Note: Descriptions are shown in the official language in which they were submitted.
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SWITCH ASSEMBLY FOR HIGH VOLTAGE OVERHEAD LINES
The present invention relates to a switch assembly for high voltage overhead
lines.
Switch assemblies are, as a rule, constructed so that one and the same stand
supports either a circuit breaker or a circuit disconnector, both of which are
provided with a supporting insulator. This results generally in a simple and
inexpensive stand construction with associated operating means. On the other
hand, a relatively large amount of space is required when each function has
its
own stand, which results in a considerable total area for the switchgear as a
whole. This large total ground area required by the switchgear is
disadvantageous
when land prices are high, when space is limited and when preparation of the
ground is very demanding. The costs entailed by assembly and foundation work
are also very high.
It is known from FR 2 661 568 published October 31, 1991, to mount a circuit
breaker and a circuit disconnector on a common frame, as illustrated in Figure
4 of
this prior publication. However, this known construction does not afford any
appreciable reduction in space requirements for several reasons. For instance,
the
disconnectors and circuit breakers are not mounted in a manner that is
beneficial
in this respect. The construction also requires a stand that includes several
widely
spaced anchoring points. The large amount of ground space required by this
stand
makes it difficult to achieve a compact switchgear lay-out, particularly when
wishing to maintain accessibility for service vehicles and the like between
the rows
of stands. Because the stand taught by this publication requires a plurality
of
anchorage points, it affords no appreciable reduction in foundation costs. It
is also
thought that correct erection of the stand would be difficult to achieve and
entails
costly assemblage. Corresponding constructions are also known from US-A4 541
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033 issued September 10, 1985 and DE-C-693 808 issued June 1940, although
these constructions are also encumbered with corresponding drawbacks with
regard to space requirements.
The object of the present invention is to provide a switch assembly for high
voltage
overhead lines that reduces the total space requirement and also brings down
assembly costs, with the intention of providing switchgear that covers a
smaller
area and improves the total economy.
Because both circuit breaker and circuit disconnector are mounted on one and
the
same stand with one single support base, the number of stands required in a
single switchgear is reduced to a minimum in comparison with conventional
techniques, while a switch assembly having such a stand will, in itself, be
space
saving and easier to erect.
According to one preferred embodiment of the invention, the stand also carries
a
current meter and earthing means, therewith also contributing to structural
compactness.
The disconnectors are preferably mounted on and carried by the circuit
breakers.
This obviates the need for separate disconnector supporting insulators and
disconnector stand members, therewith further contributing towards a compact
switch assembly.
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The disconnectors are preferably maneuvered by obliquely directed
maneuvering insulators that extend from the operating end of each
disconnector down to a central part of the stand.
In another preferred embodiment, the stand support base comprises
a base plate that can be adjusted both vertically and angularly.
This enables the switch assembly to be readily aligned correctly
in relation to the overhead high voltage lines.
The disconnectors may conveniently have a pantograph configura-
tion and may be disposed in selected angular positions relative
to remaining parts of the switch assembly, therewith affording a
high degree of flexibility in configuring the switchgear lay-out.
When the switch assembly includes current meters, preferably
optical current meters, said meters will preferably be mounted on
the circuit breaker in a manner such that the current path
between circuit breaker and circuit disconnector will pass solely
through the current meter while insulating said circuit breaker
and disconnector from one another in other respects.
These embodiments and other preferred embodiments of the inven-
tion will be apparent from the depending claims.
The invention will now be described in more detail with reference
to a detailed description of preferred embodiments thereof and
also with reference to the accompanying schematic drawings, in
which
Figure 1 is a side view of a first embodiment of an inventive
switch assembly;
Figure 2 is a side view of a second embodiment of an inventive
switch assembly;
Figure 3 is a side view of a third embodiment of an inventive
switch assembly;
Figure 4 is an end view of the switch assembly shown in Figure 3;
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Figure 5 is an end view similar to that of Figure 4 but illu-
strating a fourth embodiment of an inventive switch assembly;
Figure 6 illustrates a fifth embodiment of an inventive switch
assembly schematically and from above;
Figure 7 illustrates the base on which the switch assembly stand
is supported;
Figure 8 is a detailed illustration of part of the base shown in
Figure 7;
Figure 9 is a side view illustrating the connection between
circuit breaker and disconnector in one embodiment of the
inventive switch assembly; and
Figure 10 is a sectional view taken on the line X-X in Figure 9.
The invention is illustrated schematically in the drawings and
components that are irrelevant to the invention have been omitted
for clarity reasons.
The switch assembly illustrated in Figure 1 has a stand 1 that
includes a central member 2 and two obliquely extending members
3 and 4. The stand members are typically steel lattice structures
and extend from the lower end of the central stand member to an
support base 5 in the form of a base plate anchored to a ground
foundation 6. The upper part of the stand includes supporting
insulators, including a central supporting insulator 7 connected
to the central stand member 2 and two supporting insulators 8 and
9 disposed on respective sides of the central supporting insula-
tor 7 and connected to a respective obliquely extending stand
member 3 and 4. The central supporting insulator 7 carries a two-
element circuit breaker with the two breaker elements 10 and 11
disposed in a T-shaped mount. Each of the breaker elements 10, 11
carries on its outer end a respective circuit disconnector 12 and
13, which are supported by the side-related supporting insulators
8 and 9. The disconnectors 12, I3 are of a pantograph kind and
are shown in a connected mode in which they are in contact with
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respective insulated conductors of the high voltage line. The
supporting insulators are made typically of porcelain or polymer-
ic material. The disconnector 12 shown on the left of Figure 1 is
connected electrically to a corresponding circuit breaker element
5 10 by a conductor 16, and a current meter 17 is disposed in a
corresponding conductor for the right-hand disconnector (hidden
in the Figure). An earthing switch 18, 19 is connected to each
disconnector 12, 13.
The switch assembly includes operating means and signal transmis-
sion means, wherein operating means for coaction with the breaker
elements 10 and 11 are disposed within the central supporting
insulator 7 and extend down to a circuit breaker maneuvering unit
attached to the central stand member 2. The operating means of
15 each disconnector 12, 13 includes a respective operating switch
21 and 22 which are connected to a respective disconnector
maneuvering unit through the medium of maneuvering insulators
(not shown) and arms 23, 24 that extend parallel with respective
supporting insulators 8, 9. The disconnector is maneuvered by
20 turning its lower end, its maneuvering end, around a geometric
line that extends in the longitudinal direction of the circuit
breaker, so as to twist the disconnector in a plane perpendicular
to the plane of the paper and bend the disconnector at its pivot
point 27 and 28 respectively, therewith moving the upper end of
the disconnector, its contact end, out of contact with its
respective line conductor 14 and 15.
The current meter 17 is preferably an optical meter, and signal
transmission means 29 comprising optical fibers extends to the
lower part of the stand. The earthing switch 18, 19 is operated
from earthing units 30 and 31 via respective movement transmis-
sion means 32, 33 and 34, 35.
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The stand 1 is provided with lifting devices 60, 61 that enable the stand to
be lifted.
The illustrated lifting devices have the form of hollow beam elements that are
dimensioned and mutually spaced to accommodate the times of a fork-lift truck.
Alternatively, the lifting devices may be constructed specifically for
coaction with a
service trolley designed to this end.
It will be evident from Figure 1 that the entire switch assembly is
symmetrical in
the plane of the paper in relation to a vertical line drawn through the base
plate 5
and the central stand member 2. The switch assembly is also substantially
symmetrical in relation to the plane of the paper. The centre of gravity of
the
assembly thus lies centrally above the base plate 5, therewith providing
optimal
stability and facilitating lifting and transportation of the assembly.
The main difference between the embodiment illustrated in Figure 2 and that
illustrated in Figure 1 resides in the fact that each disconnector 12a, 13a is
supported by a respective breaker element 10a, 11a and their central
supporting
insulator 7a and the central stand member 2a on support base 5a. This
embodiment takes a further step towards providing a switch assembly that is as
compact as possible, by virtue of eliminating the side-related stand members
3, 4
of the Figure 1 embodiment and the separate disconnector supporting insulators
8,
9. The disconnectors 12a, 13a are maneuvered by maneuvering insulators 36, 37
which extend obliquely downwards from respective disconnectors to the central
stand member 2a and in which there are disposed movement transmission means
that connect with respective disconnector maneuvering units 40, 41 through the
medium of conductive arms 38, 39. The maneuvering insulator also
accommodates optical cables for transmitting signals from the current meters.
The earthing switches 42, 43 are operated from the units 46, 47 through the
medium of said arms 44, 45. Thus, all operating units and signal receiving
units
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required by the switch assembly are concentrated at the central
stand member 2a.
The embodiment of the switching assembly illustrated in Figure 3
is a slightly modified version of the embodiment illustrated in
Figure 2, with certain elements omitted. The Figure 3 embodiment
differs from the Figure 2 embodiment insomuch that one discon-
nector 12b defines an angle a with the horizontal plane instead
of being perpendicular thereto as in the previously described
embodiments. The disconnector 12b is shown in its collapsed,
disconnected position in full lines, and in its extended position
in broken lines. In the Figure 3 embodiment, the angle a lies in
a vertical plane through the longitudinal axis of the breaker
elements 10b, 11b, i.e. in the plane of the paper. Alternatively,
the disconnector may be angled in a plane extending perpendicular
to the plane of the paper in Figure 3. Figure 4 is a side view of
the switch assembly shown in Figure 3, with the disconnector 13b
shown in an upwardly extending position in contact with the high
voltage line and the disconnector 12b in a collapsed, disconnect
ing position.
Figure 5 shows an alternative in which the disconnector 12c is
angled at an angle !3 in the plane perpendicular to the plane in
which the disconnector 12b in Figure 3 is angled. Another
modification is one in which the disconnector is angled in both
of said planes, i.e. at both a and !3 angled other than 90°.
All of the aforedescribed angular positions in which a
disconnector may be mounted assume that the disconnector will
move in a direction that lies in a plane perpendicular to the
plane of the paper in Figure 3 when maneuvered. In a modified
version, the direction of movement may conceivably lie in a plane
that has an angle y other than a right angle to the plane of the
paper in Figure 3. This alternative is illustrated schematically
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in Figure 6, which shows the circuit breaker from above and the
disconnector 13d in a collapsed state, wherein only one part of
the disconnector is shown. The plane in which the disconnector
moves defines an angle y with the centre line through the circuit
breaker.
Figure 7 is a detailed illustration of the base plate 5 of the
support base. The base plate is firmly attached to the support
base 6 by means of a number of bolts 48 which are moulded in the
support base and enable the base plate 5 to be adjusted vertical-
ly and angularly. The manner in which this is achieved will be
apparent from Figure 8, which is a detailed view of the bolt
adjusting means. The vertical position of the base plate is
adjusted by screwing down or backing off an externally threaded
bush 49 into or out of the base plate, whereafter the base plate
is fixed in its adjusted position by tightening a nut 50.
Figures 9 and 10 illustrate in more detail the manner of connec-
tion between disconnector and associated breaker element 10a in
an embodiment in which the disconnector is carried by the
breaker . A current conducting bar is rigidly connected to the end
terminal 52 of the breaker element 10a by means of a joint 54.
The bar 53 is firmly fixed to the disconnector operating switch
21 via an insulating insert 56, and is connected electrically to
one end of the current meter 17. The other end of the current
meter is electrically connected to a second conductor bar 55
which is connected to the disconnector operating switch 21 and
also to the disconnector itself. The conductor bars 53, 55 thus
have the double function of leading current to the circuit
breaker and the disconnector through the current meter and also
of supporting the disconnector and the current meter.
