JP2000134795A - Lighting infall protecting device for low-voltage distribution system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize protective performance against lighting surge and increase the reliability of a low-voltage distribution system by preventing flashover from distribution lines to an electric pole, dielectric breakdown, and interphase short circuits. SOLUTION: This protective device is suitable for a low-voltage distribution system, wherein low-voltage distribution lines are branched from an on-pole transformer connected to a high-voltage distribution line, and power is supplied to consumers from these low-voltage distribution lines through incoming lines and an arrestor is connected between a common ground line and the neutral incoming line connected to the neutral low-voltage distribution line grounded on the on-pole transformer side. Near an electric pole 60 lain with the low voltage distribution lines, lightning surge protective elements 11, 12 for causing lighting surge current to flow to the ground are respectively connected between a potential line 54a and a neutral line 54c of the low voltage distribution lines, and between the potential line 54b and an electric pole ground line 62.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning intrusion protection device installed on a low-voltage distribution line and used as a protection measure against a dielectric breakdown or a burnout accident caused by a lightning surge.

[0002]

2. Description of the Related Art The damage caused by lightning surges on high-voltage distribution lines in distribution systems has been sharply reduced with the spread of surge arresters with a built-in zinc oxide element, except for instantaneous power outages caused by a substation trip due to discharge clamp flashover. are doing. The lightning arrester installed on this high-voltage distribution line operates when the generated lightning surge voltage exceeds a certain value, and the lightning surge current flows to the neutral wire (ground phase) and is discharged to the ground, It protects electric wires and various distribution equipment.

[0003] On the other hand, on the end customer side, which is branched from a high-voltage distribution line via a pole transformer and a low-voltage distribution line, the spread of various OA equipment, electric appliances, electric equipment, etc. on the background of advanced information technology. Although the importance of these elements is steadily increasing due to the high-density mounting, the risk of exposure to lightning surge via communication lines and antennas tends to increase. Therefore, in order to protect the load on the consumer side from the intrusion of the lightning surge, various academic societies and organizations are studying and drafting various measures.

As one of the measures, a countermeasure called a "bypass arrestor" method as shown in FIG. 4 has been jointly proposed mainly by a telecommunication company and a power company. According to this method, a lightning arrester 56 is provided at a predetermined location within a range including a communication line 58 from a neutral line (ground phase) of a service line 55 of a customer 59, a common ground line 57 is provided, and a lightning surge is bypassed. , Common grounding line 57, pole transformer 53 and low-voltage distribution line 5
By connecting the neutral line (ground phase) to the fourth line, one system for discharging a lightning surge current to the ground is constructed. And based on this system,
Measures have been developed that have been developed, and some have been tested for practical use. In addition, 51 is a high voltage distribution line, and 52 is a high voltage surge arrester. Improvements and developments of the above-mentioned "bypass arrestor" method are particularly popular in Germany, and are being considered for adoption in Japan by electric power companies.

[0005]

However, when the above-mentioned "bypass arrestor method" is widely implemented on the customer side, the ground impedance of the common grounding line 57 on the customer side and the type B of the pole transformer 53 are reduced. Due to the difference between the ground impedance and the ground impedance, a phenomenon in which the lightning surge current flows backward from the customer 59 to the neutral line (ground phase) of the low-voltage distribution line 54 easily occurs.

That is, as shown in FIG.
Since the common ground line 57 on the side is grounding for a house, it must have a relatively high impedance. The ground potential rises, and a lightning surge current flows to the pole transformer 53 having a low ground impedance. At this time, in the low-voltage distribution line 54 laid on the power pole 60 such as a concrete pole, the power pole 60 has a low grounding impedance, so that a flashover occurs from the low-voltage insulation insulator 61 to the power pole 60, thereby causing insulation breakdown and burnout. May occur. Furthermore, these phenomena have the danger of developing into a multi-phase flashover and leading to an interphase short circuit.

That is, in the “bypass arrester method”, a protection device such as a lightning arrester is installed on the high-voltage distribution line and on the customer side to suppress lightning surge, and as a result, the low-voltage distribution line between the high-voltage distribution line and the customer is reduced. Both will be more susceptible to lightning surges and will be exposed as the weakest point. Further, it is extremely difficult to perform the grounding work for making the ground impedance of the common ground line on the customer side an optimum value because the number of customers and each house form are different.

Accordingly, the present invention provides a relatively simple low voltage distribution line which can be said to be the weakest point of lightning surge current in a low voltage distribution system from a high voltage distribution line, a pole transformer, a low voltage distribution line to a consumer via a service line. It is an object of the present invention to provide a lightning intrusion protection device having an enhanced protection function for a low-voltage distribution system by adding a configuration.

[0009]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, a low-voltage distribution line is branched from a pole transformer connected to a high-voltage distribution line. Power is supplied to consumers via
A low-voltage distribution line was installed in a low-voltage distribution system in which a lightning arrestor was connected between the neutral line of the incoming line connected to the neutral line of the low-voltage distribution line grounded on the pole transformer side and the common grounding line. Lightning surge protection elements for discharging a lightning surge current to the ground are connected between a potential line of a low-voltage distribution line near a power pole, a neutral wire, and a power pole ground wire.

Further, according to the present invention, the potential line, the neutral line, and the neutral line between the potential line of the low voltage distribution line and the neutral line and the electric pole ground line near the electric pole on which the low voltage distribution line is installed are provided. And an arc current limiting means having electrodes connected to the power pole ground line and having gaps therebetween, and arc extinguishing chambers surrounding these electrodes.

It is desirable that the lightning surge protection element according to the first aspect or the arc current limiting means according to the second aspect be collectively housed in a housing.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a use state of an embodiment of the present invention, and a lightning intrusion protection device 10 according to the present invention.
Is applied to a 100 / 200V single-phase three-wire aerial low-voltage distribution system. Here, the present invention is also applicable to various low-voltage distribution systems of 200V three-phase three-wire system.

The lightning intrusion protection device 10 includes potential lines (voltage phases) 54a and 54b of a low-voltage distribution line 54 laid on a utility pole 60 such as a concrete pole via a low-voltage insulation insulator 61.
And a neutral wire (ground phase) 54 connected to the telephone pole ground wire 62
c is connected via an insulated cable 14. Examples of the lightning intrusion protection device 10 include an example in which a lightning surge current is released by a lightning surge protection element as shown in FIG. 2 and an example in which an arc current limiting effect is used as shown in FIG.

First, a lightning intrusion protection device 10A shown in FIG.
Is an insulated cable 1 between the potential wires (voltage phases) 54a, 54b and the neutral wire (ground phase) 54c and the telephone pole ground wire 62.
4, lightning surge protection elements 11, 12 connected via
It is configured to be housed in the housing 16 collectively. These protection elements 11 and 12 are composed of a combination of a ceramic or zinc oxide element with zinc oxide (ZnO) as a composite component and a lightning arrester. 11 and 12 may be integrally molded with an insulating resin or the like having excellent weather resistance.

The operation is as follows. When a lightning surge enters the low-voltage distribution line 54 during a lightning strike and the potentials of the potential lines 54a, 54b rise to a predetermined value, the lightning surge protection elements 11, 12
Operates to discharge the lightning surge current from the telephone pole ground wire 62 to the ground. As a result, the potential lines 54a, 5
4b through the low-voltage traction insulator, there is no possibility of flashover of the utility pole, and it is possible to prevent the occurrence of insulation breakdown, burnout accident, and the like.

Next, the lightning intrusion protection device 10B shown in FIG.
b and the neutral cable 54 c connected to the telephone pole grounding wire 62 and the insulated cable 14 penetrating through the housing 16.
a, 14b, and 14c.
Needle electrodes 15 formed at the tips of a, 14b, and 14c are opposed to each other on the same plane via a gap 18 in an arc-extinguishing chamber 17 inside a housing 16. The housing 16 is formed of a resin such as polyacetal, and when an arc is generated between the needle-shaped electrodes 15, an inert gas is generated by the heat. In the above configuration, the needle electrode 1
5, the housing 16, the arc-extinguishing chamber 17, the gap 18, etc.
The arc current limiting means is constituted.

When a lightning surge occurs in the low-voltage distribution line 54,
Flashover and arc occur between the needle electrodes 15 of the neutral wire 54c connected to the potential wires 54a, 54b or the utility pole ground wire 62, thereby suppressing an increase in potential due to a lightning surge. Then, instantaneously, the tip of the needle-shaped electrode 15 is melted by the heat of the arc, and the length of the gap 18 increases, thereby increasing the arc resistance, and furthermore, the generation of inert gas from the housing 16, The arc follow-up is interrupted.

Although not shown, a part of the housing 16 is provided with a weak portion having a small thickness.
When the gas inside is heated to a high pressure, the weak point is destroyed and the internal pressure of the arc-extinguishing chamber 17 is released at once. The strong air flow accompanying the pressure release further promotes the arc extinguishing action, and the arc follow-up flow is reliably shut off.

Therefore, when the lightning surge enters, the potential line 54
Both of the potential rises of a and 54b are suppressed to a certain value or less by the generation of the arc, and then the arc follow-up is interrupted. In this embodiment, the lightning surge voltage to be suppressed can be set to an arbitrary value by adjusting the length of the gap 18 between the needle electrodes 15.

2 and 3, the lightning surge protection elements 11, 12 and the needle electrode 15 are housed collectively in the housing 16, and the whole is integrally formed. In addition, since the insulation cable 14 or 14a to 14c is pulled out and connected to a low-voltage distribution line, the construction can be performed safely and easily even on a utility pole with poor scaffolding.

[0021]

As described above, according to the present invention, a lightning intrusion protection device having a very simple structure and easy installation and connection is installed in a pole installation part of a low-voltage distribution line, which can be said to be the weakest point during a lightning surge. By simply mounting, it is possible to stabilize the lightning protection performance of the entire distribution system and improve reliability while protecting the load of low-voltage consumers, which are becoming increasingly important.

[Brief description of the drawings]

FIG. 1 is a diagram showing a use state of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a lightning intrusion protection device in FIG.

FIG. 3 is a schematic configuration diagram of a lightning intrusion protection device in FIG. 1;

FIG. 4 is an explanatory view of a bypass arrester method as a conventional technique.

FIG. 5 is an explanatory diagram of a problem of the bypass arrester method.

[Explanation of symbols]

 10, 10A, 10B Lightning intrusion protection device 11, 12 Lightning surge protection element 14, 14a, 14b, 14c Insulated cable 15 Needle electrode 16 Housing 17 Arc extinguishing chamber 18 Gap 54 Low voltage distribution line 54a, 54b Potential line (voltage phase 54c Neutral conductor (ground phase) 60 Utility pole 61 Low voltage insulator 62 Utility pole ground wire

Claims (3)

[Claims] 1. A low-voltage distribution line is branched from a pole transformer connected to a high-voltage distribution line, and power is supplied to a customer from the low-voltage distribution line via a service line, and grounding is performed on a pole-side transformer side. In a low-voltage distribution system in which a lightning arrestor is connected between the neutral line of the service line connected to the neutral line of the low-voltage distribution line and the low-voltage distribution line near the pole on which the low-voltage distribution line is installed, A lightning intrusion protection device in a low-voltage distribution system, wherein lightning surge protection elements for discharging a lightning surge current to the ground are connected between a potential wire, a neutral wire, and a power pole ground wire. 2. A low-voltage distribution line is branched from a pole transformer connected to a high-voltage distribution line, and power is supplied to a customer from the low-voltage distribution line via a service line, and grounding is performed on the pole-side transformer side. In a low-voltage distribution system in which a lightning arrestor is connected between the neutral line of the service line connected to the neutral line of the low-voltage distribution line and the low-voltage distribution line near the pole on which the low-voltage distribution line is installed, An electrode connected between the potential wire, the neutral wire and the power pole ground wire, connected to the potential wire, the neutral wire and the power pole ground wire, and having a gap therebetween, and an arc extinguishing surrounding these electrodes A lightning intrusion protection device in a low-voltage distribution system, comprising an arc current limiting means having a chamber. 3. A lightning intrusion protection device for a low-voltage distribution system, wherein the lightning surge protection element according to claim 1 or the arc current limiting means according to claim 2 is collectively housed in a housing.