JPH05275156A - Lightning arrester with semiconductor - Google Patents

Abstract

PURPOSE:To provide a lightning arrester with semiconductor, which does not bring about power interruption even in the event of flowing of a discharge current in excess of the discharge withstand quantity of a zinc oxide element. CONSTITUTION:A non-linear resistance element 3 such as zinc oxide element, a semiconductor switch element 6 such as thyristor element, and a gap 4 are inserted serially between a power transmission line 1 and a steel tower arm on the grounded side. Otherwise, a mechanical separating device is installed instead of the gap 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a lightning arrester for protecting a transmission line from an overvoltage caused by a lightning strike.

[0002]

2. Description of the Related Art As a lightning arrester for protecting a transmission line from overvoltage caused by a lightning strike, a non-linear resistance element 3 such as a zinc oxide element and a gap are provided between the transmission line 1 and a tower arm 2 as shown in FIG. It is known that 4 and 4 are inserted in series. In such a conventional lightning arrester, for example, when an overvoltage due to a lightning strike is applied to the transmission line 1, the non-linear resistance element 3 is conducted and the gap 4 is discharged, and a lightning current is sent to the tower arm 2 to generate an overvoltage on the transmission line 1. It is supposed to suppress.

However, if a discharge current exceeding the discharge withstand capacity of the zinc oxide element flows into this lightning arrester, the non-linear resistance element 1 will be destroyed, and the lightning arrester will release pressure. As a result, there is a problem that an arc is generated and the circuit breaker of the substation operates, leading to a power failure accident and the arc may damage the lightning arrester and surrounding objects.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a lightning arrester with a semiconductor that does not cause a power failure accident even when a discharge current exceeding the discharge withstand capacity of a zinc oxide element flows. It was completed in order to do.

[0005]

A first invention made to solve the above problems is to insert a non-linear resistance element, a semiconductor switch element and a gap in series between a transmission line and a ground side. It is characterized by having done. A second invention made to solve the same problem is characterized in that the non-linear resistance element, the semiconductor switch element, and the mechanical disconnecting device are inserted in series between the power transmission line and the ground side. To do.

[0006]

In the lightning arrester with a semiconductor device according to the first aspect of the present invention, when the potential of the transmission line or the steel tower rises due to a lightning strike, the gap is discharged and a discharge current flows through the lightning arrester. After passing the discharge current, the current is reduced to several mA or less by the non-linear resistance element, and the follow current is cut off by the gap with the semiconductor switch element. Therefore, the power transmission line can be protected from overvoltage due to lightning strike. When the lightning current passing through the arrester exceeds the discharge withstand capability of the arrester, a ground fault or short-circuit current due to AC flows in the arrester, but the current is interrupted in half a cycle by a semiconductor switch element such as a thyristor element, which damages the arrester. And the accident current is cut off before the circuit breaker of the substation trips, so there will be no blackout accident.

In the lightning arrester with a semiconductor device according to the second aspect of the invention, when the potential of the power transmission line or the tower rises due to a lightning strike, the semiconductor switch element becomes conductive due to an external trigger signal or an overvoltage generated between the semiconductor switch terminals, and the lightning arrester is activated. Discharge current flows. After passing the discharge current, the current is reduced to several mA or less by the non-linear resistance element, and the semiconductor switching element interrupts the follow current. Therefore, the transmission line can be protected from overvoltage due to lightning strike. Also, when the lightning current passing through the lightning arrester exceeds the discharge withstand capacity of the lightning arrester and the lightning arrester is destroyed, the fault current can be cut off in half a cycle with a semiconductor switch and the lightning arrester can be disconnected from the line by a mechanical disconnecting device. It is possible to prevent the occurrence of an arc due to the discharge of the lightning arrester, and to prevent a power failure accident.

[0008]

【Example】

[Embodiment of the First Invention] FIG. 1 shows an embodiment of the first invention, in which 1 is a power transmission line, 2 is a ground side steel tower arm,
Reference numeral 5 is an insulator device for insulatingly supporting the power transmission line 1. In parallel with the insulator device 5, a nonlinear resistance element 3 such as a zinc oxide element, a gap 4 and a semiconductor switch element 6 are inserted in series. The semiconductor switch element 6 is composed of a thyristor element, and is of a self-ignition type that turns on when a sudden voltage rise occurs. The non-linear resistance element 3, the gap 4, and the semiconductor switch element 6 may be connected in any order.

When an overvoltage due to a lightning strike is applied to the lightning arrester, the gap 4 is first discharged, and the thyristor element, which is the semiconductor switching element 6, is turned on due to a rapid voltage rise and a discharge current is passed through the lightning arrester. After the discharge current due to lightning passes in this way, the voltage applied to the lightning arrester decreases, so that the resistance of the non-linear resistance element 3 such as a zinc oxide element is recovered and the current is reduced to several mA or less. Therefore, after the discharge current has passed, the follow-up current can be interrupted by the semiconductor switch element 6 and the gap 4, and the transmission line can be protected from overvoltage due to lightning strike.

If the lightning current passing through the lightning arrester exceeds the discharge withstand capability of the lightning arrester, the non-linear resistance element 3 is destroyed and an AC ground fault / short-circuit current flows through the lightning arrester. However, since the semiconductor switch element 6 such as a thyristor element is automatically turned off at the moment when the AC current becomes zero, the ground fault / short-circuit current is interrupted in a maximum of half a cycle, and damage to the lightning arrester is reduced. It As described above, according to the lightning arrester of the present invention, the fault current can be interrupted before the circuit breaker of the substation trips, so that a power failure accident due to the trip of the circuit breaker of the substation does not occur.

Since the non-linear resistance element 3 and the semiconductor switch element 6 are connected in series in the present invention as described above, the semiconductor switch element 6 can always maintain the insulating property. Therefore, the non-linear resistance element 3 can be shortened, and the entire lightning arrester can be downsized.

[Embodiment of the Second Invention] FIG. 2 shows an embodiment of the second invention. Instead of the gap 4 of the first invention, it is used for disconnecting from the line when the arrester fails. A mechanical disconnecting device 7 is attached. Further, in this embodiment, as the semiconductor switch element 6, a thyristor element which is turned on by a trigger signal from the outside is used.

When an overvoltage due to a lightning strike is applied to this lightning arrester, the semiconductor switch element 6 such as a thyristor element is turned on by a trigger signal from the outside, and the nonlinear resistance element 3
A discharge current is passed through the semiconductor switch element 6.
After the discharge current due to lightning passes in this way, the voltage applied to the lightning arrester decreases, so that the resistance of the non-linear resistance element 3 such as a zinc oxide element is recovered and the current is reduced to several mA or less. Therefore, after the discharge current has passed, the semiconductor switch element 6 blocks the follow-up current and protects the power transmission line from overvoltage due to lightning.

Also, when the lightning current passing through the lightning arrester exceeds the discharge withstand capacity of the lightning arrester and the non-linear resistance element 3 is destroyed and an AC ground fault / short-circuit current flows through the lightning arrester, it becomes like a thyristor element. The semiconductor switch element 6 is A
Since it automatically turns off at the moment when the current of C becomes zero, the ground fault / short-circuit current can be cut off in a maximum of half a cycle. Furthermore, since the lightning arrester can be disconnected from the line by the mechanical disconnecting device 7, the occurrence of an arc due to the discharge of the lightning arrester can be prevented, and a power failure accident can be prevented.

[0015]

As described above, according to these inventions, an overvoltage caused by a lightning strike can be flown to the ground side to protect a transmission line, and a semiconductor switching element acts to keep the current flowing in a maximum of half a cycle. Can be shut off. Furthermore, even if a discharge current that exceeds the discharge resistance of the non-linear resistance element flows through the lightning arrestor and the non-linear resistance element is destroyed, arcing due to discharge of the lightning arrester can be prevented, so the circuit breaker of the substation will trip. There is no power outage accident.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the first invention.

FIG. 2 is a circuit diagram showing an embodiment of the second invention.

FIG. 3 is a circuit diagram showing a conventional lightning arrester.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission line 2 Ground side steel tower arm 3 Non-linear resistance element 4 Gap 5 Insulator device 6 Semiconductor switch element 7 Mechanical disconnection device

Claims (2)

[Claims] 1. A surge arrester with a semiconductor, wherein a non-linear resistance element, a semiconductor switch element and a gap are inserted in series between a power transmission line and a ground side. 2. A lightning arrester with a semiconductor, wherein a non-linear resistance element, a semiconductor switching element, and a mechanical disconnecting device are inserted in series between a power transmission line and a ground side.