JPH0159807B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an insulating device for high voltage conductors, and more particularly to an apparatus for electrically insulating a high voltage conductor penetrating a wall at ground potential.

Conventionally, in order to insulate high-voltage conductors in electrical equipment from walls of earth potential, such as busbars penetrating the wall of a switchboard or conductors penetrating the tank wall of a transformer, the portion corresponding to the wall of the high-voltage conductor is made of porcelain. Alternatively, it is covered with an insulating tube made of an insulator (dielectric) such as resin, and the outer periphery of the insulating tube is provided with a large number of folds, or the thickness or length of the insulating tube is increased.

However, the optimal number of pleats in the insulating tube is not clear, and increasing the thickness or length poses problems such as an increase in the weight and price of the insulating tube.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide an insulating device for a high voltage conductor that is lightweight and inexpensive. Embodiments of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the high voltage conductor insulation device according to the present invention has a hole 1a in a wall 1 at ground potential for connection to a main body of equipment (not shown) such as a switchboard or a transformer.
It is for insulating a high voltage conductor 2 passing through the wall 1 from the wall 1, and its main body is an insulating tube 3 that is fitted into the conductor 2 to cover the portion of the conductor 2 that corresponds to the wall 1. The insulating tube 3 is made of synthetic resin such as epoxy resin, and is formed into a cylindrical shape with a diameter smaller than the hole 1a of the wall 1 and a predetermined length. and a mounting flange 4 for fixedly supporting the conductor 2 on the wall 1
is integrally molded. Further, on the outer periphery near both ends of the insulating cylinder 3, flange-shaped first folds 5, 5 are formed.
are integrally molded, and a pair of flange-shaped second folds 6, 6 are provided on the outer periphery near the middle part.
are integrally molded so as to face each other with the mounting flange 4 in between, and near the middle part (1/2) of the distance l between each first pleat 5 and each second pleat 6.
On the outer periphery of the insulating cylinder 3 in
The pleats 7, 7 are each integrally molded.

In addition, each of the first pleats 5 and the second pleats 6 are as follows:
Considering manufacturing convenience, etc., from the end of the insulating cylinder 3 and the middle of the insulating cylinder 3, the distance L between the end of the insulating cylinder 3 and the wall 1, that is, about half the length of the insulating cylinder 3.
They are provided at positions having an interval (l ₁ and l ₂ ) of 15% or less. In addition, the mounting flange 4
The joint portions of each of the pleats 5, 6, and 7 with the insulating cylinder 3 are padded in a rounded shape to prevent electric field concentration.

Each of the first pleats 5, second pleats 6 and third pleats
The folds 7 function to prevent the progress of an electron avalanche during flashover, and each has a thickness that does not cause penetration failure, and is determined by the creepage flash formula (Taepler's formula). It is formed into a circular shape with an outer diameter dimension of . The thickness of the insulating tube 3 is determined by the thickness of each pleat 5, 6,
The width of the pleat is 1/5 or less, preferably 1/15 to 1/25, of the radial length between the outer end of the fold 7 and the inner surface of the insulating cylinder 3 (hereinafter referred to as "width of the pleat").

In the above-mentioned embodiment, the insulating tube 3 is provided with the mounting flange 4, and the insulating device itself and the conductor 2 are fixedly supported on the wall 1 via the mounting flange 4. If it is supported via a support insulator or the like, it is not necessary to provide the mounting flange 4. In addition, the thickness of each pleat 5, 6, 7 and the insulating cylinder 3 is as follows:
Naturally, it is necessary to have mechanical strength and to a degree that does not cause penetration failure (for example, about 5 mm in the case of epoxy resin).

The results of a simulation experiment regarding the relationship between the number and position of the pleats of the above-mentioned insulating device, and the relationship between the width of the pleats and the thickness of the insulating tube were as follows.

That is, as shown in FIGS. 2 and 3,
Made of epoxy resin, outer diameter 40mm, inner diameter 30mm, length approx.
Inside case 8, which is shaped like a 700mm bottomed cylinder,
One rod-shaped electrode 9 with an outer diameter of 30 mm corresponding to the conductor 2
At the same time, the other grounded ring-shaped electrode 10 corresponding to the wall 1 is fitted on the outer periphery of the bottom side of the case 8 (the left side in FIG. 2), and A first fold 11 and a second fold 12 in the shape of a ring disk with an outer diameter of 90 mm are formed on the outer periphery of the electrode 10 with a distance of 100 mm between the opening end and the other electrode 10, and both folds 11,
A simulation experiment device was used in which the space between the first and second folds 11 and 12 was integrally molded with a distance of 500 mm, and a third fold 13 of the same shape was integrally molded on the case 8 by changing the position between the first and second folds 11 and 12. , the flashover value characteristics were measured by applying impulse voltages of positive and negative polarity to one electrode 9. Figure 4 shows the measured values, and the horizontal axis shows the first fold 11 and the third fold. The distance to the fold 13 is l (mm), and the vertical axis is the 50% impulse flashover voltage (voltage at which 50% of the number of repeated applications causes flashover, hereinafter referred to as "50F.OV (KV)").
It is abbreviated as. ), in which curve A shows the positive polarity impulse voltage flash characteristics and curve B shows the negative polarity impulse voltage flash characteristics.

In addition, in FIG. 4, curves C and D are obtained without providing the first and second folds 11 and 12, respectively.
It shows the flashover value characteristics when the third pleats 13 are integrally molded with different positions and positive and negative impulse voltages are applied to one electrode 9, and the straight line E
and F is either fold 11,1 in case 8
2, 13 are not provided, and the flashover value characteristics are shown when positive and negative impulse voltages are applied to one electrode 9, and the straight lines G and H are
Case 8 is not provided with any of the folds 11, 12, and 13, and case 8 has an outer diameter of 90 mm and an inner diameter of 30 mm.
The graph shows the flashover value characteristics when impulse voltages of positive polarity and negative polarity are applied to one electrode 9.

Next, as shown in FIG. 5, the first and second folds 11, each having an outer diameter of 90 mm,
Between 12 and 12, two more third pleats 13a, 13
b is integrally molded with the case 8 by changing its position, and between the first fold 11 and the third fold 13a on one side (on the right side in FIG. 5), and between the second pleat 12 and the other third fold 13a. 3 and the folds 13b were integrally molded by changing the distances 1 and 1 while keeping them equal, and applying positive and negative impulse voltages to one electrode 9 to measure the flashover value. Figure 6 shows the flash value characteristic diagram, where the horizontal axis shows the first,
The second folds 11, 12 and each third fold 13a, 1
3b, and the vertical axis is the 50% impulse flashover voltage 50% FOV (KV). Curves A and B are the positive flashover value characteristics and the negative flashover value characteristics, respectively. Showing value characteristics.

In addition, in FIG. 6, the straight lines C and D represent the case where only two third pleats 13a and 13a are provided without providing the first and second pleats 11 and 12, respectively, and the case where there are only three pleats as described above ( (Figure 2, Figure 3)
This shows the peak value of the positive 50% impulse flashover voltage in the case of FIG.

From the above simulation experiment, the third folds 13a, 13
When two sheets of b are provided, the period 〓l, which shows the same flash value of positive polarity and negative polarity, is approximately as shown in Fig. 6.
The length is 250 mm, which is approximately the middle position between the second folds 11 and 12. This is the same as when one third pleat is provided in the middle.

Moreover, in the shape of FIG. 2, the first and second folds 11,
The flashing value when three pleats, 12 and 13 near the middle, are provided is the positive polarity flashing value A in Figure 4.
Between the curve and negative polarity flashing value B curve showing the same value〓
(l = 250mm), the flash fault value is approximately 150KV (50%F.
OV). It was found that this value is almost equal to the positive flash value G (Fig. 4) when the outer diameter of case 8 without pleats is 90 mm and the inner diameter is 30 mm (same diameter as the above pleats).

It was found that this value was equal to the flashover value VFO obtained from the following Tapler equation for creepage flashover.

V _FO = Kb/ ⁸ √Co ³・⁴ √ (Co: specific capacitance, l: distance between poles, Kb: constant) From this, by providing the folds 11, 12, and 13, the thickness of the case 8 can be reduced. The same effect as increasing the folds can be obtained, and the pleats 11, 12, 13
By increasing the outer diameter of the case 8, it is possible to shorten the length of the case 8 in order to maintain the same flashover value.

Furthermore, based on the above-mentioned results, as shown in FIG.
Case 8 with the outer diameter of 12 and 13 constant at 120 mm.
Case 8 and when integrally molded with different thicknesses
Each pleat 11, 12, 1 with a constant thickness of 5 mm.
The flashover value was measured when the outer diameter of No. 3 was changed and integrally molded. FIGS. 8 and 9 show their flashover value characteristics.

That is, in FIG. 8, the thickness t of the case 8 is plotted on the horizontal axis.
(mm), 50% impulse flashover voltage on vertical axis
50% FOV (KV). Curves A and B show the flashover value characteristics when positive and negative impulse voltages are applied to one electrode 9, respectively. has fold 1 on the horizontal axis
1, 12, and 13, and the 50% impulse flashover voltage 50% FOV (KV) is plotted on the vertical axis. Curves A and B similarly indicate that one electrode 9 has a positive polarity and a negative polarity. This shows the flashover value characteristics when a typical impulse voltage is applied.

From these flash value characteristics, the thickness of the case showing the harmonious point of 50% FOV of positive and negative polarity is 8th.
It can be seen from the figure that the thickness is about 8 mm.
Since the width of the pleats in FIG. 7 is (120-30)/2=45mm, the ratio of the thickness at the harmonic point to the width of the pleats is 8:45, which is about 1/5 or less.

In addition, the saturation region in Figure 9 is calculated when the pleat width W is 75 mm or more.
If it is 125 mm, the thickness t of case 8 is 5.
mm, the ratio of thickness to pleat width is 5:75.
~5:125. That is, the most desirable ratio is 1/15 to 1/25.

As described above, the present invention insulates a high-voltage conductor penetrating a wall at earth potential from the wall, and provides first folds on the outer periphery near both ends of the insulating tube through which the high-voltage conductor passes. A pair of second pleats are provided facing each other on the outer periphery of the insulating tube near the intermediate portion of the insulating cylinder, and third pleats are provided on the outer periphery of the insulating cylinder near the intermediate portion of each of the first pleats and the second pleat, respectively.
Since the thickness of the insulating tube is 1/5 or less of the radial length between the outer end of each pleat and the inner surface of the insulating tube, the insulating device for the high voltage conductor can be reduced in weight and cost. It can be made inexpensive, and has the advantage of being able to maintain insulation coordination with respect to impulse voltages of both polarities.

[Brief explanation of drawings]

Figure 1 is a longitudinal cross-sectional view of an insulating device according to the present invention, Figures 2 and 3 are front and end views of a simulated experimental device with three pleats, respectively, and Figure 4 is a longitudinal cross-sectional view of an insulating device according to the present invention. Figure 5 is a front view of the simulated experimental device with four pleats, Figure 6 is a flash value characteristic diagram when there are four pleats, and Figure 7 is a diagram of the flash value characteristics when there are four pleats. Figures 8 and 9 are front views of a three-fold simulation experiment device in which the width of the folds and the thickness of the case can be changed relative to each other. FIG. 3 is a flashover value characteristic diagram when the thickness of the case is constant and when the width of the pleats is changed. DESCRIPTION OF SYMBOLS 1... Wall, 2... Conductor, 3... Insulating tube, 5... First pleat, 6... Second pleat, 7... Third pleat.

Claims (1)

[Claims] 1. A high voltage conductor penetrating a wall at earth potential is insulated from the wall, and a first pleat is provided on the outer periphery near both ends of the insulating cylinder through which the high voltage conductor is penetrated, and a first fold is provided on the outer periphery near the middle part of the insulating cylinder. A pair of second pleats are provided to face each other, third pleats are provided on the outer periphery of the insulating tube near the intermediate portion between each of the first pleats and the second pleat, and the thickness of the insulating tube is An insulating device for a high-voltage conductor, characterized in that the length is 1/5 or less in the radial direction between the outer end of each pleat and the inner surface of the insulating cylinder.