JP2003203744A - Blade-form spark discharge gap - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blade-form spark discharge gap having a long durable period capable of preventing a dielectric degradation between electrodes due to vapor and/or particulates produced from the electrode material at the time of electric discharge and offering an always stable discharge start voltage. <P>SOLUTION: The blade-form spark discharge gap is configured so that a pair of square column electrodes in which one edge member of each is acute and inclined and the tip is polished in a blade shape are butted together, at their forefront parts a thin plate having a high heat resistance and high electric insulation (for example, mica plate) is held pinchedly so that a pilot discharge is easily generated, and that two confronting electrodes are put in pressure contact and tight attachment. Between the electrodes, one or a plurality of electrodes in the form of isosceles triangle are installed, and a plurality of spark discharge gaps alike in a blade shape are arranged in series so as to cut the discharge current into fine fragments. Owing to the pilot discharge between the two forefront edge members inclined, a still greater discharge is induced between the inclined faces. An arc extinguishing plate is provided which generates hydrogen gas only by heating with sparks of discharging, while the whole structure of electrodes is secured to a mounting table made of porcelain. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION When a spark discharge gap is used as a lightning arrester, there is a slight delay in operation, but the voltage between the electrodes is low and the power loss between the spark electrodes is small, even if the discharge current increases. Even if an excessive surge current flows (for example, a peak value of 10 with a standard lightning impulse of 8/20 μs).
(0KA) It has the advantage that it can withstand it sufficiently. On the other hand, there is also a drawback that the electrode continues to be melted by continuous flow (a phenomenon in which a current flows at the power supply voltage after the surge has passed).

[0002]

2. Description of the Related Art In a conventional spark discharge gap, a pair of metal square pole electrodes 10.10a face each other as shown in FIG. 1a. The electric field between the electrodes when a lightning surge is applied between the electrodes G is shown by an electric force line E (solid line) in FIG.
As shown in b, the discharge concentrates on the four sides, the four corners, and the vicinity thereof, so that the discharge tends to start not at the center of the counter electrode but at the edge portion of the electrode and spread to the counter surface (in the electrode gap G).

In the above case, the initial effects of "spark extension" and "diffusion and cooling" of the electrode surface itself cannot be sufficiently exerted. Therefore, the spark is not extinguished, the metal vapor generated at a high temperature fills the gap G between the electrodes, and a continuous flow from the commercial power supply circuit may occur.

[0004]

When a strong lightning surge enters, the spark is extruded from the facing surface to the outside to extinguish the arc and does not generate a follow-up current from the commercial power source. Even if a spark discharge gap with a low melting point is used, it is possible to prevent a decrease in the insulation between the electrodes due to the vapor of the electrode material and fine particles generated during discharge, and to obtain a long-life spark discharge gap with a stable discharge start voltage. is there.

[0005]

The means of the present invention are as follows.

In a pair of square pole electrodes having a sloping surface cut at an arbitrary acute angle, the sloping surfaces are butted against each other in an upward direction or a downward direction, and a thin plate having high heat resistance and high insulation is sandwiched between them and pressure-welded. However, from the spark discharge between the two sides forming the acute angle, in order to induce a discharge with a larger current between the facing surfaces, for the edge of the thin plate, the protrusion of one side of the facing surface side is small. , The other three sides project relatively long.

In a pair of quadrangular prismatic electrodes having a sloping surface cut at an arbitrary acute angle, the sloping surfaces are opposed to each other in an upward direction or a downward direction, and in the meantime, the same height as that of the rectangular prismatic electrode is provided. Insert one or more isosceles triangular pole electrodes, join them at the same acute angle, sandwich a thin plate with high heat resistance and high insulation between them, and press-contact them. In order to induce between the continuous facing slopes, the edge of the thin plate is slightly protruded on the facing slope side of the electrode, and the other three sides are projected relatively long. gap.

In particular, the tip of the inclined surface of the electrode is ground into a blade shape. Also, a fiber arc extinguishing plate was provided above the opening of the spark discharge gap. Also, all the electrodes that form the spark discharge gap are installed on a porcelain table.

[0009]

[Operation] According to the present invention, as shown in FIG. 2a, a pair of electrodes 20, 20a whose one surface is cut at an arbitrary acute angle has tips 22, 22.
a is polished into a blade shape and the upper end of the mica piece 23 is attached to the electrode surface 21,
21a, the thickness (t) of the mica piece 23 and the thickness (t) of the mica piece 23 when it is slightly protruded and sandwiched and fixed to the porcelain mount 24
The dimension (m) of the protruding portion was calculated in consideration of the fact that the spark discharge between the tip portions 22 and 22a induces a larger discharge current on the electrode surfaces 21 and 21a when a lightning voltage is applied, and is calculated and tested. Determined by

When a lightning voltage is applied to the pair of electrodes 20, 20a, the electric field immediately before the start of discharge is represented by the electric force line E (solid line), as shown in FIG. Since the air is ionized (in the range of M), the spark discharge between the electrode tips 22 and 22a causes electrode surfaces 21 and 21a.
In the meantime, a larger discharge current will be induced.

In this case, since the spark is stretched by the inclined surfaces of the 21 and 21a and is subjected to the cooling action, it is ionized (thermoionization).
Is blocked and the arc is easily extinguished. Another factor that causes a follow-up current is vapor emitted from the electrode material during discharge (fine particles of the electrode material or carbon powder). As you can see from the electrode structure, an opening is opened at the explosion location. Therefore, the steam generated during the discharge is discharged to the outside by the explosive force.

Further, according to one example of the present invention, as shown in FIG. 3a, a plurality of isosceles triangular prism type electrodes 30 and 30a are arranged between the electrodes 20 and 20a, and their respective surfaces are 31, 3 and 3, respectively.
1a, 32, 32a, the state of the lightning discharge current when a lightning voltage is applied between the electrodes 20, 20a is as shown in FIG. 3b. That is, sparks (P) are 21 to 31 and 3
1a to 32 and 32a to 21a are cut into pieces, so that current concentrates on the electrode surface portion (cathode point, anode point) of the discharge (arc), the potential drop becomes large, and the diffusion of ions is large. Therefore, in the commercial power supply, when the current is reversed, it is prevented that a new cathode spot (where it was the anode spot before) is formed, and this interrupts the re-ignition to interrupt the follow-up current.

Further, the fiber arc-extinguishing plate 23a attached to the opening of the spark gap has a function of extinguishing the spark due to the discharge by generating hydrogen gas when heated by the heat of the spark due to the spark discharge.

Since the electrodes forming the spark gap are set on a porcelain table, they are never carbonized by being exposed to a high temperature caused by sparks.

As the material of the above electrodes, brass, copper-tungsten sintered alloy, molybdenum, stainless steel, nickel, copper, magnesium or carbon, conductive ceramics and the like can be used.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 4 shows an embodiment of a lightning arrester composed of a blade type spark discharge gap according to the present invention.
The tips 22 and 22a of 0 and 20a are blade-polished, and a porcelain mount 24 having recesses 25 and 25 'in the center is attached to the electrodes 20, 20a and fiber 23a together with the mica piece 23.
With screws 26, 26a and nuts 27, 28 and 27.
Fix with a and 28a.

At that time, when a lightning voltage is applied to the lightning arrester of the present invention as described above, it is calculated that the spark discharge at the electrode tips 22 and 22a induces a larger current at the electrode surfaces 21 and 21a. , The thickness (t) of the mica piece 23 and the protrusion size (M) into the spark gap formed by the electrode surfaces 21 and 21a follow numerical values determined by experiments.
The nuts 29 and 29a are prepared for attaching lead wires.

[0018]

EFFECTS OF THE INVENTION In the blade type spark discharge gap of the present invention, a pair of opposed surfaces obtained by cutting one surface of a quadrangular prismatic electrode are formed by an acute angle, and the tip is ground like a blade, and a mica piece is sandwiched between them. Therefore, not only the tip portion is not abraded by the discharge, but also the discharge at the tip portion becomes a spark discharge, which induces a discharge with a larger current between the facing surfaces.

Further, since the tip of the electrode is ground in a blade shape, the corona current immediately before discharge is more than twice as large as that of a normal one, so that the discharge start voltage can be lowered and the discharge voltage can be reduced. It has the characteristics that it is stable and stable. From the spark discharge generated at the tip, the main discharge induced on the nearby slope has a gradually increasing separation distance, so that the spark is stretched and cooled.

Further, the vapor emitted from the electrode material is also emitted to the outside by the explosive force from the center and the large opening. In the method of connecting multiple sets of blade electrodes in series,
In addition to the advantage that the voltage drop becomes large because the current is concentrated on each electrode surface and the sparks are fragmented during discharge, the diffusion of ions also concentrates on the electrode surface, so when the current is reversed at the commercial power supply In the meantime, new cathode spots (where they were formerly anode spots) are blocked, which interrupts the follow-up stream to prevent re-ignition.

Further, in the spark gap of the metal electrode, when the polarity is reversed in a half cycle, 200 to 30 per pair is set.
Since a re-ignition voltage of 0V is required, when a plurality of gaps are in series, an AC power source (100 to 200V)
Since it does not reach that voltage, it can be easily extinguished during a half cycle.

The fiber arc extinguishing plate attached to the opening of the spark gap has an action of generating hydrogen gas and extinguishing the spark caused by the discharge when heated by the heat of the spark caused by the spark discharge.

Further, since the electrode forming the spark gap is installed on a porcelain table, it is never exposed to high temperature due to sparks and carbonized.

Therefore, although it has good workability such as brass, even if it is used for an electrode material having a low melting point, the melting loss of the electrode is small, so that a stable discharge starting voltage can be maintained at all times, and there is a concern about a follow current. Therefore, it is possible to obtain a spark discharge gap with long life, high reliability, and economy.

[Brief description of drawings]

FIG. 1a is a conventional spark discharge gap (perspective view). FIG. 1b is an electric field distribution diagram (side view) indicated by lines of electric force in the spark discharge gap.

FIG. 2a is a blade type spark discharge gap of the present invention (perspective view). FIG. 2b is an electric field distribution diagram (side view) shown by the lines of electric force of the spark gap.

FIG. 3a is a different blade spark gap (perspective view) of the present invention. FIG. 3b is a diagram (side view) showing a state in which a lightning current acts on the spark gap.

FIG. 4 is an embodiment of the present invention.

[Explanation of symbols]

G Spark gap [Fig. 1 (b)] Area where M is ionized [Fig. 2 (b)] m Projection distance of mica plate t Thickness of mica plate Sparks associated with P discharge [Fig. 3 (b)] 10.10a Square pole electrode [Fig. 1] 20.20a Square pole electrode with inclined surface 21.21a Inclined surface

Claims (5)

[Claims] 1. A pair of quadrangular prismatic electrodes having a sloping surface cut at an arbitrary acute angle, the sloping surfaces are abutted in an upward direction or in a downward direction with each other, and a thin plate having high heat resistance and high insulation is sandwiched therebetween. In order to induce a discharge with a larger current between the facing surfaces from the igniting discharge between the two sides that form a sharp angle by pressing in contact with each other, for the edge of the thin plate, the protrusion of one side on the facing surface side is applied. A blade-type spark discharge gap characterized by a small number and the other three sides projecting relatively long. 2. A pair of quadrangular prismatic electrodes having a sloping surface cut at an arbitrary acute angle, wherein the sloping surfaces face each other in an upward direction or in a downward direction with each other, and the same height as that of the quadrangular prismatic electrode is provided therebetween. Insert one or more isosceles triangular prism electrodes and join them at the same acute angle, with high heat resistance between them.
A thin plate with high insulation is sandwiched and pressure-contacted, and in order to induce a discharge with a larger current between the continuous facing slopes from the spark discharge of the gap group, the protrusion of the end of the thin plate faces the electrodes. A blade-type spark discharge gap characterized in that the slope side is slight and the other three sides project relatively long. 3. The blade type spark discharge gap according to claim 1, wherein the tip of the inclined surface of the electrode is ground into a blade shape. 4. The blade type spark discharge gap according to claim 1, wherein an arc extinguishing plate made of fiber is provided above the opening of the spark discharge gap. 5. The blade type discharge gap according to claim 1, wherein the electrodes forming the spark discharge gap are all installed on a porcelain table.