JPH08213146A - Creeping discharge facilitating duplex spark gap - Google Patents

Abstract

PURPOSE: To safely protect electric equipment against lighting surge and reduce a spark gap. CONSTITUTION: T-shaped copper sheets 2 and 2a are bent in such a state as enveloping the short sections 21 and 21a thereof, and pressure connected to both sides of a carbon coated insulator 1 such as mica having a baked film mainly composed of carbon on one side. Furthermore, the intermediate section of the carbon coat between the sheets 2 and 2a is scraped to a long and narrow shape to form a fine gap (a), thereby preparing a surface discharge facilitating duplex spark gap. Then, the spark gap is housed in a glass tube 3 having both ends sealed with metallic caps 4 and 4a, and the lead sections of the long sections 2 and 2a of the sheets 22 and 22a are connected to the caps 4 and 4a for the electrical integration thereof.

Description

Detailed Description of the Invention

[0001]

[Industrial application] In recent years, automation has become widespread in factories, research laboratories, offices, hospitals, golf courses and other sports facilities, agricultural facilities, etc. ing. Those devices are truly vulnerable to lightning surge voltages.

Since the surge voltage enters not only from the power source side but also from the weak electric circuit side such as the signal circuit, it is necessary to take a lightning protection measure against the signal line.

[0003] Among the above facilities, there are heavy thunder areas and heavy thunder areas such as winter lightning. In addition to this, if the location conditions are mountainous areas, riverbeds or sand dunes, the earth resistivity of that location Since the lightning current is not immediately dissipated into the ground because it becomes high, the damage is also large because it spreads over a wide area along the nearby electric line.

On the other hand, as automation advances, unmanned facilities also increase. Even if the lightning arrester fails due to unmanned operation, maintenance personnel will have to be dispatched from a distance. Therefore, the demand for lightning arresters will continue to increase in the future, but it withstands considerably more energy than conventional ones, not only protecting the equipment from repeated intrusions of powerful lightning surges, but also preventing the lightning arrestor itself from burning. Therefore, there is a strong demand for easy maintenance and reduced management costs.

The present invention relates to a creeping discharge-promoted compound spark gap that can be used as a main component of a new compound arrester that meets the demands of the times.

[0006]

2. Description of the Related Art Conventionally, there are roughly classified into the following seven types of arresters.

(1) Spark gap (2) Gas discharge tube type lightning arrester (3) Semiconductor type lightning arrester (4) Series circuit of gas discharge tube type lightning arrester and semiconductor type lightning arrester (5) Gas discharge tube type lightning arrester (6) Spark gap and semiconductor type lightning arrester series circuit (7) Spark gap and semiconductor type lightning arrester parallel circuit However, (1) is a lightning surge caused by multiple lightning strikes or continuous discharges,
Although it is easy to obtain a device that can withstand a large amount of energy such as lightning strikes in the vicinity, there is a drawback that the response time at the start of operation is delayed. (2) It is easy to use a device with a small electrostatic capacity and a relatively large current capacity. However, when used in a power supply circuit, there is a weak point that the follow current due to the power supply voltage cannot be interrupted immediately after discharge. In (3), the response to lightning surge is sensitive in principle, but if a voltage exceeding the limit voltage frequently acts, the operation start voltage of the element will drop, and the circuit will suddenly be short-circuited even with the applied voltage. If the power is not turned off, it may ignite suddenly. Those with large surge resistance have large electrostatic capacity and large volume, and are not suitable for indoor use due to the above-mentioned sudden ignition (4). No worries, the electrostatic capacity is small (does not hinder the operating function of protective equipment), but if a continuous discharge type lightning surge with a long energizing time enters or multiple lightning strikes have insufficient energy capacity, it will burn out. The problem remains. In (5), if an appropriate combination can be obtained, a sensitive and relatively large energy withstanding product can be obtained, but the power supply circuit still has the drawback that the follow current cannot be interrupted. There is no guarantee that it will withstand the lightning surge of a lightning strike.
In (6), there is no concern about follow-up current even if used in the power circuit,
Since the spark gap hinders the sensitive responsiveness of the semiconductor device, it is rarely used at present.
In the case of (7), since the elements having different properties are connected in parallel, each disadvantage can be compensated, so that a considerable effect can be expected if the combination thereof is good. However, by simply connecting two elements in parallel, even if, for example, the limiting voltage of the semiconductor lightning arrestor and the operation start voltage of the spark gap match, the properties of the semiconductor lightning arrester are complicated, so far. Had difficulty coordinating their actions.

However, in Japanese Patent No. 1750682, the spark gaps connected in parallel prevent the zinc oxide element from being seriously damaged, and the zinc oxide element is not released but remains short-circuited, so that the protective device is continuously protected. The Japanese Patent Application No. 1-12991 proposes a high-sensitivity and large-capacity compound type lightning arrester capable of obtaining cooperation between the two.

According to the above proposal, the spark gap is indispensable for the high-sensitivity and large-capacity arrester. The carbon electrode used as the electrode for the spark gap operates at a low voltage, except for the problem of follow-up current, there is little variation in the operation start voltage, and no melting marks can be formed even when discharged.
It has superior performance compared to metal electrodes such as no rust.

Generally, in a lightning arrester used for a weak electric circuit, a carbon electrode is used because it is not necessary to worry about a follow current.

In addition, due to the characteristics of the air discharge, there is an unobtainable feature that the limiting voltage of the arrester decreases as the current in the gap increases.

In other words, the smaller the carbon spark gap is, the more the resistance of the spark gap increases (because the specific resistance of carbon is high), so that the current value decreases and the surge arrester is limited. This means that the voltage will rise.

[0013]

On the other hand, in a weak electric circuit, a multi-conductor cable or the like having a large number of lines is often targeted, so that the lightning arrester itself is inevitably made as small as possible.

In the above-mentioned high-sensitivity and large-capacity lightning arrester, there is a contradiction that parallel spark electrodes are required to be as small as possible, good in performance, and sturdy enough to withstand a large current.

[0015]

In view of such an actual situation, the present invention has an advantageous condition that a large current can easily flow in a metal electrode, and a carbon electrode has a high reliability and a low voltage as described above. The above-mentioned problems are solved by combining advantageous conditions that discharges are repeatedly obtained.

That is, for this reason, a metal electrode plate with a lead portion is made to face each other with appropriate gaps held at both ends of a carbon film-coated insulating plate having a carbon-based film baked on its surface. In the approximate center of the gap, a creeping discharge-promoting compound spark gap in which a minute gap made by cutting the carbon film is provided, and a spark gap is housed in a glass tube whose both ends are sealed with metal caps. The lead part is the above 2
It proposes the above-mentioned creeping discharge-promoting type double spark gap that is electrically connected to each of the two metal caps, and is housed in the above glass tube with the metal cap,
In the creeping discharge-promoted double-type spark gap that is electrically integrated with this, the minute spark gap made on the carbon film does not directly touch the outside air, so a reliable arrester can be obtained for a long time. It was done.

[0017]

In the case of a zinc oxide element, it behaves like a good insulator below the response voltage, but above that, the current is considered as a non-linear resistor that increases with the 15th to 30th power of the voltage. The response speed is fast and there is almost no time delay. An appropriate zinc oxide element is connected in parallel to the spark electrode, and the maximum value of the zinc oxide element's limiting voltage and the discharge start voltage of the spark gap are almost matched to theoretically avoid overvoltage due to the inevitable ignition delay of the spark electrode. .

However, since the spark gap naturally has variations in the discharge starting voltage and the characteristics on the zinc oxide element side are complicated, it is not always easy to coordinate the operation of the spark gap and the zinc oxide element. However, today, Japanese Patent Application No. 1-12991 describes a low voltage surge arrester with a zinc oxide element and a non-inductive resistor with appropriate characteristics connected in series and a spark gap connected in parallel. As described above, the operation cooperation between the zinc oxide element and the spark gap can be obtained practically, and the electrical equipment can be safely protected from the lightning surge even if the lightning surge with large energy due to the nearest lightning repeatedly intrudes. .

It is also mentioned above that in this case the spark gap plays an important role.

Nowadays, there is a demand for further reduction in size of the spark gap used for such a purpose. However, in the present invention, since the metal gap allows a large current to flow, the limiting voltage can be lowered. The advantage is that the carbon electrodes can be repeatedly operated at a substantially constant low voltage.

In the spark gap of the present invention, discharge is first generated in the spark gap of the minute carbon electrode, which triggers a high current at the same time as the spark gap of the metal electrode attached to the outside of the carbon electrode. A creeping discharge occurs.

Therefore, even if the spark gap is reduced in size,
Since the current between the gaps is large, the limiting voltage of the gap can be lowered, and even if it is repeatedly operated, there is almost no change in the discharge start voltage and other characteristics.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a creeping discharge-promoted double-type spark electrode according to the present invention, which will be described below with reference to the drawings.

FIG. 1 shows a creeping discharge-promoting type double-sided spark gap according to the present invention. Reference numeral 1 is an insulating plate such as mica in which a film containing carbon as a main component is baked on one side, and 2 and 2a are short pieces 21 and 21 'of a T-shaped thin copper plate as shown in FIG. 1 is folded so as to wrap it, and pressure-bonded to both ends of the carbon-coated insulating plate 1 described above.

The carbon film is cut into long and thin portions at a substantially central portion between the copper plates 2 and 2a shown in FIG.
To provide.

FIG. 3 shows a creeping discharge-promoting type double spark gap of the present invention housed in a glass tube with a metal cap, 3 is a glass tube and 4 and 4a are metal caps. The long piece lead portions 22 and 22a shown in FIG.
Then, the metal caps 4 and 4a are respectively pushed in from above and bent to be in contact with the lead portions 22 and 22a.

FIG. 4 is a perspective view of the metal caps 4 and 4a. In the figure, portions 41 and 41a are depressions for ensuring soldering, and portions 42 and 42a are holes for inserting lead wires of other lightning protection elements.

FIG. 5 is a connection diagram of a multifunctional lightning arrester proposed in Japanese Patent Application No. 1-12991, wherein 51 is a spark gap, 52 is a non-induction type lightning arrester, and 53 is a zinc oxide element. A non-inductive resistor 52 and a zinc oxide element 53 are connected in series, and this circuit is assembled into a small size and inserted into the glass tube 3 containing the spark gap 51 of the present invention together with an insulating partition plate. Then, the lead wire portion of the circuit is inserted into the small holes 42, 42a provided at the bottoms of the metal caps 4, 4a, and soldered at the recesses 41, 41a for finishing.

[0029]

As described above, according to the present invention, the operation cooperation between the zinc oxide element and the spark gap is obtained, and even if the lightning surges with large energy due to the nearest lightning repeatedly enter, the electrical equipment can be protected from the lightning surge. In addition, the creeping discharge-promoting double-type spark gap that is electrically integrated with a glass tube with a metal cap protects the minute spark gap made on the carbon film from direct contact with the outside air. Therefore, a lightning arrester with high reliability can be obtained over a long period of time.

Further, there is an effect that a multi-functional lightning arrester for a high-sensitivity, large-capacity weak current circuit can be easily constructed, and a large number of lightning arresters can be easily incorporated in the lightning arrester box, and the size can be reduced.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a creeping discharge promotion type compound spark gap according to the present invention.

FIG. 2 is a front view of a copper plate forming a spark gap.

FIG. 3 is a creeping discharge-promoted double-sided spark gap housed in a glass tube with a metal cap.

FIG. 4 is a perspective view of a metal cap.

FIG. 5 is a connection diagram of a multifunctional lightning arrester.

[Explanation of symbols]

 1 Insulation plate with carbon film 2, 2a Copper plate 22, 22a Lead part 3 Glass tube 4, 4a Metal cap 41, 41a Dimple 42, 42a Small hole 51 Spark gap 52 Non-induction type arrester 53 Zinc oxide element a Gap part

Claims (2)

[Claims] 1. A metal electrode plate with a lead portion is opposed to both ends of a carbon film-coated insulating plate having a film containing carbon as a main component baked on its surface, with an appropriate gap maintained,
A creeping discharge-promoting type double-sided spark gap in which a minute gap made by cutting the carbon film into a long and thin shape is provided almost in the center of the gap. 2. A spark tube is housed in a glass tube whose both ends are sealed by metal caps, and lead portions are respectively connected to the metal caps to be electrically integrated with each other. Creeping discharge-promoting type double-sided spark gap