JP3242766B2 - Semiconductor lightning arrester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor lightning arrester using a thyristor element.

[0002]

2. Description of the Related Art A semiconductor lightning arrester using a thyristor element has been developed as a lightning arrester for protecting a power system from overvoltage caused by lightning strike or the like. In such a semiconductor lightning arrester, when an overvoltage occurs due to a lightning strike or the like, the thyristor element is ignited to discharge a lightning surge current to the ground, thereby eliminating the overvoltage of the system caused by the lightning strike.

Conventionally, an SCR thyristor has been generally used in such a semiconductor lightning arrester. However, S
In a conventional semiconductor lightning arrester using a CR thyristor, since the critical on-current rise rate of the thyristor element is small, the thyristor element may be destroyed if the current rising steepness during discharge increases. Also SCR
Once a thyristor is fired, it cannot be extinguished until the current becomes zero, so even after discharging the lightning current by ignition, a large continuation current flows for up to half a cycle, and the resulting heat may cause element destruction. there were. Further, as described above, since the following current continues for at most a half cycle, there is a problem that the voltage drops continuously during this time.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, has a large discharge withstand voltage of a lightning arrester, has no danger of destruction of elements due to a continuation current, and has a longer voltage reduction time than before. It has been completed to provide a semiconductor lightning arrester that can be shortened.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a semiconductor lightning arrester using a thyristor element, wherein a self-extinguishing GTO thyristor is used as a thyristor element, and a thyristor is provided. A turn-off circuit that extinguishes the arc within a predetermined time after the element is ignited, and a zinc oxide element and a constant voltage in parallel with the thyristor element
A diode is connected in series, and this zinc oxide element and
Gate signal input via resistor
It is characterized in that turn-on circuits connected to power lines are provided individually . Note that the thyristor element is included.
It is preferable to connect the turn-on circuit in anti-parallel. <br/> Connect a zinc oxide element in series with the thyristor element,
It is preferable to block the following flow following the current .

[0006]

The semiconductor type lightning arrester of the present invention is used by connecting to a power system. When an overvoltage occurs due to a lightning strike on the system, the ignition input from the turn-on circuit to the gate of the self-extinguishing thyristor is performed. The signal causes the thyristor to fire. Generally, a self-extinguishing thyristor has a higher critical on-current rise rate and a shorter turn-on time than an SCR thyristor, so that even if the current rising steepness during discharge is large, there is little risk of destruction of the thyristor element. When the self-extinguishing thyristor is fired in this way, the lightning surge current is discharged to the ground through the thyristor element, and the overvoltage of the system is instantaneously eliminated. After the thyristor element is fired, a turn-off circuit issues an extinguishing signal at a predetermined time to extinguish the thyristor. Such an arc can be extinguished for the first time by employing a self-extinguishing thyristor, and the arc can be extinguished without waiting for the current to become zero. For this reason, there is no risk of element destruction due to the follow-up current, and the voltage drop time can be significantly reduced as compared with the conventional case.

Further, if a zinc oxide element is connected in series with the thyristor element, the rise of the following current flowing following the lightning surge current is suppressed, as shown in a later embodiment, and the following current is ensured. Can be shut off.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the illustrated embodiments. In the first embodiment shown in FIG. 1, 1 is a GTO thyristor provided between the power system and the ground, 2 is its gate circuit, and 3 is a snubber circuit provided in parallel with the GTO thyristor 1. This gate circuit 2 includes a turn-on circuit and a turn-off circuit. Reference numeral 4 denotes a voltage dividing circuit for dividing a voltage between the power system and the ground. The divided voltage is input to an overvoltage detecting circuit 5, and when an overvoltage due to a lightning strike on the power system is detected, a gate circuit is provided. 2 sends an ON signal. As a result, the gate circuit 2 is connected to the GTO thyristor 1
And the lightning surge current is discharged to the ground through the GTO thyristor 1, so that the overvoltage is eliminated. Also,
When the overvoltage detection circuit 5 detects an overvoltage, a signal is also sent to the delay circuit 6. The delay circuit 6 sends an off signal to the gate circuit 2 after delaying the signal by a predetermined time, and the turn-off circuit of the gate circuit 2 extinguishes the GTO thyristor 1.

As described above, according to the present invention, the self-extinguishing thyristor having a high critical on-current increasing rate and a short turn-on time, such as the GTO thyristor 1, is used. However, there is little risk of destruction of the thyristor element. Further, in the present invention, since the turn-off circuit for extinguishing the thyristor element in a predetermined time after the thyristor element is ignited is provided, it is possible to immediately cut off the subsequent current without waiting for the current to become zero.

FIGS. 2A and 2B are current and voltage waveform diagrams for explaining the operation of the semiconductor lightning arrester of the embodiment and the conventional semiconductor lightning arrester. FIG. 2A shows the semiconductor lightning arrester of the embodiment, and FIG. 1 shows a lightning arrester. Even after the discharge current disappears due to the firing of the thyristor element, the conventional SCR thyristor cannot extinguish the arc until the current becomes zero.
As shown in (1), a large amount of subsequent flow flows into the thyristor element, and the heat generated thereby may lead to element destruction. On the other hand, in the semiconductor lightning arrester according to the embodiment including the GTO thyristor 1 and the turn-off circuit, the thyristor element can be extinguished within a short time after ignition as shown in a, so that the thyristor element flows. The follow-up current is cut off in a short period of time, so that element destruction can be prevented and the voltage drop of the power system can be significantly reduced as compared with the conventional case.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention, wherein the gate circuit 2 in the first embodiment comprises only a turn-off circuit and a turn-on circuit 7 is provided independently. It is. This turn-on circuit 7
Is composed of a zinc oxide element 8 connected in parallel with the GTO thyristor 1, a constant voltage diode 9 connected in series with the zinc oxide element 8, and a resistor 10.

The operation of the turn-on circuit 7 is as follows. That is, when an overvoltage due to a lightning strike occurs in the power system, a discharge current flows through the zinc oxide element 8, but the potential V at the point A is always constant (for example, 15
V), and a current corresponding to the resistance 10 flows through the gate signal input line 11. This current is input to the GTO thyristor 1 as a gate signal, and the GTO thyristor 1 is fired. As a result, the lightning surge current is discharged to the ground, and the overvoltage is eliminated. The turn-off circuit is the same as that of the first embodiment. An over-voltage detection circuit 5 detects an over-voltage and sends an off signal to the gate circuit 2 after a predetermined time has elapsed, and the turn-off circuit of the gate circuit 2 extinguishes the GTO thyristor 1. Let it. As the operation of the turn-off circuit, in addition to the method of detecting overvoltage due to lightning surge and operating after a predetermined time,
A method of detecting and operating a lightning surge current flowing through the thyristor element is also conceivable.

FIG. 4 shows a more specific third embodiment in which the circuits of the second embodiment are connected in anti-parallel, and can cope with positive and negative lightning. Its structure and operation and effect are
Therefore, the same reference numerals are given to the corresponding portions, and the description thereof will not be repeated.

FIG. 5 is a circuit diagram showing a fourth embodiment.
A zinc oxide element 12 is connected in series with the GTO thyristor 1 of the second embodiment. Also in the fourth embodiment, when an overvoltage due to a lightning strike occurs in the power system, the GTO thyristor 1 is fired by the turn-on circuit 7, and the lightning surge current is discharged to the ground. Thereafter, after a predetermined time has elapsed, the turn-off circuit of the gate circuit 2 extinguishes the GTO thyristor 1.

As described above, since the current value of the GTO thyristor 1 that can be cut off is relatively low, there is a possibility that the interruption of the continuation of the commercial frequency flowing after the discharge of the lightning surge current may fail. However, if the zinc oxide element 12 is connected in series with the GTO thyristor 1 as in the present embodiment, the continuation current following the lightning surge current is suppressed, so that the continuation current can be reliably shut off.

FIG. 6 shows a case where the zinc oxide element 12 is provided (a).
FIG. 4 is a diagram showing voltage and current waveforms in comparison with (b) without zinc oxide element 12. In (a), the subsequent flow is a zinc oxide element 12
Therefore, if a turn-off signal is input, the GTO thyristor 1 can reliably shut off the downstream current. On the other hand, in (b), since the follow-on current is not suppressed, the current value when the turn-off signal is input increases, and there is a possibility that the interruption of the follow-on current may fail.

[0017]

As described above, according to the semiconductor lightning arrester of the present invention, a self-extinguishing thyristor such as a GTO thyristor having a higher critical on-current rise rate than an SCR thyristor is used. Even if the steepness of the current rise at the time of discharging is large, the risk of destruction of the thyristor element can be reduced. Further, the semiconductor lightning arrester of the present invention has a turn-off circuit for extinguishing the thyristor element in a predetermined time after the thyristor element is ignited, so that the thyristor can be extinguished without waiting for the current to become zero after the ignition. As a result, the voltage drop time associated with the operation of the semiconductor lightning arrester can be significantly reduced as compared with the conventional case. Further, if a zinc oxide element is connected in series with the thyristor element, the follow-up flow is suppressed, so that the use of the GTO thyristor can reliably block the follow-up flow. For this reason, there is no risk of element destruction due to the continuation current flowing after the discharge.

[Brief description of the drawings]

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

FIG. 2 shows a current for explaining the operation of the first embodiment of the present invention;
It is a voltage waveform diagram.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 6 shows a current for explaining the operation of the fourth embodiment of the present invention;
It is a voltage waveform diagram.

[Explanation of symbols]

1 GTO thyristor, 2 gate circuit, 7 turn-off circuit, 12 zinc oxide element

──────────────────────────────────────────────────続 き Continuing on the front page (72) Tatsumi Ichioka, Indies Nippon Insulators Co., Ltd. 2-56, Suda-cho, Mizuho-ku, Nagoya, Aichi Prefecture (72) Inventor Shoji Tange 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi No. Nippon Insulators Co., Ltd. (56) References JP-A-5-22955 (JP, A) JP-A-56-92432 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02H 9/04

Claims (3)

(57) [Claims] In a semiconductor lightning arrester using a thyristor element, a GT capable of self-extinguishing as a thyristor element is provided.
A turn-off circuit that uses an O thyristor, extinguishes the thyristor element for a predetermined time after the thyristor element is fired,
Zinc oxide element and constant voltage diode in parallel with the lister element
And the zinc oxide element and a constant voltage die.
Connect the midpoint of the diode to the gate signal input line via a resistor
A semiconductor lightning arrester characterized in that a separate turn-on circuit is provided. 2. The turn-on circuit including a thyristor element.
2. The semiconductor lightning arrester according to claim 1, wherein
Place. 3. A method in which a zinc oxide element is connected in series with a thyristor element to cut off a subsequent current following a lightning surge current.
The semiconductor lightning arrester according to claim 1 or 2 .