Title of Invention	CONTACT SYSTEM FOR A SHORT-CIRCUITING DEVICE IN A MEDIUM-VOLTAGE OR HIGH-VOLTAGE SWITCHBOARD PLANT
Abstract	The invention relates to a contact system for a short- circuiting device in a medium-voltage or high-voltage switch-board plant, comprising one stationary contact piece (10) each per phase, connected to the mains voltage (high voltage or medium voltage), and one mobile contact piece (36, 43) each per phase. Every stationary contact piece (31) is surrounded by an insulating material which the mobile contact piece (36, 43) is able to penetrate when the contact is closed.

Title of Invention

CONTACT SYSTEM FOR A SHORT-CIRCUITING DEVICE IN A MEDIUM-VOLTAGE OR HIGH-VOLTAGE SWITCHBOARD PLANT

Abstract

The invention relates to a contact system for a short- circuiting device in a medium-voltage or high-voltage switch-board plant, comprising one stationary contact piece (10) each per phase, connected to the mains voltage (high voltage or medium voltage), and one mobile contact piece (36, 43) each per phase. Every stationary contact piece (31) is surrounded by an insulating material which the mobile contact piece (36, 43) is able to penetrate when the contact is closed.

Full Text	Contact system for a short-circuiting device in a medium-voltage or high-voltage switchboard plant Description The invention relates to a contact system according to the pre-characterizing clause of Claim 1. Electrical switchboards for voltages in the range from 1 to 52 kV, which range is generally described as the medium-voltage range, are designed in the form of metal-encapsulated gas-insulated switchboards, see DE 43 02 416, in which load isolating switches, earthing switches and fuses are accommodated as functional units. When an arcing fault occurs in a switchboard of this kind, the effects of the arcing fault must be kept to a minimum. If the combustion time of such an arcing fault is appropriately long, the pressure and temperature within the switchboard can increase to such an extent that the metal encapsulation can burst or melt; in order that persons are not injured or even killed as a result of an uncontrolled outflow of heated gas into the room in which the switchboard is located, with many switchboards so-called designated breaking points are provided in the housing encapsulation through which, in the event of their breakage, the heated gas flows out in a controlled manner in a certain defined direction so that any operating personnel who may be in the room are not injured. A switchboard is available on the market, see also DE 31 31 417, in which a short- circuiting device is provided, which on the occurrence of an arcing fault short circuits the phases or connects them to earth so that the short circuit is diverted as soon as it occurs and the effects of the arcing fault on the interior of the switchboard are limited. For this purpose, this switchboard has a pressure sensor, which by means of a storage spring gearbox brings moving switching contact pieces, which are designed in the form of contact blades, into contact with fixed contact pieces situated on the phase conductors, the drive being designed as a spring drive; the pressure sensor acts on a latching point, which releases the drive spring and thus drives the moving contact pieces into the fixed contact pieces at high speed, as a result of which the phases are short- circuited thus suppressing the arc. With this switchboard, the fixed contact pieces are exposed within the switchboard so that certain distances have to be maintained between the fixed contact pieces and the earthed encapsulation. As a basic principle, there is a requirement to make switchboards of this type as compact as possible, as the available space is limited and therefore expensive. The object of the invention is to design the fixed contact pieces of the contact system, which are at high voltage or medium voltage, in such a way that the distance between the contact pieces and the encapsulation or between the contact pieces themselves can be kept as small as possible. According to the invention this problem is solved by the characteristics of Claim 1. Accordingly, the invention consists in each at least one fixed contact piece being assigned a screen of insulating material, which can be penetrated by the moving contact piece to make contact with the fixed contact piece when the contact is switched on, the screen being arranged between the fixed and moving contact piece. The particular advantage of the invention consists in a compact contact system for a switchboard being produced as a result of the embodiment according to the invention so that overall the switchboard itself has a smaller space requirement. At the same time, the arrangement of the screen of insulating material is chosen so that it is situated between the at least one fixed contact piece and the moving contact piece so that, when the moving contact piece approaches the at least one fixed contact piece, this does not give rise to a switch-on arc at an early stage. According to an advantageous embodiment, the screen can be designed so that at least the part of the insulating material, which lies in the movement path of the moving contact piece, is soft so that the contact piece can penetrate the material. Of course, it is also possible for the insulating material to be hard, in which case it is important however that the thickness of the part, which lies in the movement path of the moving contact piece, is dimensioned in such a way that the moving contact piece can break through this section. According to a further advantageous embodiment, the screen can also be formed by a hinged door or flap, which can be pushed open by the moving contact piece. The moving contact piece must then be designed so that it can easily penetrate the insulating material. In a preferred manner, the moving contact piece can be designed so that it tapers towards its free end, wherein, this taper can be in the form of a cone. It is also possible that the tip, that is to say the free end, of the moving contact piece is rounded in an approximately hemispherical manner. According to a particularly advantageous embodiment of the invention, the at least one fixed contact piece can be surrounded by a tubular cylinder on which the penetrable or hinged insulating material is arranged. If the fixed contact piece is mounted on one end of a rigid conductor or is formed by its face surface, the tubular cylinder can extend beyond the fixed contact piece and be closed by the penetrable insulating material at its free end. In this case, the space inside the fixed tubular cylinder in which the fixed contact piece is located can be filled with insulating fluid, e.g. with liquid, in particular with insulating oil. According to a particularly advantageous embodiment of the invention, the insulating material assigned to the fixed contact piece can have an electrically conducting coating as an electrical screen and/or field control. When the tubular cylinder is provided, the electrically conducting coating can be arranged inside the tubular cylinder. Advantageous embodiments and improvements of the invention can be seen in the further dependent claims. The invention as well as further advantageous embodiments and improvements and further advantages of the invention are explained and described in more detail with reference to the drawing, in which two exemplary embodiments of the invention are shown. In the drawings Fig. 1 shows a schematic representation of a switchboard in which the invention is realized, Fig. 2 shows a first embodiment of the invention, and Figs 3 and 4 show two further embodiments of the invention. A switchboard 10 has a metal housing 11, which is shown only schematically, the interior 12 of which is filled with an insulating gas, for example with SF6 gas. Feed conductors 13 and 14 feed into the switchboard via suitable ducts, while an outgoing conductor 15 is arranged between the two feeds 13, 14. Load isolating switches 16, 17 and 18 are arranged in the feed and outgoing conductors 13 to 15. Furthermore, short- circuit switches 19, 20 and 21 are provided, which are actuated by a latching mechanism 23, the latching mechanism 23 having a latching point, which can be released by a sensor 24. In normal operation, the load isolating switches 16 and 18 may be closed; as a result, current flows into the switchboard via the feed conductor 13 and out of the switchboard via the outgoing conductor 15, for example to a transformer, which transforms the medium voltage into low voltage. Naturally it is also possible that the switches 17, 18 are closed and the switch 16 is open. The current then flows into the switchboard and out of the switchboard via the feed conductor 14 and the outgoing conductor 15. Of course it is also possible that the conductors designated with 13 and 15 form the feed conductors and the conductor 14 the outgoing conductor from the switchboard; this depends on the external and internal circuit. Such a. circuit arrangement has also become known as a so-called Ring Main Unit, and is marketed by the company ABB AS, Division Kraftprodukter, Skien, Norway. If an arcing fault 22 occurs in a switchboard of this kind, the temperature of the insulating gas within the switchboard 10 and therefore its pressure increase so that, unless suitable measures are taken, the switchboard can explode, on account of which the switchboard can have designated breaking points according to DE 36 06 770 for example, by means of which the hot gas can flow out in a systematic and controlled manner. With the system according to Fig. 1, which does not have a designated breaking point of this kind, the increase in pressure is detected by means of a pressure sensor 24, which releases the latching point in the latching mechanism 23 and thus closes the switches 19, 20 and 21, which are open in the normal state. This produces a short circuit between the individual phases by means of which the arc 22 is diverted; because of the short circuit produced in this way, a superimposed switch, for example a circuit breaker, trips. In the case of the Ring Main Unit switchboard produced by the company ABB AS, Division Kraftprodukter, Skien, Norway, the individual switches 19, 20 and 21 are designed as blade contact switches; these blade contact switches engage in contact blade receptacles, as a result of which considerable space-saving is achieved. A reduction in the space required is effected with the embodiments according to the invention. Connected to the feed and outgoing conductors 13, 14 and 15 is a rigid conductor 30, to the face side of which a fixed contact piece 31 in the shape of a tulip connector is fixed by means of a screw fastener 32. The rigid conductor 30 and the fixed contact piece 31 are surrounded by a cylindrical tube 33, which extends beyond the fixed contact piece 31 and is closed at its free end by means of a cap 34. The cylindrical tube is made of an insulating material, which if necessary can be coated on its outside with electrically conducting material in order to improve the field line characteristic. Here, the sealing cap 34 is set into or let into a recess 35. In the embodiment according to Fig. 2 the cap 34 is made of silicone material; naturally it is also possible to make the cap from a rigid material. It is naturally also possible to provide the coating with electrically conducting material on the inside of the cylindrical tube or tubular cylinder 33, wherein furthermore the coating also continues in the area of the recess 35. Assigned to the fixed contact piece 31 is a moving contact piece 36, which is pushed towards the fixed contact piece 31 in the direction of the arrow P when the contact switches on. In order that the moving contact piece 36 can penetrate the cap 34, the tip 37 of the moving contact piece 36 is designed in the form of a cone with a tip 38. In this case, the moving contact piece is connected to earth. It must be added that in each case there is a total of one contact point per phase as shown in Fig. 2 for each feed and outgoing conductor. By means of the moving contact piece 36 the individual phases can be connected to earth or a phase short circuit produced, which can likewise be interrupted by a superimposed circuit breaker. To improve the electrical field, the moving contact piece is surrounded by a cylindrical tube 39 made from electrically conducting material in which the moving contact piece 36 slides; the end of the cylindrical tube 39 facing the fixed contact piece 31 has a peripheral bead 40 on the outside, by means of which the electrical field is uniformly distributed in the area of the contact point shown in Fig. 2. The moving contact piece 36 can also execute a circular movement. For this purpose, an L-shaped arm 41 is fixed to a rotating shaft 42, which arm 41 merges into a moving contact piece 43, which corresponds to the moving contact piece 36. A field control arrangement such as that shown in Fig. 2 is not shown in the case of the contact point according to Fig. 3. With the embodiment according to Fig. 2 a tulip connector 31 is fixed to the face of the contact piece 30; it is of course also possible to design the face of the rigid conductor in such a way that it forms a contact point with the moving contact piece, for example by making a cone-shaped depression in the face; in another embodiment the face could be flat and the tip of the moving contact piece hemispherical. In the embodiment according to Fig. 3, the conductor 30 is enclosed by a cylindrical tube 44, which has a base 45, the thickness of which is dimensioned so that it can be easily penetrated by the moving contact piece 43, which naturally can also be the contact piece 36. As an example, the cylindrical tube 33, 44 can be made of reusable thermoplastic polymer; the cap 34 can be made of a soft material such as silicone rubber for example, which allows the moving contact 36 to penetrate the cylindrical tube 33. The electrically conducting coating of the cylindrical tube is provided on the inside, particularly when the embodiments of the fixed contact piece are designed in a constructively simple manner. The embodiment according to the invention has been described with reference to an electrical switchboard; it is naturally also possible to install and use the invention in other installation systems. The inside of the cylinder 33 or 44 in which the tulip connector 31 is located can be filled with SF6 gas - like the environment - or with a liquid insulating material such as insulating oil or similar. It is naturally also possible to use the invention in such contact systems having two fixed contact pieces, which are bridged by one suitable moving contact piece to achieve a closure of the contact. In this respect the invention is not limited to contact systems such as those described in Figure 2 or Figure 3. In the embodiment according to Fig. 4 the cap is designed in the form of a flap 50, which is made of deformable material, and is fixed to the cylindrical tube 52 by a kind of film hinge 51; in the event of a short circuit, the flap 50 is opened by the moving contact piece and swiveled into the position 50a shown dotted. Such an arrangement is useful, particularly when a tulip connector such as the tulip connector 31 is not provided. The flap can also be designed in the form of a sliding plate, which is actuated by the moving contact piece. The term "insulating material", through which the moving contact piece passes, has the same meaning as the term "screen", as opposed to the term "electrical screen", which has the function of a field control. WHAT IS CLAIMED IS: 1. A contact system for a short-circuiting device for a medium-voltage or high-voltage switchboard (10), comprising at least one fixed contact piece (31) each per phase, connected to mains voltage (high voltage or medium voltage), and one moving contact piece (36, 43) each per phase, characterized in that each at least one fixed contact piece (31) is assigned a screen (34) of insulating material, which can be penetrated by the moving contact piece (36, 43) to make contact with the fixed contact piece (31) when the contact is switched on, the screen (34) being arranged between the fixed and moving contact piece (31; 36, 43). 2. The contact system as claimed in claim 1 or 2, characterized in that at least the part of the insulating material, which lies in the movement path of the moving contact piece (36, 43), is soft so that the contact piece (10) can penetrate the material. 3. The contact system as claimed in claim 1, characterized in that the insulating material is a hard material, the thickness of the part, which lies in the movement path of the moving contact piece (36, 43), being dimensioned in such a way that the moving contact piece (36, 43) breaks through this section. 4. The contact system as claimed in claim 1, characterized in that the part of insulating material, which lies in the movement path of the moving contact piece (36, 43), is designed as a door or flap (50), which can be pushed open by the moving contact piece (36, 43) . 5. The contact system as claimed in one of the preceding claims, characterized in that the moving contact piece (36, 43) tapers towards its free end. 6. The contact system as claimed in claim 5, characterized in that the moving contact piece (36, 43) is designed to taper towards its free end in the form of a cone. 7. The contact system as claimed in one of the preceding claims 1 to 4, characterized in that the tip of the moving contact piece is rounded in an approximately hemispherical manner. 8. The contact system as claimed in one of the preceding claims, characterized in that the at least one fixed contact piece (31) is surrounded by a tubular cylinder (33, 39, 44, 52) on which the penetrable material is arranged. 9. The contact system as claimed in claim 9 having a fixed contact piece, which is mounted on the end of a rigid conductor (30), characterized in that the tubular cylinder (33, 39, 44, 52) extends beyond the rigid conductor (30) and the fixed contact piece, and is closed by the penetrable insulating material at its free end. 10. The contact system as claimed in claim 9, characterized in that the space inside the fixed tubular cylinder (33, 39, 44, 52) in which the fixed contact piece (31) is located is filled with insulating fluid. 11. The contact system (10) as claimed in claim 10, characterized in that the space is filled with liquid, e.g. insulating oil. 12. The contact system as claimed in one of the preceding claims, characterized in that the insulating material assigned to the fixed contact piece is assigned an electrically conducting coating as an electrical screen and/or field control. 13. The contact system as claimed in claim 12, characterized in that the electrically conducting coating is arranged at least inside or outside the tubular cylinder (33, 35). 14. The contact system as claimed in one of the preceding claims, characterized in that the moving contact piece (36, 43) is mounted on a pivoted lever. The invention relates to a contact system for a short- circuiting device in a medium-voltage or high-voltage switch-board plant, comprising one stationary contact piece (10) each per phase, connected to the mains voltage (high voltage or medium voltage), and one mobile contact piece (36, 43) each per phase. Every stationary contact piece (31) is surrounded by an insulating material which the mobile contact piece (36, 43) is able to penetrate when the contact is closed.

Full Text

Contact system for a short-circuiting device in a
medium-voltage or high-voltage switchboard plant
Description
The invention relates to a contact system according to
the pre-characterizing clause of Claim 1.
Electrical switchboards for voltages in the range from
1 to 52 kV, which range is generally described as the
medium-voltage range, are designed in the form of
metal-encapsulated gas-insulated switchboards, see DE
43 02 416, in which load isolating switches, earthing
switches and fuses are accommodated as functional
units.
When an arcing fault occurs in a switchboard of this
kind, the effects of the arcing fault must be kept to a
minimum. If the combustion time of such an arcing fault
is appropriately long, the pressure and temperature
within the switchboard can increase to such an extent
that the metal encapsulation can burst or melt; in
order that persons are not injured or even killed as a
result of an uncontrolled outflow of heated gas into
the room in which the switchboard is located, with many
switchboards so-called designated breaking points are
provided in the housing encapsulation through which, in
the event of their breakage, the heated gas flows out
in a controlled manner in a certain defined direction
so that any operating personnel who may be in the room
are not injured. A switchboard is available on the
market, see also DE 31 31 417, in which a short-
circuiting device is provided, which on the occurrence
of an arcing fault short circuits the phases or
connects them to earth so that the short circuit is
diverted as soon as it occurs and the effects of the
arcing fault on the interior of the switchboard are
limited. For this purpose, this switchboard has a

pressure sensor, which by means of a storage spring
gearbox brings moving switching contact pieces, which
are designed in the form of contact blades, into
contact with fixed contact pieces situated on the phase
conductors, the drive being designed as a spring drive;
the pressure sensor acts on a latching point, which
releases the drive spring and thus drives the moving
contact pieces into the fixed contact pieces at high
speed, as a result of which the phases are short-
circuited thus suppressing the arc.
With this switchboard, the fixed contact pieces are
exposed within the switchboard so that certain
distances have to be maintained between the fixed
contact pieces and the earthed encapsulation.
As a basic principle, there is a requirement to make
switchboards of this type as compact as possible, as
the available space is limited and therefore expensive.
The object of the invention is to design the fixed
contact pieces of the contact system, which are at high
voltage or medium voltage, in such a way that the
distance between the contact pieces and the
encapsulation or between the contact pieces themselves
can be kept as small as possible.
According to the invention this problem is solved by
the characteristics of Claim 1.
Accordingly, the invention consists in each at least
one fixed contact piece being assigned a screen of
insulating material, which can be penetrated by the
moving contact piece to make contact with the fixed
contact piece when the contact is switched on, the
screen being arranged between the fixed and moving
contact piece.

The particular advantage of the invention consists in a
compact contact system for a switchboard being produced
as a result of the embodiment according to the
invention so that overall the switchboard itself has a
smaller space requirement.
At the same time, the arrangement of the screen of
insulating material is chosen so that it is situated
between the at least one fixed contact piece and the
moving contact piece so that, when the moving contact
piece approaches the at least one fixed contact piece,
this does not give rise to a switch-on arc at an early
stage.
According to an advantageous embodiment, the screen can
be designed so that at least the part of the insulating
material, which lies in the movement path of the moving
contact piece, is soft so that the contact piece can
penetrate the material. Of course, it is also possible
for the insulating material to be hard, in which case
it is important however that the thickness of the part,
which lies in the movement path of the moving contact
piece, is dimensioned in such a way that the moving
contact piece can break through this section.
According to a further advantageous embodiment, the
screen can also be formed by a hinged door or flap,
which can be pushed open by the moving contact piece.
The moving contact piece must then be designed so that
it can easily penetrate the insulating material. In a
preferred manner, the moving contact piece can be
designed so that it tapers towards its free end,
wherein, this taper can be in the form of a cone.
It is also possible that the tip, that is to say the
free end, of the moving contact piece is rounded in an
approximately hemispherical manner.

According to a particularly advantageous embodiment of
the invention, the at least one fixed contact piece can
be surrounded by a tubular cylinder on which the
penetrable or hinged insulating material is arranged.
If the fixed contact piece is mounted on one end of a
rigid conductor or is formed by its face surface, the
tubular cylinder can extend beyond the fixed contact
piece and be closed by the penetrable insulating
material at its free end.
In this case, the space inside the fixed tubular
cylinder in which the fixed contact piece is located
can be filled with insulating fluid, e.g. with liquid,
in particular with insulating oil.
According to a particularly advantageous embodiment of
the invention, the insulating material assigned to the
fixed contact piece can have an electrically conducting
coating as an electrical screen and/or field control.
When the tubular cylinder is provided, the electrically
conducting coating can be arranged inside the tubular
cylinder.
Advantageous embodiments and improvements of the
invention can be seen in the further dependent claims.
The invention as well as further advantageous
embodiments and improvements and further advantages of
the invention are explained and described in more
detail with reference to the drawing, in which two
exemplary embodiments of the invention are shown.
In the drawings

Fig. 1 shows a schematic representation of a
switchboard in which the invention is
realized,
Fig. 2 shows a first embodiment of the
invention, and
Figs 3 and 4 show two further embodiments of the
invention.
A switchboard 10 has a metal housing 11, which is shown
only schematically, the interior 12 of which is filled
with an insulating gas, for example with SF6 gas. Feed
conductors 13 and 14 feed into the switchboard via
suitable ducts, while an outgoing conductor 15 is
arranged between the two feeds 13, 14. Load isolating
switches 16, 17 and 18 are arranged in the feed and
outgoing conductors 13 to 15. Furthermore, short-
circuit switches 19, 20 and 21 are provided, which are
actuated by a latching mechanism 23, the latching
mechanism 23 having a latching point, which can be
released by a sensor 24. In normal operation, the load
isolating switches 16 and 18 may be closed; as a
result, current flows into the switchboard via the feed
conductor 13 and out of the switchboard via the
outgoing conductor 15, for example to a transformer,
which transforms the medium voltage into low voltage.
Naturally it is also possible that the switches 17, 18
are closed and the switch 16 is open. The current then
flows into the switchboard and out of the switchboard
via the feed conductor 14 and the outgoing conductor
15. Of course it is also possible that the conductors
designated with 13 and 15 form the feed conductors and
the conductor 14 the outgoing conductor from the
switchboard; this depends on the external and internal
circuit.

Such a. circuit arrangement has also become known as a
so-called Ring Main Unit, and is marketed by the
company ABB AS, Division Kraftprodukter, Skien, Norway.
If an arcing fault 22 occurs in a switchboard of this
kind, the temperature of the insulating gas within the
switchboard 10 and therefore its pressure increase so
that, unless suitable measures are taken, the
switchboard can explode, on account of which the
switchboard can have designated breaking points
according to DE 36 06 770 for example, by means of
which the hot gas can flow out in a systematic and
controlled manner. With the system according to Fig. 1,
which does not have a designated breaking point of this
kind, the increase in pressure is detected by means of
a pressure sensor 24, which releases the latching point
in the latching mechanism 23 and thus closes the
switches 19, 20 and 21, which are open in the normal
state. This produces a short circuit between the
individual phases by means of which the arc 22 is
diverted; because of the short circuit produced in this
way, a superimposed switch, for example a circuit
breaker, trips.
In the case of the Ring Main Unit switchboard produced
by the company ABB AS, Division Kraftprodukter, Skien,
Norway, the individual switches 19, 20 and 21 are
designed as blade contact switches; these blade contact
switches engage in contact blade receptacles, as a
result of which considerable space-saving is achieved.
A reduction in the space required is effected with the
embodiments according to the invention.
Connected to the feed and outgoing conductors 13, 14
and 15 is a rigid conductor 30, to the face side of
which a fixed contact piece 31 in the shape of a tulip
connector is fixed by means of a screw fastener 32. The

rigid conductor 30 and the fixed contact piece 31 are
surrounded by a cylindrical tube 33, which extends
beyond the fixed contact piece 31 and is closed at its
free end by means of a cap 34. The cylindrical tube is
made of an insulating material, which if necessary can
be coated on its outside with electrically conducting
material in order to improve the field line
characteristic.
Here, the sealing cap 34 is set into or let into a
recess 35. In the embodiment according to Fig. 2 the
cap 34 is made of silicone material; naturally it is
also possible to make the cap from a rigid material.
It is naturally also possible to provide the coating
with electrically conducting material on the inside of
the cylindrical tube or tubular cylinder 33, wherein
furthermore the coating also continues in the area of
the recess 35.
Assigned to the fixed contact piece 31 is a moving
contact piece 36, which is pushed towards the fixed
contact piece 31 in the direction of the arrow P when
the contact switches on. In order that the moving
contact piece 36 can penetrate the cap 34, the tip 37
of the moving contact piece 36 is designed in the form
of a cone with a tip 38. In this case, the moving
contact piece is connected to earth. It must be added
that in each case there is a total of one contact point
per phase as shown in Fig. 2 for each feed and outgoing
conductor. By means of the moving contact piece 36 the
individual phases can be connected to earth or a phase
short circuit produced, which can likewise be
interrupted by a superimposed circuit breaker.
To improve the electrical field, the moving contact
piece is surrounded by a cylindrical tube 39 made from
electrically conducting material in which the moving

contact piece 36 slides; the end of the cylindrical
tube 39 facing the fixed contact piece 31 has a
peripheral bead 40 on the outside, by means of which
the electrical field is uniformly distributed in the
area of the contact point shown in Fig. 2.
The moving contact piece 36 can also execute a circular
movement. For this purpose, an L-shaped arm 41 is fixed
to a rotating shaft 42, which arm 41 merges into a
moving contact piece 43, which corresponds to the
moving contact piece 36. A field control arrangement
such as that shown in Fig. 2 is not shown in the case
of the contact point according to Fig. 3.
With the embodiment according to Fig. 2 a tulip
connector 31 is fixed to the face of the contact piece
30; it is of course also possible to design the face of
the rigid conductor in such a way that it forms a
contact point with the moving contact piece, for
example by making a cone-shaped depression in the face;
in another embodiment the face could be flat and the
tip of the moving contact piece hemispherical.
In the embodiment according to Fig. 3, the conductor 30
is enclosed by a cylindrical tube 44, which has a base
45, the thickness of which is dimensioned so that it
can be easily penetrated by the moving contact piece
43, which naturally can also be the contact piece 36.
As an example, the cylindrical tube 33, 44 can be made
of reusable thermoplastic polymer; the cap 34 can be
made of a soft material such as silicone rubber for
example, which allows the moving contact 36 to
penetrate the cylindrical tube 33. The electrically
conducting coating of the cylindrical tube is provided
on the inside, particularly when the embodiments of the
fixed contact piece are designed in a constructively
simple manner.

The embodiment according to the invention has been
described with reference to an electrical switchboard;
it is naturally also possible to install and use the
invention in other installation systems.
The inside of the cylinder 33 or 44 in which the tulip
connector 31 is located can be filled with SF6 gas -
like the environment - or with a liquid insulating
material such as insulating oil or similar.
It is naturally also possible to use the invention in
such contact systems having two fixed contact pieces,
which are bridged by one suitable moving contact piece
to achieve a closure of the contact. In this respect
the invention is not limited to contact systems such as
those described in Figure 2 or Figure 3.
In the embodiment according to Fig. 4 the cap is
designed in the form of a flap 50, which is made of
deformable material, and is fixed to the cylindrical
tube 52 by a kind of film hinge 51; in the event of a
short circuit, the flap 50 is opened by the moving
contact piece and swiveled into the position 50a shown
dotted. Such an arrangement is useful, particularly
when a tulip connector such as the tulip connector 31
is not provided. The flap can also be designed in the
form of a sliding plate, which is actuated by the
moving contact piece.
The term "insulating material", through which the
moving contact piece passes, has the same meaning as
the term "screen", as opposed to the term "electrical
screen", which has the function of a field control.

WHAT IS CLAIMED IS:
1. A contact system for a short-circuiting device for
a medium-voltage or high-voltage switchboard (10),
comprising at least one fixed contact piece (31)
each per phase, connected to mains voltage (high
voltage or medium voltage), and one moving contact
piece (36, 43) each per phase, characterized in
that each at least one fixed contact piece (31) is
assigned a screen (34) of insulating material,
which can be penetrated by the moving contact
piece (36, 43) to make contact with the fixed
contact piece (31) when the contact is switched
on, the screen (34) being arranged between the
fixed and moving contact piece (31; 36, 43).
2. The contact system as claimed in claim 1 or 2,
characterized in that at least the part of the
insulating material, which lies in the movement
path of the moving contact piece (36, 43), is soft
so that the contact piece (10) can penetrate the
material.
3. The contact system as claimed in claim 1,
characterized in that the insulating material is a
hard material, the thickness of the part, which
lies in the movement path of the moving contact
piece (36, 43), being dimensioned in such a way
that the moving contact piece (36, 43) breaks
through this section.
4. The contact system as claimed in claim 1,
characterized in that the part of insulating
material, which lies in the movement path of the
moving contact piece (36, 43), is designed as a
door or flap (50), which can be pushed open by the
moving contact piece (36, 43) .

5. The contact system as claimed in one of the
preceding claims, characterized in that the moving
contact piece (36, 43) tapers towards its free
end.
6. The contact system as claimed in claim 5,
characterized in that the moving contact piece
(36, 43) is designed to taper towards its free end
in the form of a cone.
7. The contact system as claimed in one of the
preceding claims 1 to 4, characterized in that the
tip of the moving contact piece is rounded in an
approximately hemispherical manner.
8. The contact system as claimed in one of the
preceding claims, characterized in that the at
least one fixed contact piece (31) is surrounded
by a tubular cylinder (33, 39, 44, 52) on which
the penetrable material is arranged.
9. The contact system as claimed in claim 9 having a
fixed contact piece, which is mounted on the end
of a rigid conductor (30), characterized in that
the tubular cylinder (33, 39, 44, 52) extends
beyond the rigid conductor (30) and the fixed
contact piece, and is closed by the penetrable
insulating material at its free end.
10. The contact system as claimed in claim 9,
characterized in that the space inside the fixed
tubular cylinder (33, 39, 44, 52) in which the
fixed contact piece (31) is located is filled with
insulating fluid.
11. The contact system (10) as claimed in claim 10,
characterized in that the space is filled with

liquid, e.g. insulating oil.
12. The contact system as claimed in one of the
preceding claims, characterized in that the
insulating material assigned to the fixed contact
piece is assigned an electrically conducting
coating as an electrical screen and/or field
control.
13. The contact system as claimed in claim 12,
characterized in that the electrically conducting
coating is arranged at least inside or outside the
tubular cylinder (33, 35).
14. The contact system as claimed in one of the
preceding claims, characterized in that the moving
contact piece (36, 43) is mounted on a pivoted
lever.

The invention relates to a contact system for a short-
circuiting device in a medium-voltage or high-voltage
switch-board plant, comprising one stationary contact
piece (10) each per phase, connected to the mains
voltage (high voltage or medium voltage), and one
mobile contact piece (36, 43) each per phase. Every
stationary contact piece (31) is surrounded by an
insulating material which the mobile contact piece (36,
43) is able to penetrate when the contact is closed.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=2NEA7SYxV48+IIEh71opRw==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

278861

Indian Patent Application Number

2977/KOLNP/2008

PG Journal Number

01/2017

Publication Date

06-Jan-2017

Grant Date

31-Dec-2016

Date of Filing

22-Jul-2008

Name of Patentee

ABB TECHNOLOGY AG

Applicant Address

AFFOLTERNSTRASSE 44 CH-8050 ZURICH

Inventors:

#	Inventor's Name	Inventor's Address
1	ESPESETH, ROBERT	ERIK MUNKS VEI 17 N-3714 SKIEN
2	KUHLEFELT, JAN-HEN-RIK	FOSSUMGAT 30 N-3716 SKIEN
3	ENDRE, THOR	CHR. MICHELSENGT. 8 N-3751 SKIEN
4	GRANHAUG, OLE	OLEA CROGERS VEG 12B N-3724 SKIEN

PCT International Classification Number

H01H 79/00

PCT International Application Number

PCT/EP2007/000566

PCT International Filing date

2007-01-24

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10 2006 033 766.2	2006-07-21	Germany
2	10 2006 003 431.7	2006-01-25	Germany