JPH0636003B2 - Gapless arrester abnormality detection method - Google Patents

Description

The present invention relates to a gapless arrester abnormality detection method used for protection of an anticorrosion layer of a power cable.

[Prior Art] Insulation strength is particularly required for power cables buried in the ground. The reason is that there is not enough space in the ground. Therefore, many power cables buried in the ground have a structure in which the outer surface is covered with a synthetic resin, and an insulated conductor is inserted into a metal casing filled with high-pressure insulating gas or insulating oil. .

In a power cable having such a structure, when the metal jacket is damaged due to corrosion or electrolytic corrosion, high-pressure insulating gas or insulating oil inside leaks out, and the insulation strength decreases,
It will lead to an unexpected accident. Therefore, the outer surface of the metal jacket is coated with a synthetic resin to enhance the anticorrosion ability.

However, in general, at the connection or termination of the power cable, in order to reduce the circuit loss due to the current flowing through the metal casing, the metal casing and the metal casing or the metal casing and the terminal box casing are electrically insulated by an insulating cylinder. Electrically insulated and engaged.

However, when the metal jackets are insulated and electrically floated as described above, not only the ends of the metal jackets have an unexpectedly high potential or surges enter and affect the surrounding equipment, but also Since it may destroy the anticorrosion layer that insulates the jacket,
An anticorrosion layer protection device (hereinafter referred to as a gapless arrester) that absorbs surges is installed at the end of the metal jacket.

An example of using the gapless arrester will be described more specifically with reference to FIG. FIG. 3A shows a state of termination processing of the power cable. Reference numeral 2 is a power cable, and in the drawing, only a metal jacket to be protected against corrosion is shown (hereinafter, 2 is referred to as a cable protection layer). The conductor portion not shown in the drawing is connected to other electric equipment via the termination box 4.

Since the outer box of the terminal box 4 is grounded, the cable is insulated from the metal box and the terminal box outer box by the metal tube insulating tube 3. However, when the cable anticorrosion layer 2 is repeatedly exposed to a surge of high energy, the insulation of the metal jacket 3 is broken, or the cable anticorrosion layer 2 itself deteriorates in anticorrosion performance. A gapless arrester 1 is used to protect the tube 3 and the cable anticorrosion layer 2. As will be described later, the gapless arrester 1 has a characteristic that it has a high resistance at all times and a low resistance against a surge.

Further, FIG. 3B shows a state of connection processing between power cables. The connection between the power cables is made by a dedicated insulating connection box 5, and the metal jacket of each cable is insulated by the insulating tube 6 of the insulating connection box 5. Insulation cylinder 6
In order to protect the cable anticorrosion layer 2, the metal jacket of the cable is grounded by the gapless arrester 1.

The gapless arrester 1 used as described above has the structure shown in FIG. In the figure, 7 is a high voltage side terminal, 8 is a high voltage side electrode plate, 9 is a zinc oxide element, 10 is a ground side electrode plate, 11 is a spring, 12
Is a lower metal fitting, 13 is a pressure release hole, 14 is a pressure release plate, and 15 is a porcelain outer box.

The zinc oxide element 9 has a high resistance at all times and a low resistance against surges, but is deteriorated or destroyed by repeated surges or by high energy surges, and releases high pressure gas. The lower metal fitting 12 is provided with a pressure release hole 13 so that the outer box 15 formed by the porcelain insulator is not burst and scattered by the high pressure gas.
It is closed by a pressure release plate 14 for protection of the inside.

[Problems to be Solved by the Invention] Degradation or destruction of the gapless arrester 1 directly leads to deterioration of the cable anticorrosion layer 2 and thus a serious accident as described above. The deterioration or destruction cannot be confirmed from the appearance, and there is a problem that sufficient maintenance management cannot be performed. That is, the conventional maintenance of the gapless arrester requires a complicated procedure of stopping the line, removing the gapless arrester 1, measuring the insulation resistance or the operation start voltage, and determining the presence or absence of an abnormality. Furthermore, the mounting terminals of the gapless arrester 1 are also subjected to anticorrosion treatment, which is another obstacle in that the anticorrosion treatment must be performed again at the time of restoration.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of detecting an abnormality of a line without stopping the line and removing the gapless arrester from the line. It is to provide an anomaly detection method that can be managed.

[Means and Actions for Solving the Problems] The present invention provides a deterioration detecting means formed by sticking a metal foil on a thin plastic plate having slits in the pressure release hole of the gapless arrester, and the deterioration or destruction of the gapless arrester. The high pressure gas generated by cutting the metal foil of the deterioration detecting means and detecting deterioration or breakage of the gapless arrester as an electric signal enables remote control and maintenance of the gapless arrester.

[Embodiment] An embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 is a partial view of a gapless arrester embodying the present invention, FIG. 2 (a) is a lateral view of an example of deterioration detecting means added to the gapless arrester, and FIG. 2 (b). Is a front view thereof.

First, the deterioration detecting means 18 will be described. In FIG. 2, a slit 21 is provided in the center of the plastic plate 19, and a linear metal foil 20 such as an aluminum foil is formed so as to close the slit 21. If the plastic plate 19 is designed to have a strength to be destroyed by the pressure of the released gas due to the evaporation of the zinc oxide element 9, the slit 2
1 is not particularly necessary, and the linear metal foil 20 can be formed by the printed wiring line means. Further, the plastic plate 19 can also be used as the pressure release plate 14 shown in FIG. A signal cable 22 for detecting the cutting of the metal foil 20 is drawn out from both ends of the linear metal foil 20.

Since the deterioration detecting means 18 having such a structure is attached to the gapless arrester 1, the gapless arrester 1
The substructure of is slightly modified.

An example of the attachment will be described with reference to FIG. In the figure, reference numeral 13 is a pressure release hole formed in the lower metal fitting 12, and corresponds to the pressure release hole 13 of FIG. 4 described above. An insulating plate 16 for mounting the deterioration detecting means 18 is provided on the lower part thereof. The deterioration detecting means 18 is attached to the insulating plate 16 by screwing or other suitable means, and the pressing plate 18 covers the lead-out portion of the signal cable 22.

In the gapless arrester having the above structure, when the zinc oxide element 9 is deteriorated or destroyed, the gas generated by the temperature rise is blown out from the discharge hole 13 and the gas pressure pushes the plastic plate 19 of the deterioration detecting means 18 to spread. By breaking, the linear metal foil 20 attached to the plastic plate 19 is cut, and the deterioration of the gapless arrester 1 can be electrically detected.

EFFECTS OF THE INVENTION The present invention makes it possible to easily detect an abnormality without stopping the line and without removing the gapless arrester from the line, and it is possible to detect the abnormality electrically. Suitable for centralized management.

[Brief description of drawings]

FIG. 1 is a partial view of a gapless arrester embodying the present invention, FIGS. 2 (a) and 2 (b) are structural diagrams of deterioration detecting means, and FIGS. 3 (a) and 3 (b) are the use of a gapless arrester. FIG. 4 is a schematic diagram showing an example, and is an internal structure diagram of a conventional gapless arrester. 1 …… Gapless arrester 19 …… Plastic plate 20 …… Aluminum foil 21 …… Slit

Claims (1)

[Claims] 1. A high-voltage side electrode plate (8) connected to a high-voltage side
And a zinc oxide element (9) having a ground side electrode plate (10) connected to the ground side, an outer box (15) for housing the zinc oxide element (9), and a part of the outer box (15). The pressure relief plate (1) provided so as to cover the pressure relief hole (13) formed.
4 or 19) and a linear metal foil (20) on the surface of the pressure-release plate (14 or 19) of the gapless arrester.
Is attached, and the linear metal foil (20) is cut when the pressure-release plate (14 or 19) is broken by the released gas pressure due to the evaporation of the zinc oxide element (9). ) Gapless arrester abnormality detection method characterized by detecting disconnection.