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Патент USA US2135164

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Nov 1, 1938
A E BROCK
HIGH TENSION EXPULSION FUSE
Filed Jan. 11, 1937
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INVENTOR.
ARNOLD E_ BROCK
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2,135,164
Patented Nov. 1, 1938
UNITED STATES PATENT OFFICE
2,135,164
HIGH TENSION EXPULSION FUSE
Arnold E. Brock, Burlingame, Oalif., assignor to
Paci?c Electric Manufacturing Corporation,
San Francisco, Calif., a corporation of Cali
fornia
Application January 11, 1937, Serial No. 120,007
7 Claims.
The present invention relates generally to fuses,
and more particularly to a new and improved
construction for high tension expulsion fuses
which will greatly increase the current interrupt
‘
5 ing range thereof.
An object of the invention is to provide a high
tension expulsion fuse which will successfully op
erate to interrupt a circuit over a wider range
of currents than has heretofore been possible
with fuses of this character.
Another object of the invention is to provide
a fuse of the expulsion type which will operate
successfully to interrupt a circuit at its normal
capacity rating and also withstand and success
15 fully interrupt currents far in excess of its rated
(Cl. 200-127)
For a better understanding of the present in
vention reference should be had to the accom
panying drawing, wherein there is shown by way
of illustration and not of limitation, preferred
embodiments thereof.
In the drawing, wherein like numerals refer
to like parts throughout the several views;
Figure 1 is a side view of a complete fuse of
the type contemplated by this invention,
Figure 2 is a vertical sectional view of the fuse 10
shown in Figure l, with the central insulating
portion broken away to foreshorten this ?gure of
the drawing,
Figure 3 is a fragmentary view of a fuse similar
to the fuse shown in Figure 2 of the drawing, 15
capacity.
having two pressure responsive vents,
Another object of the invention is to provide in
an expulsion fuse of the character described, a
fuse taken along line IV—IV of Figure 3, looking
new and novel form of gas pressure relief means
20 which will become operative upon the occurrence
of an excessive gas pressure within the fuse con
taining chamber.
In the construction of expulsion fuses of the
character contemplated by this invention, it is
25 necessary, in order that the fuses successfully op
erate at low and normal current values, to pro
vide a constricted or small bore chamber through
which the fusible element is extended, and fur—
ther, to disrupt any are formed within said cham
30 ber upon a fusion of the fuse element, it is desir
Figure 4 is a horizontal sectional View of the
in direction of arrows, and
Figure 5 is a horizontal sectional view of the 20
fuse taken along line V»-V of Figure 2, looking
in direction of arrows.
For the purpose of illustrating the invention
there is shown in the drawing a fuse of the ex
pulsion type having an open end through which 25
the gases generated upon a blowing of the fuse
are expelled to extinguish the arc and interrupt
the circuit, as is well understood by those skilled
in the art.
As shown, the fuse comprises a body member, 30
able that the walls of this constricted chamber
designated generally by the numeral IE], to one
be formed or‘ a more or less combustible material
end of which there is securely attached a ferrule
if having a removable cap 32 forv the insertion
of a renewable fuse link 53. At the other end of
the body member ii) there is securely attached an 35
open ended ferrule i4 having a fuse link terminal
it with a clamping screw If‘). The ferrules H
and ill have a contact making portion which is
which will produce‘ a deionizing gas to assist in
the interruption of any are established therein.
35 While a fuse of this construction has been found
to operate in a very successful manner in the
interruption of currents up to the normal rated
capacity of the fuse, such a construction is open
to the objection that when the fuse is subjected
40 to a high overload current or a short circuit, the
pressures generated often burst the fuse con
taining chamber.
The above described characteristics are ob
tained, in accordance with the present inven
45 tion, by con?ning the fuse in an enclosing body
member having a constricted or small bore cham
ber of fibre or other deionizing gas producing
material, and the objections thereto are over
come by providing an auxiliary gas outlet which
50 is adapted to become operative to discharge gas
from the fuse containing chamber upon the oc
adapted to be inserted in suitable fuse support
ing clips to which the conductors of the protected 40
circuit are connected. In some installations these
fuse clips will be adapted to hold the fuse struc
ture until it is removed from the circuit by an
operator, and in other installations it is contem
plated that the fuse illustrated may be used with 45
the so-called, drop-out type of fuse support which
will permit the fuse to swing out of engagement
with at least one of the contact clips upon a
melting of the fuse link l3 due to an overload
currence of an excessive pressure such as might
current.
50
Upon referring to Figures 2 and 3 of the draw
ing it will be seen that the fuse link l3 has an
be caused by the interruption of a high overload
current are within said fuse enclosing body mem
55 ber.
enlarged buttonlike head which is adapted to be
secured at its upper end in good contact making
engagement with the end of the ferrule H by 55
2.
2,135,1e4
means of the cap 52, and at its lower end, after
extending through the body member 20, the fuse
link !3 is adapted to be brought out around
through the open end of the ferrule M and
clamped upon the terminal i5 by means of the
clamping screw
In these ?gures of the draw
ing it will also be noted that the body member
5 is formed of an outer tubular member ll
wlich is of a highly refractory material, such
10 as Bakelite or porcelain, and an inner lining
forming member :8 th is preferably of horn
?bre. In practice the Join ?bre lining member
i8 is tightly ?tted within the outer refractory
tubular n ember El
extends throughout the
entire length thereof. W’h this construction
it will be seen that the hOl‘i ?bre lining member
i 8 provides a constricted chamber through which
the fuse 13 will extend in close proxlrm't" with the
walls thereof, and w‘ ‘le horn ?bre is speci?ed as
a preferred material, it is to be understood that
this lining member !8 may be formed of any
material which, upon volatilization or burning, is
capable of producing a deionizing gas that will
create a high pressure and expel the lower end
of the fuse link from the chamber and at the
time extinguish any are formed therein.
This operation of the fuse is in the nature of an
explosion in which the pressures generated are
more or less proportional to the current flowing
30 in the are up to its point of interruption, and
conseq iently it often happens, upon a high cur
rent overload or a short circuit on the protected
line, that unless means are provided to relieve
this pressure, the fuse body forming member is
subjected to a bursting strain. In the past, to
avoid the building up of a bursting pressure with—
in the body forming member or" the fuse, it has
been the practice, where high currents
in
terrupted, to enlarge the size of the bore through
40 which the fuse extends.
This provides for a
free escape of the gases and thus prevents the
building of a bursting pressure within the fuse
body forming member, but resort to this ex
pedient necessarily locates the fuse link 53 more
in the deionizing gas producing lining
45 remote
l8 and thus reduces the gas generating capacity
of the fuse to such an extent that it will not al
ways operate successfully at its normal or low
current values.
To overcome the above disadvantages and at
the same time provide a constricted fuse link con
taining chamber of small diameter, the ferrule l l,
as shown in Figures 2 and 4 of the drawing and in
accordance with one embodiment of t-is inven
tion, is provided with a pressure relief outlet 59
through which the generated gases produced by
an are within the fuse enclosing chamber are
permitted to escape before the pressure reaches
a value which might burst the body forming
member id. In its preferred form the pressure
relief outlet is has a shouldered and threaded
portion into which a closure disc 29 and a tubular
securing plug El are adapted to be inserted. The
closure disc 253 may be made of any material,
65 such as ?sh paper or from lead sheet of any de
sired thickness, depending upon the pressures in
volved.
In a modi?ed form of the invention, the ferrule
ll may be provided with more than one of these
70 pressure relief outlets I9, as illustrated in Figure 3
of the drawing.
Where more than one pressure
outlet 59 is provided, the closure discs 20 thereof
may be constructed so as to be responsive to
different pressures and/or they may be made of
different materials. In the latter event, for ex
ample, a ?sh paper closure disc 20vmight be made
responsiveto a predetermined de?nite pressure,
and a lead closure disc 20 might be used in con
junction therewith, which is responsive to both
heat and pressure, the heat generated by a sus
tained arc serving to weaken the lead disc and
eventually cause it to rupture and provide an
additional outlet for the escape of gases from
within the fuse link enclosing chamber. In prac
tice it is contemplated that these pressure relief 10
outlet closure discs 29 will be proportioned so as
not to rupture below a pressure which is necessary
to a successful and efficient interruption of the
are at the normal rated current capacity for which
the fuse link is designed. In order to provide a 15
plurality of pressure relief outlets having different
pressure response characteristics, it is also con
templated that the pressure relief outlets l9
might be made of different diameters, and that
these outlets of different diameters might be like 20
wise provided with closure discs 20 of the same or
different materials.
Figures 4 and 5 of the drawing more clearly
illustrate the close proximity of the fuse link I3
with the lining member l8 of the body forming
member 58, and the latter ?gure also illustrates
more detail the terminal l5 and its clamping
screw l6, which serve, on one form of fuse, as a
connection for the looped lower end of the fuse
link.
In conclusion it may be added that the present
invention, in addition to providing a constricted
enclosing chamber with a pressure relief
means which will prevent bursting of the fuse
enclosing body member I0 upon the generation of
an excessive pressure therein, also by a location
of the pressure relief means at the upper end of
the fuse, greatly reduces overstrain upon the fuse
supporting clips, prolongs their life when they are
of the drop-out character and prevents a com
40
plete dislodgment of the fuse from its support, as
now often happens in the interruption of an are
under short circuit and heavy overload current
conditions.
While I have, for the sake of clearness and in 45
order to disclose the invention so that the same
can be readily understood, described and illus
trated speci?c devices and arrangements, I de
sire to have it understood that this invention is
not limited to the speci?c means disclosed, but 50
may be embodied in other ways that will suggest
themselves to persons skilled in the art. It is
believed that this invention is new and it is desired
to claim it so that all such changes as come with
in the scope of the appended claims are to be
considered as part of this invention.
Having thus described my invention, what I
claim and desire to secure by Letters Patent is
I. In an expulsion fuse of the character de
scribed, the combination of a body forming mem 60
ber of insulating material having a normally
closed contact making ferrule at one end and an
open ended ferrule at its other end through which
the arc disrupting gases are discharged under
normal operating conditions, fuse link connecting 65
means carried by each of said ferrules for attach
ing a fusible link therebetween, a fusible link ex
tending through said body forming member and
connected to said ferrules, said normally closed
contact making ferrule having a gas discharging 70
aperture formed therein, and means for closing
said aperture operable under abnormal operating
conditions to open said aperture and form an
auxiliary gas discharge outlet upon the occurrence
of a predetermined excessive gas pressure within
2,135,164
said body forming member, said aperture and its
closing means being positioned upon the normally
closed contact making ferrule remote from the
fuse link connecting means thereof, whereby the
fuse link may be replaced after a normal opera
tion of the fuse Without disturbing said means
for closing said aperture.
2. In an expulsion fuse of the character de
scribed, the combination of an insulating open
ended body forming member having a normally
closed contact making ferrule at one end thereof
and an open ended contact making ferrule at the
other end thereof through which the arc disrupt
ing gases are normally discharged, a removable
cap means for closing the end of said normally
closed ferrule and securing one end of a fusible
link thereto, means carried by said open ended
ferrule for securing the other end of said fusible
link thereto with the link extending out through
and around the open end thereof, and a pressure
responsive vent located in the side of said nor
mally closed ferrule independently of said remov
able cap means at the end of said ferrule adapted
to open and permit a further discharge of gas
from said body forming member at this point in
the event of an excessive back pressure of gas
during the interruption of are within said body
forming member.
3. In a high tension expulsion fuse, the combi
30 nation of a body forming member of highly re
fractory insulating material, contact engaging
ferrules secured upon the ends of said body form~
ing member, a lining of combustible material
within said body member having deionizing gas
producing properties, a fusible element connected
to said ferrules extending through said body
member and in close relation with said lining,
3
tending through said expulsion chamber, said
latter ferrule having an auxiliary gas discharge
outlet in one side thereof adjacent the arcing
path of the fusible element, and a closure means
secured over said outlet adapted to rupture in the
event of an excessive heat and gas pressure Within
said expulsion chamber.
5. In an expulsion fuse of the character de
scribed, the combination of a cylindrical body
forming member of insulating material having 10
deionizing gas producing properties and forming
a con?ned expulsion chamber for a fuse element,
an open ended contact engaging ferrule provid
ing an elongated open gas discharge outlet at
one end of said body forming member, a second 15
contact engaging ferrule secured to and forming
a closure at the other end of said body forming
member, means carried by said ferrules for secur—
ing the opposite ends of a fuse element thereto
with the fuse element extending through said 20
expulsion chamber, said latter ferrule having a
plurality of gas discharge outlets of different
diameters formed therein, and a fragile closure
means secured over each of said outlets.
6. In an expulsion fuse of the character de 25
scribed, the combination of a cylindrical body
forming member of insulating material having
deionizing gas producing properties and forming
a con?ned expulsion chamber for a fuse element,
an open ended contact engaging ferrule provid 30
ing an open gas discharge outlet at one end of
said body forming member, a second contact
engaging ferrule secured to and forming a closure
at the other end of said body forming member,
means carried by said ferrules for securing the 35
ends of a fuse element thereto with the fuse ele
ment extending through said expulsion chamber,
one of said ferrules being open at its end to pro
said latter ferrule having a plurality of gas dis~
vide for the free discharge of the deionizing gas
charge outlets formed therein, and a fragile clo
40 from said body member upon a normal fusion of
said fusible link and the other of said ferrules
having an auxiliary gas discharge outlet in one
side thereof adjacent the arcing path of the fusi
ble element, and a disc of heat sensitive ruptur
45 able material secured over said auxiliary gas dis
charge outlet adapted in the event of a heating
and an excessive gas pressure to rupture and
open said auxiliary gas discharge outlet during
the interruption of an abnormal are within said
50 body forming member.
4. In an expulsion fuse of the character de
scribed, the combination of a cylindrical body
forming member of insulating material with a
deionizing gas producing lining forming a con
55 ?ned expulsion chamber for a fuse element, an
open ended contact engaging ferrule providing an
elongated gas discharge outlet for a diameter
greater than that of the expulsion chamber at
one end of said body forming member, a second
60 contact engaging ferrule secured to and forming
a closure at the other end of said body forming
member, means carried by said ferrules for secur
ing the ends of a fuse thereto with the fuse ex
sure means secured over each of said outlets, each 40
of said
rupture
'7. In
scribed,
fragile closure means being adapted to
at a different pressure than the other.
an expulsion fuse of the character de
the combination of a cylindrical body
forming member of insulating material having 45
deionizing gas producing properties and forming
a con?ned expulsion chamber for a fuse element,
an open ended contact engaging ferrule providing
an elongated open gas discharge outlet of a diam
eter greater than that of the expulsion chamber 50
at one end of said body forming member, a second
contact engaging ferrule secured to and forming
a closure at the other end of said body forming
member, means carried by each of said ferrules
for securing the ends of a fuse thereto with the‘ 55
fuse element disposed in said expulsion chamber,
said latter ferrule having a gas discharge outlet
formed in the side thereof remote from its end
and adjacent the arcing path of the fusible ele
ment, and a fragile heat and pressure responsive 60
closure disc disposed over and closing said outlet.
ARNOLD E. BROCK.
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