ACCIDENTAL ARC DETECTOR FOR ELECTRIC POWER DISTRIBUTION SWITCHING EQUIPMENTS

DETECTEURS D'ARCS ACCIDENTELS SE PRODUISANT DANS DES INSTALLATIONS DE COMMUTATION UTILISEES POUR LA DISTRIBUTION D'ENERGIE ELECTRIQUE

English Abstract

The invention relates to a detector for accidental arcs in electric power
distribution switching equipments in which the detector consists of at least
one light guide in which the light generated by the arc and reaching it via
its casing is used as a triggering or warning factor. The detector is intended
to permit the break-protected fitting of the light guide in a switching
equipment. This is achieved in that the detector (1) consists of a support rod
(2), a light guide (3) wound helically around the support rod (2) and two plug
connectors (4) fitted at the ends of the support rod for connection to opto-
electronic components, and the detector (1) also consists of a light and u/v
radiation-permeable heat-shrink sleeve (5) fitted over the support rod (2),
the light guide (3) and the plug connectors (4).

French Abstract

La présente invention concerne un détecteur d'arcs accidentels dans des installations de commutation servant à la distribution d'énergie électrique. Ce détecteur comprend au moins un guide d'ondes lumineuses dans lequel la lumière générée par l'arc et qui atteint le détecteur par son gainage est utilisée comme facteur de déclenchement et d'alarme. Le détecteur doit permettre d'installer le guide d'ondes dans une installation de commutation de manière à éviter tout risque de rupture. A cette fin, le détecteur (1) comprend une barre d'appui (2), un guide d'ondes lumineuses (3) à enroulement hélicoïdal autour de la barre d'appui (2) et deux connecteurs à fiches (4) fixés aux extrémités de la barre d'appui pour permettre le branchement de composants opto-électroniques. Le détecteur (1) comprend aussi une gaine thermorétractable (5) perméable à la lumière et aux rayons ultraviolets, passée par dessus la barre d'appui (2), le conducteur de lumière (3) et les connecteurs à fiches (4).

Claims

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Claims
1. Detector for accidental arcs in electric power
distribution switching equipment, whereby the detector
consists of at least one optical waveguide in which the
light generated by an accidental arc and reaching it
radially via its casing is used as a triggering or
warning criterion, whereby in addition the optical
waveguide is located in the vicinity of live parts,
characterized by the fact that the detector (1) consists
of a support rod (2), an optical waveguide (3) wound
helically around the support rod (2), two plug
connectors (4) located at the ends of the support rod
for connection to optoelectronic components, and that
the detector (1) also consists of a heat-shrink sleeve
(5) which is permeable to light and to UV radiation and
is fitted over the support rod (2), the optical
waveguide (3) and the plug connectors (4).
2. Detector as claimed in Claim 1, characterized by the
fact that the plug connectors (4) each consist of a
first part (6) and a second part (7), that the first
part (6) has a cavity (8) into which the end of the
support rod can be introduced, that on the outer end
there is a second part (7) which is provided with a
diameter which is significantly smaller than the first
part (6), and that the cavity (9) of the second part
tapers toward the end to a diameter which is
approximately equal to the diameter of the optical
waveguide.

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3. Detector as claimed in Claim 1 or 2, characterized by
the fact that the optical waveguide (3) is guided in the
vicinity of the plug connector (4) through a boring (10)
which runs diagonally from the outer surface to the
center of the support rod (2), so that on the end, the
optical waveguide (3) runs parallel to and is centered
in relation to the support rod (4).
4. Detector as claimed in one of the preceding claims,
characterized by the fact that the support rod (2) is
flexible.

Description

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Accidental arc detector for electric power switching
equipment
This invention relates to a detector as described in the pre-
characterizing portion of Claim 1.
DD 271 397 Al describes an optical waveguide accidental arc
detector of the prior art which is located in the vicinity of
power supply buses without any special mountings. Figure 2 of
this prior art publication shows the optical waveguide
accidental arc detector in contact against both narrow sides
of a bus bar which has a rectangular cross section. This
prior art publication, however does not indicate in any
additional detail how the optical waveguide can be fastened
to the bus bar. In Figure 3 of the above-referenced prior art
publication, the optical waveguide is wound around the bus
bar. In this arrangement, there is a danger that the optical
waveguide can break, in particular at the points of contact
with the corners of the bus bar, or in the areas near these
corners. This arrangement also results in a severe
restriction of the bonding surface of the bus bar.
There are also disadvantages to a direct surface mounting of
the optical waveguide, as described in further detail in DE
43 31 716. This prior art publication also illustrates and
describes various arrangements of an optical waveguide
accidental arc detector.
Figure 1 shows an arrangement in which the optical waveguide
is oriented essentially vertically and is wound around the
three bus bars. Disadvantages of this arrangement are that
the distance from the point of origin of an accidental arc
can be different, and that the accidental arc does not always
occur in the vicinity of the detector.
With the meandering orientation illustrated in Figure 3, of
course, the latter phenomenon cannot occur, but there is

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always a danger, as with all other orientations, that the
relatively thin and barely visible optical waveguide may be
damaged during installation or other activities.
The invention also teaches that the optical fibers are located
on bulkheads and other flat contact surfaces in the vicinity
of the bus bar, in which case the optical waveguide can be
fastened by means of adhesive or by fastening elements such
as fastening lugs or spacers.
One problem with this arrangement is that bulkheads or similar
elements are not always located close enough.
DD 271 397 A1 describes an optical waveguide accidental arc
detector of the prior art which is located in the vicinity of
power supply buses without any special mountings. Figure 2 of
this prior art publication shows the optical waveguide
accidental arc detector in contact against both narrow sides
of a bus bar which has a rectangular cross section. This
prior art publication, however does not indicate in any
additional detail how the optical waveguide can be fastened
to the bus bar. In Figure 3 of the above-referenced prior art
publication, the optical waveguide is wound around the bus
bar. In this arrangement, there is a danger that the optical
waveguide can break, in particular at the points of contact
with the corners of the bus bar, or in the areas near these
corners. This arrangement also results in a severe
restriction of the bonding surface of the bus bar.
There are also disadvantages to a direct surface mounting of
the optical waveguide, as described in further detail in DE
43 31 716. This prior art publication also illustrates and
describes various arrangements of an optical waveguide
accidental arc detector.
Figure 1 shows an arrangement in which the optical waveguide
is oriented essentially vertically and is wound around the

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three bus bars. Disadvantages of this arrangement are that
the distance from the point of origin of an accidental arc
can be different, and that the accidental arc does not always
occur in the vicinity of the detector.
With the meandering orientation illustrated in Figure 3, of
course, the latter phenomenon cannot occur, but there is
always a danger, as with all other orientations, that the
relatively thin and barely visible optical waveguide may be
damaged during installation or other activities.
The invention also teaches that the optical fibers are
located on bulkheads and other flat contact surfaces in the
vicinity of the bus bar, in which case the optical waveguide
can be fastened by means of adhesive or by fastening elements
such as fastening lugs or spacers.
One problem with this arrangement is that bulkheads or similar
elements are not always located close enough.
The object of the invention is therefore to create a detector
as described in the pre-characterizing portion of Claim 1
which makes it possible to lay the optical waveguide in
electrical switching equipment so that the optical waveguide
is protected against breaking.
The invention teaches that this object is achieved by the
features disclosed in the characterizing portion of Claim 1,
while particularly advantageous refinements of the invention
are described in the subclaims.
The invention teaches that it is easily possible to protect
the optical waveguides, and that unexpectedly, there is no
significant adverse effect on the optical characteristics of
the detector.

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The invention, additional embodiments and improvements to the
invention and additional advantages are described and
explained in greater detail below with reference to the
embodiment illustrated in the accompanying drawings, in which:
Figure 1 is an illustration of the detector, and
Figure 2 is an illustration of the plug connector.
Figure 1 shows the detector 1. The detector 1 consists of a
flexible support rod 2 which has a diameter of approximately
4 mm, an optical waveguide 3 which is wound in a spiral
fashion around the support rod 2, and two plug connectors 4
which are located on the ends of the support rod for
connection to optoelectronic elements. The detector 1 also
consists of a heat- shrink sleeve 5 which is permeable to
light and W radiation, and which is fitted over the support
rod 2, the optical waveguide 3 and the plug connectors 4.
The heat-shrink sleeve 5, before installation, has a diameter
which i6 larger than the diameter of the support rod 2. When
heat is applied, the diameter of the heat-shrink sleeve
decreases so that the optical waveguide 3 which is located
between the support rod 2 and the shrink-fitted hose 5 is
clamped in position.
In this manner, the optical waveguide is protected against
mechanical damage. The surface of the optical waveguide is
also protected from dirt. The dirt collects on the surface of
the heat-shrink sleeve 5 instead.
The heat-shrink sleeve 5 can be perforated over its entire
length.
The two plug connectors 4 each consist of a first part 6 and
a second part 7.

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The first part 6 has a cavity 8 into which the end of the
support rod can be introduced. The diameter of the
rotationally symmetrical first part 6 is approximately 2 mm
larger than the diameter of the support rod. The inside
diameter of the cavity 8 is 4.2 mm, so that the support rod 2
can be introduced with a clearance of 0.2 mm.
The second, also rotationally symmetrical part 7 located on
the outer end is provided with a diameter which is
significantly smaller than the first part 6. This diameter is
a function of the size of the socket of an optical coupling
device connection.
The cavity 9 of this part 7 tapers toward the end to a
diameter of approximately 0.3 mm, i.e. approximately the
diameter of the optical waveguide.
In the vicinity of the plug connector, the optical fiber is
guided through a boring 10 which runs diagonally from the
outside surface to the center of the support rod, so that on
the end, the optical waveguide runs parallel to and is
centered in relation to the support rod 4.
Nomenclature
Detector
Support rod 2
Optical waveguide 3
Plug connector 4
Heat-shrink sleeve 5
Part 6 (first part)
Part 7 (second part)
Cavity 8, 9
Boring 10

Representative Drawing