Note: Descriptions are shown in the official language in which they were submitted.
__ ~ 21gl4~9
[67190/954192]
GAS-FILLED SURGE VOLTAGE PROTECTOR
Field Of The Invention
The present invention relates to the f ield of surge
voltage protectors for communications networks, and more
specifically to the current-carrying elements of the electrodes
of a gas-filled surge voltage protector.
Backqround Information
Gas-filled surge protectors having one, two or three
discharge paths are used in communications networks and in
related equipment to protect against voltage surges that can
occur, for example, as a result of a lightning strike. Such
surge protectors consist of two end electrodes and an optional
third electrode in the form of a center electrode and one or
two cylindrical hollow ceramic insulators. The ceramic
insulator in a two-elestrode surge protector is usually
soldered to the end electrodes at the end (seer e.g., U.S.
Patent 4,266,260) . In three-electrode s~urge protectors, the
ceramic insulators are soldered to both the center electrode
and one of the end electrodes either on the cirsumference or at
the end (see U S. Patent 3,885,203 or U.S. Patent 4,212,047).
The electrodes are contacted on their outer circumference
either inside a casing with the help of spring - loaded
insulation-piercing connecting devices or with electrode
terminals soldered or welded at one end tangentially or
radially to one electrode and provided with a pluggable contact
element or designed for soldering at the other end (see U.S.
Patent 4,212,04~ or U.S. Patent 4,984,125).
In known three-electrode surge protectors whose
electrodes are made of copper, a contact ring is soldered or
welded, etc. to the flanged base part of each end electrode.
Express Mail No. EM 271945401 IJS
~ 4~9
Either the contact ring i8 already part of the electrode
terminal (as described in U.S Patent 5, 388, 023) or an
electrode terminal can then be welded to its outer
circumference (as described in German pl~hl; ':h~l Patent
Application No. 43 30 178, which corresponds to U.S. Patent
Application Serial No. 290,274, filed on August 15, 1994).
This contact ring may have a cylindrical lateral surface
Instead of a contact ring, a contact disk may also be used
Fur~hf~ , if the electrode is made of a material
other than copper, such as Vacon, an iron-nickel alloy, the
flanged base part of the electrode may itself have a
cylindrical contact surface, preferably with a width of at
least approximately 1 mm.
~llmmary Of The Tnvention
The present invention provides a gas - f illed surge
protector having two cup- shaped electrodes whose edges are each
soldered to an end of a cylindrical hollow ceramic insulator,
where the edge of each electrode is designed as a cylindrical
contact surface to which an electrode t,-rm;n~l is attached
The gas - f illed ~surge protector of the present invention has
current- carrying elements which allow it to safely and
repeatedly withstand even extrene loads, such as those that may
occur due to lightning with a current surge of approximately 20
kA.
Such an obj ect is achieved in accordance with the
present invention by f orming the end of the electrode terminal
contacting the cylindrical contact surface as an open ring that
surrounds the cylindrical contact surface in a form-fitting
3 0 manner and which has an inside diameter that matches the
diameter of the cylindrical contact surface. The electrode
terminal is made of a cold-hammered material such as steel, an
iron alloy, bronze or brass The open ring of the electrode
terminal surrounds the cylindrical contact surface for an angle
of at least 270O at the circumference= and has a rectangular
cross section whose width is equal to or approximately equal to
the width of the cylindrical contact surface and whose height
~ 91~09
is at least equal to its width.
Such a design o~ the electrode ~rmi n~ assures a
large-area currellt transfer from the electrode t~rm;n~l to the
respective electrode of the surge protector. To compensate for
irregularities i~ the area of the contact surfaces, it is
advisable to electroplate the cylindrical contact surfaces of
the electrodes and/or the inside lateral surface of the open
ring of the respective electrode terminal with a layer of tin
approximately 5 to 15 ,um thick. A tin-lead alloy is suitable
for this purpose.
The end of the electrode termir~al which is designed
as an open ring according to the present invention cannot be
placed radially on the electrode because of the large angle of
more than 270~ at the circumference, because of the cross-
sectional shape of the ring and because it is made of a cold-
hammered material. Instead, the open ring must be forced
axially onto the electrode with a slight widening effect. This
axial push-mounting can be facilitated by providing a bevel on
the inside peripheral edges of the open ring.
In three-electrode surge protectors with two ceramic
insulators and a ring- shaped center electrode, the center
electrode can be contacted in the same way as the contact rings
of the two end electrodes. Thus, the open ring of the
electrode ~Prm;n~l is pushed directly onto the center electrode
which is designed with a contactable outside surface.
If necessary, the form- fitting connection between the
electrode t,-rm; n; 1 q and the electrodes can 'oe staoilized
mechanically by applying a spot of soft solder to the edge of
the contact surf aces .
Brief Descriotion Of The Drawinqs
Figure 1 shows a view of an exemplary embodiment of a
three- electrode surge protector with electrode terminals in
accordance with the present invention.
Figures 2 and 3 show an electrode terminal of the
surge protector of Fig. 1.
Figure 4 shows a cross section of an electrode
_ ~ 2191~9
terminal arranged on a contact ring of an end e~ ectrode made of
copper .
Figure 5 shows a cross section of an electrode
term' nal arranged on the contact disk of an end electrode made
of copper.
Figure 6 shows a cross section of the arrangement of
an electrode terminal on the contact surface of an end
electrode made of an iron-nickel alloy.
Det~;led~esrr~tion ~ ,
Figure 1 shows - a three- elec~=rode surge protector with
additional fail - saf e and vent - saf e dev-~ces . Two ceramic
insulators 4 and 5 are each connected to a center electrode and
e~uipped with end electrodes 2 and 3 at their respective outer
ends. According to Figure 4, a contact ring 6 or 7 is soldered
onto the end of each end electrode made o~ copper. Each
contact ring 6 and 7 has an approximately rectangular cross
section and an outer lateral surface which forms a cylindrical
contact surface. An example o~ such a contact ring is shown in
German Published Patent Application ~o. 43 30 178. An
electrode tPr~n;n~l 61 or 71 is applied to the contact surface
(not shown in Figure 1) of each of the contact rings 6 or 7,
respectively. The center electrode is provided with an
electrode terminal 81 A spring clip 11 is attached to the
center elec~rode and includes arms 12 and 13 which support
short-circuit caps 14 and 15, respectively, arra~ged axially
with end elPctrodes 2 and 3. The caps 14 and 15 press
auxiliary surge protectors 17 and 18 and a fusible pellet
against the two end electrodes 2 and 3. The ~ ry surge
protectors 17 and 18 may be spark gaps in air or Yaristors.
According to Figures 2 and 3, electrode terminals 61,
71 and 81 are each designed as an ope-n ring ~ at the ends
contacting the electrodes, so they clamp around the cylindrical
contact surface. To assure a sufficient contact force, the
inside diameter of open ring 9 and the outside diameter of the
cylindrical contact surfaces are designed for a tight fit. To
improve contact, a layer of tin 10 approximately 5 to 15 ~m
sl4ns
thick is applied to the cylindrical contact sur~aces of contact
rings 6 and 7. In addition, the inside peripheral edges of the
open ring are provided with a chamfer 19.
The cross section of open ring 9 is subst~nti~l ly
rectangular, where the width b is equal to the width of contact
ring 6, 7 and the height h is slightly greater than the width
b. For example, the height h may be 1.5 mm.
The open ring 9 is made of brass, i . e ., a copper- ~inc
alloy. Open ring 9 surrounds the contact ring or the center
electrode over an angle a of at least 270~ at the
circumference, preferably 30~) to 330~. Open ring 9 also has a
transition to a connecting piece 63, 73 or 83 that is provided
with a convf~nt;nn~l contact terminal at its other end (not
shown). It is ad~isable to design open ring 9 and the
connecting piece as punched parts
In another embodiment, shown in Figure 5, open ring 9
of the electrode tF~ n~ iS placed on the cylindrical contact
surface of a contact disk 62, which replaces contact ring 6 of
Figure 4. : ~
2 o In yet another embodiment, as shown in Figure 6, open
ring 9 of the electrode terminal i9 placed on a cylindrical
contact sur~ace formed directly by flanged base part 22 of an
electrode 21 made o~ an iron-nickel alloy.
