JPH0244221Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an oil tank used for electrical testing of bushings.

Electrical tests such as AC withstanding voltage tests and partial discharge tests on bushings used in transformers etc. are performed by immersing part or all of the bushings in oil.
If the product is large, the part immersed in the oil will be long, and the existing oil tank will not be able to secure the insulation distance for the predetermined applied voltage. For this reason, conventionally, as shown in FIG. 1, a cylindrical leg tank 2 of the same diameter is connected oil-tightly to the existing tank 1, and then insulating oil 3 is replenished. The insulation distance A between the tank and the bottom of the tank was ensured. The dashed line in the figure shows the lower part of the test bushing when only tank 1 is used, and since it is not possible to apply the specified voltage with the insulation distance a at this time, it is necessary to add the tank as described above. That's what I was doing.

However, when using this device, the diameter is several meters.
The cost of manufacturing the extension tank 2 and the material cost of thousands of liters of refilling insulating oil are high, and the cost of connecting and disassembling the extension tank and replenishing and extracting the insulating oil is enormous. It took a lot of man-hours.

This idea solves the above-mentioned conventional drawbacks.
The object of the present invention is to provide an oil tank for bushing electrical testing that is economical and requires less man-hours.

An embodiment of this invention will be described below with reference to FIGS. 2 to 4.

The oil tank 5 of the present invention includes an auxiliary tank 6 for oil level adjustment that opens downward, and a cylindrical body 7 of this auxiliary tank.
and a main tank 9 having an upward opening 8 large enough to insert the main tank. This main tank has a structure similar to the conventional electrical test tank. The auxiliary tank 6 is constructed by airtightly connecting a top plate 10 to the upper end of a cylindrical body 7, and its detailed structure is shown in FIG.

In this embodiment, the cylindrical body 7 and the top plate 10 are integrally formed of an insulating material, and although the material is not particularly limited, it is preferable that the insulating oil in the cylindrical body 7 can be monitored from the outside. A transparent insulating material such as polyethylene may be used.

The top plate 10 has a mounting surface 11, a screw hole 12, and a through hole 13 for airtightly connecting the middle part of the bushing.
A ring-shaped mounting seat 14 having
It is attached by bolting to a metal reinforcing plate 15 inserted under the . A shield ring 16 is welded around the reinforcing plate 15, and a through hole 17 for passing through a bushing, similar to the mounting seat 14, is provided in the center. Further, a gasket 18 is clamped between the mounting seat 14 and the top plate 10. On the other hand, a ball valve 20 is attached to the top plate 10, which is an on-off valve that connects the inside of the auxiliary tank 6 with the outside in a disconnectable manner. That is, a pipe 21 threaded at both ends is fitted into a hole provided in the top plate 10, and this pipe 21 is airtightly attached to the top plate 10 with a nut 23 via a packing 22.
One connection port of a ball valve 20 is fixedly connected to 1, and the other connection port is opened upward.

To conduct an electrical test on a bushing using the oil tank 5 configured as described above, first, the middle part of the test bushing 4 is hermetically connected to the mounting seat 14 via a gasket, etc., the ball valve 20 is opened, and the test bushing 4 is suspended by a hoist or the like of an electrical testing apparatus, and as shown in FIG. 2, the cylindrical body 7 is inserted into a main tank 9 containing insulating oil until it is almost immersed in the insulating oil. Next, when the ball valve 20 is closed and the test bushing 4 is hoisted up by a hoist, the insulating oil is pushed by atmospheric pressure and rises together with the auxiliary tank 6. If the lifting by the hoist is stopped when the lower end of the cylindrical body 7 is immersed in the insulating oil in the main tank 9 to a depth of 50 to 100 mm, as shown in the third figure, the immersion depth in the auxiliary tank 6 is The insulating oil rises to the oil level B, and as the effective depth L of the insulating oil increases, a desired insulation distance A is obtained. Note that as the oil rises into the auxiliary tank 6, the oil level in the main tank 9 drops to the oil level D compared to the state of the oil level C in FIG. Since it can be much smaller than the diameter, replenishment of insulating oil is hardly required.

If an electrical test is performed in the state shown in FIG. 3 and the ball valve 20 is opened after the test, the insulating oil in the auxiliary tank 6 will return to the main tank 9.
The test bushing 4 may be lifted up and removed from the auxiliary tank 6 from the side, etc., and the above operation may be repeated for the next test bushing.

In the above embodiment, the supply of insulating oil into the auxiliary tank 6 is carried out by immersing the auxiliary tank 6 in the insulating oil and then raising it, so that the oil level can be changed very quickly and easily to the oil level B. Although this device has the advantage of being able to raise the oil level up to a certain level, it is also possible to use the above device to connect a vacuum pump to the ball valve 20 to raise the oil level. In this case, suspend the test bushing 4 and the auxiliary tank 6 to the position shown in the third figure, open the ball valve 20 in this state, and evacuate the inside of the auxiliary tank 6 with the vacuum pump. Since the oil level rises, once the desired oil level is achieved, the ball valve 20 can be closed and the exhaust can be stopped.

The above describes the case where a part of the test bushing is immersed in oil to conduct an electrical test.
FIG. 5 shows an example in which an electrical test is carried out by immersing the entire bushing under test in oil.

In this case, the main tank 9 is a slightly deep tank for immersion tests, and the auxiliary tank 6 is the fourth tank.
Use the one shown. The test bushing 4 is suspended from a hanging bushing 31 serving as a test device, and the connecting portion is covered with an oil-submerged shield 32.

The middle part of the hanging bushing 31 is attached to the auxiliary tank 6.
The insulating oil is airtightly mounted on the mounting seat 14 of the auxiliary tank 6 by the same operation as described above, and the desired insulation distance A is obtained by raising the insulating oil into the auxiliary tank 6 until it reaches the oil level B.

This invention is not limited to the above-mentioned embodiments; for example, the top plate of the auxiliary tank 6 may be in the shape of a curved plate, or only the top plate 10 may be formed of a metal plate, and this may be covered with a cylindrical shape made of an insulating material. The bodies may be connected in an airtight manner, and in this case, the mounting structure of the mounting seat 14 and the ball valve 20 to the top plate becomes simple. Further, the ball valve 20 may be attached near the top of the cylindrical body 7,
Further, an on-off valve of a type other than a ball valve may be used.

As explained above, according to this invention, by using a relatively shallow tank and combining it with an auxiliary tank that is small and inexpensive to manufacture, the oil level of the insulating oil can be raised with a simple operation to achieve the desired insulation. Furthermore, since there is no need for large-scale replenishment or extraction of insulating oil, it is possible to achieve reductions in costs and man-hours required for electrical testing of bushings.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing an example of a conventional oil tank, Figs. 2 and 3 are longitudinal cross-sectional views showing an example of the oil tank of this invention in a used state, and Fig. 4 is a partial cutaway of the auxiliary tank. The front view and FIG. 5 are longitudinal sectional views showing another embodiment of this invention in a state of use. 4... Test bushing, 5... Oil tank, 6...
Auxiliary tank, 7... Cylindrical body, 8... Upward opening,
9...Main tank, 10...Top plate, 14...Mounting seat, 20...Ball valve, 21...Pipe, 3
1...Butting for hanging.

Claims (1)

[Scope of utility model registration request] An auxiliary tank in which the upper end of a cylindrical body is hermetically connected to a top plate provided with a mounting seat for airtightly attaching the middle part of the test bushing or the bushing for hanging the bushing; An oil tank for Bushing electrical testing, comprising an on-off valve that is provided and provides closeable communication between the inside of the auxiliary tank and the outside, and a main tank that has an upward opening large enough to insert the cylindrical body of the auxiliary tank. .