JPS59150353A - Ground-fault current detection and display for power cable and distribution apparatus - Google Patents

Abstract

PURPOSE:To obtain a ground-fault current detection and display thereof which won't change the ground resistance free from burning due to an overcurrent by arranging an ignition agent in the perimeter of a resistor which has a resistance element rising in the temperature with an overcurrent in parallel with a resistance element reducing in the resistance value as the temperature rises. CONSTITUTION:A systhetic resin support member 2 is fitted into both ends of an insulation cylinder 1 made of a transparent resin with a heat resistance such as polycarbonate. A seal material 4 is packed between a protective cover 3 fitted into both end circumferences of the insulation cylinder 1 and the cylinder itself 1. A resistor 7 is connected to electrodes 5 and 6 piercing the protective cover 3 and the support 2. When a ground-fault current flows through the resistor 7, the temperature rises sharply. Then, the resistance value of a special resistance 13 (for example, silver oxide) making a part of the construction of the resistor 7 reduces and with a reduction in the combined resistance, the heat generation is eased to prevent the burning out of the resistor 7 by heat. Thus, after the start of operation, ground wire is alway closed to receive no electric impact from a power cable.

Description

TECHNICAL FIELD AND OBJECTS The present invention relates to a power cable for high-voltage power distribution lines and a ground fault current detection indicator for power distribution equipment.

The ground fault current detection indicator is connected to the ground wire of the power cable, and when a ground fault occurs in the power cable, a ground fault current flows through this ground wire, and the ground fault current indicates a fault in the power cable. It looks like this. This display is characterized by a structure that does not open the ground wire even if a ground fault current flows and operates. In other words, the ground wire is 7
Since the circuit is closed, there is no risk of induced voltage being generated on the cable surface and the power distribution equipment not only due to lightning surges but also during energized conditions.

The purpose of this invention is to detect and display the ground fault voltage flowing in the ground wire, to reduce the labor and time required to search and find faulty cables, and to repeat the process by replacing the display element without changing the ground resistance. An object of the present invention is to provide a ground fault current detection indicator that can be used.

EXAMPLE Hereinafter, an example of a ground fault current indicator embodying the present invention will be described with reference to the drawings. 1 is an insulating cylinder made of heat-resistant transparent synthetic resin such as polycarbonate; A support member 2 made of synthetic resin is fitted. A protective cover 3 is fitted around the outer periphery of both ends of the insulating tube 1, and a sealing material 4 is filled between the cover and the insulating tube 1.
The insulating tube 1 is sealed. Reference numeral 5.6 denotes an electrode protruding into the insulating tube 1 from outside the insulating tube 1 through the protective cover 3 and the support member 2, and a resistor 7 is connected between the two electrodes within the insulating tube 1. There is.

8 is a display tube that covers the resistor 7, and has electrodes 5 at both ends.
, 6 are fitted to seal the resistor 7, and the outer peripheral surface is colored with a highly visible color so that it is visible from outside the insulating cylinder 1. Reference numeral 9 denotes an incendiary agent placed around the resistor 7. The ground fault current detection indicator configured as described above is connected in series to the electric cable of the high voltage distribution line and the ground wire of the power distribution equipment.

Next, details of the resistor 7 will be explained according to FIG.
0.11 is a terminal of the resistor 7, and a resistor element 12 is connected between them. 13 is a special resistor connected in parallel to the resistor element 12 between terminals 10 and 11 in a state covering the resistor element, and is made of silver oxide (A(120), etc.) that resists electrically as the temperature rises. It is made of a material whose resistance value decreases. 14 is a synthetic resin coating such as epoxy that covers the resistor 7 except for the tips of the terminals 10 and 11.

Next, the operation of the earth fault current indicator configured as described above will be explained.

Now, when a ground fault current flows through the ground wire due to a lightning surge or other malfunction, Joule heat is generated in the resistor 7, and the thermal energy ignites the ignition agent 9, which generates combustion gas inside the display cylinder 8. is ejected from both ends of the display tube 8 due to the pressure, and the outer circumferential surface of the display tube 8 and the inner circumferential surface of the insulating tube 6 are colored black.

At this time, the temperature of the resistor 7 rises rapidly due to the ground fault current flowing through the resistor 7, but as the temperature of the resistor 7 rises, the temperature of the special resistor 13 rises and the resistance value decreases. , the combined resistance of the resistor 7 and the special resistor 13 is reduced, the heat generation of the resistor 7 is alleviated, and the resistor 7 is not blown out by heat.

Therefore, this ground fault current detection indicator visually recognizes that the color inside the insulating tube 1 has changed from the color of the display tube 8 to black due to the coloring action of the combustion gas, so that the ground fault current can be detected in the ground wire. You can confirm that it has flowed. Since the grounding wire is always closed even after operation, it will not receive an electric shock from the power cable.

Effects As detailed above, the present invention provides a resistor 7 in which the resistance element 12 whose temperature rises as an overcurrent passes through it and the special resistor 13 whose resistance value decreases as the temperature rises are closely connected in parallel.
By forming this, when a ground fault occurs in a power cable or power distribution equipment, the ground fault current flowing through the grounding wire can be detected and displayed, and the faulty power cable or power distribution equipment can be detected and displayed without increasing the grounding resistance. It has an excellent effect of shortening the effort and time required for discovery.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a ground fault current detection indicator embodying the present invention, and FIG. 2 is a schematic diagram of a resistor thereof. Insulating cylinder 1, resistor 7, display cylinder 8, pyrotechnic agent 9, resistance element 1
2. Special resistance 13°

Claims (1)

[Claims] 1. Resistance element (12
) and a special resistor (13) whose resistance value decreases as the temperature rises.
) are brought into close contact with each other in parallel to form a resistor (7), and the periphery of the resistor (7) is coated with an incendiary agent (9),
It is characterized in that electrodes (5°6) are connected to both ends, the resistor (7) is sealed with a display tube (8), and the display tube (8) is further covered with a transparent insulating tube (1). Ground fault current detection indicator for power cables and power distribution equipment.