JPS6023589B2 - dc electrical equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to DC electric equipment, and more particularly to an improved insulation structure of a high voltage lead wire outlet portion to which a DC high voltage is applied.

In recent years, with the practical application of DC power transmission, high voltage, large capacity converter transformers and smoothing reactors have become necessary.

By the way, in many cases, the insulation of these DC electric devices to which a DC high voltage is applied is inconvenient if the secondary AC insulation configuration is used. Particularly inconvenient is the part that has a creeping insulation structure. That is, an electrical device to which only an alternating current voltage is applied at the high-voltage lead wire outlet connected from the coil to the pushing has the insulated structure shown in FIG. 1, for example.

An inner insulating tube 2 and an outer insulating tube 3 are arranged in the same manner so as to wrap around the coil 1 having the same cylindrical shape, and shields 4 and 5 are attached close to each other above and below the coil 1. On the outside of these shields 4, 5 are angle rings 6, 7 and 8.
, 9 can be attached. The lower part of the coil 1 is the support stand 10
It is fixed to the ground tank 11 via. These bodies are housed in oil 12 and sealed. In order to conduct electricity from a part of the coil 1, a high voltage lead wire 13 is drawn out through the insulating cylinder 3. This high voltage lead wire 13 is constructed by insulating a core wire 13b with an insulator 13a made of oil-impregnated paper. Second
The figure is an enlarged and detailed view of the coil extraction portion "A" in FIG. 1, and the same parts as in FIG. 1 are given the same reference numerals. In FIG. 2, 13c is a connecting portion between the coil and the core wire b of the high voltage lead wire 13, and 3a, 3b, and 3c are outer insulating cylinders shown from the ground side. By the way, when a DC voltage is applied to the outlet portion of the high-stress lead wire 13 of such a conventional AC insulation system, a problem arises because the mechanism of potential distribution is completely different.

In other words, the light current voltage is distributed according to the dielectric constant, whereas the DC voltage is distributed according to the resistivity, and the dielectric constant ratio of oil and oil-impregnated paper is as small as 1:1.48, whereas The extremely large resistivity ratio of 1:50 to 1:100 of the soaked paper causes some inconveniences. This will be explained with reference to Figure 3, which shows a simple model. Figure 3 shows a coil with a DC voltage of 100 This is a model showing the equipotential lines when % is applied.
The same parts as those in the figure are given the same reference numerals. From this figure, the equipotential lines indicate a direction in which the resistivity ratio between the oil and the oil-impregnated paper is large, so it is concentrated in the oil-impregnated paper area. Especially when the high voltage lead wire 13 is connected to the coil 1
Most of the heat is concentrated in the portion 13c that is connected to the insulating run 3 and the portion that penetrates the insulating run 3. By the way, if the electric potential concentrates at the boundary between the oil and the oil-impregnated paper, it is inconvenient when applying a DC voltage for the following reasons. The pressure resistance of oil and oil-impregnated paper is approximately 1:io, and oil-impregnated paper is better. Space charges tend to accumulate at the boundary between oil and oil-impregnated paper, so the pressure resistance is usually lower than that of oil. Especially when the insulation distance is long ~
These desires are significant. For this reason, the conventional AC insulation system has an extremely disadvantageous structure from the viewpoint of DC withstand voltage. The present invention has been made in consideration of the above points, and an object of the present invention is to obtain a DC electric device that can improve the dielectric strength of the boundary between oil and oil-impregnated paper, that is, the so-called creeping structure.

Embodiments of the present invention will be described below with reference to the drawings.

In the first diagram, in which parts that are the same as those in FIG.
The oil-impregnated paper barriers 23a, 23b of the parentheses are attached to the outer insulating cylinders 3a,
It is installed between 3b and 3c in the same 0 shape as this and with an oil gap between them in the penetrating direction. The other parts are exactly the same as FIG. 2 showing the prior art.
FIG. 5 is a model for explaining the operation of the present invention, in which an oil-impregnated paper barrier 23 is added between the outer insulating cylinders 3a and 3b.

In the insulation configuration configured in this way, when a DC voltage is applied, the DC potential distribution is determined by the ratio of the resistivity of the oil and the oil-impregnated paper, but the oil-impregnated paper barrier 23 allows a current path with a low resistance value to be formed. Since the current is blocked near the surface of the insulation 13a of the high voltage lead wire 13, the current flows along the surface of the insulation 13a of the high voltage lead wire 13 and the surface of the oil-impregnated paper/liar 23. Since the equipotential lines are perpendicular to the direction in which the current flows, it is obvious that the equipotential lines shown by broken lines appear in the figure. The oil-impregnated paper barrier It is clear that 23 improves the withstand voltage of such an insulating structure. According to the inventor's experiments, a relationship between the number of oil-impregnated paper barriers and pressure resistance was obtained as shown in FIG. From the above explanation, it can be seen that such an insulation configuration is extremely effective in terms of DC withstand voltage. It goes without saying that the insulation configuration described above is not limited to oil insulation, but also applies to gas insulation such as SF gas insulation, and has similar effects.

In this case, the gas is mixed with oil and the solid insulator such as epoxy polyethylene corresponds to oil-impregnated paper.As explained above, according to the present invention, the high-voltage lead wire is drawn out from the coil by penetrating the insulating tube. A disk-shaped insulating barrier is installed on the insulator, and this insulating bar is placed between a plurality of insulating tubes provided in the same D shape on the outer circumference of the coil, and in the same 0 shape in the penetration direction. Since the insulating medium is disposed through a gap, the creepage distance is increased and the potential distribution is uniformly controlled, so it is possible to obtain a DC electric device having an insulating structure with dramatically increased DC withstand voltage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view showing a high-voltage lead wire outlet of a conventional AC electric device. FIG. FIG. 3 is a diagram showing equipotential lines when a DC voltage is applied to a conventional insulation structure, FIG. This figure is a diagram showing the potential distribution of the insulating structure according to the present invention, and FIG. 6 is a curve diagram showing the withstand voltage depending on the number of barriers according to the present invention.

3a, 3b, 3c...Outer insulating tube, 11...
...Grounded tank, 12...Oil, 13...
High voltage lead wire, 13a... Insulator, 13b...
... Core wire, 23a. 23b...Oil soaked paper barrier.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. An insulating medium is stored together with a coil in a tank, and a high-voltage lead wire with a core wire insulated by an insulator is connected from the coil by passing through a plurality of insulating cylinders arranged concentrically outside the coil. In the DC electrical equipment taken out, a disk-shaped insulation barrier is attached to the insulator of the high voltage lead wire, and this insulation barrier is placed between each of the insulation cylinders concentrically therewith, and in the penetrating direction of the insulation medium. A direct current electrical device characterized by being arranged through a gap.