JP2001338742A - Arrester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance arrester which prevents breakage of the arrester due to AC overvoltage by the melt down a fuse, and continuing the function of the arrester, after the melt down of the fuse. SOLUTION: A specified number of zinc oxide elements connected in series are divided into at least two zinc oxide element groups, and the fuse is connected in parallel with either of zinc oxide element groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning arrester capable of greatly extending the duration of short-time AC overvoltage.

[0002]

2. Description of the Related Art FIG. 5 is a conceptual diagram showing the configuration of a conventional lightning arrester disclosed in Japanese Patent Publication No. 5-74923. In the figure, 1 is a line, 2 is a line-side terminal, 3 is a metal flange attached to the upper and lower parts of the insulator tube, and 4 is a porcelain insulator tube. Reference numeral 5 denotes a connecting conductor which is connected to a zinc oxide element group 6 which is stacked in a large number in series. 1
Reference numeral 0 denotes a fuse that blows when an overcurrent flows. Reference numeral 13 denotes a separation gap that is used to disconnect the lightning arrester from the system voltage after the fuse 10 is blown. Numeral 14 denotes an arc-resistant insulating cylinder, which is used to generate an arc when the fuse 10 is blown.
This is intended to prevent the occurrence of uneven thermal destruction by touching the inner surface of the.

[0003]

The lightning arrester, which serves to protect the equipment from lightning surge and switching surge, has better protection characteristics as the limiting voltage characteristics are lower. In recent years, high-performance lightning arresters and 1000 kV lightning arresters with significantly reduced protection levels have been introduced. However, 1
1.5 pu (1 pu is the ground voltage of the system, and 550 / √3 = 31 in the case of the 500 kV system), which has not been a problem in the past due to the reduction of the limiting voltage characteristic in the surge region of kA or more.
The surge arrester operates even at an AC overvoltage of 8 kV).

For this reason, in the lightning arrester having a reduced protection level, various inventions have been made in which various measures are taken against AC overvoltage. As one of the inventions, in the conventional lightning arrester shown in FIG. 5 described above, when the AC overvoltage continues, the fuse 10 is blown to disconnect the lightning arrester from the system, thereby preventing the lightning arrester from being destroyed. Was the purpose. However, when the lightning arrester is disconnected, the insulation of power devices such as transformers and circuit breakers is exposed to the threat of lightning surges and switching surges, and is left unprotected. or,
A great deal of time and money was required to replace the fuse 10.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, prevents the lightning arrester from being destroyed by an AC overvoltage due to the blowing of a fuse, and maintains the function as a lightning arrester even after the fuse is blown. The purpose is to provide lightning arresters.

[0006]

According to a first aspect of the present invention, a lightning arrester according to the first aspect divides a predetermined number of zinc oxide elements connected in series into at least two zinc oxide element groups and forms one of the zinc oxide element groups. A fuse is connected in parallel.

According to a second aspect of the present invention, in the lightning arrester according to the first aspect, each of the divided zinc oxide element groups is housed in an insulator, and the zinc oxide element is housed in the insulator outside any one of the insulators. A fuse is connected in parallel with the group.

According to a third aspect of the present invention, in the lightning arrester according to the first aspect, the divided zinc oxide element group is housed in a grounded container, and both ends of one of the zinc oxide element groups are insulated and pulled out, and a fuse is externally provided. Are connected.

The invention according to claim 4 is the invention according to claims 1 to 3.
The arrester according to any one of the above, wherein the fuse is a permanent fuse that can be used repeatedly.

[0010] The invention of claim 5 is the invention of claims 1 to 4.
The lightning arrester according to any one of the above, further comprising a fuse blowing detector for detecting blowing of the fuse.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 In the first embodiment, the present invention is applied to an insulator-type lightning arrester, in which a plurality of zinc oxide elements connected in series are divided into at least a zinc oxide element group, and any one of the divided zinc oxide element groups is used. In parallel, a fuse is connected that does not blow with a lightning surge or switching surge but blows with an AC overvoltage for a short time. Hereinafter, this will be described with reference to FIGS. FIG. 1 is a conceptual diagram showing the structure of a lightning arrester, FIG. 2 is an explanatory diagram showing limiting voltage characteristics, and FIG. 3 is a graph showing the relationship between the limiting voltage and the energy duty of switching surge / AC overvoltage.

In FIG. 1, 1 is a system line, 2 is a line side terminal for connecting an arrester to the line, 3 is a metal flange attached to both ends of a porcelain insulator 4, and 4 is an upper insulator. It is. Reference numeral 5 denotes a conductor, which is a zinc oxide element group 6 or zinc oxide element group 8 described later, and flanges 3 and 3 provided on both ends of the zinc oxide element group 6 or zinc oxide element group 8.
Is to be connected. Reference numeral 6 denotes a group of zinc oxide elements housed in the upper insulator tube 4, and is formed by stacking a large number of zinc oxide elements in series according to the rating.

The upper insulator 4 is connected in series with a lower insulator 7 as a lower insulator 7 via respective flanges 3 and 3 on the lower side. A zinc oxide element group 8 in which a large number of zinc oxide elements are stacked in series according to the rating is also accommodated inside the lower insulator tube 7. Here, the zinc oxide element groups 6 and 8 also include a case where the zinc oxide element group is composed of one zinc oxide element. The one zinc oxide element group 8 is shunted (shunted) by the fuse 10. That is, a fuse 10 that is blown by a temperature rise due to an overcurrent is connected in parallel between the flanges 3 on both sides of the lower insulator tube 7. Reference numeral 9 in the drawing denotes a fuse connection plate for connecting the fuse 10 in parallel with the lower insulator tube 7.
As shown in the figure, the fuse 10 is arranged in parallel with the insulator 7 in which one of the divided zinc oxide element groups 8 is housed, that is, outside the insulator 7 in parallel with the zinc oxide element group 8 housed in the insulator. It is connected to the.

The lower side of the fuse connection plate 9 is also used as a ground terminal and is connected to the ground 12.
A fuse blow detector 11 detects the blow of the fuse 10 based on the presence or absence of a leakage current and sends a signal to a display panel or the like (not shown).

In FIG. 2, characteristic A is JEC-2372.
In the limiting voltage characteristic of the high performance lightning arrester for the 500 kV system described in the above, the limiting voltage of the nominal discharge current of 10 kA is 870 kV.
V (standard value). The characteristic B should also be called an ultra-high performance lightning arrester in which the protection level of the high performance lightning arrester is further reduced by 15%.

[0016] Energy responsibilities that are problematic when reducing the protection level of the lightning arrester include the duty of switching surge operation and the duty of short-time AC. FIG. 3 is a calculation example of each of the responsibilities. The processing energy of the switching surge operation duty increases relatively slowly as the limit voltage decreases, but the processing energy of the AC overvoltage increases sharply. For this reason, in realizing an ultra-high-strength lightning arrester having a protection level of 820 kV or less, the processing energy of short-time AC overvoltage is the biggest problem, but the present invention has the structure described in the first embodiment. This solves this problem.

Next, the operation of the surge arrester according to the first embodiment will be described. In FIG. 1, a zinc oxide element group 6 responsible for the characteristic B is accommodated in the upper insulator tube 4.
Further, a zinc oxide element group 8 corresponding to the difference between the characteristic A and the characteristic B is accommodated in the lower insulator tube 7. The sum of the zinc oxide element group 6 and the zinc oxide element group 8 corresponds to the characteristic A. The fuse 10 is set not to be blown by the lightning surge and the switching surge but to be blown by the AC overvoltage. In a normal state, the protection characteristic of the lightning arrester is an ultra-high performance lightning arrester having characteristic B as shown in FIG. Here, when an AC overvoltage of 1.5 pu is applied, 2 volts are applied to the zinc oxide element.
A current of 000 A flows.

The fuse 10 is designed to be blown, for example, within 0.1 second before the zinc oxide element group 6 is destroyed by energy. At this time, the characteristics of the surge arrester are such that the zinc oxide element group 8 of the lower unit, that is, the zinc oxide element group 8 of the lower insulator 7 in the first embodiment is the zinc oxide element group (upper unit).
6 is connected in series, so that characteristic A is obtained. As a result,
AC current corresponding to 1.5pu is 20A from 2000A
To drastically decrease.

According to the first embodiment, in the above example, the allowable intermittent time for the AC overvoltage of 1.5 pu is:
This is 10 seconds corresponding to the fusing time of 20 A, which is sufficient for the current surge arrester's AC overvoltage tolerance of 1.5 pu2 seconds. Also, after the fuse 10 is blown,
The protection level of the high performance surge arrester of JEC-2372 is maintained. When the fuse 10 is blown, the fuse 10
Since the current flowing through the lightning arrester in the steady state stops flowing, the blowout of the fuse 10 can be easily detected. Fuse blow detector 11 is based on this principle,
A signal for fuse blowing can be sent to an indoor display device or the like (not shown). Here, if the blown fuse 10 is replaced, it can be reused as an ultra-high performance lightning arrester (characteristic B) again. Further, in the first embodiment, by using a permanent fuse which can be used repeatedly as the fuse 10, the fuse replacement can be omitted.

Embodiment 2 In the second embodiment, the present invention is applied to a gas-insulated tank-type lightning arrester.
It will be described based on. FIG. 4 is a conceptual diagram showing the structure of the lightning arrester. In FIG. 4, reference numeral 15 denotes a grounded container. As in the first embodiment, the grounded container 15 is divided into three zinc oxide element groups in which a large number of zinc oxide elements are stacked in series according to ratings. Then, a zinc oxide element group 6 as a first group, a zinc oxide element group 6 as a second group, and a zinc oxide element group 8 as a third group are accommodated in series.

Reference numeral 16 denotes an insulating spacer for connecting another gas insulating device, and reference numeral 17 denotes a shield for reducing the electric field of the insulating spacer 16. A conductor 5 connects the center conductor of the insulating spacer 16 and the zinc oxide element 6 of the surge arrester. Reference numeral 18 denotes a shield, which is the first lightning arrestor.
It is arranged so as to be located on the dielectric side of each of the zinc oxide element groups 6, 6, and 8 of the third group, and alleviates the electric field to ensure a withstand voltage with respect to the grounding container 15.

19 is an insulating bushing, 20 is an insulating stand, 1
0 is a fuse, and 11 is a fuse blown detector. The insulating stand 20 is necessary for measuring the leakage current of the lightning arrester and for operating the lightning arrester operation counter. The other configurations, operations, and effects are the same as those in the first embodiment.

[0023]

According to the first to fifth aspects of the present invention,
It is possible to provide a high-performance lightning arrester that prevents the lightning arrester from being destroyed by an AC overvoltage due to the blowing of the fuse and that continues to function as a lightning arrester even after the blowing.

According to the invention of claim 4, it is possible to provide a high-performance lightning arrester which does not require replacement of a fuse.

According to the fifth aspect of the present invention, it is possible to immediately know the blowing of the fuse and to perform quick replacement.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a structure of a lightning arrester according to a first embodiment.

FIG. 2 is an explanatory diagram illustrating a limiting voltage characteristic according to the first embodiment.

FIG. 3 is a graph showing the relationship between the limited voltage and the energy duty of switching surge and AC overvoltage according to the first embodiment.

FIG. 4 is a conceptual diagram showing a structure of a gas-insulated tank-type lightning arrester according to a second embodiment.

FIG. 5 is a conceptual diagram showing a structure of an insulator-type lightning arrester according to a conventional invention.

[Explanation of symbols]

1 track, 3 flange, 4 insulator tube (upper side), 6 zinc oxide element group, 8 zinc oxide element group, 10 fuse,
11 Fuse blow detector.

Claims (5)

[Claims] 1. A surge arrester characterized in that a predetermined number of zinc oxide elements connected in series are divided into at least two zinc oxide element groups, and a fuse is connected in parallel with any one of the zinc oxide element groups. 2. A divided zinc oxide element group is housed in a porcelain tube, and a fuse is connected outside of any one of the porcelain tubes in parallel with the zinc oxide element group housed in the porcelain tube. Item 2. An arrester according to Item 1. 3. The divided zinc oxide element group is housed in a grounded container, both ends of one of the zinc oxide element groups are insulated and drawn out, and a fuse is connected outside the grounded container. 2. The lightning arrester according to 1. 4. The lightning arrester according to claim 1, wherein the fuse is a permanent fuse that can be used repeatedly. 5. The apparatus according to claim 1, further comprising a fuse blowout detector for detecting a blown fuse.
A lightning arrester according to any one of the above.