U.S. patent number RE29,391 [Application Number 05/308,294] was granted by the patent office on 1977-09-06 for surge protector assembly.
This patent grant is currently assigned to Joslyn Mfg. and Supply Co.. Invention is credited to Chester J. Kawiecki.
United States Patent |
RE29,391 |
Kawiecki |
September 6, 1977 |
Surge protector assembly
Abstract
A surge protector assembly includes a unitary miniature surge
protector having a pair of hollow electrode members extending
within and sealed to a ceramic cylinder. The electrodes are
provided with end walls which face one another within the cylinder
to define a gap, and which are adapted to soften or melt under
continuation of a predetermined arc discharge. Cylindrical contact
members are slidably receivable within the electrodes and are
spring-biased for urging the electrode end walls toward one another
for shorting the gap, as, for example under extended breakdown
conditions. The unitary surge protector and the contact members are
received within a cylindrical holder having a spring means for
urging the contact members toward the aforementioned end walls. The
holder is threadedly received within a base member which makes
electrical connection with the surge protector.
Inventors: |
Kawiecki; Chester J. (Santa
Barbara, CA) |
Assignee: |
Joslyn Mfg. and Supply Co.
(Chicago, IL)
|
Family
ID: |
26976178 |
Appl.
No.: |
05/308,294 |
Filed: |
November 20, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
781134 |
Dec 4, 1968 |
03543207 |
Nov 24, 1970 |
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Current U.S.
Class: |
337/28; 361/120;
361/124 |
Current CPC
Class: |
H01T
1/14 (20130101); H01T 4/06 (20130101) |
Current International
Class: |
H01T
4/06 (20060101); H01T 1/14 (20060101); H01T
1/00 (20060101); H01T 4/00 (20060101); H01H
079/00 (); H02H 003/22 () |
Field of
Search: |
;337/31-33,161,166,186,239 ;317/61,62,66,61.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Broome; Harold
Attorney, Agent or Firm: Klarquist, Sparkman, Campbell,
Leigh, Hall & Whinston
Claims
I claim:
1. A surge protector assembly comprising:
a unitary surge protector including a pair of aligned conductive
electrodes each comprising a hollow cylindrical member having a
first closed end wall with the opposite end being open and flared
to provide an annular flange, and a ceramic spacer cylinder sealed
between the flanges of said electrodes for positioning said
electrode end walls in facing relation internally of said cylinder
forming an arc discharge gap therebetween, said spacer cylinder
forming an enclosure with said electrodes,
elongated contact members within each said hollow cylindrical
member and bearing on the inside of the electrode end wall in the
direction of the opposite electrode, said contact members each
extending outwardly past the electrode's annular flange,
a cylindrical holder within which said protector is received in
substantially coaxial relation with respect to said holder, said
holder being provided with a spring at one end thereof bringing
pressure against one of said contact members urging the same
against its corresponding electrode end wall,
and a base member receiving said holder, said base member being
provided with means for matingly engaging the exterior of said
holder in supporting relation, and for providing outside electrical
connection for said contact members.
2. The assembly according to claim 1 wherein each of said contact
members is substantially cylindrical and loosely slidably received
within a hollow cylindrical member for longitudinal alignment of
said contact members relative to said surge protector and said
cylindrical holder by a said hollow cylindrical member.
3. The assembly according to claim 1 wherein each of said electrode
end walls is centrally indented from said gap, with said contact
members bearing on the opposite sides of said indentations.
4. The assembly according to claim 3 wherein each of said contact
members is substantially cylindrical having a first diameter less
than the inside diameter of said hollow cylindrical members, said
contact members being loosely slidably received within said hollow
cylindrical members, and at least one contact member having a
length adjacent an end wall indentation which is of smaller
diameter being comparable to the size of said indentation, said one
contact member bearing thereagainst and forcing said end walls
together under conditions of predetermined arc discharge across
said gap.
5. The assembly according to claim 2 wherein said contact members
are each provided with enlarged heads at the point where said
contact members extend beyond said electrode flanges, the spacing
of said heads from said flanges totaling a distance greater than
the spacing of said gap.
6. The assembly according to claim 5 wherein said cylindrical
holder is formed of insulating material having a first contact at
one end for making connection with the head of one of said contact
members and having a metal cap threadedly received on the other end
wherein said cap includes a second contact biased by said spring
against the head of the remaining contact member, said means for
providing outside electrical connection including means for making
connection with said cap and with said first contact as said
cylindrical holder is threadedly received in said base member.
7. The assembly according to claim 2 further including a conductive
cage longitudinally received in said holder against the pressure of
said spring, said cage coaxially supporting a first of said contact
members and also having spring fingers grasping the outside of said
spacer cylinder received therewithin, said cylindrical holder being
metal and having external threads engageable with a said base
member.
8. The assembly according to claim 7 wherein the second of the
contact members is soldered to its corresponding electrode.
9. A surge protector assembly comprising:
a unitary surge protector including a pair of aligned conductive
electrodes each comprising a hollow cylindrical member having a
first closed end wall with the opposite end being open and flared
outwardly to provide an annular flange, and a ceramic spacer
cylinder sealed between the flanges of said electrodes for
positioning the electrode end walls in facing relation interiorly
of said cylinder forming an arc discharge gap therebetween, said
end walls being indented from said gap, wherein said spacer
cylinder forms an enclosure together with said electrodes within
which a given pressure is maintained,
elongated cylindrical contact members loosely slidably received
within said hollow cylindrical member for alignment longitudinally
of said surge protector by said hollow cylindrical members, at
least one of said contact members having a short length adjacent an
end wall indentation which is of smaller diameter being comparable
in size to the indentation for bearing thereagainst, each contact
member extending outwardly past the electrode's annular flanges,
and each contact member having an enlarged head at a distance
beyond a corresponding electrode flange wherein the combined
spacing of the heads from the flanges totals a distance greater
than the spacing of the gap between indentations,
a cylindrical holder formed of insulating material for
longitudinally receiving said surge protector and said contact
members, said cylindrical holder having a first contact at one end
for making connection with the head of one of said contact members
and having a metal cap threadedly received on the other end of the
holder wherein said cap includes a second contact spring-biased
against the head of the remaining contact member,
and a base member comprising a first plate threadedly receiving
said cap and making electrical contact therewith, said base member
further including a second plate for making electrical connection
with said first contact.
10. A surge protector assembly comprising:
a unitary surge protector including a pair of aligned conductive
electrodes each comprising a hollow cylindrical member having a
first closed end wall with the opposite end being open and flared
outwardly to provide an annular flange, and a ceramic spacer
cylinder sealed between the flanges of said electrodes for
positioning the electrode end walls in facing relation interiorly
of said cylinder forming an arc discharge gap therebetween, said
end walls being indented from said gap, wherein said spacer
cylinder forms an enclosure together with said electrodes within
which a given pressure is maintained,
first and second elongated cylindrical contact members loosely
slidably received within said hollow cylindrical members and being
aligned longitudinally of said surge protector by said hollow
cylindrical members, at least one of said contact members having a
short length adjacent an end wall indentation which is of smaller
diameter being comparable in size to the indentation and bearing
thereagainst, each contact member extending outwardly past the
electrode's annular flanges,
a cylindrical holder formed of conductive material for
longitudinally receiving said surge protector and said contact
members, a conductive cage longitudinally received in said holder,
said cage coaxially supporting a first of said contact members and
also having spring fingers grasping the outside of said spacer
cylinder received therewithin, and a spring between said cage and a
first closed end of said cylindrical holder, the second end of said
cylindrical holder being open,
and a base member threadedly receiving said holder and provided
with electrical connecting means for making contact with the
exterior of said holder, said base member also having a contact for
making connection with the second contact member when said holder
is threadedly engaged with said base.
11. A surge protector assembly comprising:
a unitary surge protector including a pair of aligned conductive
electrodes each comprising a hollow cylindrical member having a
first closed end wall with the opposite end being open and flared
to provide an annular flange, and a ceramic spacer cylinder sealed
between the flanges of said electrodes for positioning said
electrode end walls in facing relation internally of said cylinder
forming an arc discharge .Iadd. gap .Iaddend.therebetween, said
spacer cylinder forming an enclosure with said electrodes,
elongated cylindrical contact members slidably received within each
said hollow cylindrical member, and bearing on the inside of the
electrode end wall in the direction of the opposite electrode, said
contact members each extending outwardly past the electrode's
annular flange,
and a conductive cage coaxially supporting a first of said contact
members at one end of said cage and said first contact member, said
cage also having spring fingers receiving and grasping the outside
of said spacer cylinder received therewithin, said cage extending
longitudinally part way along said spacer cylinder.
12. The assembly according to claim 11 wherein the second contact
member is soldered to its corresponding electrode. .Iadd. 13. An
over voltage arrester comprising:
a tubular insulating member,
a pair of electrodes mounted in a gastight manner in said tubular
member and each having an electrode surface spaced apart from a
corresponding electrode surface of the other electrode,
said electrodes each comprising a hollow member having a closed end
wall with the opposite end being open and flared to provide a
flange sealed to one end of said tubular member,
contact blocks formed of good thermal conducting material and being
thermally coupled to respective ones of said electrodes conducting
away heat therefrom during operation of the voltage arrester,
said electrodes facing oppositely of each other, and having their
closed ends positioned inwardly from the ends of said tubular
member, and
means urging the electrodes inwardly of said tubular insulating
member..Iaddend. .Iadd. 14. An over voltage arrester in accordance
with claim 13 wherein at least one of said contact blocks is firmly
secured to a said electrode..Iaddend. .Iadd. 15. A surge protector
assembly comprising:
a unitary surge protector including a pair of aligned conductive
electrodes each comprising a hollow member having a first closed
end wall with the opposite end being open and flared to provide a
flange, and a ceramic spacer cylinder sealed between the flanges of
said electrodes for positioning said electrode end walls in facing
relation internally of said cylinder forming an arc discharge gap
therebetween, said spacer cylinder forming an enclosure with said
electrodes,
contact means for each said hollow member and bearing thereon in
the direction of the opposite electrode, said contact means each
extending outwardly past the electrode's annular flange, and at
least one of said contact means extending inside the electrode,
a holder within which said protector is received in substantially
coaxial relation with respect to said holder, said holder being
provided with a spring at one end thereof bringing pressure against
one of said contact means urging the same toward the other, and
means for engaging the other of said contact means and providing
for outside electrical connection for said contact means..Iaddend.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to my copending application Ser. No.
684,706, filed Nov. 21, 1967, and entitled, "Surge Protector."
BACKGROUND OF THE INVENTION
Surge protector assemblies are usually fairly complex in
construction involving a plurality of parts which must be assembled
in the right order each time the surge protector device is
replaced. These parts include spark-gap elements, holders, solder
pellets, and the like and may provide fusing or fail-safe features.
Frequently these devices as assembled do not have uniform operating
characteristics, and moreover are apt to short out or fail under
heavy current conditions before such action is desired. At the same
time, operating characteristics are sometimes unpredictable, and
the device may not fail safe or short out before the connecting
conductors fail or vaporize.
SUMMARY OF THE INVENTION
According to the present invention, a unitary surge protector
comprises hollow cylindrical members having closed end walls spaced
from one another within a ceramic cylinder to form a gap.
Cylindrical contact members are slidable within the outside ends of
the electrode cylindrical members, whereby the electrode
cylindrical members substantially longitudinally align the contact
members. The surge protector with contact members is received
within a cylindrical holder having a spring means for urging the
contact members against respective electrode end walls, so that
under predetermined arcing conditions, the contact members will
force the electrode end walls together to provide a fail-safe
feature. A base member threadedly receives and provides electrical
connections for the device.
It is accordingly an object of the present invention to provide an
improved surge protector assembly which is easy to assemble and
replace after failure of a previous unit.
It is a further object of the present invention to provide an
improved surge protector assembly having uniform and improved
operating characteristics.
The subject matter which I regard as my invention is particularly
pointed out and distinctly claimed in the concluding portion of
this specification. The invention, however, both as to organization
and method of operation, together with further advantages and
objects thereof, may best be understood by reference to the
following description taken in connection with the accompanying
drawings wherein like reference characters refer to like
elements.
DRAWINGS
FIG. 1 is an end view, partially broken away in cross section of a
surge protector assembly according to the present invention;
FIG. 2 is a transverse cross section taken at 2--2 in FIG. 1;
FIG. 3 is a longitudinal cross section taken at 3--3 in FIG. 1;
and
FIG. 4 is a cross section of an alternative embodiment of the
present invention.
DETAILED DESCRIPTION
The assembly according to the present invention includes a surge
protector of the type set forth in my aforementioned application
Ser. No. 684,706, filed Nov. 21, 1967, entitled, "Surge Protector,"
and assigned to the assignee of the present invention.
Referring to the drawings, this surge protector 10 is suitably
quite small, including cylindrical spacer tube 12, preferably
taking the form of a ceramic tube approximately five-sixteenths
inch in diameter and approximately five-sixteenths inch in length.
In assembling the surge protector according to the present
invention, the ends of the ceramic spacer cylinder 12 are suitably
metalized, and brazing washers 14 and 16 which may be formed of
copper or an alloy of copper and silver are located on the
metalized ends. Then, thin walled, hollow, cylindrical electrodes
20 and 22, preferably formed of a nickel, iron, cobalt alloy having
a coefficient of expansion compatible to that of alumina, are
inserted into either end of the ceramic tube 12, each of these
electrodes having an annular lateral flange 24 for making contact
with brazing washers 14 and 16. The electrodes 20 and 22, which are
substantially cylindrical, are flared outwardly at their rearward
ends at the aforementioned flanges 24.
To secure electrodes 20 and 22 within spacer tube 12, the assembly
of these components with brazing washers 14 and 16 in place is
suitably raised in temperature to braze the assembly, with the
interior of the envelope suitably being at least partially
evacuated. The envelope may be provided with a gaseous environment
at a given pressure. A unitary sealed surge protector is thereby
formed, having desirable characteristics as described in my above
referenced patent application. Electrodes 20 and 22 include end
portions having respective end walls 34 and 36 which face one
another and which define a gap 38 therebetween. The electrode end
walls are slightly cup-shaped or indented where they face one
another as indicated at 40.
The surge protector is provided with a pair of cylindrical contact
members 42 or 44 (or 44') which are loosely slidably received
within the hollow cylindrical electrodes 20 and 22. Thus, the
contact members are not tightly received within the cylindrical
electrodes, but are received closely enough whereby the cylindrical
electrodes align the contact members in a direction substantially
longitudinally or axially of the surge protector. Each contact
member extends outwardly past flange 24. At least one of the
contact members (and suitably both) is provided with smaller
diameter end portion 46, or 48, for abutting electrode end walls 34
and 36, respectively. Specifically, the smaller diameter portions
are adjacent indentations 40, on the convex side of the
indentations. The diameter of portions 46 and 48 is similar in size
to that of the aforementioned indentations, i.e. both desirably
have substantially the same diameter. In the embodiment of FIG. 3
only one of the contact members, i.e. contact member 42, is
provided with a reduced diameter portion 48, while contact member
44' directly engages the central indentation of end wall 36. The
contact members are spring biased toward one another, as will
hereinafter more fully appear, for causing electrode end walls to
make contact under predetermined arcing conditions.
In the embodiment of FIGS. 1, 2, and 3, contact member 42 is
provided at its upper end with an extension 50 for securing the
contact member coaxially within an aperture in the end wall of a
metal cage 52. Cage 52 is provided with fingers 54 which extend
along and grip the sides of cylindrical tube 12. The cage 52 is
also closely received within cylindrical metal holder 56, and a
spring 58 is positioned inside holder 56 between the top thereof
and the top of cage 52. Thus, spring 58, in compression, tends to
urge cage 52 and contact member 42 against end wall 34 of electrode
20, with the surge protector 10 received in cage 52. The same
spring pressure urges contact member 44' against end wall 36.
Contact member 44' is desirably soldered to end wall 40 of
electrode 22 as indicated at 88 in FIG. 3 to prevent loss of the
contact member during assembly, it being understood that such
solder melts under extended breakdown conditions freeing the
contact member for longitudinal movement.
Holder 56 is externally threaded at 60 for engaging internal thread
62 in base member 64. Also, the holder 56 is provided with shoulder
66 just above threaded portion 60 whereby the holder may threadedly
engage insulating base 64 and be drawn up with shoulder 66 bearing
upon conducting collar 68 for providing an external electrical
connection to contact member 42. The base also includes a lower
contact 70 for centrally engaging and making connection with
contact member 44'. Contact 70 is spaced at a distance below the
top surface of base member 64 so that when cylindrical holder 56 is
drawn up tight, spring 58 is compressed, causing both contact
members 42 and 44' thus to bear against respective end walls of the
electrodes. For convenience in threadedly engaging holder 56 into
base member 64, the top or head of cylindrical holder 56 is
provided with a slot 72.
A conducting plate or bus 74 extends along the top surface of base
member 64 and terminates in a stud connection and nut 76 which
secures a lug 78 to the base member. A wire 80, which may comprise
the protected line, is clamped to lug 78. Similarly, a stud and nut
connection 82 secures lug 84 to the base member, this stud making
connection with contact 70, internally of base 64. A wire 86,
joined to lug 84, is suitably connected to ground.
When a predetermined voltage level is reached across the surge
protector, e.g. as a result of a high voltage transient on the line
to be protected, the gap 38 breaks down into an arc discharge,
thereby shorting out the high voltage transient, and protecting the
equipment on the line. The occurrence of a short period discharge
will not alter the operating characteristics of the surge protector
and it will remain operative. However, an arc discharge for an
extended period of time, for example carrying long duration
currents, may melt the electrode end walls so that they fuse and
short out the device, or may soften end walls 34 and 36. The
pressure of spring 58 in the latter case will force contact members
42 and 44' towards one another. The reduced diameter portion 48,
bearing against the top indented end wall, will force such indented
end wall toward the opposite indented end wall, as contact member
44' forces the latter upwardly. Thus, each end wall by virtue of
being indented has an area adjacent the opposite electrode
permitting central distortion of the walls toward each other. The
force of spring 58 will cause the electrode end walls to make
substantially permanent contact after an extended or predetermined
arc discharge, thereby providing a desired fail-safe feature. Thus,
for an extended discharge which would tend to alter the
characteristics of the device, the device will be permanently
short-circuited, and therefore easily located and replaced. The gap
will fail-safe in this manner within a predetermined time, but will
not short out for every momentary discharge. The characteristics
may be accurately predetermined. It is also observed that
replacement of the shorted unit is accomplished by slidably
withdrawing cage 52 carrying surge protector 10 and contact members
42 and 44' from holder 56, after holder 56 is unscrewed from base
member 64. A replacement unit is easily inserted, and such
replacement does not involve special skill on the part of
maintenance personnel replacing the device.
FIG. 4 illustrates, partially broken away in cross section, an
alternative embodiment of a surge protector assembly according to
the present invention. In this embodiment, contact members 42 and
44 are provided with enlarged heads 90 and 92, respectively. The
combination of the surge protector 10 and the contact members 42
and 44 is received within a cylindrical holder 94, formed of
insulating material, this cylindrical holder having a first metal
contact surface 96 at the lower end thereof communicating with a
lower external spring contact 98. Cylindrical holder 94 is also
provided with a metal cap 100 threadedly secured to cylindrical
holder 94 and including a hollow hex-head portion 102. Hollow head
portion 102 receives a spring retainer contact 104 within which is
located a spring 106 which may be compressed between contact 104
and the top of head portion 102. When cap 100 is fully engaged upon
cylindrical holder 94, spring 106 urges contact 104 downwardly
against enlarged head 90 of contact member 42. Thus, smaller
diameter portions 46 and 48 of contact members 42 and 44
respectively face the end walls of the surge protector providing
pressure therebetween. Under predetermined conditions of prolonged
arc breakdown, the surge protector operates in the same manner as
hereinbefore described in connection with the first embodiment of
the present invention to cause end walls 34 and 36 to make a
permanent fail-safe contact. The spacing of heads 90 and 92 from
flanges 24 must total a distance greater than the spacing of gap 38
(between electrode indentations) so that the electrodes may make
contact.
The cap 100 is also threaded on its exterior periphery and is
threadedly engaged into an aperture in connector ring 108 extending
from a connector plate 110. Connector plate 110 supports a stud and
nut combination 112 which may be connected to a line being
protected. With cap 100 threadedly engaging ring 108, spring
contact 98 is compressed against metal plate 114 to which stud and
nut arrangement 116 are secured. The latter combination is suitably
connected to ground by means not shown. Both the plate 110 and the
plate 114 form part of a common base member 118.
In the embodiment of FIG. 4, as in the previous embodiment,
replacement of the surge protector involves removal of the
cylindrical holder 94 and cap 100 from ring 108, by unscrewing the
cap and holder from ring 108, followed by removal of cap 100 from
holder 94 by unscrewing the two. The surge protector 10 together
with contact members 42 and 44 is then easily replaced without
requiring special skill or reassembly of a gap device by
maintenance personnel.
* * * * *