JPS5947866B2 - Lightning arrester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a lightning arrester, and more particularly to a lightning arrester that takes measures against failures in the components of the lightning arrester.

For convenience of explanation, a case will be described in which a lightning arrester is installed to protect a power transmission line from lightning, and a failure occurs in a part of the lightning arrester.

By using a high-temperature sintered body mainly made of zinc oxide with extremely good non-linear characteristics as a lightning arrester element, it becomes possible to realize a non-following type lightning arresterzp, a lightning arrester without a series gap has appeared. .

Since this lightning arrester has a small insulator tube size as a storage container, it can also be installed on a power transmission tower between the power transmission line and the tower.

Therefore, it has become possible to protect power transmission lines from overvoltage by installing lightning arresters on towers.

However, if the above-mentioned lightning arrester element constituting the lightning arrester becomes defective and becomes penetrated, a grounding accident will occur, and power transmission cannot be restarted until the lightning arrester is removed.

This invention was made in view of the above-mentioned circumstances, and when a failure occurs in a lightning arrester, the failed part 75 of the lightning arrester is automatically removed from the live parts of the power transmission system, etc., and protection is transferred to protection measures. It is an object of the present invention to provide a lightning arrester that can restart operation after a period of time.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

In Figure 1 showing an overview of the configuration (only one phase is shown in the figure), 1 is a grounded steel tower, 2 is an insulator for supporting the track, and 3I'i is supported on the steel tower 1 via the insulator 2. This is a live part of a power transmission line, etc.

4 is an arc horn which is a protection means, 5 is an arc horn 4
6 is a lightning arrester element constructed by enclosing a non-linear resistor made of a zinc oxide sintered element in an insulator tube or the like, and one end thereof is connected to the steel tower 1.

Reference numeral 7 denotes a fusible electrode portion made of a low melting point metal such as aluminum or copper, and this electrode portion is configured to be melted by a fault current when the arrester element 6 is in a penetrating state.

Reference numeral 8 denotes a horn-shaped electrode part made of a metal with a relatively high melting point and is connected to the line-side live part. Reference numeral 9 denotes a discharge gap composed of an electrode part 7 with a low melting point and an electrode part 8 with a high melting point. is provided in series with the lightning arrester element 6, and is set to a gap length such that it does not discharge at a normal ground voltage but quickly discharges as the voltage rises.

An electrical equivalent circuit of such a configuration is shown in FIG.

In FIG. 2, 21 indicates the capacitance of the line supporting insulator 2, 5 indicates the arc horn and the gap 4, 61 indicates the resistance of the non-linear resistor of the arrester element 6, and 9 indicates the discharge gap.

Here, the electrode part 7 arranged in series with the lightning arrester element 6 will be described in detail. Its shape is a horn-shaped electrode as shown in FIG. 3, and only an impulse current flows through it during normal operation.

Further, the diameter of the electrode portion 7 may be determined based on the mechanical strength required to withstand wind pressure.

On the other hand, the electrode portion 7 is required to be quickly melted by the fault current arc that flows into the arrester element 6 when it is out of order, and for this purpose, it is better to be as thin as possible.

There are some differences depending on the level of system voltage, but in practical terms 5
It may be selected within a range of about φ to 10 mφ.

FIG. 4 shows a state in which the electrode portion 7 is melted.

Next, the relationship between the voltage and time (vt) characteristics will be explained with reference to FIG.

Solid lines A, A, and B indicate the discharge starting voltage at the discharge gap 9, the discharge voltage at the protective gap 5 formed by the arc horn 4, and the insulator for supporting the power transmission line, respectively, in the normal operating state shown in Fig. 1. Indicates the withstand voltage of 2.

4 shows the withstand voltage between the electrode portion 8 and the defective arrester element 6 in the state shown in FIG. 4 in which the electrode 7 is melted.

Also, the one-dot line indicates the peak value of the normal ground voltage.

That is, the structure is such that the discharge starting voltages of each part have the magnitude relationship as described above.

Next, the state of use of the device configured as described above will be explained.

First, under normal operating conditions, a normal ground voltage is applied to the discharge gap 9, but no discharge occurs at this voltage.

On the other hand, in the case of a lightning strike, a discharge occurs quickly in the discharge gap 9 due to an increase in potential, and the lightning arrester element 6 equipped with a non-linear resistor is inserted into the system to protect against this overvoltage.

Regarding the discharge gap 9, after the lightning current treatment, the discharge force axis dynamically stops and returns to its original state.

Since the lightning arrester element 6 is of a non-current type, only an impact current flows through the electrode portion 7, and there is no fear that the discharge surface of the electrode portion 7 will be damaged during normal operation.

Now, a defect has occurred in the arrester element 6, and the arrester element 6 is in a penetrating state.

When a discharge occurs in the discharge gap 9, the power transmission line 3→electrode section 6
The fault current of the system flows through the path of →discharge gap 9→electrode section 7→surge arrester element 6→steel tower 1.

Since the electrode portion 7 is melted by this fault current arc, the arrester element 6 is completely separated from the power transmission line 3 when the system is reclosed, as shown in FIG.

At this time, the air insulation strength between the electrode portion 8 and the lightning arrester element 6 becomes the value shown by the mark in FIG.

That is, power can be retransmitted, and when lightning voltage intrudes, the power transmission line 9 is protected by the arcing horn 4 forming the protective gap 5, and the defective arrester element 6 is excluded from the system.

Therefore, if a failure occurs in the lightning arrester element 6, which is a non-linear resistor installed on the power transmission line 3, and a fault current flows into it,
By melting the electrode portion 7 of the air gap by the arc of the fault current, a large air gap can be secured, and power can be retransmitted.

Further, overvoltage protection of the power transmission line 3 during power retransmission is ensured by the arc horn 4 attached to the line supporting insulator 2.

In the embodiment, the magnitude of the discharge starting voltage in each gap 5, 9 is set depending on the length of the protective gap 5, the discharge gap 90, but for example, the shape of the discharge surface of the arc horn 4, the shape of each electrode part 7, etc. , 8 may be made to have different shapes to set the respective discharge starting voltages in a desired relationship.

Furthermore, in the embodiment, the case where the power transmission line 3 is used as the charging section has been described, but in view of the gist of the present invention, the present invention can be widely applied to cases other than the power transmission line 3.

Further, although an example in which an arc horn 4 is used as a protection means is shown in the embodiment, a lightning arrester element 6 is used in place of the arc horn 4.
An element similar to the above is provided in parallel with the surge arrester element 6, and a horn-shaped electrode is provided at the end of the added surge arrester element on the power transmission line 3 side, and a horn-shaped electrode opposite to this horn-shaped electrode is provided on the power transmission line 3 side. The protective gap 5 created by the arc horn 4 shown in the embodiment by the gap formed by the two horn-shaped electrodes
It is also possible to achieve the same function as .

In this way, in this invention, the meltable electrode part provided on the live part side of the arrester element is melted when the arrester element fails, and overvoltage protection is provided by the protection means provided in parallel to the series body of the arrester element and the live part. Since the structure is configured to shift, overvoltage protection can be achieved in a state where the faulty arrester element is separated from the live part.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a circuit similar to that shown in FIG. 1, FIG. 3 is a detailed diagram of the fusible electrode section, and FIG. A schematic diagram showing the failure condition, Figure 5 is the first
FIG. 5 is a diagram showing voltage-current characteristics in the states shown in FIGS. In the figure, 1... Steel tower, 3... Live part, 4...
Arc horn, 5... protection gap, 6... lightning arrester element, 7... fusible electrode part, 8... electrode part, 9... discharge gap. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A lightning arrester element composed of a non-linear resistor and having one end connected to the ground side, which is provided at the other end of the lightning arrester element with a predetermined gap between it and a live part, and which melts when the lightning arrester element fails. a fusible electrode part, and a series body of the lightning arrester element and the live part, which is provided in parallel between the live part and the ground side, and protects the live part from overvoltage when the electrode part melts. Lightning arrester with protective measures. 2. The lightning arrester according to claim 1, wherein the protection means comprises an arc horn. 3. A patent claim characterized in that the gap between the arc horn is larger than the gap between the electrode part and the live part, and the gap between the electrode part side end of the lightning arrester element and the live part when the electrode part is melted is also smaller. The lightning arrester according to item 2 of the scope. 4. The lightning arrester according to any one of claims 1 to 3, wherein the lightning arrester is for protecting power transmission lines.