JPH02114480A - Electric discharging gap - Google Patents

Abstract

PURPOSE:To form an electric discharging gap being excellent in the effect of protection even against sharp transient building-up overvoltage, by securing a first electrode and a second electrode respectively to both-end openings that spacers form, in such a manner that the electrodes may be opposed at their respective electric discharging portions to each other, and forming the inner face of each of the spacers into the shape of a convex face. CONSTITUTION:A first electrode 12 and a second electrode 13 are provided in between spacers 11 in such a manner that the electrodes are opposed at their respective electric discharging portions 12a, 13a to each other. Furthermore, each of the spacers 11 had its inner face formed into the shape of a convex face which includes a site 11a where each of the spacers 11 is closest to the electric discharging portion 12a of the first electrode 12 and also a site 11b where each of the spacers 11 is closest to the electric discharging portion 13a of the second electrode 13, and then the first electrode 12 and the second electrode 13 are secured respectively to both-end openings that the spacers 11 form in such a manner the electric discharging portion 12a and the electric discharging portion 13a may be opposed to each other in between the spacers 11. Accordingly, spark discharge takes place between the electric discharging portion 12a of the first electrode 12 and the electric discharging portion 13a of the second electrode 13, so that the rise of lightning impulse discharge starting voltage is suppressed. Thus, an electric discharging gap is formed with the excellent effect of protection against any overvoltage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a discharge gap for protecting various electrical equipment from momentary overvoltages.

Prior Art Conventionally, this type of discharge gap has been constructed as shown in FIG. In FIG. 2, 1 is a cylindrical spacer made of dielectric ceramic. 2 and 3 are electrodes, each having a discharge portion 21.31L.

These electrodes 2 and 3 are connected to the respective discharge portions 21L.
, 3 & are opposed within spacer 1.
It is attached to the openings at both ends.

Regarding the conventional discharge gap configured as above,
The operation will be explained below. Now, when a momentary overvoltage is applied between electrode 2 and electrode 3, the discharge part 21L of electrode 2
A momentary overvoltage is also applied between the discharge portion 31L of the electrode 3 and the discharge portion 31L of the electrode 3. When the overvoltage exceeds a certain voltage, a spark discharge occurs between the discharge part 2a of the electrode 2 and the discharge part 3a of the electrode 3, and a current flows between the electrodes 2 and 3, suppressing the voltage rise. , will protect electrical equipment from overvoltage.

Problems to be Solved by the Invention In such a conventional configuration, when the instantaneous overvoltage waveform shows a steep rise, the response of the spark discharge is delayed, and the voltage at which the discharge starts (referred to as the lightning impulse discharge start voltage) increases. There is a problem that the cost increases, making it impossible to protect the protected equipment. As a countermeasure to this problem, it has been a challenge to realize a discharge gap in which the lightning impulse discharge starting voltage does not increase even in the case of a steep rising waveform.

Means for Solving the Problem In order to solve this problem, the present invention comprises a first electrode and a second electrode each having a substantially cylindrical spacer made of dielectric porcelain and a discharge portion, The electrode and the second electrode are respectively attached to openings at both ends of the spacer so that their discharge portions face each other within the spacer, and the inner surface of the spacer is formed into a convex shape.

Effect: With this configuration, even when an overvoltage with a steep rising waveform is applied, a portion of the spacer inner surface is prevented from reaching the discharge portion of the first electrode and the discharge portion of the second electrode because the inner surface of the spacer is convex. Due to the close structure, a partial discharge occurs in this part, which acts as a trigger, and a spark discharge occurs between the discharge part of the first electrode and the discharge part of the second electrode.
This means that the increase in lightning impulse discharge starting voltage is suppressed.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a front sectional view of a discharge gap in one embodiment of the present invention. In FIG. 1, 12 is a first electrode;
12sL is a discharge part of the first electrode 12. 13 is the second
131L is the discharge part of the second electrode 13.

Reference numeral 11 denotes a substantially cylindrical spacer made of dielectric ceramic. The inner surface of this spacer 11 is convex, and 1
11L and 11b are parts of the inner surface of the spacer 11;
1L is the discharge part 12+L of the spacer 11 and the first electrode 12
11b is the position where the spacer 11 and the discharge portion 131L of the second electrode 13 are the closest. Then, the discharge part 12a of the first electrode 12 and the second
The discharge portions 3 & of the electrodes 13 are mounted on the spacer 110 at both ends of the spacer 11 so as to face each other within the spacer 11 .

The operation of the discharge gap configured as described above will be described below. When a momentary overvoltage is applied between the electrode 12 of the first electrode 1 and the second electrode 13, the first electrode 1
2 discharge section 121L and the second discharge section 131L of the second electrode 13
A momentary overvoltage is also applied during this period. Then, when the overvoltage exceeds a certain voltage, the discharge portion 1 of the first electrode 12
A spark discharge occurs between the discharge portion 131L of the second electrode 13 and the first electrode 12, and a current flows between the first electrode 12 and the second electrode 13, suppressing the voltage rise and protecting the electrical equipment from overvoltage. . Here, when the waveform of the overvoltage radially shows a steep rise, spark discharge between the discharge parts is unlikely to occur. However, in this embodiment, the discharge portion 12 of the first electrode 12
A voltage of -xV (V: overvoltage value) expressed by the following formula is applied between the position 111L where the side surface of the first electrode 12 and the inner surface of the spacer 11 are closest, and the discharge portion 121L of the first electrode 12 and the spacer 11 are Since the gap between the inner surface 111L and the inner surface is narrow,
Partial discharge occurs here. Similarly, a voltage of Xv is applied between the discharge portion 13& of the second electrode 13 and the position 11b where the inner surface of the spacer 11 is closest, and a partial discharge occurs here as well. These partial discharges act as a trigger, and the discharge portion 12! of the first electrode 12! A spark discharge occurs between L and the discharge portion 13& of the second electrode 13. Therefore, even in the case of a steeply rising overvoltage, the lightning discharge starting voltage does not increase, and the protection effect for the protected equipment is good.

FIG. 3 shows the characteristic of lightning impulse discharge starting voltage versus discharge time in the conventional discharge gap and the discharge gap of this embodiment. In FIG. 3, B is the characteristic of the conventional discharge gap, and B is the characteristic of the discharge gap of this embodiment. In the conventional discharge gap, when the discharge time is short, that is, when the overvoltage rises sharply, the lightning impulse discharge starting voltage becomes very high. In contrast, in the discharge gap of this embodiment, even when the discharge time is shortened, that is, even when there is a steep rise in overvoltage, the lightning discharge starting voltage only increases slightly.

Effects of the Invention As described above, according to the present invention, the first electrode and the second electrode each have a substantially cylindrical spacer made of dielectric porcelain and a discharge portion, and the first electrode and the second electrode have a discharge portion. By attaching two electrodes to the openings at both ends of the spacer so that their discharge portions face each other within the spacer, and by making the inner surface of the spacer convex, it is possible to resist a steep rise in overvoltage. , it is possible to realize a discharge gap with a small increase in lightning impulse discharge starting voltage and a good protective effect, and its practical effects are great.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of a discharge gap according to an embodiment of the present invention, FIG. 2 is a front sectional view of a conventional discharge gap, and FIG.
The figure shows the lightning impulse discharge starting voltage-discharge time characteristics of the discharge gap of the embodiment shown in FIG. 1 and the conventional discharge gap shown in FIG. 2. DESCRIPTION OF SYMBOLS 11... Spacer, 12... First electrode, 12λ... Discharge part of first electrode, 13...
...Second electrode, 13a...Discharge part of the second electrode. Name of agent Patent attorney Shigetaka Awano and 1 other person Kurei-4:-

Claims (1)

[Claims] It consists of a substantially cylindrical spacer made of dielectric porcelain, and a first electrode and a second electrode each having a discharge portion, and the discharge portions of the first electrode and the second electrode are opposed to each other within the spacer. attached to the openings at both ends of the spacer so as to
A discharge gap characterized in that the inner surface of the spacer is convex.