U.S. patent number 3,649,790 [Application Number 05/081,779] was granted by the patent office on 1972-03-14 for gas-blast circuit breaker with double-nozzle contact system.
This patent grant is currently assigned to Aktiengesellschaft Brown, Boveri & Cie. Invention is credited to Edmund Friedrich, Harald Strubin.
United States Patent |
3,649,790 |
Friedrich , et al. |
March 14, 1972 |
GAS-BLAST CIRCUIT BREAKER WITH DOUBLE-NOZZLE CONTACT SYSTEM
Abstract
A gas-blast circuit breaker includes within a contact chamber
which is filled with a pressurized arc extinguishing gas a hollow
shaft rotatable about its axis, a pair of normally open power
switching contact structures located at opposite sides of the shaft
and which are connectable temporarily in series during an opening
operation of the breaker, and a normally closed supplementary
switching means of the knife blade type arranged in a current path
electrically in parallel with the power switching contact
structures. Each of the power switching contact structures includes
a movable contact carried by the rotatable shaft and a nozzle
communicating with the interior of the shaft for carrying off the
flow of arc extinguishing gas when the movable contact disengages
from its associated stationary contact, and the supplementary
switching means includes a movable contact blade carried by the
rotatable shaft in association with a stationary contact. The
operating sequence of the switches during a circuit breaking
operation is that when the hollow shaft is rotated, the circuit
through the power switching contact structures is completed before
the circuit through the supplementary switching means is opened
thereby enabling the contacts of the latter to open in an arc-free
manner and transfer the load current to the circuit through the
then in series connected power switching contact structures.
Inventors: |
Friedrich; Edmund (Rheinheim,
DT), Strubin; Harald (Neuenhof, CH) |
Assignee: |
Aktiengesellschaft Brown, Boveri
& Cie (Baden, CH)
|
Family
ID: |
4415555 |
Appl.
No.: |
05/081,779 |
Filed: |
October 19, 1970 |
Foreign Application Priority Data
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Oct 31, 1969 [CH] |
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16237/69 |
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Current U.S.
Class: |
218/86; 218/63;
218/72 |
Current CPC
Class: |
H01H
33/122 (20130101); H01H 33/86 (20130101) |
Current International
Class: |
H01H
33/12 (20060101); H01H 33/86 (20060101); H01H
33/04 (20060101); H01H 33/70 (20060101); H01h
033/80 () |
Field of
Search: |
;200/148H,148R,145R,146R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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845,715 |
|
May 1939 |
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FR |
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612,712 |
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May 1935 |
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DT |
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463,355 |
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Mar 1937 |
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GB |
|
Primary Examiner: Macon; Robert S.
Claims
We claim:
1. In a gas-blast circuit-breaker, the combination comprising a
contact chamber filled with a pressurized arc extinquishing gas, a
hollow shaft located within said contact chamber and which is
arranged for rotation about its axis, a pair of normally open power
switching contact structures of the gas-blast type located at
opposite sides of said hollow shaft and which are connectible
temporarily in series during an opening operation of said circuit
breaker, each said contact structure including a nozzle
communicating with the interior of said hollow shaft and a movable
contact member arranged to temporarily engage and then be
disengaged from a stationary contact member as said hollow shaft is
rotated to initiate a circuit opening operation, each said movable
contact member and the nozzle correlated therewith being spacially
arranged on said shaft such that as the contact members disengage
the nozzles come into alignment respectively with said stationary
contact members for flow of arc extinguishing gas from said chamber
into and through said nozzles into and through said hollow shaft
for discharge, and normally closed supplementary switching means
arranged in a current path electrically in parallel with said pair
of series connectible power switching contact structures comprising
movable contact means mounted on said hollow shaft and stationary
contact means correlated therewith, the relative locations of the
movable contact members of said power switching contact structures
and of the movable contact means of said supplementary switching
means on said hollow shaft being such that as said shaft is rotated
the said temporary connection of said power switching contact
structures in series takes place before the said supplementary
switching means open.
2. A gas-blast circuit-breaker as defined in claim 1 wherein said
hollow rotatable shaft includes a partition wall dividing the
interior thereof into separate gas discharge passageways for the
gas entering therein through said nozzles.
3. A gas-blast circuit-breaker as defined in claim 1 wherein said
stationary contact members of said power switching contact
structures are resiliently mounted.
4. A gas-blast circuit-breaker as defined in claim 1 wherein said
normally closed supplementary switching means arranged in a current
path electrically in parallel with said pair of series connectible
power switching contact structures are constituted by knife
switches the knives of which are mounted on said rotatable
shaft.
5. A gas-blast circuit-breaker as defined in claim 4 wherein two
sets of knife switches are provided respectively on opposite sides
of said power switching contact structures, and each set of knife
switches serves to close a current path electrically in parallel
with said power switching contact structures.
6. A gas-blast circuit-breaker as defined in claim 5 wherein each
set of knife switches includes two knife members located on and at
opposite sides of said rotatable shaft.
Description
The present invention relates to a gas-blast circuit-breaker having
a double-nozzle contact system, in which the extinction gas streams
in the two nozzles are orientated opposite each other, the nozzle
contact members being pivoted about an axis during making and
breaking, and having a parallel current switching position,
conducting operating current and being adapted to switch under
no-current conditions.
The prior art discloses a gas-blast circuit-breaker having a
contact system with two pivotable nozzle contact members. For the
switching operation, the nozzle contact members are pivoted about
an axis which is disposed outside the nozzle, the pivoting motion
proceeding along a circular arc relative to which the nozzle axis
forms a tangent (U.S. Pat. No. 3,454,734). The extinction gas flows
in the nozzles are orientated opposite to each other and are
allowed to escape through an exhaust valve disposed in the middle
between the two nozzles. A further similar system with a pivotable
nozzle contact bridge, high-pressure gas being supplied along the
axis of rotation, is disclosed by the U.S. Pat. No. 3,327,082.
Finally, parallel current switching positions, adapted to switch
under no-current conditions, have been known for a considerable
period in gas-blast circuit-breakers (see, for example, German,
laid-open spec. Pat. No. 1,253,790).
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a space-saving
construction for a gas-blast circuit-breaker of the kind mentioned
heretofore and which permits rapid motion of the contact members by
virtue of a system designed for small inertia forces and therefore
permits short switching periods to be obtained with a driving
system of moderate complexity.
In accordance with the invention, this objective is attained by a
circuit breaker structure which includes a contact chamber filled
with a pressurized arc extinguishing gas, a hollow shaft located
within the contact chamber and which is rotatable about its axis,
and a pair of normally open power switching contact structures of
the gas-blast type located at opposite sides of the hollow shaft,
but which are connectible temporarily in series during an opening
operation of the breaker. Each of the gas-blast contact structures
includes a nozzle on and communicating with the interior of the
shaft and a movable contact member arranged to temporarily engage a
stationary contact member as the shaft is rotated to initiate a
circuit opening operation, and the nozzles come into alignment with
the stationary contact members as these contact members disengage
to enable the arc extinguishing gas to flow from the chamber into
and through the nozzles into and through the hollow shaft to a
point of discharge. Moreover, normally closed supplementary
switching means are arranged in a current path electrically in
parallel with the normally open gas-blast contact structures, and
the contacts of these switches, which are also actuated by rotation
of the shaft, do not disengage until the temporary circuit through
the power switching contact structures has been closed.
A representative embodiment of the invention will now be described
in detail and is illustrated in the accompanying drawings
wherein:
FIG. 1 is a sectional view taken along the longitudinal axis of the
circuit breaker on line I--I of FIG. 2; and
FIG. 2 is a plan view of the circuit breaker contact structure
itself, the circuit breaker chamber within which the contacts are
housed and which is included in FIG. 1 being deleted.
With reference now to the drawings, the contact structure for the
circuit breaker is located within a chamber 1 the walls of which
are made from insulating material, and this chamber is filled with
a pressurized gas obtained from a suitable gas source, not shown,
which is in constant communication with the chamber. As shown in
FIG. 2, the contact structure of the circuit breaker includes a
pair of juxtaposed, U-shaped contact supports 2, 2' carried
respectively by terminal contact members 2a, only the latter
contact member correlated to contact support 2 being included in
the drawing. Each leg of each of the U-shaped contact supports 2,
2' carries a pair of parallel spaced contact plates 3, 3' and each
pair of these plates forms the stationary contacts of a knife
switch. The movable contact of each knife switch is constituted by
a knife blade 8, 8' carried by an electrically conductive hollow
rotatable shaft 5 located intermediate the sets of contact plates
3, 3'. Thus there are four knife switches in all, S1 to S4,
switches S1 and S2 being electrically in series and paralleled with
switches S3 and S4 also connected in series. In the closed position
of the circuit breaker, all four of these knife switches S1 to S4
are closed.
The power switching contact structure for the circuit breaker and
with which a gas-blast is associated for interrupting the power
current is constituted by two other switches S5 and S6 also
connectible electrically in series. Switch S5 includes a stationary
contact member 4 resiliently mounted on contact support 2
intermediate the two sets of contact plates 3, 3' of switches S1
and S3 and a movable contact structure carried by the rotatable
shaft 5 comprising a nozzle 6 and arcuate contact member 7.
Similarly, switch S6 includes a stationary contact member 4'
resiliently mounted on contact support 2' intermediate the knife
switches S2 and S4 and a movable contact structure carried by shaft
5 comprising a nozzle 6' and arcuate contact member 7'. Nozzles 6
and 6' face outwardly from and are located on opposite sides of the
hollow shaft 5 and are aligned along an axis normal to the
rotational axis of the shaft.
The end of the hollow shaft 5 is closed by a cover plate 11 and the
interior of the shaft is divided longitudinally into two separate
gas discharge passageways by means of a partition wall 9 which also
mounts an auxiliary electrode 10 which is common to the two
switches S5 and S6. As is evident from the drawings, one of these
passageways serves for the discharge of gas from switch S5 as
indicated by arrows 12a, and the other passageway serves to
discharge gas from switch S6 as indicated by arrows 12b.
Opening and closing of the circuit through the breaker structure is
effected by rotation of shaft 5 which is effected by any suitable
type of drive, but which has not been illustrated in the interest
of simplifying the drawings, and also because the details of the
drive are not essential to an understanding of the invention.
As previously explained, when an electrical circuit is closed
through the circuit breaker, the contacts of all four of the knife
switches S1 to S4 are closed and this is indicated by position A of
the knife blades 8 in FIG. 2. Also, as will be seen from FIG. 2,
the arcuate contact member 7 of each switch S5, S6 is then in a
position where it does not make contact with the correlated
stationary contact member 4. Thus, all of the current is conducted
through the electrically paralleled knife switch paths S1-S2 and
S3-S4, and no current passes through the power interrupting
switches S5 and S6.
When it is desired to open the circuit breaker, the hollow shaft 5
is rotated counterclockwise, as viewed in FIG. 1 towards position
B. During this rotation, the arcuate contacts 7,7' engage their
corresponding stationary contact members 4,4' before the knife
blades 8,8' lose their contact with the contact plates 3, 3' and
consequently all of the load current is then transferred in an
arcless manner from the knife switches S1 to S4 to the power
interrupting switches S5 and S6. As rotation of shaft 5 continues,
the contacts of the knife switches open in a practically arc-free
manner, followed shortly thereafter by disengagement of the arcuate
contact members 7, 7' with their stationary contact members 4, 4'
whereupon the power current is interrupted drawing arcs
therebetween which are swept into the nozzles 6, 6' to electrode 10
partially by the magnetic effect and also by the flow of
pressurized gas into these nozzles from the gas-pressurized chamber
1. This gas flow is initiated by employment of a conventional blast
valve arrangement associated with the hollow shaft 5 and which is
opened to a lower pressure region as the shaft 5 is rotated from
the initial closed-circuit position and not later than when the
contacts are separated. Optimum outward flow of the discharge gases
through the nozzles 6, 6' obviously occurs when position B is
reached, in which position, the two nozzles are centered with
respect to the longitudinal axis of the contact system through the
power interrupting switches S5, S6.
The partition wall 9 offers the obvious advantage of avoiding any
interaction between the two gas flows from switches S5 and S6 as
could be the case in the event that back-arcing should occur at
either of these switches during the time the power currents were
being interrupted.
As rotation of shaft 5 continues in the counterclockwise direction,
for example, after the switching arcs become extinguished, contacts
7, 8 and 7', 8' ultimately reach position C which is 90.degree.
away from the starting position, and which represents the full-open
position of the circuit breaker, i.e., the optimum voltage
isolation position since it is evident from FIG. 2 that the movable
contact members of all of the switches S1 to S6 will then be
farthest away from their respective stationary contact members.
* * * * *