U.S. patent number 3,590,188 [Application Number 04/576,740] was granted by the patent office on 1971-06-29 for fluid-blast circuit interrupter with piston assembly and electromagnetic driving means.
This patent grant is currently assigned to Westinghouse Electric Corporation. Invention is credited to William H. Fischer, Russell E. Frink.
United States Patent |
3,590,188 |
Frink , et al. |
June 29, 1971 |
FLUID-BLAST CIRCUIT INTERRUPTER WITH PISTON ASSEMBLY AND
ELECTROMAGNETIC DRIVING MEANS
Abstract
An improved piston-type fluid-blast circuit interrupter is
provided having a stationary operating cylinder, within which
reciprocates a movable piston assembly carrying the movable contact
assembly of the interrupter. Electromagnet means including three
accelerating coils, one movable with the piston assembly, another
located in the closed end of the operating cylinder, and a third
coil movable with a driver unit, are all connected in series during
the opening operation of the interrupter. The driver unit is
mechanically connected through the closed end of the operating
cylinder with the movable piston assembly. The magnetic attraction
between the piston coil and the coil at the closed end of the
operating cylinder, and the magnetic repulsion forces between the
coil at the closed end of the operating cylinder and the coil
carried by the driver unit, all contribute to magnetically
assisting the fluid-driving motion of the piston assembly and so
effecting interruption. The movable contact structure comprises a
main movable contact and an inner movable arcing probe movable
together and insulated from each other with the three accelerating
coils connected between the main movable contact and the movable
arcing probe in the closed position of the interrupter.
Inventors: |
Frink; Russell E. (Pittsburgh,
PA), Fischer; William H. (Pittsburgh, PA) |
Assignee: |
Westinghouse Electric
Corporation (Pittsburgh, PA)
|
Family
ID: |
24305792 |
Appl.
No.: |
04/576,740 |
Filed: |
September 1, 1966 |
Current U.S.
Class: |
218/43; 335/201;
218/145 |
Current CPC
Class: |
H02B
11/04 (20130101); H01H 33/882 (20130101); H02B
7/00 (20130101); H02B 11/20 (20130101) |
Current International
Class: |
H01H
33/88 (20060101); H02B 11/20 (20060101); H02B
7/00 (20060101); H02B 11/04 (20060101); H02B
11/00 (20060101); H01h 033/90 () |
Field of
Search: |
;200/148,146,50.15
;335/201,18 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,190,079 |
|
Apr 1965 |
|
DT |
|
514,359 |
|
1938 |
|
GB |
|
Primary Examiner: Macon; Robert S.
Claims
We claim as our invention:
1. In combination, a pressurized metallic tank having a pair of
spaced terminal bushings extending therein, said pressurized
metallic tank having an arc-extinguishing gas disposed therein at
least at atmospheric pressure, a circuit-interrupting element
supported within said tank and comprising separable stationary and
movable contact structures, said stationary contact structure being
hollow so as to provide an exhausting flow of gas therethrough
during interruption, a movable piston assembly carrying the movable
contact structure and reciprocally operable within a stationary
operating cylinder having a closed end portion, said movable
contact structure including concentrically arranged conducting
tubes, one an outer main movable contact and the inner one an
arcing probe contact both movable together and both insulated from
each other, electromagnetic piston-assisting means including a
first accelerating coil carried by said movable piston assembly and
a second stationary accelerating coil supported at the closed end
portion of the operating cylinder, said electromagnetic means also
including a third movable accelerating coil carried by a movable
driver-unit disposed externally of the operating cylinder and
mechanically connected through the closed end of the operating
cylinder with the movable piston assembly so as to move therewith,
said electromagnetic piston-assisting means being electrically
connected between said concentrically arranged conducting tubes,
and inserted electrically into the series electrical circuit during
the opening operation to magnetically assist the movement of said
piston assembly during fault-current interruption.
2. The combination according to claim 1, wherein the pressurized
gas is sulfur-hexafluoride (SF.sub.6) gas.
3. The combination according to claim 1, wherein the stationary
contact structure comprises a hollow outer tubular main contact
having outer contact fingers and an inner nozzle-conducting member
spaced from the surrounding fingers.
4. The combination of claim 1, wherein the movable piston assembly
carries an insulating nozzle member which slides over the
stationary tubular main contact to direct the gas flow through the
stationary inner conducting nozzle member.
5. The combination according to claim 3, wherein the movable piston
assembly carries an insulating nozzle member which slides over the
stationary tubular main contact to direct the gas flow through the
stationary inner conducting nozzle member.
6. The combination of claim 1, wherein the mechanical means
interconnecting the driver unit and the movable piston assembly
comprises a spaced pair of conducting connecting rods which serve
additionally as coil-connecting means.
7. The combination of claim 1, wherein the mechanical means
interconnecting the driver unit and the movable piston assembly
comprises at least one piston rod which serves additionally as a
coil-connecting function.
8. A fluid-blast piston-type circuit interrupter including a first
relatively stationary main contact structure, a cooperable movable
main contact structure cooperable therewith to carry the line
current in the closed-circuit position of the circuit interrupter,
said movable main contact structure establishing arcing and
including a main movable first contact portion and a movable first
arcing probe contact portion movable together with the first arcing
probe portion insulated from the main movable first contact
portion, a second separable series pair of cooperable contacts one
stationary and the other movable and separable in response to
separation of the first contacts, piston means including a piston
operable within an operating cylinder for forcing fluid under
pressure toward said arcing to effect the extinction thereof,
electromagnetic means for assisting in the fluid-driving motion of
said piston means including first, second and third accelerating
coils, said three accelerating coils being electrically connected
in series between said movable first arcing probe contact portion
and said stationary contact of the second separable series pair of
cooperable contacts, said first accelerating coil being supported
by the movable piston, said second accelerating coil being
supported by the closed end of the operating cylinder for magnetic
attraction, means defining a driver unit mechanically connected to
the movable piston and extending externally of the closed end
portion of the operating cylinder and carrying said third
accelerating coil, whereby the repulsive magnetic forces between
the third accelerating coil and the second accelerating coil
further assist piston-driving motion, and the separation of the
first and second series-related contact structures will thereby
electrically insert said three accelerating coils into the circuit
to utilize attractive and repulsive magnetic forces to augment the
driving motion of the piston means.
9. The fluid blast piston type circuit interrupter of claim 8,
wherein the first relatively stationary main contact structure is
hollow so as to permit an exhausting flow of fluid therethrough
during the interruption process.
10. The fluid blast piston-type circuit interrupter of claim 9,
wherein an insulating nozzle member is carried by the movable
piston assembly and slides over the hollow stationary first main
contact structure.
11. The fluid blast piston-type circuit interrupter of claim 8,
wherein the fluid comprises sulfur-hexafluoride (SF.sub.6) gas.
12. The fluid blast piston-type circuit interrupter of claim 8,
wherein the mechanical means for connecting the driver unit
mechanically to the movable piston comprises at least one piston
rod which serves additionally as a coil connecting function.
13. The combination according to claim 8, wherein the first
relatively stationary contact structure comprises a hollow outer
tubular main contact having outer contact fingers and an inner
nozzle conducting member spaced from the surrounding fingers.
14. The fluid blast piston-type circuit interrupter of claim 8,
wherein an operating mechanism is provided to give an initial
motion to the movable piston to thereby facilitate the transfer of
the main current arc to the first arcing probe portion and thereby
insert the three accelerating coils serially into the circuit.
Description
This invention relates generally to fluid-blast circuit
interrupters, and, more particularly, to fluid-blast circuit
interrupters of the type having a piston assembly associated
therewith for generating fluid under pressure to be forced into the
established arc to effect the extinction thereof.
As well known by those skilled in the art, the general trend in
metal-clad switchgear over the past decade has been to higher
voltages and to higher interrupting ratings. In 1955, approximately
80 percent of the production of a large electrical company was 5
kv. switchgear. In 1965, for example, the same manufacturer
accounted for only 47 percent of his total switchgear production in
5 kv. units. In addition to this general trend to higher voltage
switchgear, the trend has been to higher interrupting ratings for
circuit breakers. Up until 1957, the highest interrupting rating
available in metal-clad switchgear was 500 MVA. In that year, the
first 750 MVA breakers were made available. In 1958, metal-clad
switchgear with 1,000 MVA breakers were made available. Currently,
in 1966, 34.5 kv. metal-clad switchgear with breakers having an
interrupting capacity of 1,500 MVA are now for the first time
available.
The first requirement for any line of switchgear is a reliable
circuit breaker. Various types of interrupters have been proposed.
However, to increase the voltage and interrupting ratings, it has
been proposed to use puffer-type structures. Basically, the puffer
concept is not new. It consists essentially of a pair of separable
contacts, a piston and a cylinder all mounted in a reservoir
containing a suitable arc-interrupting gas. The contacts and piston
are mounted in such a way that as the contacts are parted, the
piston moves to drive the gas in the cylinder through the arc to
interrupt it. Such devices were investigated as long as 20 years
ago using the then-available interrupting gases. A moderate degree
of success was attained at that time. However, the devices were too
inefficient to warrant further development.
The discovery of the ability of sulfur-hexafluoride (SF.sub.6) gas
to interrupt an arc gave the puffer interrupter a new boost, and
the first commercial application of the puffer interrupter was a
load-break disconnecting switch capable of switching load currents
at voltages up through a 161 kv. on a single break.
Following this, a series of prototype puffer interrupters were
built with the final one being capable of interrupting 50,000
amperes at 22 kv. across a single break. However, the back pressure
in the operating cylinder created by the arc required a
piston-driving force of 10,000 to 12,000 pounds for interruption of
the highest currents. This would require too large a mechanism to
make this a practical breaker. At this point in the development
period, the discovery was to use a magnetic puffer. This would
provide a good interrupter, and the power to operate it would not
be too great. It was proposed to use the short circuit current to
drive the piston. Experience with magnetic air circuit breakers has
shown the tremendous force available from coils carrying fault
current. It was proposed to shunt this current into coils and let
them do the work of mechanically driving the piston.
A series of calculations was made to determine what force could be
obtained from coils carrying high current. The calculations were
based on a system of 3-- 10 inch diameter 10 turn coils arranged
for attraction and repulsion over a 7 inch stroke. These
calculations showed that a 21,000 ampere short circuit current
through these coils would produce a force of 12,100 pounds at the
beginning of the stroke. A 42,000 ampere short would produce a
force of 48,000 pounds. The discovery was made that here was a
means of obtaining the high force required to drive the piston for
the circuit interrupter. Accordingly, a general object of the
present invention is to provide an improved fluid-blast circuit
interrupter having magnetic means serially connected into the
electrical circuit, and taking advantage of the short circuit
energy to improve the fluid-blast operation of the interrupter.
Another object of the present invention is to provide an improved
fluid-blast type of circuit interrupter having improved
piston-operated means associated therewith, and electromagnetic
driving means to assist in the operation of said piston means.
Another object of the present invention is the provision of an
improved fluid-blast circuit interrupter in which a plurality of
accelerating coils are used to assist in the operation of the
associated piston assembly to more rapidly generate fluid under
pressure, which is subsequently ejected into the arcing region to
rapidly effect the extinction thereof.
Another object of the present invention is the provision of an
improved fluid-blast circuit interrupter having highly effective
piston-moving means and fluid-directing means associated
therewith.
Still a further object of the present invention is the provision of
an improved fluid-blast circuit interrupter of compact size, and
operating in a highly efficient manner to quickly generate the
required amount of high-pressure fluid, such as gas, and to
effectively direct the gas under high pressure toward the
established arc to effect circuit interruption.
Still a further object of the present invention is the provision of
an improved fluid-blast circuit interrupter having a stationary
operating cylinder with a cylinder head closing one end thereof, in
which a stationary accelerating coil is positioned, and providing a
movable piston assembly carrying the movable contact structure in
which a second accelerating coil, which is movable, is carried to
assist in the opening and fluid-compressing stroke.
Still a further object of the present invention is the provision of
an improved fluid-blast circuit interrupter having more efficient
venting means associated with the contact structure to highly
effectively direct the generated fluid blasts into the arcing
region for most efficient arc extinction.
In U.S. Pat. application filed Sept. 1, 1966, Ser. No. 576,616 now
U.S. Pat. No. 3,524,958, issued Aug. 18, 1970 to Russell E. Frink,
and assigned to the assignee of the instant application, there is
illustrated and described a novel fluid-blast circuit interrupter
having piston means associated therewith, which is assisted by an
electromagnetic driving means, which is inserted into the series
electrical circuit during the opening operation. It is a further
object of the present invention to improve the interrupting circuit
interrupter of the aforesaid patent application rendering it of
highly efficient operation and of compact dimensions.
In U.S. Pat. application filed Sept. 1, 1966, Ser. No. 576,739 now
U.S. Pat. No. 3,524,959, issued Aug. 18, 1970 to Russell E. Frink,
and assigned to the assignee of the instant application, there is
illustrated and described a novel fluid-blast circuit interrupter
incorporating piston means assisted by an electromagnetic driving
structure including a pair of accelerating coils, and utilizing
arcing-horn means to effect arc transfer, and consequent insertion
of the two accelerating coils into the circuit during the opening
operation. It is a further object of the present invention to
improve upon the transfer-arcing means of the aforesaid patent
application to provide an improved fluid-blast circuit interrupter
of highly efficient operation and operable in a very short span of
time, such, for example, as three cycles.
In U.S. Pat. application filed Sept. 1, 1966, Ser. No. 576,707, by
William H. Fischer, and assigned to the assignee of the instant
application, there is disclosed movable arcing-horn means for
effectively inserting electromagnetic means, including a pair of
accelerating coils, into the electrical circuit to augment the
piston-driving effect of an associated fluid-moving means. It is
still a further object of the present invention to improve upon the
movable arcing-horn means of the aforesaid Fischer application to
provide an improved circuit interrupter of compact and highly
efficient construction.
In U.S. Pat. application filed Sept. 1, 1966, Ser. No. 576,583 by
William H. Fischer, and assigned to the assignee of the instant
application, there is described and claimed a novel fluid-blast
circuit interrupter using novel venting-arcing horn arrangements
for inserting the electromagnetic means serially into the circuit
to assist the piston-driving effort of an associated fluid-moving
means for rapid circuit interruption. It is still a further object
of the present invention to improve upon the vented arcing-horn
means of the aforesaid Fischer application to provide an improved
and highly effective circuit interrupter suitable for widespread
commercial application.
As well known by those skilled in the art, a fluid-blast circuit
interrupter utilizing piston means for fluid-pressure generation,
and a subsequent forcing of the fluid under pressure into the
established arc, the mechanical effort required of the operating
mechanism becomes more severe during the interruption of
high-amperage fault currents. If the mechanical driving effort is
provided exclusively by the piston-operating arrangement, to
accommodate high-current fault interruption, an extremely powerful
operating mechanism is required. In an effort to reduce the power
requirements imposed upon the associated operating mechanism, it is
desirable to provide some means utilizing the energy in the
associated electrical circuit to assist the mechanical requirements
of the moving piston means during fault-current interruption. By so
doing, it results that the power requirements of the operating
mechanism may be held to a minimum. In other words, for low, or
load-current interruption, the power supplied by the associated
operating mechanism may be sufficient in itself to provide the
desired piston-driving effort suitable for high-pressure gas
generation. On the other hand, during heavy fault-current
interruption, a desirable "assist" is provided by the
electromagnetic means, as set forth in the present invention, as
described hereinafter.
As set forth in U.S. Pat. No. 3,524,958 if a pair of accelerating
coils have the windings suitably arranged, there will be an
attractive force set up between the two coils. On the other hand,
the pair of coils may be so wound as to provide a repulsive force
existing between the coils. It is a further object of the present
invention to incorporate these attractive and repulsive magnetic
forces to assist in the fluid-driving effort of a piston assembly
operated in conjunction with a fluid-blast circuit interrupter.
##SPC1##
By incorporating the novel electromagnetic means with the
particular positioning and arrangement of the associated elements,
it has been possible to meet the stringent requirements, as set
forth above.
In accordance with a preferred embodiment of the invention, there
is provided a stationary operating cylinder within a surrounding
metallic tank structure containing a suitable arc-extinguishing
gas, such as sulfur-hexafluoride (SF.sub.6) gas, at a pressure of
say 75 p.s.i. One end of the aforesaid stationary operating
cylinder is closed by a stationary piston head having a stationary
accelerating coil encapsulated therein. Movable longitudinally
within the stationary operating cylinder is a movable piston
assembly carrying the movable contact structure, the latter
comprising an outer main contact and an inner arcing contact
insulated from the outer main contact. Associated with the movable
piston assembly is a movable accelerating coil. The movable piston
assembly is connected through the closed end of the operating
cylinder with a movable driving assembly, the latter comprising a
movable repulsion coil. A stationary contact assembly is situated
adjacent the open end of the stationary operating cylinder. The
arrangement is such that during the opening operation the main arc,
established between the main contacts, is carried by the gas flow
to impinge onto the movable arcing contact to thereby insert
serially into the electrical circuit being interrupted the three
accelerating coils. Thus, the initial mechanical movement of the
movable piston assembly, as supplied by a conventional mechanism,
is augmented and assisted by the electromagnetic driving means
including a plurality of, such as three, accelerating coils
inserted serially into the electrical circuit. This is particularly
advantageous during heavy fault-current interruption.
Further objects and advantages will readily become apparent upon
reading the following specification taken in conjunction with the
drawings, in which:
FIG. 1 is an end elevational view of a three-phase truck-mounted
removable circuit-interrupter unit, involving three individual
pole-units;
FIG. 2 is a side elevational view of the truck-mounted removable
three-phase circuit-interrupting unit illustrated in FIG. 1;
FIG. 3 is a vertical sectional view taken through one of the three
pressure tank structures of FIGS. 1 and 2, illustrating the
circuit-interrupting element mounted therein, the contact structure
being illustrated in the closed-circuit position;
FIG. 4 is a vertical sectional view of the pressure tank taken
along the line IV-IV of FIG. 3 looking in the direction of the
arrows, the contact structure being illustrated in the
closed-circuit position;
FIG. 5 is a considerably enlarged horizontal sectional view taken
through the interrupting element of FIG. 3, substantially along the
line V-V of FIG. 3, the contact structure being illustrated in the
closed-circuit position;
FIG. 6 is a fragmentary view of a portion of the contact structure
illustrating the establishment of the main-current arc during the
initial portion of the circuit-opening operation;
FIG. 7 is a view similar to that of FIG. 6, but showing the
main-current arc as having transferred to the movable arcing
contact;
FIG. 8 is a fragmentary view, similar to that of FIGS. 6 and 7, but
showing the contact structure in the position at which the
transferred arc is about to be interrupted;
FIG. 9 illustrates a vertical sectional view taken through the
improved interrupting element of the present invention, the contact
structure being illustrated in the closed-circuit position;
FIG. 10 is a diagrammatic view illustrating the accelerating coils
with their connections to the contact structure;
FIGS. 11 and 12 show, respectively, in plan, and in vertical
section, the supporting spider member secured to the main movable
contact tube;
FIGS. 13--15 illustrate views of the supporting rear casting clamp
for the rear terminal stud;
FIGS. 16 and 17 illustrate, respectively, side and front views of
the movable rear main contact, which is threaded to the rear end of
the main movable contact tube;
FIG. 18 is a vertical sectional view taken through the movable
piston assembly with the contact structure omitted, and
illustrating the terminals for the movable accelerating piston coil
and the insulating nozzle member;
FIGS. 19 and 20 illustrate, respectively, in vertical section, and
in end elevational view, the end moving driving accelerating, or
repulsion coil for the interrupting element;
FIGS. 21 and 22 illustrate, respectively, in vertical section, and
in end elevation, the stationary accelerating cylinder-head coil,
which is fixedly secured in the end of the operating cylinder to
close the same at one end;
FIG. 23 is an end elevational view of the stationary conducting
supporting casting, which is clamped to the terminal stud of the
front terminal bushing;
FIGS. 24 and 25 are, respectively, vertical sectional views and end
elevational views of the piston accelerating coil;
FIG. 26 is a side elevational view of the upper connecting rod for
the movable piston assembly;
FIG. 27 is a side elevational view of the lower connecting rod for
the movable piston assembly;
FIG. 28 is an end elevational view of the movable piston
member;
FIG. 29 is an end elevational view of the insulating spacer element
disposed interiorly of the movable piston accelerating coil;
FIG. 30 is an end elevational view of the front insulating clamping
plate for the movable piston assembly;
FIG. 31 is a perspective view of a substation for housing, for
example, 34.5 kv. outdoor metal-clad switchgear for controlling
transformer and feeder circuits;
FIG. 32 is a diagrammatic plan view of the substation of FIG. 31
illustrating the multiplicity of metal-clad switchgear cells
disposed in contiguous relationship, and fronting on an operating
aisle;
FIG. 33 is a diagrammatic view of the transformer, bus, capacitor
and feeder circuits to indicate the functioning of the cell units
of FIG. 32;
FIG. 34 is an end elevational view of the metal-clad switchgear
units of FIG. 32, indicating the aisle service area and the space
occupied by the 26 cell units;
FIG. 35 is a sectional view taken through one of the cell units
illustrating the elevating mechanism for providing vertical travel
of the individual removable circuit-interrupting units, the figure
showing the circuit-interrupting unit in the lowered disconnected
position;
FIG. 36 is a fragmentary vertical sectional view illustrating the
engaging portions of the frame of the removable
circuit-interrupting unit and the lifting channel members
vertically movable within the cell structure; and,
FIG. 37 is a perspective view looking into the interior of the
breaker compartment of the cell structure with the circuit breaker
in the lowered disconnected position; and,
FIG. 38 is a fragmentary perspective view of the cell
structure.
Referring to the drawings, and more particularly to FIGS. 1 and 2
thereof, the reference numeral 1 indicates a three-phase
truck-mounted fluid-blast circuit interrupter unit of the type
which may be rolled into an associated cell structure 2 (FIG. 35).
As well known by those skilled in the art, in metal-clad switchgear
equipment it is customary to have cells or cubicles 2, as shown in
FIG. 35, into which are rolled removable interrupting unit
equipment 1.
In more detail, with reference to FIG. 2, a frame assembly 7 is
provided to support the circuit breaker 1 on support bosses 7a
welded to the underside of the tanks. The frame assembly 7 is
welded up from structural steel sections 9, 10. Rollers 19 are
provided to facilitate operative movement into and out of the
cooperable cell structure 2.
In the movable switchgear interrupting equipment 1, set forth in
FIGS. 1 and 2, after the equipment is rolled into the associated
cubicle structure 2, suitable means are provided to effect a
vertical upward movement of the entire equipment on vertically
movable rails 20, (FIG. 37) as hereinafter discussed, so that the
main movable disconnecting contacts 3, 4 may contactingly engage an
associated pair of spaced stationary disconnecting contacts 5, 6
(FIG. 35), which are supported by the cubicle, or cell structure
2.
The present invention is particularly concerned with the
interrupting structure of the equipment illustrated in FIGS. 1 and
2. It will be noted that, generally, there is provided an operating
mechanism compartment, generally designated by the reference
numeral 8, and three heavy metallic tanks 11, which enclose the
respective interrupting elements 12 associated with each pole-unit
13. Disposed within each of the three-tank structures 11 is the
interrupting assembly, generally designated by the reference
numeral 12, and comprising a stationary insulating operating
cylinder 14 having one end 15 thereof open, and having the other
end 16 thereof closed by a base portion 17, the latter including a
stationary accelerating coil 18 embedded in a suitable plastic 21,
for example, epoxy resin, as shown in FIG. 21.
The front end 14a of the stationary operating cylinder 14 is
supported, as by bolted connections, to four bosses 22, (FIG. 4)
the latter being welded interiorly of the tank structure 11.
Extending downwardly through an opening 23 provided adjacent the
front end 14a of the stationary operating cylinder 14 is a
line-terminal stud 24, which extends upwardly through the front
terminal bushing 25 of each pole-unit 13. The terminal stud 24 is
clamped to a stationary conducting supporting casting, generally
designated by the reference numeral 26, and shown more clearly in
FIGS. 3 and 23 of the drawings.
With reference to FIGS. 5 and 9 of the drawings, it will be noted
that the stationary support casting 26 has a clamping portion 26a
of bifurcated construction, which clamps by bolts 27 to the lower
interior end of the terminal stud 24 extending through the front
terminal bushing 25 of the device. In addition, the stationary
casting 26 has a spider portion 26b with an integrally formed
support ring 26c, which is bolted as at 28 (FIG. 9) to the
stationary operating cylinder 14. Moreover, the stationary
conducting casting 26 has a threaded supporting portion 26d, which
adjustably threadedly secures a stationary contact assembly,
generally designated by the reference numeral 31 (FIG. 5). With
reference to FIG. 9, it will be observed that once the proper
adjustment of the stationary contact structure 31 is obtained,
clamping bolts 32 may be tightened, and the structure is then
rigid.
As shown in more detail in FIGS. 5 and 9 of the drawings, the main
stationary contact assembly 31 comprises a main stationary contact
33 of generally tubular configuration, and having a plurality of
flexible main contact fingers 33a formed at the right-hand end
thereof. Disposed interiorly of the tubular main contact structure
33 is a conducting metallic arcing nozzle member 34, which is
fixedly secured, as by brazing at 35, to the interior of the outer
main contact tube 33 up against a shoulder portion 33b (FIG. 5)
thereof. Both the main flexible contact fingers 33a and the nozzle
arcing member 34 have arc-resisting tip portions of a suitable
arc-resistant metal, such as copper-tungsten or silver-tungsten
alloys.
Movable lengthwise of the stationary operating cylinder 14 is a
movable piston assembly 36 carrying a movable contact structure 37.
As shown more clearly in FIGS. 3, 4 and 5 of the drawings, a pair
of insulating operating links 41 cause the rightward opening
movement of the movable piston assembly 36 carrying therewith the
movable contact structure 37.
The movable piston assembly 36 (FIG. 5) includes an annular
insulating clamping plate 42 (FIG. 30), an annular insulating
spacing plate 43 having notches 44 provided therein, as shown in
more detail in FIG. 29, to accommodate a moving first accelerating
piston coil 45 shown in FIGS. 24 and 25. In addition, the moving
piston assembly 36 includes an insulating annular piston plate 46
(FIG. 28) having an outer peripheral groove 47, in which a piston
ring 48 is inserted to prevent the escape of compressed gas 51 out
of the region 52 of the operating cylinder 14 and around the outer
periphery of the piston assembly 36. As mentioned previously, the
right-hand base end 16 of the operating cylinder 14 is closed by
the annular head 17. As a result, gas within the region 52 is
compressed, and is forced to flow in a leftward direction through a
movable insulating nozzle member 53, which is clamped between the
two insulating plates 42, 46 and interiorly of the insulating
spacing member 43. See FIG. 5 in this connection.
The left-hand end 53a of the movable nozzle member 53 constantly
slides upon the outer surface of the main tubular contact 33, and
assists the guiding motion of the piston assembly 36, as well as
providing the desired flow for the compressed gas past the
separable contact structure 31, 37. FIGS. 6--8 generally show the
flow path for the compressed fluid 51, as indicated by the arrows
54.
As shown in more detail in FIG. 5 of the drawings, the insulating
links 41 have pivotal connections, by means of pivot pins 55, to
bifurcated members 56, the latter being bolted by bolts 57
extending through the three insulating members 42, 43 and 46. In
addition, with reference to FIGS. 11, 12 and 5, it will be noted
that the main tubular movable contact 58 has a supporting spider 61
(FIGS. 11 and 12) fixedly secured thereto, as by brazing at 62, and
the support spider 61 has holes 63 in the radially outwardly
extending arms 64 thereof, through which extend supporting bolts
65, which additionally clamp the insulating plates 42, 43 and 46
together.
The movable first accelerating coil 45 has a configuration
configuration more clearly shown in FIGS. 24 and 25, and has a pair
of terminal lugs 66, 67 having threaded openings 66a, 67a
therethrough. The first accelerating coil 45 is wound of heavy
copper strap, for example, with the outer terminal lug 66 thereof
electrically and mechanically connected to an upper conducting
guide and piston rod 68 (FIG. 26), which extends through an
aperture 71 (FIG. 21) in the cylinder head 17, and is electrically
connected, by a bolted connection 72 (FIG. 9), to one terminal end
73 (FIG. 20) of a movable repulsion third coil 74 encapsulated in a
driving unit 75 (FIG. 19) secured to the right-hand extremity of
the movable contact structure 37, the latter comprising the outer
tubular main contact tube 58 and an inner arcing tube 76 insulated
therefrom, as shown in FIG. 5.
As will be more fully brought out hereinafter, the two first and
second accelerating coils 18, 45 are so wound that they
magnetically attract each other, whereas the second and third
accelerating coils 18, 74 are so wound as to magnetically repel
each other. The net result is a magnetically assisted opening
fluid-driving motion of the piston assembly 36, as accelerated by
the driving unit 75.
The other terminal 77 (FIG. 20) of the movable driving repulsion
coil 74 is electrically connected to the inner arcing contact 76,
which has a tubular configuration, as more clearly illustrated in
FIG. 5.
With reference to FIG. 9 of the drawings, it will be noted that the
terminal lug 67 connected to the inner strap of the movable
accelerating coil 45 has a threaded connection 67a (FIGS. 18 and
24) to a relatively large conducting guide rod 78 (FIG. 27), which
is bolted to the piston assembly 36 by a nut 81 (FIG. 9) so as to
make metal-to-metal contact with terminal 67 of piston coil 45.
The right-hand end 78a of the relatively large conducting guide rod
78 extends through an opening 82 (FIG. 22) provided in the head 17
of the operating cylinder 14, and moves in sliding relationship
with a tubular sliding contact 83 (FIG. 9). This sliding contact
construction 83 shown more clearly in FIG. 9, is of ball
construction, and is set forth in detail and claimed in U.S. Pat.
application filed Oct. 13, 1965, Ser. No. 495,475, now U.S. Pat.
No. 3,301,986, issued Jan. 31, 1967 to Russell E. Frink and
assigned to the assignee of the instant application.
The right-hand end of the relatively large guide rod 78 is fixedly
secured by bolts 84, 85 to an insulated portion 86 (FIGS. 9 and 20)
of the moving driving unit 75. Reference may be had to the
diagrammatic view of FIG. 10 for assistance in understanding the
electrical connections to the three accelerating coils 18, 45 and
74.
The inner tubular arcing contact 76 has an arc-resisting tip
portion 76a, which is fixedly secured to the left-hand extremity
thereof, as by brazing. Additionally, the tubular arcing contact 76
has a support ring 88 brazed thereto, which serves to seat a split
insulating spacing member 91, which serves to insulate the
left-hand end of the inner tubular arcing contact 76 from the outer
tubular main contact 58. Also the right-hand end of the inner
movable tubular arcing contact 76 has a tubular threaded insert 92
fixedly secured thereto, as by brazing. An insulating washer 93,
together with a pair of clamping nuts 94, 95, serves to support the
electrical strap connection 96 to the moving driving coil 74 and
also to fixedly and insulatingly support the inner arcing tube 76
from the outer main contact tube 58.
Threadedly secured to the right-hand end of the main contact tube
58, as at 97 is a rear secondary main contact structure, generally
designated by the reference numeral 98. The rear secondary movable
main contact structure 98 assumes the form of a casting, shown in
FIGS. 16 and 17, and has a pair of movable secondary main
contacting portions 101, of wedge configuration, which mate with
two sets 102 (FIG. 5) of flexible main stationary secondary contact
fingers 103, which are secured to downwardly extending arms 104 of
a rear secondary contact support casting 105, shown in more detail
in FIGS. 13--15 of the drawings.
The stationary second accelerating coil 18 has one terminal lug 106
(FIG. 21) thereof, as mentioned, making sliding electrical contact
with the lower conducting guide rod 78, and has a pair of terminal
lugs 107, 108 electrically connected to the outer strap 18a thereof
making threaded supporting and electrical connection by a pair of
bolts 111 (FIG. 15), which extend through the two mounting holes of
the rear supporting casting 105 of the device.
The rear support casting 105 has a laterally extending bifurcated
clamping portion 112 (FIG. 13), which embraces the rear terminal
stud 113 extending upwardly through the rear terminal bushing 114
of the interrupting unit 1. As shown in FIG. 3, the rear support
casting 105, by securement to the cylinder head 17, serves
additionally for the entire support of the right-hand end of the
operating cylinder 14, as viewed in FIG. 3.
With reference to FIGS. 3 and 4 of the drawings, it will be noted
that a crankshaft 115 is pivotally connected, as by means of pivot
pins 116, to each of the two insulating operating links 41. The
crankshaft 115 is pinned so as to rotate with a drive shaft 117,
one end of which is journaled in a bearing 118 (FIG. 4) provided
internally of the tank structure 11. The other end of the drive
shaft 117 extends through a seal 121 externally of the tank
structure, and has welded thereto, at the outer extremity thereof,
a crank arm 122, which is connected to the operating mechanism 123
disposed within the mechanism compartment 8. The operating
mechanism 123 may be of any suitable type. Preferably, however,
there is employed a spring-stored-energy operating mechanism of the
type set forth in U.S. Pat. No. 3,183,332 issued May 11, 1965 to
Russell E. Frink and Paul Olson and assigned to the assignee of the
instant application.
With reference to FIGS. 3 and 4 of the drawings, it will be
observed that counterclockwise rotative motion of the external
crank arm 122 and drive shaft 117 will effect rightward opening
fluid-driving motion of the piston assembly 36, as viewed in FIGS.
3 and 5. This mechanical movement, as brought about by the
operating mechanism 123, causes a flow of compressed gas from the
region 52 past the spider 61, and through the orifice opening 124
provided in the insulating nozzle member 53. This gas flow serves
to transfer the main current arc 125, which is initially
established between the separable main contacts 33a, 58 across the
insulating spacer 91 to be successively carried to positions
illustrated in FIGS. 7 and 8 of the drawings. Since the rightward
opening movement of the piston assembly 36 also causes separation
of the rear movable secondary main contacts 101 away from the rear
stationary secondary main contacts 103, there occur two breaks in
the electrical circuit, as illustrated in FIG. 10 of the drawings.
Since the arc voltage at the two breaks builds up, and since the
resistance through the parallel circuit, including the accelerating
coils 18, 45 and 74, offers less impedance, the arc 125 transfers
to the separable arcing contacts 34, 76, and thereby inserts the
three accelerating coils serially into the electrical circuit. Fig.
8 illustrates the arc location at the time when the accelerating
coils are in series circuit, and at a time when the gas flow is
about to effect final arc extinction. Continued opening movement
inserts an isolating gap into the circuit, as indicated by the
dotted lines 126 in FIG. 5.
From the foregoing description, it will be observed that there is
provided a first piston coil 45, a stationary second coil 18, and a
moving repulsion third coil 74, all of which are inserted
electrically into the circuit by an interrupting break and an
auxiliary secondary break, with reference being had to FIG. 10 in
this connection.
Certain broad features of the electromagnetic means which is used
in the present invention are set forth and claimed in U.S. Pat.
application, filed Sept. 1, 1966, Ser. No. 576,616, now U.S. Pat.
No. 3,524,958 issued Aug. 18, 1970 to Russell E. Frink, and
assigned to the assignee of the instant invention. Additionally,
certain features of the contact and nozzle construction are set
forth and claimed in U.S. Pat. application, filed Sept. 1, 1966
Ser. No. 576,711, now U.S. Pat. No. 3,529,108 issued Sept. 15, 1970
to Robert M. Roidt, and assigned to the same assignee. The concept
of having opposite venting through both the stationary contact
structure and the movable tubular arcing contact to maintain the
arc terminals thereon is set forth and claimed in U.S. Pat.
application filed Sept. 1, 1966 Ser. No. 576,583 by William H.
Fischer, and assigned to the assignee of the instant application.
The broad concept of using an arcing horn to insert the
accelerating coils 18, 45 and 74 into the circuit is set forth and
claimed in U.S. Pat. application filed Sept. 1, 1966 Ser. No.
576,739, now U.S. Pat. No. 3,524,959, issued Aug. 18, 1970 to
Russell E. Frink, and assigned to the assignee of the instant
application.
Although various suitable arc-extinguishing fluids may be used, it
is preferred to use a highly efficient arc-extinguishing gas, such
as sulfur-hexafluoride (SF.sub.6) gas, at a pressure of say 75
p.s.i., for example. Suitable gas-pressure measuring equipment 127
(FIG. 1) is provided within the mechanism compartment 8, so that an
alarm circuit may be actuated upon an unduly low-pressure decrease
within the tanks. However, the circuit interrupter may lose down to
40 p.s.i. before difficulty is encountered.
OPENING OPERATION
When the circuit interrupter unit 1 is closed, the current path is
from the front terminal bushing 25, to the front support casting
26, to the tubular stationary contact 33, to the tubular moving
contact 58, to the movable T-shaped contact member 98, to the rear
stationary auxiliary contact fingers 103, to the rear stationary
terminal casting 105 (FIG. 15), and to the rear terminal bushing
114 stud 113 of the rear terminal bushing.
When the circuit breaker is opened, the movable piston assembly 36
is moved to the right by the operating mechanism 123, compressing
the gas within the space 52 of the operating cylinder 14, and
drawing arcs 125, 128 (FIG. 10) between the left-hand main contacts
33a, 58 and between the contacts 101 of the movable T-shaped
contact member 98 and the stationary contact fingers 103 on the
right-hand end of the interrupting element 12. These arcs are
paralleled by the three accelerating coils 18, 45, and 74, and
since the three accelerating coils form a lower impedance path, the
current quickly transfers to the accelerating coils. The current
path is now from the stationary arcing contact 34, through the arc
125 to the moving tubular arcing contact 76, through the strap
connector 96 at the right to the "driver" or third coil, 74 to the
upper guide rod 68, to the first piston coil 45, to the lower guide
rod 78, to the sliding ball contact 83, to the second cylinder coil
18 and to the rear terminal casting 105. The three accelerating
coils are so wound so that the movable piston coil 45 is attracted
by the stationary cylinder coil 18, and the "driver" coil 74 is
repelled by it. This magnetic attractive and repulsive action
provides a powerful "assist" to the moving piston 36 in driving gas
through the main arc 125 and accomplishing its interruption. Tests
show that for a maximum fault level, approximately 10 percent of
the driving energy is supplied by the operating mechanism 123, and
90 percent by the three accelerating coils 18, 45 and 74.
The following table indicates the remarkable interrupting
performance of a three-phase model. Tests were made at 38 kv. and
22 kv., and with an ungrounded neutral, and at maximum settings.
##SPC2##
With reference to FIGS. 1 and 2 of the drawings, it will be noted
that there is provided a pressure-control panel assembly 131. It
consists of a pressure gauge, a filling valve, and a pressure
switch. From this assembly there is a manifold connecting to the
tanks 11 of the three interrupting pole-units 13. The pressure
switch is arranged to provide an alarm if the gas pressure leaks
off, the alarm being provided before the lower limit for fault
interruption is reached. At the lowest pressure limit, the switch
will operate to trip the breaker and lock it out. The switch is
temperature compensated.
Each pole-unit assembly 13 includes the grounded metallic tank 11
with a pressure-release rupture disc 132 (FIG. 3) mounted in the
bottom of the tank 11. It is placed at the bottom of the tank 11 so
that if it operates, the fragments will be directed toward the
floor. As shown, the top of each tank 11 has two flanges 133 (FIG.
2) to which the bushings 25, 114 are bolted.
In fluid-blast circuit interrupters of the piston-operated, or
"puffer" type, the operating mechanism has, in the past, been
required to supply the energy requirements to interrupt high
currents. However, pressure in the cylinder from the back pressure
of the arc made the mechanism power, required to drive the piston,
so excessive as to make the designs uneconomical. The interrupting
assembly of the present invention, which has been described above,
uses coils of 61/2 turns each, for example, creating approximately
90 percent of its driving energy by a magnetic interaction of the
accelerating coils when interrupting currents of the order of
40,000 amperes. A three-phase model has, in fact, interrupted over
50,000 amperes, and this was not its limit.
In addition to the basic interrupting ability of the puffer-type
circuit interrupter described above, there are several other
advantages to this type of interrupter. First of all, since the
interruption is in an atmosphere of SF.sub.6 gas, there is complete
freedom from fire hazard. Secondly, since the interruption takes
place inside a sealed pressure vessel, there is virtually no
interruption noise. As described above, the contacts for the
breaker operate in a sealed chamber filled with sulfur-hexafluoride
(SF.sub.6) gas at 75 p.s.i. for example. A separate chamber is
provided for each phase, and the piston, magnetically driven by the
fault current in the circuit, forces the high-velocity stream of
gas through the arc stream and extinguishes the arc 125 in 11/2
cycles, or less. Experience has indicated little or no decrease in
interrupting ability down to 30 p.s.i. gas pressure. At atmospheric
pressure, the breaker will maintain its insulation value and will
safely interrupt load currents at rated voltage.
Sulfur-hexafluoride (SF.sub.6) gas has proved to be remarkably
inert, with excellent interrupting and insulating properties.
Chemically, sulfur-hexafluoride (SF.sub.6) gas is one of the most
stable compounds, and, in the pure state, or under normal service
conditions, is inert, nonflammable, nontoxic, and odorless.
As pointed out above, the interruption takes place in SF.sub.6 gas,
stored under pressure in a metal tank. Gas flow for interruption is
provided by the magnetically assisted piston, and no separate
tanks, external piping compressors, or blast valves are required.
Also, with the SF.sub.6 gas at a nominal pressure of 75 p.s.i. the
gas does not liquify at the temperatures that will be experienced
in operation, and there is no need for auxiliary heaters.
Experience has shown that there is little deterioration of the gas
with repeated interruptions, which eliminates the need for its
reconditioning, as would be necessary with oil as the interrupting
medium.
Internal insulation is furnished by the SF.sub.6 gas, with
sufficient striking distances to withstand operating voltage at
atmospheric pressure. The gas also insulates the bushings.
As shown in FIGS. 35 and 37, the circuit-breaker unit 1 may be
lifted from the disconnect, or test position, to the connected
position by a motor-operated four-screw elevating mechanism 138
mounted in the stationary cell structure 2. Guide pins 148 (FIG.
36) will ensure proper location of the breaker unit 1 upon the
elevating mechanism 138, and will ensure alignment of the primary
and secondary contacts 3, 5 and 4, 6 (FIG. 35). Each stationary
section includes a control station, limit switches and line within
electrical interlock to prevent operation of the raising and
lowering mechanism when the control jumper is in place. In
addition, each circuit-breaker unit 1 is equipped with a mechanical
interlock, which prevents raising or lowering the breaker in the
stationary structure 2 without tripping open the breaker. The
circuit-breaker unit 1 cannot be closed when the circuit-breaker
unit is at any point between the connected and the test
positions.
As shown in FIGS. 36 and 37, the removable circuit breaker unit 1
is raised to the engaged position by four jackscrews 154 in the
corners of the cell 2. These jackscrews 154 are coupled together by
a roller chain 156 (FIG. 38) around the top of the cell 2. The
lower ends of the jackscrews 154 engage nuts 158 (FIG. 37), which
lift the two channel-shaped members 20, which, in turn, lift the
breaker unit 1 to the engaged position. Both the up and down
position of the removable circuit-breaker unit 1 are controlled by
limit switches, which cut off the motor 161 (FIG. 37) when the
breaker is in the correct position.
The lifting frame assembly 138 comprises a pair of
parallel-disposed lifting rails 20 of channel-shaped configuration
which extend completely lengthwise of the breaker cell 2 as shown
more clearly in FIG. 37. The lower inwardly extending flange 20a
underlies the flange 9a of the steel section 9, as shown in FIG.
36, with the spaced guide pins 148 on the rails 20 centering in
holes 162 (FIG. 36) disposed adjacent the ends of each steel angle
section 9.
In the perspective view of FIG. 31, illustrating a multiplicity of
such units, the circuit-breaker units and the housing cell
structures 151 are so designed and constructed that the 3,000
ampere removable circuit-breaker unit may be placed in any 1,200
ampere housing, but mechanical interference prevents placing a
1,200 ampere breaker in the operating position of a 3,000 ampere
housing.
A sheltered operating aisle 153 (FIG. 34), of ample width for
handling the removable circuit-breaker units, extends the length of
the metal-clad switchgear equipment 151. The enclosures are
weatherproof with sloping roof sections for all areas. Heating is
provided in the operating area.
From the foregoing description it will be apparent that there has
been illustrated and described a novel fluid-blast circuit
interrupter utilizing electromagnetic means, including a plurality
of accelerating coils, to speed up the piston motion on heavy or
fault-current interruption. By so doing, the energy requirements of
the operating mechanism 123 (FIG. 2) may be minimized. In addition,
the use of such electromagnetic accelerating coil means 134 (FIG.
10) has enabled the compression of the required gas flow to be
obtained in a minimum of time. Finally, the several elements of the
interrupting assembly 12 have been so positioned and interrelated
in a compact and closely spaced arrangement, so that all three
pole-units 13 may be operated from the same operating mechanism
123.
Details of the lifting mechanism are set forth and claimed in U.S.
Pat. application filed Sept. 19, 1966 Ser. No. 580,426 by John M.
Kozlovic now U.S. Pat. No. 3,435,162, issued Mar. 25, 1969 and
assigned to the assignee of the instant invention.
Although there has been illustrated and described a specific
structure, it is to be clearly understood that the same was merely
for the purpose of illustration, and that changes and modifications
may readily be made therein by those skilled in the art, without
departing from the spirit and scope of the invention.
* * * * *