JPS6035797B2 - protective gap device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protective gap device that is installed at the entrance of an electrical station such as a power station or substation, for example on the line side of a disconnector, to protect switchgear such as a disconnector from lightning surges. It is about improvement.

Figure 1 shows the electrical system of a 2-bank power station with a 2-line power receiving single bus, where T is the power station side, L is the line side,
On the electric station T side, Trl and Tr2 are transformers, B-TI
and B-T2 bridge and disconnector, D-TI and D-T2 and Dc
indicates a disconnector, and on the line L side, LI and L2 are both lines, B-LI and B-L2 are disconnectors, D-L1a and D
-L1b, -L2a and D-L2b are disconnectors.

Generally, in an electric station, as shown in FIG. 1 as an example, dedicated earth protectors LA1 and LA2 are installed on the electric station T side.
In addition, coordination gaps G1 and G2 (GI' in the figure,
(G2' position may also be used) to protect each device such as a transformer, a circuit breaker, a disconnector, etc. from overvoltage.
However, for some reason, if the shield breaker B-LI or B-L2 on the line L side is in the barrier state, the surge that enters from the line LI or L22 will be affected by the voltage near the transformers Trl and Tr2. Lightning arrester L installed only in
A1 and LA2 are disabled, and the breakers B-L1 and B-L
Protection of equipment on the L side of the line, including 2, will inevitably rely on the coordination gaps GI and G2. Therefore, the coordination gaps GI and G2 must have discharge characteristics that are sufficiently coordinated with the voltage value of the shield breaker B-LI or B-L2 in the barrier. As this type of coordination gap, a Hayabusa gap etc. has traditionally been used, and its flashover voltage v-time t characteristic has a characteristic that rises rapidly from around 10 seconds, as shown in curve a in Figure 2. For,
A serious drawback is that sufficient insulation coordination cannot be achieved with protected equipment such as shields and disconnectors.

That is, since there is a time region in which the v-t characteristic between the poles of the shingle breaker shown by curve b in the same figure is exceeded, protection of the shingle breaker cannot be expected in such a time region. Therefore, some ideas have been considered, such as installing a lightning arrester on the line L side, or using a movable gap structure that allows the gap length of the coordination gap G to be adjusted according to the open/closed state of the disconnector. Although protection can be expected, it is economically disadvantageous because it is expensive.On the other hand, the latter is economically advantageous compared to the former, but it takes a certain amount of time to change the gap length, so it is difficult to protect against surges caused by multiple lightning. has no effect. Furthermore, there is a risk that peripheral equipment may be damaged by the arc generated by the flashover. As described above, at present, there is no protection gap that can sufficiently protect line equipment while meeting economic efficiency. SUMMARY OF THE INVENTION An object of the present invention is to provide a protective gap device which has a simple structure and is therefore highly economical, and which can sufficiently protect line equipment even against lightning surges with extremely large peak voltages.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The main parts of the protective gap device according to the present invention include, as shown in FIG. 3, a high-voltage side main electrode portion 2 which is inserted and fixed into one opening (upper part in the figure) of a cylindrical metal body 1 serving as a device container; It is composed of a ground side main electrode part 3 which is inserted and fixed into the other closed end (lower part in the figure) and faces the high voltage side main electrode part 2. The high voltage side main electrode part 2 is composed of a cylindrical discharge electrode 4 and a rod-shaped arc electrode 5 with a hemispherical tip, which is formed integrally with the discharge electrode 4 and is coaxially located in the center of the electrode 4. Ru. The main electrode section 2 has the opposite side of the discharge electrode 4 integrally fixed to an external connection terminal 6 connected to an external line, and the integrated end portion is placed at the center of a circular insulating spacer 7. The main electrode section 2 and the external connection terminal 6 are arranged and fixed at approximately the center of the metal body 1 by airtightly fixing the outer peripheral end of the insulating spacer 7 to the upper open end of the metal body 1. Furthermore, the connection terminal 6 is located outside the room inside the room where the main electrode section 2 is partitioned by the insulating spacer 7. Tips 4 of the discharge electrode 4 and arc electrode 6
', 5' are each made of a material with excellent arc resistance such as Cu-W alloy or graphite, and the arc electrode 5
are located further inside than the discharge electrode 4. The ground side main electrode part 3 is connected to a cylindrical discharge electrode 10 fixed via an insulator 9 attached to the inside of a metal plate 8 that airtightly closes the lower open end of the metal body 1 and the inside of the metal plate 8. A rod-shaped arc electrode 11 with a hemispherical tip is fixed to and coaxially located in the center of the discharge electrode 10, and an arc-resistant material such as Cu-W alloy or carbon attached to the outer peripheral surface of the tip of the arc electrode 11. Trigger electrode 12 made of a material with excellent properties,
Furthermore, each of these electrode parts and most of the high-voltage side main electrode part 2 are surrounded by appropriate gaps, and a certain gap is provided so that a coaxial cylindrical electrostatic capacitor is formed between them and the metal body 1. It is composed of cylindrical electrode plates 13 provided and arranged.

The tips 10' and 11' of the discharge electrode 10 and the arc electrode 11 on the ground side are made of Cu-W like the main electrode part 2 on the high voltage side.
It is made of a material with excellent arc resistance such as alloy or graphite, and the arc electrode 11 is located further inside than the discharge electrode 10. Further, the cylindrical electrode plate 13 is provided with a plurality of holes at appropriate locations (not shown in the figure), and the arc of the main electrode passes through these holes into the gap between the cylindrical electrode 13 and the metal body 1. It is now available for distribution. A discharge current detection coil 14 is attached to the base of the arc electrode 11 as required.

15 is a ground side connection lead fixed to the outside of the metal plate 8;
Reference numeral 16 denotes a sealing material that airtightly seals the extraction portion of the extraction lead 17 of the detection coil 14, and the inside of the sealed metal body 1 is filled with an insulating gas such as SF6 having excellent arc extinguishing ability. .

Although not shown in this figure, the attachment between the metal body 1 and the insulating spacer 7, and the attachment between the metal body 1 and the metal plate 8, are fixed using bolts or the like with packing etc. inserted, and can be easily dismantled. Therefore, maintenance and inspection can be easily performed. Figure 4 shows the high voltage side and ground side main electrode parts 2,
This figure shows a specific example of the dimensions of No. 3 and the electric field distribution, and this example is for the case where the impulse discharge voltage is 1800 KV.

As is clear from this figure, in the present invention, the high-voltage side main electrode 2 and the ground-side main electrode 3 that face each other vertically are designed such that the ground-side main electrode 3 has an overall smaller dimension than the high-voltage side main electrode 2. The electric field distribution is made to be symmetrical. That is, generally speaking, the high-voltage side grounding side main electrodes 2 and 3, which rise against each other, have the same dimensions and the same shape, but as mentioned above, when the container is formed of the metal body 1 and this is grounded, the grounding side main electrodes 2 and 3 rise up. 3 and the electric field becomes gentle, the ground side main electrode i is made smaller in shape than the high voltage side main electrode 2, thereby making the electric field distribution of both electrodes symmetrical. Next, the operation of the protective gap device according to the present invention will be explained.

Now, excessive voltage due to lightning surge is added to the protection gap,
The metal D formed by the metal body 1 and the electrode plate 13
When the voltage applied to the cylindrical electrostatic capacitor exceeds a certain value, an arc is fired between the ground side discharge electrode 10 and the trigger electrode 12, which then becomes a trigger and causes the tip of the high voltage side discharge electrode 4 to fire. 4' and the tip 10' of the discharge electrode 10 on the ground side, the arc then moves between the tips 5' and 11' of the arc electrodes 5 and 11 on the high voltage side and the ground side, and the lightning surge caused by the lightning strike is discharged. be done. This discharge is carried out in SF6 gas, which has excellent arc-extinguishing performance, so overvoltage is suppressed, and a good flashover voltage vs time t characteristic as shown by the dotted line C curve in Fig. 2 is obtained. Sufficient protection coordination can be achieved with protective equipment such as disconnectors. Furthermore, the operational characteristics of the protective gap according to the invention will be explained.

FIG. 5 shows the voltage one-hour characteristics when the aforementioned lightning surge is discharged between the tips 4' and 10' of the discharge electrode 4 on the high voltage side and the discharge electrode 10 on the ground side. A comparison is made between the case in which the filter is provided (indicated by the d curve) and the case in which it is not provided (indicated by the e curve). BIL is the withstand voltage value of the protective equipment. The one-hour voltage curve d of the protective gap when the trigger electrode 12 is provided is flatter than the one-hour curve e when the trigger electrode 12 is not provided, and a constant discharge voltage V is always obtained with respect to the discharge time T. This is because, as mentioned above, the incoming lightning surge voltage is divided by the electrostatic capacitor obtained by the cylindrical electrode plate 13, and this voltage is used to discharge between the ground side discharge electrode 10 and the trigger electrode 12 in advance. It is. Therefore, according to the protection gap of the present invention, even if a lightning surge with a large peak voltage arrives, it can be discharged at the withstand voltage value BIL of the protective equipment such as a disconnector, and the line equipment can be sufficiently protected. It becomes possible. The present invention can also achieve the intended purpose with the structures listed below. m The ground side arc electrode 11 is connected to the cylindrical electrode plate 13 and raised above the ground, and the discharge electrode 10 is grounded.

(2) A trigger electrode 12 is provided on the inner circumferential surface of the discharge electrode 10 and is opposed to the arc electrode 11.

'31 For the purpose of adjusting the trigger voltage, a capacitor is installed in addition to the cylindrical electrode plate 13. '4} A discharge detection coil 14 is provided outside the metal body 1.

'51 In order to extend the duration of the trigger discharge light,
In the ground side main electrode section 3, the discharge electrode 10 and the arc electrode 11 are connected with a suitable resistor.

As described above, in the present invention, one open end of the metal body is closed with an insulating support, the other open end is closed with a grounded metal plate, and the inside is filled with arc-extinguishing gas. A cylindrical first electrode part and a second electrode part formed integrally with the first electrode part and coaxially located in the center of the first electrode part. and a high voltage side main electrode supported by the insulating support in the sealed container, a cylindrical first electrode part, and a second electrode coaxially located in the center of the first electrode part. It is composed of an electrode part and a third electrode part attached to one of the first electrode part and the second electrode part in contrast to the other electrode part, and is arranged in the sealed container. a protective gap device comprising a ground side main electrode facing the high voltage side main electrode and insulatedly supported by the metal plate, wherein a cylindrical electrode plate having a plurality of holes on the circumferential surface is disposed in the sealed container; The high-voltage side main electrode and the ground side main electrode are surrounded and provided at a constant interval so that a coaxial cylindrical electrostatic capacitor is formed between the metal body and the cylindrical electrode plate. The metal body and the cylindrical electrode plate are configured to electrically connect one of the first electrode part and the second electrode part of the ground side main electrode and ground the other electrode part. applying a divided voltage of the surge voltage applied to the electrostatic capacitor formed between the first electrode portion and the second electrode portion to the first electrode portion;
A third electrode attached to either one of the second electrode parts.
An arc is generated between one electrode section and the other electrode section, and a main discharge is caused between the two main electrodes based on this arc.

Therefore, according to the present invention having such a configuration, even if a lightning surge with a large peak voltage arrives, it can be discharged at the withstand voltage value of the protective equipment, so unlike the conventional method, a lightning arrester may be provided on the line side, or the gap length may be increased. There is no need to make adjustments according to the open/closed state of the shield, disconnector, etc., and it becomes possible to protect the protective equipment while satisfying economic efficiency and providing sufficient insulation from the protective equipment. In addition, a cylindrical electrode plate having a plurality of holes on the circumferential surface is used to encase the high-voltage side main electrode and the ground side main electrode, and a fixed cylindrical electrostatic capacitor is formed between it and the metal body. Because they are spaced apart, the discharge arc does not come into direct contact with the metal body, and even if it is a sealed type, accidents such as explosions can be avoided, and the arc-extinguishing gas generated by arc energization can be decomposed and generated. Objects are forced between the electrode plate and the metal body through a plurality of holes in the circumferential surface of the electrode plate, and do not cause a change in the discharge voltage.
Furthermore, since it is a sealed type, there is no need to consider the influence of discharge arc on other equipment, and there are no restrictions on the installation location.

[Brief explanation of the drawing]

Figure 1 is a system diagram of a 2-bank power station with a 2-line power receiving single bus.
FIG. 2 is a characteristic curve diagram comparing and comparing the flashover voltage one-hour characteristics of a conventional comb gap, a protected equipment gap, and a protection gap of the present invention; FIG. 3 is a longitudinal sectional front view of an embodiment of the present invention; The figure shows a specific example of the dimensions and electric field distribution of the high-voltage side and ground side main electrode parts, and FIG. 5 is a one-hour characteristic curve of the discharge voltage across the gap in the device of the present invention. 1...metal body, 4...high voltage side discharge electrode,
5... High voltage side arc electrode, 6... High voltage side connection terminal, 7... Insulating support, 8... Ground metal plate, 10...・Ground side discharge electrode, 11...
. . . Ground side arc electrode, 12 . . . Trigger electrode, 13 . . . Cylindrical electrode plate. Figure 2 Figure 3 Figure 5 Figure 1 Figure 4

Claims (1)

[Claims] 1 A closed container formed by closing one open end of a metal body with an insulating support and closing the other open end with a grounded metal plate and filling the inside with an arc-extinguishing gas, and a cylindrical first container. and a second electrode part formed integrally with the first electrode part and located coaxially in the center of the first electrode part, and the insulating support is placed in the closed container. a high voltage side main electrode supported by a cylindrical first electrode portion;
A second electrode part coaxially located in the center of the first electrode part, and attached to either the first electrode part or the second electrode part so as to face the other electrode part. and a ground-side main electrode that is insulated and supported by the metal plate while facing the high-voltage side main electrode in the airtight container. A cylindrical electrode plate having a plurality of holes on the circumferential surface is arranged so as to surround the high voltage side main electrode and the ground side main electrode and form a coaxial cylindrical electrostatic capacitor between it and the metal body. The first electrode part or the second electrode part of the ground side main electrode is electrically connected to the cylindrical electrode plate with an interval of . A divided voltage of a surge voltage applied to an electrostatic capacitor formed between the metal body and the cylindrical electrode plate is applied between the first electrode part and the second electrode part. An arc is generated between the third electrode section attached to either the first electrode section or the second electrode section and the other electrode section, and based on this arc, the two main electrodes A protective gap device characterized in that the main discharge occurs between the gaps.