Note: Descriptions are shown in the official language in which they were submitted.
CA 02545945 2006-05-09
SC-5395-C
FUSE, INSTALLATION ADAPTER FOR A FUSE, METHOD OF ADAPTING A FUSE
FOR INSTALLATION AND KIT FOR ADAPTING A FUSE FOR INSTALLATION
Technical Field
[0001] This patent relates to fuses used in electrical power distribution
systems and
more particularly to a fuse, an installation adapter for a fuse, a method of
adapting a fuse for
installation in a non-standard mounting for the fuse and a kit for adapting a
fuse for installation
in a non-standard mounting for the fuse.
Background
[0002] Power distribution system operators use a variety of devices to protect
system
infrastructure from damage resulting from a fault occurring in the power
distribution system.
A commonly used fault protection device is a fuse. A fuse includes a fusible
element that
responsive to a fault condition, i.e., a current in excess of a threshold
value for a predetermined
period of time, opens the current carrying circuit to isolate equipment on one
side of the fuse
from the fault on the other side of the fuse. The fusible element is typically
a conductor that
responsive to the fault current melts or otherwise separates to open the
circuit.
[0003] Power distribution system equipment is designed, manufactured and
installed
to have a long service life. Fuses used to protect system components engage
the system in a
mount that electrically couples the fuse into the power distribution system
between a source
and a load. The fuse mount is specified and has electrical contacts that
engage electrical
contacts, e.g., ferrules, of the fuse. Typically, the mount is specified for a
particular fuse type
to be used in the system. As fuse designs become obsolete and new fuse
technology is
introduced, it may become desirable to use a different fuse type in the
system. Doing so
generally requires the system operator to replace the fuse mounts to
accommodate the new fuse
type. Such replacement may involve costs and environmental concerns that
exceed the
advantages of using the new fuse type. However, such replacement may become
inevitable if
the originally specified fuse type is made obsolete and is no longer
commercially available.
Brief Description of the Drawings
[0004] Fig. 1 is a side view of a fuse including an installation adapter, the
installation
adapter being shown in cross-section;
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[0005] Fig. 2 is a side view of a fuse including an installation adapter
according to
another embodiment;
[0006] Fig. 3 is a schematic illustration of an installation adapter kit;
[0007] Fig. 4 is a partial cross-section view of fuse including fusible
element and an
auxiliary fusible element; and
[0008] Fig. 5 is a partial view of an arcing rod assembly that may be used in
the fuse
shown in Fig. 4.
Detailed Description
[0009] An installation adapter couples to a fuse to permit the fuse to be
installed in a
non-standard mount for the fuse. A fuse and corresponding mount, e.g., a
standard mount for
the fuse are mutually designed such that fuse is easily installed into the
mount and removed
from the mount for replacement. Typically, electrical contacts of the fuse,
e.g., ferrules,
engage electrical contacts of the mount with the engagement of the ferrules
with the electrical
contacts securing the fuse in the mount. The electrical contacts of the mount
are sized and
spaced to correspond to the size and spacing of the ferrules. Thus, a fuse of
one type may not
be easily installed in a mount for which it is not designed, e.g., a non-
standard mount for the
fuse.
[0010] In accordance with one of the herein described embodiments, an adapter
may
be fitted to the fuse to allow the fuse to be fitted to a non-standard mount,
i.e., a mount for
which the fuse was not designed to engage. The adapter may include a first
adapter member
that secures to one of the fuse ferrules and a second adapter that secures to
the other of the fuse
ferrules. The adapters include electrical contacts that are either spaced at a
predetermined
distance to fit the non-standard mount or that may be adjustable to allow the
fuse fitted with the
adapter members to couple to the non-standard mount. Alternatively, providing
at least one of
the electrical contacts of the fuse has a configuration permitting it to
couple to a corresponding
contact of the mount, the installation adapter may include a single adapter
member, which may
or may not include an adjustment feature.
[0011] A kit may be produce that includes a fuse having a predetermined
configuration, an installation adapter and instructions for configuring the
fuse using the
installation adapter to fit a non-standard mount. The installation adapter may
contain one or
more adapter members. A corresponding method utilizes an installation adapter
to provide for
configuring a fuse to be compatible with a non-standard mount.
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[0012] A fuse may be adapted in accordance with the described embodiments to
have
dual operating characteristics, e.g., a slow operating, low fault current
characteristic and a fast
operating, high fault current characteristic.
[0013] Referring to Fig. 1 an installation adapter 100 including a first
adapter
member 102 and a second adapter member 104 is fitted to a fuse 106. The fuse
106 may
include a housing 108 having a first end 110, a second end 112 and an outer
surface 114. The
housing 108 has a predetermined length separating the first end 110 from the
second end 112.
The housing furthermore has a predetermined diameter (although other than
round
configurations may be envisioned). The first end 110 includes a first coupling
ferrule 116 and
the second end 112 includes a second coupling ferrule 118 that allows the fuse
106 to be
coupled to a mount (not depicted) configured for the fuse 106, e.g., a
standard mount for the
fuse 106. That is, the first and second coupling ferrules 116 and 118 are
sized and spaced to
engage contacts of a standard mounting for the fuse.
[0014] The installation adapter 100 may include the first adapter member 102,
if
necessary. The first adapter member 102 may not be necessary if the first end
110 and the
ferrule 116 may suitably engage a contact of the non-standard mounting (not
depicted) to
which the fuse is being adapted for installation. If necessary, the first
adapter member may
include a generally annular member 120 that may be received about a portion of
the first end
110 and a portion of the first coupling ferrule 116 and to electrically couple
to the first
coupling ferrule 116. The first adapter member may further have an electrical
contact 122 to
engage a first contact of the non-standard mounting. The fastener, such as a
set screw or
securing bolt 124 engages a threaded aperture 126 formed in the annular member
120 and
engages against either or both of the fuse housing 108 at the first end 110
and the ferrule 116.
[0015] The installation adapter 100 may also include the second adapter member
104.
The second adapter member 104 may have a generally annular member 128 that is
received
about a portion of the second end 112 and a portion of the second coupling
ferrule 118. The
member 128 electrically couples to the second coupling ferrule 118. The second
adapter
member 104 may further have a sleeve portion 130 that extends along the outer
surface 114 of
the housing 108 from the second end 112 and member 128 toward the first end
110. The
sleeve portion 130 may include an insulating surface 132 and a conductive
layer 134. A
second electrical contact 136 may be formed at an end 138 of the sleeve
portion 130. The
conductive layer 134 electrically couples the member 128 engaging the ferrule
118 with the
electrical contact 136. The electrical contact 136 may be formed as part of an
end assembly
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140 formed at the end 138. The end assembly 140 may include an insulating
annular portion
142 and a conductor (not depicted) that couples to the contact 136.
[0016] In an embodiment illustrated in Fig. 1, the member 128 may include an
annular collar 144. The collar 144 is received about the portion of the second
end 112 and the
portion of the second ferrule 118. The collar 144 may include a fastener 146,
such as a set
screw or securing bolt, which is received within a threaded aperture 148 for
securing the collar
144 to the second end 112. The collar 144 further includes a bore 150 within
which the sleeve
130 is received such that when the collar 144 is secured to the second end
112, the conductive
layer 132 is electrically coupled to the ferrule 118. An optional conducting
member (not
depicted) may be provided as part of the collar 144 that couples the ferrule
118 to the
conductive layer 132.
[0017] In an alternative embodiment illustrated in Fig. 2, the member 128 may
include an annular collar 152. The collar 152 is received about the portion of
the second end
112 and the portion of the second ferrule 118. The collar 152 may include a
clamp member
154 formed integral therewith and a fastener 156, such as a securing bolt,
that is received
within a threaded aperture (not depicted) for securing the collar 152 and
hence the sleeve 130
to the second end 112. The collar 152 may be received within a bore (not
depicted) formed in
the sleeve 130 such that when the collar 152 is secured to the second end 112,
the conductive
layer 132 engages the ferrule 118.
100181 The first adapter member 102 and the second adapter member 104 allow
contacts 120 and 136 to be positioned to the fuse 106 in appropriate spaced
relationship to
engage the contacts of the intended non-standard mounting for which the fuse
is being adapted.
That is, the contact 120 is positioned by the first adapter member 102
substantially adjacent the
ferrule 116. The contact 136 is positioned relative to the contact 120 based
upon the
dimensions, e.g., length, of the sleeve 130. Both the first adapter member 102
and the second
adapter member 104 positively engage the first end 110 and the second end 112
of the fuse
106, respectively, to ensure the distance relationship is maintained.
Additionally, alignment
features may be provided within the first adapter member 102 and the second
adapter member
104. Such alignment features may engage corresponding alignment features
formed on the
fuse first end 110, second end 112, ferrule 116, ferrule 118 or any suitable
part of the fuse. For
example, as shown in Fig. 1, the ferrule 116 may include a dimple 160 that is
engaged by a
spring loaded ball or similar structure 162 formed in the first adapter member
102.
Alternatively, and as shown for example also in Fig. 1, the ferrule 118 is
formed with a slot
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164 engaged by a spring loaded ball or similar structure 166. Various other
alignment features
formed on each of the adapter members 102/104 and the fuse 106 may be used,
such as,
without limitation: a dimple, a slot, a tab, a notch, a flat, a spline or a
combination thereof. The
alignment features may secure the position of the contacts 120 and 136
lengthwise as well as
prevent rotation of the contacts 120 and 136 relative to the fuse 106.
[0019] As shown in each of Figs. 1 and 2, the sleeve 130 extends along the
housing
108 of the fuse 106 such that the distance between the contact 120 and the
contract 136 is less
than a distance between the ferrule 110 and the ferrule 112. It will be
appreciated that for
certain applications the sleeve 130 may extend away from the first end 110
effectively
providing a spacing between the contacts 120 and 136 that is longer than the
spacing between
the ferrules 110 and 112. Furthermore, the contacts 120 and 136 are shown
aligned along the
housing 108 of the fuse 106. The contacts need not be so aligned, and in
certain applications
the contacts 120 and 136 be rotated about the housing 108, e.g., at 90 or 180
of each other.
The adapter members 102 and 104 may also provide a radial offset relative to
the housing 108,
i.e., one or both contacts may be radially displaced from a centerline of the
fuse 106 by
unequal distances. It will be appreciated that the adapter members 102 and 104
may take on
various configurations to provide for contact positioning to allow the fuse to
be fitted to the
non-standard mounting. Also, while the assembly 140 and contact 136 are shown
fixed
relative to the sleeve 130, the assembly 140 may be made adjustable along the
sleeve 130. In
this manner, the distance between the contact 120 and 136 may be field
settable. For example,
the assembly 140 may have an annular collar configuration slidable along the
sleeve 130 with a
suitable fastener to secure it to the sleeve 130 at the desired location. The
fastener or another
portion of the assembly 140 may be made to engage the conductive layer 132 to
provide
electrical conductivity between the contact 136 and the ferrule 118.
[0020] With reference to Fig. 3, for the convenience of the installer, a kit
200 may
include an installation adapter 202 packaged together with a fuse 204 and use
instructions 206.
The installation adapter 202 may configured as described above for the
installation adapter 100
and thus it may include first and second adapter members 208 and 210, although
in certain
applications only one of the two adapter members may be required. The
installation
instructions inform the installer how to properly adapt the fuse 204 using the
installation
adapter 202 for use in a non-standard mounting, and may further contain
various instructional
guidance and cautions.
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100211 An installation adapter as described herein may permit a fuse to be
installed in
a mounting for a different fuse. That different fuse may have differing
operational
characteristics than the fuse to be adapted to fit the mounting. Fig. 4
illustrates a fuse 300 that
may two distinct operating characteristics. For example, the fuse 300 may have
both a slow
acting, low fault current operating characteristic and a fast acting, high
fault current
characteristic. The fuse 300 may further incorporate solid arc extinguishing
material. In this
regard, the fuse 300 may be suitable for use replacing liquid power fuses used
in combination
with fault current limiting resistors.
100221 The fuse 300 may include a housing 302 that has a length extending from
a
first end 304 to a second end 306 and an interior space 308 having an interior
surface 310. An
arc extinguishing material 312, such as a solid arc extinguishing material
like boric acid or any
suitable arc extinguishing material, may be disposed on the interior surface
310 for at least a
portion of the length. A passageway 316 is formed in the arc extinguishing
material 312 and
extends within the arc extinguishing material longitudinally with respect to
the housing 302. A
fuse assembly 320 is disposed within the housing 302 and may have a portion
extending
through the passageway 316. The fuse assembly 320 may include a fusible
element assembly
322 and an arcing rod assembly 324 coupled to the fusible element assembly
322.
100231 The fusible element assembly 322 may have a fuse element 326 of having
a
first fault clearing rating coupled to link assembly 328 including a
releasable attachment
member 330. The fusible element assembly 322 is secured within the interior
space 310
adjacent the first end 304.
100241 The arcing rod assembly 324 (Fig. 5) may include a drive mechanism 332
including a drive spring 333 coupled to a head structure 335 of an elongate
arc rod 334. The
arc rod 334 may include a coupling member 336 that releasable secures to the
attachment
member 330. The arc rod 334 may further include an auxiliary fuse element 338
having a
second fault clearing rating that is different than the first fault clearing
rating. The arcing rod
assembly 324 is secured within the interior space 310 between the first end
304 and the second
end 306. The arc rod assembly 324 includes a portion that extends through the
passageway
316, and the coupling member 336 is releasably coupled to the releasable
attachment member
330. For example, the releasable attachment member 330 may be a hook and the
coupling
member 336 may be a loop sized to engage the hook. The drive mechanism 332 is
configured
to impart a driving force via the spring 333 and head assembly 335 on the
arcing rod assembly
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324 to move the arcing rod assembly 324 within the housing 302 toward the
second end 306
during operation of the fuse.
[0025] The arcing rod assembly 324 may include a first wire portion 340 and a
second wire portion 342, the second wire portion forming at least a portion of
the auxiliary fuse
element 338. The first wire portion 340 and the second wire portion 342 may be
coupled by a
mechanical compression fastener 344 or another suitable fastener such that
they are
mechanically and electrically coupled. Each of the first wire portion 340 and
the second wire
portion 342 may be lengths of a suitable conductive, fusible wire. For
example, each of the
first wire portion and the second wire portion may be lengths of nichrome wire
(copper wire or
silver wire). The diameter of the second wire portion 342 may be made smaller
in the range of
about 0.5 mm to about 1.0 mm than the diameter of the first wire portion 340
in the range of
about 1.2 mm to about 3.0 mm such that when exposed to the a fault current,
the second wire
portion 342 melts in a controlled manner, while the first wire portion 340
remains substantially
intact.
[0026] As indicated, the fuse 300 may have dual operating characteristics. The
dual
operating characteristics may be provided by configuring the fuse element 326
with a first
operating characteristic. For example, the fuse element 326 may have a low
current, slow
acting fault protection characteristic in the range of about 1 ampere to about
50 amperes
operating in about 30 milliseconds to about 1 second. The auxiliary fuse
element 338 may
have a second operating characteristic that is different than the first
operating characteristic.
For example, the auxiliary fuse element 338 may respond quickly to high
current faults such as
in the range of 50 amperes to about 500 amperes in about 10 milliseconds to
about 30
milliseconds.
[0027] Upon action of either the fuse element 326 or the auxiliary fuse
element 338
in response to a fault current, for example, the melting of the fuse element
326 or the second
wire portion 342, the arcing rod assembly 324 is separated from the fusible
element assembly
322. The drive mechanism 332 drives the arcing rod assembly toward the second
end 304, and
hence draws the first and second wire portions 340 and 342 through the
passageway 316. A
resulting arc is extended within the passageway 316 and is extinguished by the
arc
extinguishing material 312. Under higher magnitude fault conditions, e.g. 50 ¨
500 amperes,
auxiliary fuse element 326 melts almost instantaneously and because of its
long length the
elongation of the arc is greatly accelerated and thus allows the current to be
extinguished much
more quickly. The second wire portion may be made to have a diameter of about
0.5 mm to
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about 1.0 mm. Correspondingly, the passageway diameter may be about 3.0 mm to
about 5.0
mm.
[0028] While the present disclosure is susceptible to various modifications
and
alternative forms, certain embodiments are shown by way of example in the
drawings and the
herein described embodiments. It will be understood, however, that this
disclosure is not
intended to limit the invention to the particular forms described, but to the
contrary, the
invention is intended to cover all modifications, alternatives, and
equivalents defined by the
appended claims.
[0029] It should also be understood that, unless a term is expressly defined
in this
_____________________________________________________________ patent using the
sentence "As used herein, the term' 'is hereby defined to mean..." or a
similar sentence, there is no intent to limit the meaning of that term, either
expressly or by
implication, beyond its plain or ordinary meaning, and such term should not be
interpreted to
be limited in scope based on any statement made in any section of this patent
(other than the
language of the claims). To the extent that any term recited in the claims at
the end of this
patent is referred to in this patent in a manner consistent with a single
meaning, that is done for
sake of clarity only so as to not confuse the reader, and it is not intended
that such claim term
by limited, by implication or otherwise, to that single meaning. The scope of
the claims
should not be limited by the preferred embodiments set forth in the examples
above but should
be given the broadest interpretation consistent with the Description as a
whole.
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