U.S. patent number 3,827,010 [Application Number 05/232,129] was granted by the patent office on 1974-07-30 for composite sectionalized open-type drop-out-type fusible output with series enclosed current limiting fuse.
This patent grant is currently assigned to Westinghouse Electric Corporation. Invention is credited to Frank L. Cameron, John W. Carothers, Woodrow G. Shaw.
United States Patent |
3,827,010 |
Cameron , et al. |
July 30, 1974 |
COMPOSITE SECTIONALIZED OPEN-TYPE DROP-OUT-TYPE FUSIBLE OUTPUT WITH
SERIES ENCLOSED CURRENT LIMITING FUSE
Abstract
A sectionalized open-type drop-out fusible cutout is provided
having a high-current interrupting section, a
mechanically-connected low-current interrupting section in
electrical series therewith, the low-current section including a
tensioned fuse and attached fuse-link cable, which, when fused,
releasing the cable, effecting the breaking of the associated
toggle linkage, and drop-out indicating action of the open-type
fusible device. A high-current section includes a current-limiting
fuse section, which is operative only during the interruption of
heavy fault currents, and not operable during the interruption of
relatively low overload currents, which overload currents are
interrupted solely by the low-current section. The low-current
section is of the expulsion type, having a fuse-link cable
extending out through the lower open end of the fuse tube thereof,
and maintaining the toggle linkage in its underset condition. The
fusing of the low-current interrupting section, effects fusing of
the fuse link and releases the fuse-link cable, and consequent
breaking of the toggle linkage to permit consequent drop-out action
of the open-type fusible cutout device. The aforesaid composite
sectionalized open-type fusible device may be associated, with a
load-break extension device, which will permit manual load breaking
of load currents without either of the series fuse sections
operating. Preferably, associated with the load-break device is an
auxiliary arc-chute structure, serving to interrupt the load
current within the arc-chute structure upon manual operation of the
cutout device.
Inventors: |
Cameron; Frank L. (Irwin,
PA), Carothers; John W. (Irwin, PA), Shaw; Woodrow G.
(Export, PA) |
Assignee: |
Westinghouse Electric
Corporation (Pittsburgh, PA)
|
Family
ID: |
22871980 |
Appl.
No.: |
05/232,129 |
Filed: |
March 6, 1972 |
Current U.S.
Class: |
337/168; 337/171;
337/175; 337/169 |
Current CPC
Class: |
H01H
31/127 (20130101) |
Current International
Class: |
H01H
31/00 (20060101); H01H 31/12 (20060101); H01h
071/20 () |
Field of
Search: |
;337/168-179 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Miller; J. D.
Assistant Examiner: Bell; Fred E.
Attorney, Agent or Firm: Crout; W. R.
Claims
What is claimed is:
1. A composite open-type drop-out fuse cutout comprising, in
combination, means defining a pair of spaced line-contact
assemblies, a pivotally-mounted composite fuse-holder assembly
including a toggle linkage and a fuse-tube assembly pivotally
supported adjacent one end thereof to one of said line-contact
assemblies, said composite fuse-holder assembly carrying a main
movable contact adjacent the other end thereof to make main
contacting engagement with the other line-contact assembly, means
including a fuse-link extending through said fuse-tube assembly for
maintaining said toggle linkage in an underset condition, means
biasing said toggle linkage to a collapsed condition, said
fuse-tube assembly including an enclosed current-limiting
fuse-section disposed adjacent said other end of the composite
fuse-holder assembly, said low-current interrupting section
accommodating said fuse-link, whereby on low-current interruption
the low-current section only need be replaced in a re-fusing
operation, and during heavy fault-current interruption both the
low-current section and the enclosed current-limiting fuse-section
fusing, and the enclosure of the current-limiting fuse-section
preventing external emission of arc products.
2. The combination according to claim 1, wherein said composite
open-type drop-out fuse cutout is adaptable for load-break
operation, and delayed-acting load-break means having separable
contacts and including a latching device is situated adjacent the
free end of the rotatable fuse-holder assembly, the separable
contacts of said load-break means being electrically in parallel
with the circuit including said movable main contact and said one
line-contact assembly.
3. The combination according to claim 2, wherein said load-break
means includes a latching device, whereupon manual separation of
said main movable contact from said other line-contact assembly
will nevertheless cause continued latched contacting engagement of
said delayed-acting load-break means for a predetermined time.
4. The combination according to claim 2, wherein said load-break
means is responsive to the collapse of said toggle linkage during
fault-current interruption to effect release of said latching
device, whereby during fault-current interruption the fuse-holder
assembly may freely rotate about said one line-contact assembly to
an open indicating observable position.
5. The combination according to claim 1, wherein the low-current
interrupting section is an expulsion-type interrupting section and
includes a standard-type fuse-link.
6. The combination according to claim 1, wherein a readily
detachable means interconnects mechanically the enclosed
current-limiting fuse section and the low-current interrupting
section.
7. The combination according to claim 1, wherein a flipper exerts
tension force upon the fuse-link cable, and biasing means is
associated with said flipper to create said force tension.
8. The combination according to claim 2, wherein the load-break
means includes an arc-chute structure including a pair of
closely-spaced insulating plates.
9. The combination according to claim 8, wherein said
closely-spaced insulating plates evolve an arc-extinguishing
gas.
10. The combination according to claim 1, wherein the free end of
the fuse-holder assembly is capable of readily adapting attaching
parts to adapt it to a load-break device.
11. The combination according to claim 1, wherein the low-current
section includes an expulsion-type fuse tube having a plurality of
apertured gas-evolving blocks stacked therein.
12. The combination according to claim 11, wherein said apertured
blocks are of boric acid.
13. The combination according to claim 1, wherein only a single
fuse element is employed in the enclosed current-limiting fuse
section.
14. A composite fuse-holder assembly including an enclosed
current-limiting section and a serially-related low-current
interrupting section, toggle means clamped to one end of said
composite fuse-holder assembly, said toggle-means comprising a
toggle-leg member fixedly clamped to one end of the fuse-holder
assembly, a toggle-link hinge-member pivotally connected to said
toggle-link member so as to form a toggle-linkage therewith, a
fuse-link having a fuse-link cable disposed interiorly of said
fuse-holder assembly and having one end of the fuse-link cable
extending out of one end of the composite fuse-holder assembly and
removably attached to said toggle-link hinge-member, whereby said
toggle-means is maintained in an underset condition, said
toggle-link hinge-member having a pair of laterally-extending
trunnion-bearings so as to make said composite fuse-holder assembly
adaptable for insertion into a conventional-type open-style fuse
mounting, said fuse-holder assembly including an enclosed
current-limiting fuse-section disposed adjacent the other end of
said composite fuse-holder assembly, the device functioning during
low-current interruption to cause only fusing of the low-current
section and no fusing of the current-limiting fuse-section, and
said device further functioning on heavy fault-current interruption
for both fuse sections to fuse with the enclosed housing of the
current-limiting fuse section preventing the emission of hot arc
gas products externally of the device.
15. The combination of claim 14, wherein the low-current
interrupting section is an expulsion-type fuse device having the
upper end closed and causing the ejection of fuse products out of
the lower open end of the expulsion-type fuse.
16. The combination according to claim 14, wherein the enclosed
current-limiting section and the low-current interrupting section
are mechanically separable.
17. The combination of claim 14, wherein the low-current
interrupting section accommodates a standard-type fuse-link
available in variant ratings and interchangeable within the
low-current interrupting section.
18. The combination according to claim 14, wherein the fuse-holder
assembly has an auxiliary contact-blade rotatably mounted adjacent
the upper free end of the fuse-holder assembly.
19. The combination according to claim 18, wherein the auxiliary
contact-blade is biased in the direction of opening drop-out motion
of the composite-type fuse-holder assembly.
20. The combination according to claim 14, wherein an optional
load-break device including a rotatable auxiliary contact-blade may
be attached adjacent the free end of the composite-type fuse-holder
assembly at the option of the user.
21. The combination according to claim 16, wherein the detachable
connection includes a rotatable sleeve having a threaded connection
to one of the fuse sections.
22. The combination according to claim 14, wherein a spring-biased
fuse-link flipper maintains tension upon the fuse-link cable.
23. The combination according to claim 22, wherein the toggle link
member has a shoulder portion and the fuse-link flipper latches
under said shoulder to somewhat relieve the tension-pressure upon
said fuse-link cable.
24. The combination according to claim 14, wherein the low-current
section includes a plurality of apertured gas-evolving blocks.
25. The combination according to claim 24, wherein said blocks are
of boric acid.
26. An open-type drop-out type fusible cutout including means
insulatingly supporting in spaced relation a pair of main-line
contacts, a hinge-support associated with one of said main-line
contacts, a rotatable fuse-holder assembly adapted for pivotable
mounting about said one hinge-support and including in series
relationship an enclosed current-limiting fuse-section and a
serially-related low-current interrupting section of the
expulsion-fuse type, said rotatable fuse-holder assembly having a
movable main contact adjacent its outer free end, and load-break
means carried partially by the outer free end of the rotatable
fuse-holder assembly and also by said other line-terminal assembly,
said load-break means including a quick-break auxiliary
contact-blade, and an arc-chute with the arc-chute enclosing a
cooperable auxiliary contact.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
United States patent application, filed Aug. 26, 1970, Ser. No.
67,175, by Frank L. Cameron, and assigned to the assignee of the
instant application, teaches the use of a composite sectionalized
protective indicating-type fuse structure having a high-current
interrupting section and a mechanically-connected low-current
interrupting section in electrical series therewith. The
low-current interrupting section is replaceable, following a
low-current interruption, which has no effect upon the high-current
interrupting section, the latter remaining intact, and may be
further used. During high-current interruption, both sections are
simultaneously fused, and collectively contribute together to a
quick interruption of the connected electrical circuit, again there
being an external indicated condition of the blown condition of the
fuse by an ejection of the fuse-link cable.
Also, United States patent application, filed Aug. 26, 1970, Ser.
No. 67,183, by James N. Santilli, and likewise assigned to the
assignee of the instant invention, shows a similar composite-type
fuse structure, in which a high-current interrupting section and a
low-current interrupting section are utilized in series, the
low-current interrupting section being capable of being utilized
with a standard-type fuse-link.
BACKGROUND OF THE INVENTION
Today's distribution systems are changing in numerous ways. There
are to be found higher-density load areas, with attendant
higher-fault-current short-current capacities than existed in the
past. This is coupled with an increasing accent on safety, noise
reduction, and convenience. In view of these new requirements, some
formerly widely-used interrupting devices and circuit-protective
devices are no longer fully suitable by today's standards. A case
in point is the distribution fuse cutout. These devices, while
adequate for relatively rural areas, have beeen, and are used in
large quantities to protect distribution transformer circuits. The
advantages of this type of device are its low cost, relative ease
of refusing, and the wide standardization of fuse characteristics,
which prevail. The device is less than desirable from the
standpoint of limited interrupting rating a performance that is
characterized by loud noise, and the expulsion of considerable arc
products, and its relatively unsafe performance in view of the
materials expelled. Maintenance men are subjected to this
hazard.
SUMMARY OF THE INVENTION
In accordance with a preferred embodiment of the present invention,
there is provided a dual composite sectionalized open-type
drop-out-type fusible cutout device, comprising a high-current
section mechanically connected and in electrical series with a
separable low-current section. The high-current section is capable
of interrupting relatively high fault currents, and, for certain
applications, may preferably be of the current-limiting type. The
low-current interrupting section, on the other hand, is peculiarly
adapted for the interruption of relatively low currents (which have
no effect upon the high-current unit), and results in a drop-out
indicative action of the associated toggle-linkage device, which
thereby gives an indicating readily discernible visible view of the
operated and blown condition of the device by the dropout
action.
The low-current interrupting section preferably includes an
expulsion-type of fuse tube, which ejects the fuse link terminal
and the associated attached fuse link cable, releasing the toggle
linkage during fuse operation and thereby permits the assembly to
drop to an external observable indicating position, and moreover
permits ready drop-out action of the fusible device.
The improved composite open-type sectionalized fusible device of
the present invention may be utilized either with, or, optionally,
without an auxiliary load-break extension device, as illustrated,
and described, in part, in U.S. Pat. No. 3,235,688, issued Feb. 15,
1966, to Austin J. Fink, Robert J. Lawrence, and Gene L. Miller,
and assigned to the assignee of the instant application.
However, the improved composite open-type sectionalized fusible
cutout device of the present invention may be utilized, to
advantage, even in the absence of such a load-break extension
device, and, in such an eventuality, utilized merely as a fusible
protective device having the two series-related interrupting
sections and having no manual load-break characteristics.
It is, accordingly, a general object of the present invention to
provide an improved composite open-type sectionalized fusible
cutout device having indicative drop-out characteristics.
Another object of the present invention is to provide an improved
protective open-type fusible device having high and low-current
interrupting sections separably and detachably mechanically and
electrically connected together, so that replacement of the
low-current section may easily take place without affecting the
continued further use of the high-current interrupting section.
Another object of the present invention is the provision of an
improved drop-out type fusible cutout device having interrupting
capabilities far in excess of those attained heretofore.
Another object of the present invention is the provision of an
improved open-type composite sectionalized fusible cutout device of
the drop-out type, which may be adapted both with, and without, an
auxiliary load-break extension device.
Still a further object of the present invention is the provision of
an improved composite sectionalized drop-out fusible cutout device
having a current-limiting fusible section associated therewith.
Another object of the present invention is the provision of an
improved drop-out type fusible cutout device having a high-current
current-limiting section, and a serially-related low-current
expulsion-type fuse-tube section having a fuse-link therein,
capable, when fused, of actuating an associated toggle-linkage
device to permit thereby quick drop-out action to an observable
indicating position.
Still a further object of the present invention is the provision of
an improved fusible device of the type set forth in the
immediately-preceding paragraph capable of being used with a
standard-type fuse-link, such as "k" or "T" links, for example,
inserted into the low-current section, with the advantage of ready
replacement and known electrical characteristics.
Further objects and advantages will readily become apparent upon
reading the following specification, taken in conjunction with the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of a composite open-type
sectionalized fusible cutout device embodying the principles of the
present invention, and incorporating, as an optional addition, a
manually-operable load-break extension device, the cutout device
being shown in the closed-circuit position;
FIG. 2 is a side elevational view of the composite fuse-holder
assembly, only, with the auxiliary blade assembly, which is
utilized in conjunction with the fusible device of FIG. 1, the
fusible cutout device being illustrated in its unfused intact
condition;
FIG. 3 is a sectional view taken substantially along the line
III--III of FIG. 2;
FIG. 4 is a fragmentary vertical side elevational view taken
substantially along the line IV--IV of FIG. 2;
FIG. 5 is a top plan view of the composite fuse-holder assembly of
FIG. 2;
FIG. 6 is an enlarged side-elevational view, partially in section,
of the high-current interrupting section, in this instance being of
the current-limiting type, the high-current section being
illustrated in its unfused intact condition;
FIG. 6A is an end view of the current-limiting fuse of FIG. 6;
FIG. 7 is a vertical sectional view taken through the low-current
interrupting section, illustrated in this particular instance as of
the expulsion-fuse type.
FIG. 8 is a top plan view of the auxiliary interrupter with a
portion being sectionalized to show the auxiliary contents;
FIG. 9 is a top plan view of the stationary latch for the main
contact;
FIG. 10 is a front elevational view of the top casting;
FIG. 11 is a diagrammatic view illustrating the component parts of
the cutout device, including the load-break attachment, the device
being indicated in the closed-circuit position;
FIG. 12 is a diagrammatic view, similar to that of FIG. 11, but
illustrating the position of the parts during the initial portion
of the opening operation, while the main contacts are open, and the
auxiliary contacts are still latched closed;
FIG. 13 is a diagrammatic view illustrating the fusible cutout
device without the optional load-break attachment, the device being
illustrated in the closed circuit position;
FIGS. 14-18 are various views of the load-break mounting
bracket;
FIGS. 19 and 20 are front and side elevational views of the spacer
washer used in the absence of the load-break mounting bracket of
FIGS. 14-18, when the load-break attachment is not desired;
FIG. 21 is an enlarged side elevational view of a standard-type
fuse-link, with a portion of the fuse-tube casing broken away to
illustrate the interiorly-disposed fusible link;
FIG. 22 illustrates the cutout device of FIG. 1 closed, with the
load current being carried by the main contacts;
FIG. 23 illustrates the cutout device half open, with the
quick-break blade and arc-chute contact now carrying the load
current;
FIG. 24 illustrates a further step in the opening operation, when
the quick-break blade is beginning to be released, showing the main
contacts of the cutout having been open sufficiently to prevent the
arc from restriking between the opened main contacts;
FIG. 25 illustrates the quick-break blade having been released upon
further opening movement of the cutout device, and illustrating how
the blade snaps the full length of the arc-chute elongating and
de-ionizing the arc, with the coil spring at the bottom of the
blade providing the opening energy thereof;
FIG. 26 illustrates the disposition of the load-break device during
a closing operation, when the blade is half closed with the main
cutout contacts still disengaged, showing that the circuit is
closed upon the load-break contacts, and not at the main
contacts;
FIG. 27 is a side elevational view of the composite sectionalized
fuse-holder assembly, without the load-break attachment feature,
the device being fragmentarily illustrated as in contact with the
associated stationary maincontact assembly supported by the upper
end of the porcelain insulating support;
FIG. 28 is a fragmentary side-elevational view taken along the line
XXVIII--XXVIII of FIG. 27, illustrating the upper portion of the
composite sectionalized fuse-holder assembly of FIG. 8;
FIG. 29 is a top plan view of the upper end of the sectionalized
composite fuse-holder assembly of FIG. 27, taken substantially
along the line XXIX--XXIX of FIG. 27;
FIG. 30 is an elevational view of the fuse-link flipper, and
diagrammatically indicating the rotatable pivot therefor;
FIGS. 31-32 are detail views of the top contact bracket for the
fuse-holder assembly,
FIGS. 33 and 34 are detail views of the auxiliary-contact biasing
spring; and,
FIGS. 35-37 are various views of the toggle-link hinge member, with
FIG. 37 being a partial sectional view taken along the line
XXXVII--XXXVII of FIG. 36.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Today's distribution systems are changing in numerous ways. There
are to be found higher density load areas, with attendant higher
fault current short-circuit capacities than existed in the past.
This is coupled with an increasing accent on safety, noise
reduction and convenience. In view of these new requirements, some
formerly widely-used interrupting devices and circuit-protective
devices are no longer fully suitable by today's standards. A case
in point is the distribution fuse cutout. These devices, while
adequate for relatively rural areas, have been and are used in
large quantity to protect distribution transformer circuits. The
advantage of this type of device is its low cost, relative ease of
refusing, and the wide standardization of fuse characteristics
which prevail. The device is less than desirable from the
standpoint of limited interrupting rating, a performance that is
characterized by loud noise and the expulsion of considerable arc
products, and its relatively unsafe performance in view of the
materials expelled.
The present invention is particularly concerned with a new type of
device, which, in many instances, wil supplant the fuse cutouts and
answer, or overcome the objectionable features associated generally
with fuse cutouts. In more detail, the present invention may be
called a fused distribution limiter. The fused distribution limiter
has a very high fault-current interrupting rating, is still low in
cost, operates with a minimal noise and discharge, and yet retains
time-current characteristics, which do not depart from application
patterns set in the past. Especially desirable is the feature that
the fused distribution limiter of the present invention can be used
physically interchangeably with the commonly-used distribution
cutouts. The present device of our invention will replace the same
voltage of fuse cutout, and will fit into the same mounting, or
fuse-support assembly as is used for the cutout. The device is
further characterized by the feature that on many conditions of
fault interruption, the work of refusing and replacement of the
blown fuse-link is no more extensive than that which is performed
with the standard fuse cutout. Only in the event of very high-fault
currents does the improved and new current-limiting section of the
device operate to give the characteristically higher interrupting
rating and lower discharge associated with current-limiting fuses.
Our fuse distribution limiter may, optionally, be used for either
load-break, or non-load-break applications by the simple expedient
of easily-mounted bolt-on parts. The constructional details of the
improved fuse distribution limiter of the present invention may be
best understood by reference to FIGS. 1-7 of the drawings, which
illustrates the improved composite sectionalized drop-out fusible
device of the present invention, taken in conjunction with the
readily attachable load-break extension device.
FIG. 1 illustrates the device in the closed-circuit position and is
designated by the reference numeral 1. As shown, there is provided
an upstanding insulating support 2, which has a centrally-disposed
back-bracket 3, which may be bolted, or otherwise suitably secured
to the cross-arm (not shown) of a transmission-line pole. Disposed
at the upper end of the insulating support 2 is an upper main
stationary contact assembly, generally designated by the reference
numeral 4. Also, associated with the lower end of the insulator
support 2, and extending laterally therefrom, is a lower stationary
main contact assembly 6.
Referring more particularly to the upper end of the interrupting
device 1, it will be observed that the upper stationary main
contact assembly 4 includes a top casting 7 supporting the main
stationary contact assembly, generally indicated at 4, and a
secondary, or auxiliary contact assembly, generally indicated at 9.
The top casting 7 is comprised of suitable conducting material,
such as aluminum bronze, for example; and is secured to the
insulator support 2 by any suitable means, such as by a bolt 10
extending through an aperture in the casting and an aperture
extending through the insulator support 2. A nut, not shown,
secures the bolt 10 to the insulator 2 and is accessible through an
aperture from the rear of the insulator support 2. The casting 7
includes a curved rearwardly-extending portion 7a to mate with the
curvature of the insulator support 2, thus providing a snug
fit.
A line-terminal clamp, generally indicated at 12, is associated
with the conducting casting 7, and has a terminal bolt 10 extending
through an aperture 15 in the casting 7, as shown in FIG. 13. A
clamp 17 is secured to casting 7 by means of nut 18.
The main stationary contact assembly 4 includes a leaf contact
member 20 curved in a basically U-shaped configuration, and having
a notch, or other opening, not shown, at one end for attachment by
means of a bolt 21 to an apertured contact mount 22 integral with,
and protruding from the top casting 7. The stationary contact 20
may be comprised of any suitable conducting material, such as
phosphor bronze, for example.
A first contact latching device 24 is associated with the main
stationary contact 4, and is comprised of a basically U-shaped wire
25 having leg portions 25a, 25b (FIG. 9) connected by a bight
portion 25c. The bight portion 25c is recurved to fit around the
shank of bolt 21 for anchoring the first latching device 24 to the
contact mount 22, as shown in FIG. 1. The outer ends of legs 25a,
25b are bent inwardly towards each other, and are received in the
ends of a metal tube 26, which tube 26 serves as a contact-engaging
member, as hereinafter described.
The auxiliary contact assembly 9, shown in FIGS. 1 and 2, comprises
a support member 27 having a flat base 28 for attachment to the
casting 7 and an integral rib 29 (FIG. 8) on the base for
supporting an auxiliary contact assembly and an arc-chute. The
support member 27 includes a pair of outwardly-extending studs 30,
31 for affixing the base member to the top casting 7 by means of a
pair of bolts 32 (only one being shown) extending through apertures
33, 33 in the top casting 7 and into the studs 30, 31.
A pair of auxiliary contact strips 34, 34 are mounted at opposite
sides of the rib 29 by means of a rivet 35 extending through the
rib 29, and the inner ends of the contacts 34, 34 as shown in FIG.
8. The outer ends 34a of the contacts 34 are flared outwardly with
respect to each other, to serve as a guide for the incoming
auxiliary blade 36 to be hereinafter described. Each contact blade
34 includes an integral tabular indentation 34b immediately
adjacent the outer end 34a, each indentation 34b extending inwardly
toward the other substantially half the thickness of the rib 29, so
that the indentations 34b normally touch, thus comprising a second
latching device, or stop 37, for the auxiliary blade 36, as
hereinafter described. The contacts 34, 34 may be constructed from
any desirable conducting material, such as phosphor bronze, for
example.
The arc-chute 39 is comprised of a pair of opposing arcing plates
41, 43 fixedly mounted to the rib 29 by any suitable means, such as
bolts 45, and attached to each other at various points around their
perimeters by suitable means, such as bolts 46. The arcing plates
41, 43 have the outer edge flared, as in FIG. 8, to provide a
converging entrance portion 48 to the slot 49 between the plates
41, 43. The inner sides of the plates 41, 43 are spaced from each
other, except at the top and rear, where they are joined, to
provide access for the auxiliary blade 36. The plates 41, 43 are
recessed, as at 51 and 52, to provide space for the contacts 34.
Indentations 54, 54 are provided in the interface of each plate 41,
43 to serve as a seat for compression springs 55, 55, each
compressed between one of the indentations 54 and the indentation
formed by the previously-described tabular stop 34b, 34b on the
contacts 34, 34. It is seen that the tabular portion 34b on each
blade 34 serves a dual purpose in providing stop means for the
auxiliary blade 36 and a spring seat for the biasing springs 55.
One of the plates 43 includes an integral insulating hood 56 (FIG.
8) comprising a bottomless box extending over the main contact
assembly 4, and having cutout front and rear portions 56a, 56b.
Generally, the arc plates 41, 43 are comprised of a material which
is capable of evolving an arc-extinguishing gas when in the
proximity to an electric arc. However, the present loadbreak fuse
cutout is of the open, or non-enclosed type intended for outdoor
usage, and when so applied, the arc plates 41, 43 must be comprised
of suitable material having acceptable arc-quenching and
weather-resistant abilities.
The use of highly-polymerized formaldehyde as an arc interrupter,
is broadly disclosed and claimed in U.S. Pat. No. 3,059,081, issued
Oct. 16, 1962 to Gordon C. Gainer and Albert P. Strom, and assigned
to the same assignee as the present application.
The lower stationary contact assembly 6 comprises a
suitably-configured hood plate 58 having a top wall portion 58a,
side wall portions 58b, and a rear wall portion 58c. The rear wall
58c is curved to mate with the outer periphery of the insulator 2
and includes laterally-extending apertured ear portions 58d, (only
one shown) for connection to a bracket 59 surrounding the insulator
2 and having studs 60 (only one shown) extending through the
apertured ears 58d and secured thereto by nuts, 61, 61.
A flexible stationary contact plate 63 is secured to the inside of
the rear wall by a suitable means, such as a rivet 64. The plate 63
may be comprised of any suitable conducting material, such as
aluminum bronze, for example.
A line terminal clamp 66, similar to the previously-described line
terminal clamp 17, is attached to the hood plate 58.
The hood 58 has provided on its side walls 58b means providing a
hinge pivot 67 for a composite fuse holder assembly to be
hereinafter described. More specifically, trunnion guide slots 68
are provided in the side walls 58b of the hood 58, and have offset
trunnion bearings, or seats 68a associated therewith.
The improved fusible device 1 of the present invention comprises
two serially-related fusible sections 70, 71, one section 70 being
a high-current section and attached to a mechanically-connected
low-current section 71, the two sections 70, 71 preferably being
removably threaded, or otherwise detachably secured together, as
indicated more clearly in FIG. 1 of the drawings. With reference to
FIG. 6 of the drawings, it will be observed that the high-current
interrupting unit 70 generally comprises an enclosed cartridge
device, or casing 72 at least partially filled with a granular
material 73, such as white sand, for example, and enclosing a fuse
link 74 of silver, for example, which extends from one end ferrule
76 to the other end ferrule 77.
As shown in FIG. 6, the right end ferrule assembly 77 include a
threaded sleeve 78, which accommodates, in threaded engagement, a
slip nut 80 having a flange portion 80a, which abuts the upper end
ferrule assembly 82 of the lower low-current unit 71, which is
preferably of the expulsion-fuse type, and has a bore 84 therein
for accommodation of a fuse and a fuse-link cable, the latter being
designated by the reference numeral 86 in FIG. 1.
The low-current section 71, as more clearly illustrated in FIG. 7,
comprises an insulating expulsion tube 87, having a plurality of
boric-acid blocks 88 stacked therein between a pair of end plugs 89
and 90. The boric-acid blocks 88 evolve a condensible gas,
including water vapor, during the heat of interruption, which
occurs upon fusing of the fuse-link 85 disposed within the bore 84
of the low-current section 71.
The expulsion section utilizes an interrupting medium of compressed
boric acid, rather than the more commonly-used hard fibre, or
"Delrin." The use of boric acid in this section significantly
reduces the discharge occurring when the device operates to clear
low-magnitude fault currents. At high values of fault current, that
is current magnitudes higher than from 400 to 1,200 amperes, the
current-limiting section operates as well, so that the total
discharge occurring continues at a reduced level.
Extending out the lower open end 84a of the expulsion fuse tube 87
is the fuse-link cable 86. This cable extension is a portion of the
fuse-link, generally designated by the reference numeral 85, and
enclosed within the fuse tube 87, having at the upper end thereof a
fusible portion 85a, as well understood by those skilled in the
art.
The lower end of the fuse-link cable extension 86 is secured by a
wing bolt 91 to a toggle-link hinge member 93, shown in detail in
FIG. 2 of the drawings. Disposed adjacent the lower end of the fuse
tube 87 is a bottom clamping casting 95, shown in more detail in
FIGS. 2 and 3. The clamping casting 95 receives the fuse tube 87
therein, and is affixed thereto in any suitable manner, as by
cement and being pinned at 95a. A pair of spaced integral leg
portions 95b are provided on casting 95. The legs 95b are apertured
at the outer ends to receive therethrough a shaft 96, which shaft
96 is also received in suitably-apertured integral leg members 97
on toggle link 93, thereby pivotally hinging the casting 95 to
toggle member 93, which together constitute a unitary toggle
assembly, designated by the reference numeral 99.
The toggle member 93 is provided with an eyelet 100 enabling the
prong of a switch stick to be inserted therein, so that the
fuse-holder assembly 102 may be bodily lifted out of the trunnion
bearings 68a following fuse operation and dropout action for a
refusing operation. Also, the toggle-link hinge member 93 is
provided with trunnions, or stub shafts 103, which cooperate with
the trunnion bearings 68a of the lower hood 58. The base of each
stub shaft 103 is provided with a cam 104 having a narrow end 105.
The cam provides maximum clearance for removal and replacement of
the fuse-holder assembly 102, and, by cam action reduces the side
play of the fuse-holder assembly 102 in the slots 68 as the cutout
nears the closed position assuring that the main contact and
auxiliary blade will always be aligned for proper closing
regardless of the angle of the closing force. A contact portion 107
on the toggle member 93 cooperates with the flexible contact 63 to
engage therewith when the load-break fuse-cutout assembly 102 is in
the closed position, as illustrated in FIG. 1 of the drawings.
A fuse-link flipper 108 is rotatably mounted on a shaft 109
extending between the legs 93a of the toggle hinge member 93. The
flipper 108 includes a pair of off-set leg members 108a having
apertures at their ends surrounding the shaft 109, and having a
bight portion 108b connecting the legs 108a. The bight portion 108b
carries an integral latch portion 110 normally bearing against an
integral catch 112 on the bottom of hinge casting 95. The latch 110
is normally held in engagement with the catch 112 by the tension of
fuse cable 86 against the bight 108b, thus preventing dropout
operation of the cutout 102, and reducing the strain on the fuse
link 85, that would otherwise be exerted by the downward pressure
of the top contact 20 when latched. An integral spacer 114 on
casting 95 abuts an integral stop-brace portion 116 to hold casting
95 and toggle link 93 in under-toggle relationship. Thus, the top
leaf contact member 20 and the bottom flexible contact plate 63
collectively constitute a toggle-link biasing means 11 acting to
break the underset toggle linkage 118.
INTERCHANGEABILITY
The novel fuse-holder assembly 102 of the present application is
capable of use, optionally, with and without the load-break
structure 122. The ferrule stud 124 at the upper end of the
current-limiting fuse 70 has a notch 124a provided therein, which
is in alignment with the slot 78a provided in the lower ferrule
sleeve 78, as illustrated in FIG. 1. If the device is to be used in
conjunction with the load-break attachment 122, as illustrated in
FIG. 1, a hardware item, or load-break bracket 126, as illustrated
in FIGS. 14-18, is slipped over the ferrule stud 124, so that the
projection 126a (FIG. 15) fits within the recess 124a provided in
the ferrule stud 124. The spring support bolt 128 is then forced
through the apertures 126b provided in the downwardly-extending
tabs 126c, as illustrated more clearly in FIG. 16 of the drawings.
A torsion spring 130 surrounds the spring-support bolt 128 in a
manner more clearly illustrated in FIG. 4 of the drawings. The
rotatable auxiliary contact blade 36 has an aperture 36a provided
through the lower portion thereof, which is pivotally mounted upon
the torsion-spring support bolt 128, the latter having a threaded
end portion 128a, which accommodates a castellated nut 132, which
is fixedly secured upon the spring bolt 128 by a cotter pin 134.
The rotatable auxiliary contact blade 36, in addition, has an
offsetting boss portion 36b, which engages one end of the torsion
spring 130, and is biased against the stop 126d, shown more clearly
in FIG. 14 of the drawings. Thus, the rotatable auxiliary
load-break contact blade 36 is pivotally mounted upon the
spring-support bolt 128 to the bracket 126, and is capable of being
latched, so that it may move in the direction indicated by the
arrow 135 in FIG. 2, but not in the direction of the arrow 136
indicated in FIG. 2, since it is prevented from so doing by the
stop portion 126d, a part of the load-break bracket 126.
However, if the load-break disconnecting device 122 is not desired
to be used in conjunction with the fuse-holder assembly 102, then
merely a square apertured spacer washer 137 is used in place of the
load-break bracket 126, as illustrated in FIGS. 19 and 20 of the
drawings.
Whether the load-break blade assembly 122 is used or not, the next
item to be assembled upon the ferrule stud 124 of the
current-limiting fuse 70 is the contact-and-pry-out assembly
bracket 138, as illustrated more clearly in FIGS. 31 and 32. This
will permit the latch 24 to be pried out by a downward pull exerted
by a hook-stick upon the eyelet 139, as described hereinafter.
The contact bracket 138 includes a movable main contact portion
142. In addition, it provides two spaced apertured ear portions
138a supporting a pin 143, about which encircles a torsion spring
144 biasing an unlatching mechanism assembly 145 in a clockwise
direction, as viewed in FIGS. 2 and 27. The latch release lever 146
has an unlatching nose portion 147 which engages the latch 26 to
effect opening motion of the fuse-holder 102.
Thus, in any event, the contact-and-pry-out bracket device 138 is
used with the fuse-holder assembly 102, regardless of whether the
load-break bracket 126 and load-break blade 36 is used. As a final
item upon the stud portion 124 is placed a washer 140, and, finally
the locking nut 141. Thus, depending upon whether the load-break
bracket 126 is used the device 1 may be used with, or without the
load-break attachment 122. FIGS. 2 and 27 illustrate the two forms
of the invention.
A torsion flipper spring 120 encircles shaft 109, thus constantly
urging the flipper 108 in a counterclockwise direction around pivot
shaft 109. The flipper 108 also aids the fuse action in clearing
faults by flipping the fuse cable 86 out of the fuse tube 87 during
a fuse operation.
As shown, the manually-operable unlatching mechanism assembly,
generally indicated at 145, is carried by the ferrule stud 124 for
unlatching the latch 24 to effect load-break operation of the fuse
cutout 1. The unlatching assembly 145 comprises the rotatable
unlatching arm 146 apertures at 146a to receive the pivot shaft
143. The shaft 143 extends through a pair of spaced upstanding ears
138a, thus pivotally relating to the unlatching device 145 with the
upper end of the current-limiting fuse 70. The free end 147 of the
unlatching arm 146 extends around the ferrule 149 on top of contact
portion 142 to normally rest beneath the latch tube 26 of latch 24,
as seen in FIG. 1, when the switch 1 is in the closed position.
Integrally formed with the unlatching arm 146 is an operating ring,
or eyelet 139 to render the unlatching device 145 suitable for
operation by the usual hookstick device. A hook-eye spring 144
(FIG. 5) encircles the shaft 143 and has its end 144a bearing
against the arm 146 to bias the unlatching device clockwise about
pivot 143 in the normally latched position, as shown in FIGS. 1 and
5. It is seen that the unlatching mechanism 145 and the latch 24,
or first latch device, comprise a positive latching assembly, which
prevents accidental opening due to vibration or shock. The lineman
must forceably pull down on eyelet 139 by his hookstick effecting
thereby rotation of the rotating arm 146 to release the latch
24.
As shown in FIG. 1, the load-break fuse cutout is in its normal
closed position with the main contact 142 latched into engagement
with the main line contact 20 by the first latching device 24. At
the same time the auxiliary blade 36 is received between the
contact strips 34 inwardly of the stop means, or second latching
device 37. At the lower end of the fuse-holder 102, the casting 95
and toggle hinge 93 are held in under-toggle relationship by the
fuse-link cable 86 bearing upwardly against flipper 108.
The load-break fuse cutout 1 may optionally operate either as a
fuse cutout, or as a loadbreak switch as has been described
heretofore. In the operation of the load-break fuse cutout 1 as a
fuse cutout, an overload or fault current passing through the
device will fuse the fusible section 85 (FIG. 21) whereupon the
cable extension 86 will become slack, and will enable the flipper
108 to urge the cable 86 downwardly out of the tube 87 as the
flipper 108 rotates counterclockwise under the urging of spring
120. Operation of the flipper 108 releases the latch 110 on flipper
108 from engagement with catch 112 on casting 95, thereby
permitting the fuse-holder assembly 102 to drop downwardly and
outwardly about the hinge pivot 68a to the fully open disconnected
position (not shown). The downward movement of the fuse-holder 102
lowers contact 142 away from the first latching device 24, thus
effecting release of the main contact 142 with respect to the main
stationary contact 20. At the same time the auxiliary blade 36 is
carried downwardly between contacts 34, 34 and out of engagement
therewith during the initial downward movement of the fuse-holder
102, so that the fuse-holder 102 is thereafter allowed to freely
move outwardly around pivot 67, as previously described.
The thickness of the blade 36 is slightly smaller than the spacing
between the contacts 34, 34 to allow the blade 36 to easily drop
out of the auxiliary contact assembly 9 during the above-described
cutout operation, and also to minimize the contact between the
blade 36 and contacts 34, 34 when the cutout 1 is closed, whereby
the major share of the current is carried through the main
stationary contact assembly 4 and main movable contact 142.
In the operation of the load-break fuse cutout 1 as a load-break
switch, the operating member 146, supported by the ferrule 149, is
moved downwardly and outwardly, the downward movement pivoting the
unlatching arm 147 upwardly about pivot 143 to engage the latch
tube 26 and thereby release the first latching device 24 from
engagement with contact 142, and the outward motion effecting
rotation of fuse-holder 102 about the pivot 67 effecting
disengagement between contact 142 and contact 20. During the
initial outward movement of contact 142 away from contact 20, the
auxiliary blade 36 is prevented from disengaging from contacts 34,
34 by stop means or the second latching device 37 on contacts 34
engaging blade 36. As the contact 142 moves further outwardly, the
blade 36 rotates about pivot bolt 128 (FIG. 4) on the load-break
bracket 126, remaining for a time in engagement with contact stop
or latching means 34, 34 and carrying the full line current at this
time to prevent arcing between the main contacts 142 and 20 as they
separate. The relative movement between fuse-holder 102 and blade
36 will act to stress spring 130 (FIG. 4). As the ferrule 149 moves
further outwardly, blade 36 slides downwardly over stop or latching
means 34, 34 and, when the main contacts 20, 142 have separated a
sufficient distance to prevent flashover, is completely withdrawn
from between the contacts 34, 34 in the downward direction,
whereupon spring 130 quickly moves the blade 36 outwardly from the
contacts 34, 34 in the opening direction and between the arc-plate
means 41, 43 with a snap action out through the slot in the plates
41, 43 until the movable blade 36 is again substantially parallel
with the fuse-holder assembly 102 and in engagement with the stop
means 126d on arm 126. The movement of the rotatable blade 36
through the arc shute 39 will extinguish the arc formed when the
blade 36 disengages from stationary auxiliary contacts 34, 34. As
is generally known, the arc is extinguished by attenuation and
confinement between the plates 41, 43, and the gas blast produced
by the gas-evolving material, as hereinbefore described.
To close the load-break fuse cutout 1, the operating device 146 is
moved inwardly by the maintenance man, rotating the fuse-holder 102
about bearing 67, effecting engagement of the auxiliary contact
blade 34, 34 before the main movable contact 142 engages main
stationary contact 20. The stop means 126d on arm bracket 126 bears
against rotatable blade 36 during the closing operation effecting
engagement with the contacts 34, 34 before the main contacts 142
engage, and forcing the blade 36 inwardly between guide members
34a, 34a and beyond stop means 34b to its normally closed position,
as shown in FIG. 1.
Upon the occurrence of relatively low-current faults, the standard
fuse link 85 is fused and separates to clear the circuit and to
allow the toggle arrangement 99 to unlatch, dropping the fuse
device 102 to the dropout lower position. The expulsion section
utilizes an interrupting medium of compressed boric acid, rather
than the more commonly-used hard fiber or "Delrin." The use of
boric acid in this section 71 significantly reduces the discharge
occurring when the fusible device 1 operates to clear low-magnitude
fault currents. At high values of fault current, that is current
magnitudes higher than 400 to 1,200 amperes, for example, the
current-limiting section 70 operates as well, so that the total
discharge occurring continues at a reduced level.
Thus, from the foregoing remarks, it is apparent that during
relatively low-fault current interruption, only the lower unit 71
operates, the upper unit 70 remaining intact, and merely
replacement of a standard-type fuse-link 85 is required to convert
the device again into operating condition, and to again close the
circuit through the connected line. In the case of a relatively
high fault current, both the high current and the low-current
interrupting sections 70, 71 fuse simultaneously, and there is a
reduced display since part of the interrupting effort is
accommodated in the enclosed high-current interrupting unit 70,
such as the current-limiting section.
LOAD-BREAK OPERATION
In electrical parallel with the top main contacts 20 and 142 is
another set of auxiliary contacts 34, and a quick-break stainless
steel blade 36 located between two pieces of insulating plate 41,
43, composed, of Delrin, for example. The lineman inserts his
hookstick in the fuse holder hook-eye 139, and pulls down in the
usual manner. First the main contacts 20 and 142 separate; however,
current is still carried through the quick-break blade 36 until the
main contacts 20, 142 are far enough apart to prevent arcing.
Second, the blade 36, by means of a strong spring action, then
snaps away from its contact 34, drawing an arc within the arc chute
39. A deionizing gas is generated from the "Delrin" plastic when
subjected to this arc heat. The gas, combined with the snap action
of the blade 36, quickly extinguishes the arc thus completing a
simple and safe load-break operation.
An important factor of this load-break operation in part lies in
the arc chute 39, made of Delrin plastic, for example. This is a
tough, temperature and moisture resistant material, which is highly
suitable for this purpose. The material cannot be ignited under
load-break conditions, due to the fast extinguishing action of the
arc-chute. The quick-break blade 36 is preferably made of stainless
steel, for example. Pitting and erosion of the blade 36 after many
operations, does not impair the load-breaking ability of the
cutout. An important advantage is that a conventional standard
hookstick is the only tool needed to open the cutout 1 under full
load. Also, of important for the safety of linemen is the fact that
the arc is completely confined within the Delrin arc-chute 39 with
no chance of external arcing, as with fuse-link-break type of
devices, nor is safety dependent upon replacement of a gas capsule.
In addition, under such load-break operations, no fuse-link need be
replaced. Tests have clearly shown that the arc-chute 39 will
interrupt 200 amperes over 200 times with the Delrin arc-chute 39
not tracking nor forming conducting carbonized paths during the
entire life of the cutout.
FIG. 22 illustrates the cutout 1 closed with the load current being
carried by the main contacts. FIG. 23 illustrates the cutout half
open with the quick-break blade 36 in the arc-chute now carrying
the load current. FIG. 24 illustrates the quick -break blade 36
just before the releasing action. It will be noted that the blade
36 cannot be released until the cutout is opened sufficiently to
prevent the arc from restriking between the main contacts 20,
142.
FIG. 25 illustrates the blade 36 released and further opening of
the cutout releases the blade 36, and it snaps the length of the
arc chute elongating and deionizing the arc with the coil spring
130 at the bottom of the blade 36 providing the opening energy.
FIG. 26 illustrates the blade half closed during a closing
operation. This figure illustrates that the cutout's main contacts
20, 142 engage after the quick-break blade 36 closes, thus
preventing burning and pitting due to pre-striking during a closing
operation.
The present device 1 is capable of use either with or without the
load-break feature 122, as previously described. The foregoing
description has described the load-break attachment 122; however,
it is to be clearly understood that the device is capable of use
without the load-break attachment 122, as illustrated in FIGS. 27,
28 and 29 of the drawings. With respect to these figures, showing
the use of the fusible device 1 without the load-break attachment
122, it is to be noted that many parts are similar in construction
to the device, as described hereinbefore.
By the use of the hook-stick, the latch releasing lever 146 may be
rotated about its pivot 143 to effect release of the latch 26 and
permit opening motion of the fuse-holder assembly 102.
It will be obvious to those skilled in the art that the
current-limiting fusible section 70, illustrated in FIG. 6 of the
drawings, could be replaced by other current-limiting devices, such
as those described in U.S. Pat. No. 3,569,891 -- Cameron, issued
Mar. 9, 1971. Merely, by way of illustration only, has the
particular type of current-limiting fuse section 70, illustrated in
FIG. 6, been described in connection with the present invention.
Alternates and different types of current-limiting fuses could be
substituted for that illustrated in FIG. 6. In addition, although
boric acid blocks were described in conjunction with the
expulsion-type fusible device, illustrated in FIG. 7, other types
of expulsion fuses could be utilized with the condition, however,
that the fuse-link cable 86 therein would necessarily have to be
severed to enable breaking of the toggle linkage 118.
From the foregoing description, it will be apparent that there has
been provided an improved composite sectionalized dropout-type of
fusible device 1, in which the noise and display has been minimized
by utilizing two interrupting sections 70, 71 in series, one being
a high-current interrupting section operable only during
high-current interruption, whereas the other low-current
interrupting section 71 is operable both during low and
high-current interruption Thus, the two sections 70, 71 cooperate
together to reduce the interrupting effort required by each.
To effect a fusing operation during low-current interruption, it is
merely necessary to unscrew the connecting slip ring 80 and to
replace the standard-type fuse-link 85, illustrated more in detai
in FIG. 21 of the drawings. Upon replacement of a standard
fuse-link cable 86, the low-current section 71 may again be
mechanically attached to the high-current section by screwing the
connecting slip ring 80 about the threaded lower ferrule portion 78
of the upper high-current interrupting unit 70. The fuse-link cable
86 is then attached to the capstan device 150, and the fuse
structure 102 is then capable of being reinserted back into the
circuit.
From the foregoing description, it will be apparent that there has
been provided an improved fusible device, particularly adapted for
dropout operation, in which two fusible sections 70, 71 are
arranged in electrical series and adapted to be selectively fused.
In other words, during low-current interruption, only the lower
expulsion-type fusible device 71 functions, and the upper
high-current unit 70 remains intact. During high-current fault
interruption, however, both sections 70, 71 fuse simultaneously,
thereby relieving each of them by their combined action, and the
interrupting capability is increased with a concomitant lowering of
noise and display. For load-break operation, merely by the
expedient of attaching additional hardware parts, the
load-break-extension device 122 may be readily accommodated. On the
other hand, should such a load-break function not be required, the
device 1 is fully capable of being operated independently thereof,
and as a composite two-sectioned fusible device, as illustrated in
FIG. 27 of the drawings.
Also, from the foregoing description, it will be apparent that
there has been provided a new circuit-interrupting device designed
for use with a standard fuse-support assembly, the device being
characterized by a higher and improved interrupting ability,
achieved at the same time with a reduced noise and display level.
Moreover, the device is capable of being used with standard-type
fuse-links, which may be changed, depending upon the desires of the
maintenance man. Obviously, the fuse-links are of standard
characteristics, and their level of current protection may be
readily ascertained.
Although there has been illustrated and described specific
structures, it is to be clearly understood that the same were
merely for the purpose of illustration, and that changes and
modifications may readily be made therein by those skilled in the
art, without departure from the spirit and scope of the
invention.
* * * * *