Electricity: electrical systems and devices – Safety and protection of systems and devices – High voltage dissipation
Reexamination Certificate
2000-12-04
2002-08-06
Sircus, Brian (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
High voltage dissipation
Reexamination Certificate
active
06430018
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a three-electrode-discharge surge arrester and, more particularly, to a three-electrode-discharge surge arrester eliminating a surge current generated between two line wires and a ground wire.
2. Description of the Related Art
A description will now be given, with reference to
FIG. 1
, of a conventional three-electrode-discharge surge arrester.
The conventional three-electrode-discharge surge arrester has a pair of axially placed line electrodes
10
formed of metals such as Fe—Ni alloys, with a predetermined gap therebetween, so that cylindrically shaped discharging parts
12
provided respectively on the inner edges of the pair of line electrodes
10
oppose each other.
Between the opposing discharging parts
12
of the pair of line electrodes
10
is a ground electrode
20
provided with a penetration hole
28
in the center.
Between the ground electrode
20
and each of the line electrodes
10
is each of a pair of cylindrical insulating housings
30
, within each of which the discharging part
12
of the line electrode
10
is inserted. The cylindrical insulating housings
30
are formed of insulators such as ceramic. Circular electric terminals
14
formed respectively on the outer side of the pair of line electrodes
10
seal the outer openings of the pair of cylindrical insulating housings
30
airtight. The cylindrical insulating housings
30
are placed airtight between each of the line electrodes
10
and the ground electrode
20
.
A terminal
24
of the ground electrode
20
is held between the pair of cylindrical insulating housings
30
. The circumference of the terminal
24
of the ground electrode
20
exposes itself between the pair of cylindrical insulating housings
30
.
In the conventional three-electrode-discharge surge arrester shown in
FIG. 1
, two line wires (not shown in the figure) can be connected to the circular electric terminals
14
sealing the outer openings of the pair of cylindrical insulating housings
30
, respectively. Also, a ground wire (not shown in the figure) can be connected to the terminal
24
of the ground electrode
20
exposing itself between the pair of cylindrical insulating housings
30
. Then, a surge current generated between either of the two line wires and the ground wire can be eliminated by causing a discharge to occur in a gap between either of the discharging parts
12
of the line electrodes
10
and its opposing discharging part
22
of the ground electrode
20
.
However, in the above-mentioned conventional three-electrode-discharge surge arrester, when a discharge occurs between each of the discharging parts
12
of the line electrodes
10
and its opposing discharging part
22
of the ground electrode
20
, particles of metals such as Fe—Ni alloys forming the discharging parts
12
and
22
disperse from the discharging parts
12
and
22
by sputtering, to land on the inner peripheral surfaces of the cylindrical insulating housings
30
. Then, the sputtered particles, unduly connected with conductive trigger lines
32
, which are formed on the inner peripheral surfaces of the cylindrical insulating housings
30
and electrically connected to the line electrodes
10
and the ground electrode
20
, cause deteriorated insulation between each of the line electrodes
10
and the ground electrode
20
. This prevents stable and accurate discharges from occurring repeatedly over a long period of time between each of the discharging parts
12
of the line electrodes
10
and its opposing discharging part
22
of the ground electrode
20
.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide an improved and useful three-electrode-discharge surge arrester in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide a three-electrode-discharge surge arrester which can cause stable and accurate discharges to occur repeatedly over a long period of time and can eliminate a surge current generated between two line wires and a ground wire.
In order to achieve the above-mentioned objects, there is provided according to the present invention a three-electrode-discharge surge arrester having two discharging parts of a pair of line electrodes, the two discharging parts opposing each other and defining a gap therebetween; a ground electrode disposed between the two discharging parts and provided with a penetration hole in the center thereof; and two cylindrical insulating housings between each of the line electrodes and the ground electrode,
wherein each of the two discharging parts has a substantially conical shape; each of inner surfaces of upper and lower parts of the penetration hole is substantially funnel-shaped, in accordance with the substantially conical shape; and oblique parallel gaps for a primary discharge are formed between the inner surfaces of the upper and lower parts of the penetration hole and the two discharging parts, respectively,
wherein parallel gaps for a secondary discharge are formed between peripheral parts of the ground electrode around the penetration hole and peripheral parts of the pair of line electrodes, respectively, each of the peripheral parts of the pair of line electrodes opposing each of the peripheral parts of the ground electrode around the penetration hole, and
wherein each of the oblique parallel gaps is formed narrower than each of the parallel gaps.
The three-electrode-discharge surge arrester according to the present invention has the substantially conical discharging parts of the line electrodes. To suit this shape, the upper and lower parts of the penetration hole of the ground electrode each have the substantially funnel-shaped inner surfaces. Between each of the substantially conical discharging parts of the line electrodes and its opposing substantially funnel-shaped inner surface of the penetration hole of the ground electrode is the oblique parallel gap for a primary discharge.
Therefore, when a primary discharge occurs in the oblique parallel gaps formed between each of the substantially conical discharging parts of the line electrodes and each of the substantially funnel-shaped inner surfaces of the penetration hole of the ground electrode, metal particles are sputtered from the substantially conical discharging parts of the line electrodes and the substantially funnel-shaped inner surfaces of the penetration hole of the ground electrode. However, the sputtering is blocked by the ground electrode around the penetration hole and the discharging parts of the line electrodes, so that the sputtered metal particles are kept from landing on the inner peripheral surfaces of the cylindrical insulating housings each placed between the ground electrode and each of the line electrodes. This prevents deteriorated insulation, otherwise caused by the sputtering, between each of the line electrodes and the ground electrode.
Also, the metal particles sputtered from the substantially conical discharging parts of the line electrodes land on the opposing substantially funnel-shaped inner surfaces of the penetration hole of the ground electrode, and the metal particles sputtered from the substantially funnel-shaped inner surfaces of the penetration hole of the ground electrode land on the opposing substantially conical discharging parts of the line electrodes. Therefore, the substantially conical discharging parts of the line electrodes and the substantially funnel-shaped inner surfaces of the penetration hole of the ground electrode keep supplementing sputtered metals to each other.
This prevents changing significantly the width and length of the oblique parallel gaps between the substantially conical discharging parts of the line electrodes and the substantially funnel-shaped inner surfaces of the penetration hole of the ground electrode, because metals forming the substantially conical discharging parts of the line electrodes and the substantially funnel-shaped inner surfaces of the penetration hole of the ground e
Nguyen Danny
Shinko Electric Industries Co. Ltd.
Sircus Brian
LandOfFree
Three-electrode-discharge surge arrester does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Three-electrode-discharge surge arrester, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Three-electrode-discharge surge arrester will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2917566