JPS6158415A - Conduit bus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a conduit bus bar having a characteristic of attenuating, in particular, sudden wave surge voltage.

[Technical background of the invention and its problems] In recent years, substations (or switchgears) using SF and gas-insulated devices have made remarkable progress, and have been put into practical use from the original 66 kV class to the 500 kV class at present. S
Fb gas insulated substations have many advantages such as being able to reduce the size of the site, being highly safe, and being easy to maintain, so they are expected to continue to develop in the future.

In such an SF6 gas insulated substation, the SF & gas insulated switchgear, which is the main equipment that makes up the substation, opens and closes the disconnector and disconnector to disconnect the circuit. When the electrodes are connected or connected, a discharge occurs between the electrodes. The surge voltage generated by this discharge is sometimes more than twice the rated value, and the time it takes to reach the peak value of the first wave becomes a high-frequency vibration wave of 100 n3 or less. Moreover, the coaxial 1i, 5-structure type, in which the center conductor is concentrically surrounded by a bus duct like a conduit busbar, has extremely good frequency characteristics and can propagate voltages up to 1GH frequency with almost no attenuation, making it possible to prevent surges. The signal reaches equipment connected to gas-insulated switchgear, such as bushings and transformers, without being attenuated.

Next, the effect of such high frequency voltage on the separate parts of the pond will be explained using a transformer as an example. FIG. 3 is a schematic cross-sectional view showing an example of a typical example of a conventional GIS substation, showing the connection state of a transformer connected to a gas-insulated switchgear. The transformer TR is constructed by storing the contents of the transformer, in which a winding 2 is wound around an iron core 1, together with insulating oil in a tank 3, and attaching a cooler 4 for cooling the insulating oil and a conservator 5 for preventing oil deterioration. ing. The high voltage lead wire 6 of its winding 2 is passed through the oil duct l-7 to the gapless arrester 11 and roughly from the oil/gas bushing 8 to the S F
It is connected to an S Fb gas switchgear (not shown) via a high-voltage central conductor 10 of the b gas pipe busbar duct 9.

Now, in such a configuration, when the switchgear operates, a high-frequency surge with an extremely high rise is generated, and this high-frequency surge is applied to the transformer through the conduit busbar. The response of the transformer winding to such a high frequency surge with a high wave front steepness is as follows. A case will be described in which the high cell cap disk winding 2 shown in FIG. 4, which has excellent impulse voltage resistance characteristics, is used as a transformer winding.

When a steep high-frequency surge voltage is applied to the Hi-Cell Cap disc winding, the Hi-Cell Cap winding has a series capacitance of O
Since the is large, the potential distribution seems to be better, but in reality it is different. That is, in Figure 4, the series capacitance is such that the voltage is applied to the first turn of the first stage plus half of the total turns N=16 of the second stage plus N/2=8. It is the first thing that is formed. However, when the voltage becomes a steep wave surge, the voltage wave that enters the first turn becomes N/2.
The peak value will be reached in the first turn before reaching the next turn with . For such a steep surge voltage, the several times the potential distribution, which is the aim of the high cell cap disk winding, becomes meaningless. This pointless boundary differs depending on the voltage d5 and capacitance of the winding, but it is said that the time required to reach the negative peak value of the -th wave is about 0.5 μs or less.

In this way, the transformer is defenseless against high-frequency surges with a steep rise even if a vial winding with good lightning impulse characteristics is used. Now, let's consider whether the lightning arrester 11 can operate and protect the transformer. Now, suppose that a high-frequency surge enters the conduit bus 9 due to the operation of the switch. The waveform diagram of the steep wave voltage at each part at that time is shown below. Not shown in Fig. 5. First, @sharp voltage with voltage peak value E charges the ground capacitance Co of the oil/gas bushing 8 and reaches the terminal of the lightning arrester 11. At this time, the ground capacitance CO of the bushing 8
Therefore, the peak value of the steep wave voltage becomes slightly smaller E', and the wave front steepness also becomes slightly smaller. In the lightning arrester 11, the v-
Since the current flows according to the i characteristic, the voltage is suppressed below the limit voltage of the lightning arrester 11, and its peak value becomes E''.

However, since the surge arrester only lowers the peak value without changing the wave front steepness, it is not possible to solve the above problem, that is, change the winding distribution in the transformer winding 2 of the steep wave surge voltage.

[Object of the invention] The object of the present invention is to
F. To provide a conduit bus bar that prevents dielectric breakdown in equipment such as transformers due to high frequency surges generated by the operation of gas insulated switchgear.

[Summary of the invention] The conduit busbar according to the present invention is characterized in that a fully bent half-conductor having a resistivity higher than the resistivity of the metal used for the center conductor is attached around the center conductor. be.

[Embodiments of the Invention] The present invention will be described below with reference to an embodiment shown in FIG. In FIGS. 1a and 1b, a conduit busbar 20 according to the present invention is constructed by surrounding a central conductor 10 with a conduit busbar duct 9 and filling the interior with S Fb insulating gas. In the present invention, a metal or semiconductor resistor 12 having a higher resistivity than the resistance of the center conductor 10 is attached to the outer surface of the center conductor 10 and the inner surface of the duct 9 by vapor deposition or plating.

The metal or semiconductor resistor 12 is selected from materials such as tungsten, nichrome, and molybdenum, and the thickness of the coating is approximately 180 μm (for tungsten, the skin depth at the IMH of the material).

In the conduit busbar of the present invention constructed in this manner, when a high frequency surge occurs and propagates, the high frequency current flowing through the line is pushed out to the outer surface of the conductor 10 due to the line's self-inductance. The skin depth of the current is used as the basis for this extrusion.

The skin depth referred to here means that the current density on the metal surface is 1/e.
The depth is , and is supported by the following equation.
・7. Here, δ is the skin depth, ρ is the resistivity of the material, and [: is the frequency. For example, if the metal is tungsten, I M
In Hz, δ = 180 μm, and it can be considered that currents of 1 MHz or higher mostly flow at a distance of 180 μm from the surface.

Therefore, by providing a high-resistance metal or semiconductor resistor 12 on at least one of the outer surface of the center conductor 10 and the inner surface of the conduit duct 9 to a skin depth of about IMhh, high-frequency waves can be suppressed. The current component causes heat loss through the resistor 12, and high frequency electrical energy can be reduced. Therefore, destruction of other equipment due to high frequency voltage can be prevented.

Moreover, in the conduit bus 20 of the present invention, the commercial frequency current,
Since the skin effect does not occur and the flow is uniform and not much reaches the surface of the high-resistance element 12, the power at the commercial frequency is very small, and the thermal considerations for the conduit busbar can be kept the same as in the past. The metal of the resistor 12 attached to the center conductor can be formed inexpensively by plating. In addition, by using metals or semiconductors for the high-resistance element 12, such as tungsten, nichrome, or molybdenum, which have a low saturated vapor pressure and a high melting point, when high-frequency energy is converted into heat, the Due to this, the surface becomes highly humid and deformed,
IJ is a highly reliable pipeline busbar with no risk of damage.
It will be done.

In another embodiment of the invention shown next in FIGS. 2a and b,
High-resistance elements 12 made of high-resistivity metal or semiconductor are formed into a cylindrical shape, and are arranged in multiple layers concentrically around a center 8 and 10.

In this 414 configuration, the region where high frequency waves propagate W1 in the space where SF and insulating gas exist is divided, the surface area in contact with high frequency waves increases, and the resistance loss increases accordingly. However, at commercial frequencies, the high resistance element 12
Because of this, almost no flow can occur, so there is almost no loss, and only high frequencies can be efficiently attenuated.

[Effects of the Invention] As described above, according to the present invention, metal or half-metal high resistance elements are attached to the outer surface of the center conductor and the inner surface of the pipe duct, so that the pipe busbar By converting the high frequency energy into heat using a high resistance material, the high frequency surge propagating inside can be sufficiently reduced, the transformer can be protected from the high frequency surge, and an inexpensive and highly reliable conduit bus bar can be obtained. I can do it.

[Brief explanation of the drawing]

1a and b are a cross-sectional view and a vertical cross-sectional view showing an embodiment of the pipe busbar according to the present invention, FIGS. 2 a and b are a cross-sectional view and a longitudinal cross-sectional view showing an embodiment of the present invention, and FIG. Figure 3 is a schematic configuration diagram showing a commonly used gas-insulated substation, Figure 4 is a configuration diagram showing the high cell cap winding of a transformer, and Figure 5 is a diagram showing the surge voltage generated in a conventional switchgear. It is a characteristic diagram which does not show the attenuation state accompanying propagation. TR...Transformer, 1...Transformer core 2.
...Transformer winding, 3...Transformer tank 6...
High voltage lead wire 7...Lead wire duct 8...Oil/gas bushing 9...Gas pipe O1 line duct 10...Center container, 11...Surge arrester 12...High resistance element, 20... ...Pipeline Bus Line (8733) Agent Patent Attorney Yoshiaki Inomata (1 person from G) Figure 1 ((1) d,...) Figure 2

Claims (6)

[Claims] (1) In a gas-insulated conduit busbar connected to a gas-insulated switchgear, the resistivity is higher than that of the metal used for the center conductor at least either around the center conductor or inside the outer conduit duct. A conduit busbar characterized by having a metal or semiconductor resistor with resistivity attached. (2) The pipe busbar according to claim 1, wherein a metal or semiconductor resistor having a high resistivity and a particularly low vapor pressure is used. (3) The pipe busbar according to claim 1, characterized in that the metal or semiconductor resistor having high resistivity is a resistor having a particularly high melting point. (4) A conduit according to claim 1, characterized in that the conduit is a metal or semiconductor resistor having high resistivity, and its thickness is approximately the skin depth at a current of 1 MHz due to the skin effect. Bus line. (5) As a metal or semiconductor resistor with high resistivity, the foil is formed into a cylindrical shape, and the foils are arranged concentrically in a multi-cylindrical shape around a central conductor, as claimed in claim 1. The listed pipe busbar. (6) The pipe bus bar according to claim 1, wherein the metal or semiconductor resistor having high resistivity is selected from among nichrome, tungsten, manganese, zinc, lead, germanium, and silicon.