JPS5922357B2 - Gas insulation protective gap device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is installed at the entrance of a substation, for example, on the line side of a disconnect switch, to protect switchgear from lightning surges, and to measure ultra-high voltages. The present invention relates to a gas insulation protection gap device which is also equipped with a voltage measuring device.

Generally, in a substation, as shown in Fig. 1, the transformer T side of the power generation substation (a dedicated lightning arrester LA is provided, and a coordination gap G is provided on the track side, so that the transformer T
, L, disconnector B, disconnector, and other equipment from overvoltage.

However, if the circuit breaker B on the railroad side is in an open state, the surge arrester LA installed only near the transformer T will respond to surges entering from the railroad. becomes ineffective, and the protection of line-side equipment including circuit breaker B must necessarily rely on coordination gap G.

That is, it must have discharge characteristics that are sufficiently coordinated with the breaker B when the circuit is open.

As this type of cooperation gap, a bar gap has been used conventionally, but this final voltage (→-waiting time 1
) The characteristic rises rapidly from around 10 μsec as shown in FIG.

In other words, since there is a time region in which v- between the poles of breaker B exceeds the characteristic (b in FIG. 2), protection of breaker B cannot be expected in such a time region.

For this reason, some ideas have been devised, such as installing a lightning arrester LA on the railroad side, or using a movable gap that can adjust the gap length of the coordination gap G depending on the open/closed state of the breaker B.
The former can be expected to provide complete protection, but is not economical, while the latter is cheaper than the former, but because it takes a certain amount of time to change the gap length, it is not effective against surges caused by multiple lightning strikes. There is no.

Additionally, there is a risk that peripheral equipment may be damaged due to the arc generated by the flashover.

SF that eliminates the inconvenience of such a protection gap
Several 6-gas gaps have also been proposed.

However, although these SF6 gas gaps are convenient as protective gaps, they do not have the ability to measure commercial frequency ultra-high voltages.

On the other hand, as is well known, in order to measure commercial frequency ultra-high voltage,
Electromagnetic induction type voltage transformers and electrostatic induction type capacitor type voltage transformers are used.

In general, capacitor-type voltage transformers, which are inexpensive and relatively easy to manufacture, are mainly used in sealed switchgear, but in this case, oil-immersed paper capacitors are usually used, and oil and gas Since an airtight insulating container is required between the two, both the size and weight become large, and as a result, this becomes a major hindrance to downsizing the device.

In addition, in order to eliminate such inconveniences, there have been proposals to install a capacitor-type voltage transformer at the connection bus terminal of a sealed switchgear, but even in this case, downsizing can certainly be expected; , and it is desired to make it inexpensive.

The present invention has been made in view of the above points, and provides sufficient protection for sealed switchgear from surge voltages, as well as an electrostatic induction type voltage measuring device that can easily measure ultra-high voltages at commercial frequencies. The purpose of the present invention is to provide a gas insulation protection gap device.

A preferred embodiment of the invention will now be described with reference to FIG. 3.

The gas insulation protective gap device according to the present invention is composed of a high voltage side main electrode section A and a ground side main electrode section B, which are inserted and fixed into one open end of a metal body 1.

The high-voltage side main electrode part A has a cylindrical discharge electrode 4 at the tip 3'c of a hollow conical insulating spacer 3 and a hemispherical bar-shaped arc electrode 5 positioned inside the cylindrical discharge electrode 4. The insulating spacer 3 is inserted into one open end of the metal body 1, and the insulating spacer 3 is fixed to the metal body 1 so that the tip 3' of the insulating spacer is located inside the metal body 1. There is.

The tips 4a and 5a of the discharge electrode 4 and the arc electrode 5 are made of a material with excellent arc resistance, such as a Cu-W alloy or graphite.

Further, a plug-shaped external connection terminal 6 is formed integrally with the discharge electrode 4 and the arc electrode 5.

The ground side main electrode section B is connected to a cylindrical discharge electrode 9 fixed to the inside of the metal plate 7 through an insulator 8 attached to the inside of the metal plate 1 that closes the other opening of the metal body 1. A hemispherical bar-shaped arc electrode 10 is fixed and located within the discharge electrode 9, and further surrounds the high voltage side electrode section A, the ground side discharge electrode 9 and the arc electrode 10, and is between the metal body 1. It consists of cylindrical electrode plates 2 arranged at regular intervals so as to form a coaxial cylindrical electrostatic capacitor.

Note that this electrode plate 2 has a plurality of holes 2a made therein. Also, the tips 9a and 1 of the ground side electrodes 9 and 10
0a are the tips 4a and 5a of the high voltage side electrodes 4 and 5
Similarly, it is made of materials with excellent arc resistance such as graphite and Cu-W alloy.

The dimensions of the high voltage side electrode section A and the ground side electrode section B are configured as shown in FIG. 4, which will be described later, in order to obtain good discharge characteristics.

Further, a trigger electrode 11, which will be described later, is fixed to the outer periphery of the ground side arc electrode 10.

This trigger electrode 11 is also made of a material with excellent arc resistance.
For example, it is made of carbon or Cu-W alloy.

Furthermore, a coil 12 for detecting discharge current is attached to the outer periphery of the arc electrode 10 as required.

13 is a ground side connection lead fixed to the outside of the metal plate 1.

Further, a drawer bushing 14 is fixed to the metal body 1G so that the potential of the electrode plate 2 can be taken out.

Note that this bushing 14 is connected to a high impedance high voltage amplifier (not shown).

And an insulating spacer 3 for supporting the fuselage 1 and the high voltage main electrode part A.
The inside of the main body, which is sealed by a metal plate T, is filled with SF6 gas which has excellent arc extinguishing ability.

A specific example of the dimensions of the high voltage side and ground side main electrode sections, A and B, and an electric field vector diagram are shown in FIG.

In this example, the impulse discharge voltage is 1800 KV.

The upper and lower electrodes have an asymmetric structure.

In other words, as is clear from the electric field vector diagram, the direction of the electric field (indicated by the arrow) and the length of the line marked with the arrow (the length of the electric field) at the tips of the upper and lower electrodes are the electric fields in the opposite directions. The dimensions of the upper and lower electrodes are made different so that the sizes of the electrodes are almost the same.

That is, when the upper and lower electrode structures are drawn with a line perpendicular to the electrode axis direction centered between the gears, the structure is asymmetrical with respect to this line.

First, the function of the protection device of the present invention configured as described above will be explained.

The excessive voltage caused by the lightning surge is applied to the protective gap, and the voltage applied to the concentric cylindrical capacitor formed by the metal body 1, electrode plate 2, and 11, and then this acts as a trigger, causing the distal end 4a of the discharge electrode to
and 9a, and then the arc moves between the arc electrode tips 5a and 10a, and a lightning surge caused by a lightning strike is discharged.

At this time, overvoltage is suppressed because the discharge is performed in SF6 gas with excellent arc extinguishing performance, and as shown by curve C in Figure 2, a good voltage V temporary time characteristic of the flashover can be obtained, and the circuit breaker etc. Optical insulation coordination can be achieved with protective equipment.

Furthermore, the operational characteristics of the protective gap according to the embodiment of the present invention will be explained.

FIG. 5 shows the voltage one-hour characteristics when the lightning surge is discharged between the discharging electrodes 9 and the tip portions 9a and 4a of the discharge electrode 4, and shows the most preferred embodiment in which the trigger electrode 11 is provided (6 (shown by a curve) and the case where it is not provided (shown by a 0 curve) are compared.

In particular, when the trigger electrode 11 is provided, the voltage one-hour curve of the protective gap becomes flatter than when it is not provided, and a constant discharge voltage V is always obtained with respect to the discharge time T.

As mentioned above, the incoming lightning surge voltage is divided by the electrostatic capacitor obtained by the cylindrical electrode plate 2, and this voltage is used to connect the ground side discharge electrode 9 and the trigger electrode 1 in advance.
This is because the voltage between 1 and 1 is discharged.

However, even if the trigger electrode 11 is not provided, the discharge voltage can be kept fairly constant by dividing the voltage by the electrostatic capacitor obtained by the cylindrical electrode plate 2.

For this reason, preferably a trigger electrode 11 is provided.

The protective gap device according to the present invention can discharge at the withstand voltage value BIL of a protective device such as a circuit breaker even if a lightning surge voltage with a large peak voltage arrives.

Next, the case of measuring ultra-high voltage using the device of the present invention will be explained with reference to the circuits shown in FIGS. 3 and 6.

That is, the capacitance between the high voltage side main electrode part A and the electrode plate 2 is C1, the capacitance between the electrode plate 2 and the metal body 1 is C2,
Further, if the voltage applied between the high-voltage side main electrode section A and the ground is Vl, then the voltage V2 applied to the voltmeters V and M connected via the bushing 14 and the amplifier AMP is determined by the following equation.

1ゞ・=c1+c2ゞ・ In this way, ultra-high voltage of commercial frequency can be easily measured.

The present invention is not limited only to the above embodiments, but the following embodiments can be adopted.

■ Connect the ground side arc electrode 10 to the cylindrical electrode plate 2,
A structure in which the discharge electrode 9 is grounded while floating above the ground.

■ A structure in which the trigger electrode 11 is provided inside the discharge electrode 9.

■ A structure in which a capacitor is added to the outside of the cylindrical electrode plate 2 for the purpose of adjusting the trigger voltage.

■ A structure in which the discharge detection coil 12 is provided outside the metal body 1.

(2) In order to lengthen the connection time of the trigger discharge light, the ground side main electrode part B (here, a structure in which the discharge electrode 9 and the arc electrode 10 are connected with an appropriate resistor).

■ The main electrode part on the high voltage side is composed of a discharge electrode 4 and an arc electrode 5, and the high voltage electrode has a structure in which the discharge electrode and the arc electrode are common.

■ Structure of a voltage detection device using an electromagnetic instrument transformer using a normal capacitor type PD in place of the amplifier AMP.

■ A structure in which one of the plurality of supporting insulators 8 is removed, a drawer bushing 14 is attached at this position, and a hole is made in the metal plate 1 to lead out the conductor.

As variously explained above, the present invention has the following effects.

Since one device can serve as both a protection device and an ultra-high voltage measuring device, it is extremely advantageous in terms of downsizing and economical efficiency.

In particular, there is no need to pay much attention to the installation of the measuring device.

■ Simple and easy structure and installation (as it can be attached and detached, inspection and repair is very easy).

(2) At least the ground side electrode part is provided with separate electrodes for discharge and arc current, so there is no change in discharge voltage even after several operations.

- Due to the presence of the cylindrical electrode plate 2, the arc does not directly touch the metal body 1, thereby avoiding explosion.

■ Since it is a sealed type, there is no need to consider the effect of arc on other equipment.

In addition to the effects of the present invention described above, the following effects can be obtained when the embodiment shown in FIG. 3 of the present invention is employed.

(2) By providing a trigger electrode, characteristics such as less variation in discharge voltage and flatness can be obtained.

■ The main electrodes on the high voltage side and the ground side have an asymmetric structure, and the direction and magnitude of the electric field in the parts where the electrodes face each other, that is, the electric field vector, is symmetrical, which reduces the lightning surge voltage. The discharge characteristics can be made the same depending on the polarity.

■ By making a plurality of holes 2a in the cylindrical electrode plate 2 forming the electrostatic capacitor, the decomposition products of SF6 gas generated by arc energization pass through the holes 2a and reach the electrode plate 2 and the metal body 1. Since it can be emitted between the two, it does not cause a change in the discharge voltage.

[Brief explanation of drawings]

Figure 1 is an electrical connection diagram showing the protection method of a two-bank power generation substation with a single bus for receiving power, Figure 2 is a characteristic curve diagram showing the hourly characteristics of the flashover voltage at a typical gap, and Figure 3 is the main 4 is a diagram showing a specific example of dimensions and the electric field vector at the tip of the electrode; FIG. 5 is a characteristic curve diagram showing the hourly characteristics of the discharge voltage between the gaps; FIG.
The figure is an equivalent circuit diagram showing ultra-high voltage measurement. T...Transformer, LA...Surge arrester, B...
...Disconnector, D...Disconnector, G, G'
...Protection gap, BL...Bus bar, L
...Line, A...High voltage side main electrode section, B
...... Ground side main electrode part, 1... Metal body, 2... Pole plate, 3... Support insulator, 4
...High voltage side discharge electrode, 5...High voltage side arc electrode, 6...External connection terminal, 1...
・Metal plate, 8...Support insulator, 9...
Ground side discharge electrode, 10... Ground side arc electrode,
11...Trigger electrode, 12...Coil, 13...Grounding side connection lead, 14...
・Bushing, AMP...Amplifier, V, M...
····voltmeter.

Claims (1)

[Claims] 1. A high voltage side electrode part supported by a support insulator that closes one open end of the metal body, and a high voltage side electrode part that closes the other open end of the metal body and is attached to a grounded metal plate. a first electrode attached to the metal plate via an insulator; and a plate electrically connected to the second electrode and arranged concentrically with the metal body at a constant distance. a ground side electrode part facing the high voltage side electrode part, and an arc-extinguishing gas filled in the metal body, and the surge voltage applied to the metal body is transmitted through the electrode plate.
A voltage is applied between the first and second electrodes of the ground side electrode portion, and based on this discharge, a main discharge is caused between the high voltage side and the ground side electrode portions. In order to use the capacitance between the A protective gap device characterized in that it is connected. 2. The gas insulation protection gap device according to claim 1, wherein the first electrode is an arc electrode and the second electrode is a discharge electrode. 3. The gas insulation protection gap device according to claim 1, wherein the first electrode is a discharge electrode and the second electrode is an arc electrode. 4. The gas insulation protection gap device according to claim 1, wherein the first and second electrodes are connected via a resistance element. 5. The gas insulation protective gap device according to claim 1, wherein the electrodes of the high voltage electrode section and the ground side electrode section have an asymmetric structure. 6. The gas insulation protection gap device according to claim 1, wherein the electrode plate is provided with a plurality of holes. γ The gas insulation protection gap device according to claim 1, wherein the electrode Q of the ground side electrode portion is provided with a trigger electrode. 8. The gas insulation protective gap device according to claim 1, wherein the electrode of the high-voltage side electrode portion is composed of a discharge electrode and an arc current-carrying electrode.