due to its water head pressure, and is also set to a length that prevents the insulating oil itself from flowing forcefully into the bushing pocket 8 from the opening 6a of the mounting seat 6 due to the water head pressure. Since the outlet side is opened in the shape of a bulge, the insulating oil flowing out from the bottleneck 14a flows along the bulge-shaped portion, and its flow rate is gradually reduced, causing almost no bubbles to be generated inside the oil supply pipe 14. Finally, as shown by the arrow in FIG. 3, the oil flows from the opening 6a along the inner wall surface of the mounting seat 6 into the oil storage part 17 in the bushing pocket part 8, and this oil storage part 17 is filled with insulating oil. When the insulating oil is filled, the insulating oil will eventually overflow from the oil storage portion 17 and will flow down the inner wall surface of the insulating shielding cylinder 5 sequentially toward the bottom as shown by the arrows in the figure. . The amount of insulating oil that has flowed into the insulating shield cylinder 5 gradually increases, filling the bushing pocket 8, and finally reaches the exhaust valve 18 just before it overflows from the exhaust valve 18. By closing it, the work of filling insulating oil into the bushing pocket 8 is completed.

Next, when moving the mobile transformer to another site, first close the lubrication valve 15, then remove the high-pressure bushing 7 from the bushing mounting part 2, and then remove it from the bushing pocket part 8. Drain the insulating oil to the outside using a manual pump, etc., cover the mounting seat 6 with a blind cover, move the mobile transformer, and perform the same operation as above again at the next use site.
Attach the high-pressure bushing 7 and inject insulating oil into the bushing pocket 8.

Note that the insulating oil injection method of the present invention is not limited to the method of injecting insulating oil into the bushing pocket 8 of a mobile transformer, and can be used even when used in an existing transformer or when replacing a bushing. The present invention is realized.

Further, the insulating oil discharged from the bushing pocket portion 8 can be reused by purifying it with an oil purifier.

Furthermore, in the present invention, the insulating oil is allowed to gradually flow down into the bushing pocket part 8 along the inner wall surface of the bushing pocket part 8, without providing the oil storage part 17 in the bushing pocket part 8. It is also possible to enclose it.

Further, the insulating oil may not be supplied from the conservator 12, but may be supplied by attaching a separate oil tank or the like to the oil supply pipe 14.

Further, the outlet side of the bottleneck 14a may not be shaped like a bump, but may be formed to have a step perpendicular to the large diameter portion 14b in the oil supply pipe 14.

As described above, in the present invention, the insulating oil is supplied from the conservator 12 to the bushing insulating shield tube, and the flow rate and inflow pressure are significantly suppressed by the bottleneck provided in the oil supply pipe 14 in the middle of the installation. seat 6
from the opening 6a of the oil storage part 1 along the wall surface of the mounting seat 6.
7 and fills this oil reservoir 17 with insulating oil,
The insulating oil filled in the oil storage part 17
The insulating oil from the conservator 12 is sealed in the bushing pocket part 8 by overflowing from the bushing pocket part 8 and flowing down along the wall surface of the insulation shielding cylinder 5. The flow rate of the insulating oil is significantly suppressed and the oil is applied to the bushing pocket 8 so that it flows along the walls of the mounting seat 6 and the insulation shielding cylinder 5. Air bubbles are less likely to form on the base 7a of the bushing pocket 7 and the wall surface of the insulating shielding cylinder 5, and since the air inside the bushing pocket 8 is discharged into the atmosphere from the exhaust valve 18 while lubricating is performed, the air bubbles do not immerse in the oil. High pressure bushing 7
It is possible to maintain a good insulation condition on the surface of the base 7a and the wall surface of the insulation shielding tube 5, and as a result,
Accidents such as deterioration and damage to the insulation of the bushing pocket portion 8 and the surface of the base portion 7a of the high-voltage bushing 7 during voltage application caused by air bubbles present in the oil can be significantly reduced. In addition, since the insulating oil is filled by a natural oiling method, there is no need to use a vacuum pump as in the past.Furthermore, in the present invention, it is only necessary to open the oiling valve 15, so the vacuum pump does not need to be used. In addition to not using it, there is also the advantage that lubrication work can be done easily and economically without requiring any special effort. Furthermore, there is no need to adjust the flow rate and flow rate of the insulating oil during lubrication by performing special operations on the lubrication valve 15, and it is only necessary to provide a small-diameter bottleneck in the lubrication pipe 14, and this bottleneck 14a can be easily formed by, for example, press-fitting a small diameter pipe into the oil supply pipe 14, and there is no need to specially improve the oil supply pipe 14 or the oil supply valve 15 itself, simplifying the oil supply system. It has a simple structure and can be manufactured at low cost.
Furthermore, during oiling work, even if the oiling valve 15 is fully opened, the inside of the bushing pocket 8 is adjusted so that the insulating oil does not spray out forcefully through the bottleneck 14a, as described above. In addition, there are almost no bubbles generated during lubrication, and the lubrication work can be done by simply opening the lubrication valve 15.
All you have to do is operate the exhaust valve 18 and monitor it so that the insulating oil does not overflow from the exhaust valve 18, so anyone can easily do it without any special skills, and it has many excellent effects. It has the following.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, in which Fig. 1 is a side view of the transformer, Fig. 2 is a vertical cross-sectional view showing how the bushing is installed, and Fig. 3 is a longitudinal cross-sectional view showing an enlarged view of the main parts. It is. 1... Case, 2... Bushing mounting part, 6... Mounting seat, 8... Bushing pocket part, 14... Lubrication pipe,
15... bottleneck, 17... oil storage area.

Claims (1)

[Claims] 1. The middle of the piping away from the bushing pocket of the oil supply pipe that communicates the conservator installed above the case with the bushing pocket formed in the bushing mounting part of the case and partitioned in an oil-tight manner from the inside of the case. A bottleneck is formed in the conservator, and the insulating oil in the conservator is passed through the bottleneck to extremely reduce the flow velocity and guided to the inlet of the bushing pocket, and then the oil is passed through the bottleneck. To a bushing pocket in a transformer, the insulating oil is caused to flow down along the inner wall surface of the transformer so as to seal the insulating oil in the bushing pocket so that no air bubbles are generated under normal pressure conditions. Insulating oil injection method.