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Патент USA US2134572

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Oct. 25, 1938.
w. E, PAUL
Filed May 27, 1937
2 l 3 4 5. 7 2
Patented occas, 1938
. William E. Paul, Schenectady, N. Y., assignor to
General Electric Company,
a corporation of
' New York
‘ iApplication May 27, 1937, Serial No. 145,057
(Cl. 20G-150)
` 15 Claims.
'I‘he circuit breaker illustrated is of the high
My invention relates to electric circuit break
voltage oil-blast type and comprises an insulating
ers, more particularly> to high voltage >circuit
breakers of the oil blast type wherein pressure
generated by arcing at one part of the circuit is
5 utilized for directing a blast .of arc-extinguish
casing or iibre cylinder i forming a pressure-con
fining chamber containing a suitable arc-extin
guishing liquid 2, such as oil for example, in 5
ing fluid through an arc at another part of the
g It has been proposed in ircuit breakers of the
aforesaid type that the contact structure be ar
10 ranged so that two arcs in series are progres
sively formed. The first orpressure generating
arc has a substantially constant length and -is
utilized to cause a‘ blast of oil or other arc-ex
tinguishing liquid~ at the subsequently formed
15 main arc for interrupting the same. With this
arrangement there may be difficulty in interrupt
ing with equal facility comparatively small and ,
'heavy short circuit currents by reason of the
substantially ñxed length of the pressure gener
20 ating arc.
This is due to the fact that insum
cient pressure may be generated for interrupting
a low current arc, assuming of course that the»
contact separation is suitable for large currents.
Another limiting factor in this design is that
the speed of operation is somewhat retarded by
the movement or ‘fwipe” of the contact structure
prior to actual arc formation and the interrupt
ing action of the blast. That is, a certain wipe
' takes place even before formation of the pres
sure generating arc, and a subsequent wipe or
following action of the contacts occurs prior to
formationof the main arc which is subject to
the oil blast. Where the interruption of high
voltage alternating current power circuits within
two or three cycles is required, theseiactors are
35 very important in determining the ultimate op
erating speed of the breaker.
The principal object oi my invention is the
provision of anrimproved high voltage circuit
breaker of the oil blast type that is emcient and
reliable particularly as regards arc interruption ‘
throughout the entire rated interrupting range of
the breaker, and is also capable of high speed
circuit interruption.
My invention. `will be more fullyv set forth in
the following description referring to the ach1
companying drawing, and the features of novelty
which» characterize my invention will be pointed
out with particularity in the claims annexed to
and forming a part of this specification.
Referring to the drawing, the single figure
thereof is an elevational view, partly in section
and partly diagrammatic,v of ahigh voltage eleca
tric circuit breaker embodying the present
which are immersed the relatively movable con
structure comprises a
tacts. The breaker contact
fixed or terminal contact 3y electrically connected
at 4 to the metallic terminal housing 5, a pivoted
arcing contact 6 normally biased by a spring 'i
into contact engagement with the fixed contact 3,
a stationary intermediate contact 8 electrically
connected at 9 to the intermediate contact t, and
a movable rod contact l0 which is guided for
reciprocal movement through the bottom plate li
of the breaker casing. The breaker as shown is
in the open-circuit posi tion, the contacts t and
lil being insulated from each other by the in
sulating oil in the casing. The contact rod I0
is suitably operated between its closed circuit
position, wherein it engages in butt contact the
intermediate contact t, and the open circuit posi
tion by an operating mechanism generally indi
cated at i2.
The power circuit is completed in the closed 25
position of the breaker through the terminal
structure 4_5, coacting contacts 3 and S, inter-J
mediate contact structure 3--Q, and the contact
rod lil which is suitably connected to the other
rod lil is lowered tc open
terminal. When the immediately
formed in the
the circuit, an arc is
insulating oil between the contacts ti and lil,
thereby generating pre ssure depending on the
arc current within the breaker casing.
'I'he upper part of the casing i is provided with \
a. pressure relief passage i3 within which the
pivoted -contact 6 is located so as normally to
close the, passage. Accordingly, when sumcient
arc pressure builds up within the lower part of
the casing, the contact t is pivoted clcckwise
against the bias of spring ‘i thereby opening the
circuit at that point. C oncur-rently a
is released through the chimney-like
to exhaust into the upper housing t
collected and subsecluently returned
blast of oil
passage it
where it is
to- the arc 45
Accordingly, the arc formed 'between the con
tacts 3 and t is traversed by a high velocity oil
is interrupted at that point. ~
‘blasty and the circuit
It will be apparent that the tension of the spring
l may be adjusted so > that the contact t will
open only when the desired arc pressure is geri-s
eratecl within the casin g. ln this manner even
comparatively low current arcs are eiiectively in
terrupted since the are pressure is substantially 55
confined until it builds up to the desired blast
value. Interruption of the arc at the contact 6
necessarily extinguishes the series arc at the con
tacts 8, l0 so that an isolating gap in oil between
these contacts is effective to prevent re-estab
lishment of arcing. The contact 6 therefore
may return to its initial position under bias of
the spring ll.
In order, however, to prevent premature clos
ing of the contact G a suitable retarding device,
generally indicated at I4, is operatively connected
to the contact S through a pivoted lever i 5 and an
insulating link I6 connected at Il to an extension
of the contact 6. Any suitable retarding or
escapement device may be employed, a dash-pot
i8 being illustrated by way of example. When
the contact S is opened the dash-pot plunger is
raised without resistance, the opposite stroke,
however, retarding the reclosing movement of the
Contact 6.
En this manner, the arc gases etc.,
tending to decrease the dielectric strength of the
oil, can escape from the region of the contacts
S-i t before reclosure of contact S, thereby mini~
mizing the possibility or" reignition of the arc.
In the case of heavy short circuit currents the
arc pressure, particularly where the arc is
lengthened as by looping under the iniiuence of
magnetic forces, may be so great as to damage
the breaker. For the purpose of controlling the
arc pressure in the case of heavy currents, there
is provided means for short-circuiting the initial
part or" a heavy current arc, thereby shortening
the same, so that the pressure is correspondingly
decreased. To this end a conducting sleeve or
ring is iixed with respect to and surrounds the
contact portion of the intermediate contact 8.
lThe member i 9, which is larger in diameter than
the contact rod lil so that no actual contact is
in a manner presently described by the iioating
lever 22 of the operating mechanism l2 is con
nected in series with a conductor loop 23. The
opposite sides of the loop are secured with respect
to a pair of insulating jaws 24 and 25 ,pivotally
connected at 26. The 'jaw 24 is secured to a fixed
mounting at 2l, and the relatively movable jaw
25 is operatively connected by means of a link
28 to a slidably mounted stop member 29 adapted
to coact with the lower end of the Contact rod
I0. A compression spring 30 bearing between a
fixed guide 3l and the jaw 25 tends to maintain
the conducting loop in a compressed position as
When the floating lever 22 is rotated under 15
bias of the main operating spring 32 so as to
cause downward or opening movement of the
contact l0 the current traversing the circuit
creates magnetic forces tending to expand the
loop 23 in a manner well known in the art. The 20
tensionof the spring 30 bears a predetermined
relation to the magnitude of the current so that
only in response to moderately heavy currents is
the stop member 29 moved by the magnetic forces
acting against the bias of spring 30.
Assuming now that a moderately heavy load
current is to be interrupted, the loop 23 is ex
panded by the magnetic forces so as to slide the
stop member 29 a short distance toward the
right as viewed so that the step 29’ is beneath the 5
insulating end portion l0' of the contact rod.
The opening stroke of the contact is thereby re
duced by a predetermined amount and the arc
correspondingly shortened. If a heavy short cir
cuit is involved the member 29 will be moved so
that the step 29" is beneath the Contact end l0',
thereby further shortening the arc.
It will be apparent that any desired number
made between the two, is provided with laterally
to disposed pressure relief vents 20 and in the pres
of steps may be used in this connection, or as a
ent instance is electrically connected to the con
wedge-shaped so as to limit the arc length more
tact Ei.
it shall be understood that the conducting ring
is not necessarily electrically connected to the
contact il and that under certain conditions a
small insulating gap may separate the same. A
heavy current are by reason of the magnetic
forces tending to cause looping or bowing will
shift laterally to the surrounding conductor and
strike between the lower edge of the member I9
simple alternative the stop member may be 40
closely with respect to the current to be inter
Referring more particularly to the operating
mechanism I2 which may be of any suitable high
speed trip~free type, the floating lever 22 is
pivotally connected at one end to the armature
33’ of a tripping magnet 33 and at the other end
is connected to the contact rod l0 through a link
34. The central part of the lever coacts through
and the contact rod i0 as indicated at I9', there~
by shortening the length of the arc and decreas
ing the arc pressure correspondingly. In the case
of light currents, the arc tends to strike directly
suitable power device.
between the contacts 8 and l0 so as to utilize the
maximum arc length for building up the blast
nection with the armature 33' to cause upward or
It will be apparent that the conducting ring l 9
may be formed in any suitabe manner, such as for
example like a’squirrel cage, the spacing between
the bars in this case serving as pressure relief
openings for the gas pressure generated when
the contacts separate. This gas pressure may
otherwise produce an abnormal accelerating ef
fect on the rod I0.
A further device is preferably also employed for
regulating the arc pressure due to heavy load or
short-circuit currents. This comprises a current
responsive control mechanism generally indicated
a guide member 35 with an operating arm 36 of a
It will therefore be apparent that the lever 22
can be pivotally rotated about its pivotal con
circuit-closing movement of the rod I0 when the
arm 36 of the power device is rotated clockwise.
The guide member 35 comprises a cylinder
guided for vertical reciprocal movement at 3l and
at 38. For the purpose of allowing a limited
amount of “wipe” between the power device and
the operating mechanism the cylinder 35 has
mounted therein a. spring buffer arrangement 39
for coacting with the roller 40 of the power device.
The cylinder 35 is connected to the lever 22
through a pin and slot connection 4I-42, the
slot 42 in the lever 22 being slightly elongated
'for permitting pivotal movement of the lever
with respect to the tripping magnet 33. A corn
pression spring 43 acting between the guide 35 70
and lever at 43’ is utilized for biasing the lever
70 at 2l for determining the length of stroke of the
contact rod l0 under certain conditions. Since
the arc pressure is dependent inter alia on the
toward thel right so as to center the magnet end
length of the arc, the opening travel of the con
of the lever during the resetting operation. At
tact l0 is shortened as the current increases.
the end of the operating stroke the spring bulïer
To this end the contact l0 which is'operatedD 39 takes up the additional “wipe” of the mecha
2,134,572 «
nism formerly assumed by the contact structure.
In this manner the connections between the
floating lever 22, which is directly controlled by
Athe tripping magnet 33, and the movable con
5 tact structure can be rigid so that opening of
the circuit immediately upon release of the iioat
ing lever is effected by the spring 32.
The operation of the tripping magnet 33 is well
opening of said biased contact and an arc-extin
guishing liquid blast through the arc at that
point, and retarding means for delaying reclosure
of said movable contact after extinction of said
3. An electric circuit breaker of the oil blast
type comprising a pressure-confining casing con
taining an arc-extinguishing liquid, relatively
known in the art and can be readily understood movable contact structure adapted to form two
breaks in ‘series in said liquid including a mov
10 from the drawing, the tripping coil M for caus
able contact normally biased to closed circuit po
ing release of the armature 33' from the perma
sition, an intermediate relatively iixed contact
nent magnet 33 being energized from the con .electrically
connected to said biased contact and
ventional line current transformer at M’.
a movable rod contact coacting with said fixed
The operation of the mechanism I2 is as fol
lows: In the open circuit position shown the contact, the are pressure generated at the break
between said ñxed and. rod contacts being utilized
magnet 33 is' reset so that the armature 33’ con
stitutes a iixed pivot for the ñoating lever 22. to open said biased contact and drive an arc
interrupting liquid blast through the arc at "that
When the power device at 36 is actuated, the point, and a retarding device operatively con-`
guide member 35 is raised and the lever 22 ro
nected to said biased contact for permitting free
20 tated clockwise about the armature 33' against opening _movement thereof and for retarding re
the bias of spring 32 so as to close the breaker
closure thereof for decreasing the possibility of
at the contacts 8--I0. When the breaker is reestablishment of arcing betweenv said ñxed and
tripped in response to overload or short-circuit,
the tripping coil 44 of the magnet releases the rod contacts.
4. An electric circuit breaker of the oil blast
type comprising a pressure-confining casing conrapidly about its central pivot at 4i in counter ' , taining anew-extinguishing liquid, said casing
clockwise direction by the opening spring 32. Re
being vertically positioned and having a chimney
setting of the mechanism is effected by simply like exhaust passage at the upper part thereof,A
lowering the arm 3B of the power device so that and relatively movable contact structure adapted
30 the armature 33’ again engages the magnet. It ’to form two breaks in series in substantially
will be apparent that the mechanism is trip
alinement in said liquid including a mov
free in operation since at any time duringthe Vertical
able contact normally biased to lclosed circuit
closing stroke the spring 32 is effective to rotate position, said contact being .positioned in said
the lever 22 about its central pivot pin upon' passage so as to close the same in said closed
circuit position, and means at one of said breaks
35 release of the armature 33’.
The “wip-e" connection at 39 it will be noted for creating arc pressure» in the lower part of
is between the power device and the lever 22 said chamberl for opening said biased contact
so that release of the armature 33’ is effective and driving an arc-extinguishing liquid blast
to cause instant separation of the coacting butt through said passage and the arc at that point.
40 contacts ill-ld which have no “wipe” contact.
Accordingly, the pressure-generating arc is in
stantly formed after the tripping impulse and
the pressure created for interrupting the arc is
generated at the earliest possible moment.
It should be understood that my invention is
not limited to speciñc details of construction .and
arrangement thereof herein illustrated, and that
changes and modifications may occur to one
skilled in the art Without departing from the
50 spirit of my invention.
What l claim as new and desire to secure by
Letters Patent -of the United States, is:
l. An electric circuitbreaker of the oil blast
type comprising a pressure-confining casing con
55 taining an arc-extinguishing liquid and relatively
movable contact structure adapted to form two
breaks in series in said-liquid including a mov
able pivoted contact normally biased toward
closed circuit position, said pivoted contact nor
5. An electric circuit breaker of' the oil blast
type comprising a pressure-confining casing hav
ing an exhaust Ipassage and containingan arc
exting‘uishing liquid, and relatively movable con
tact structure adapted to form two breaks in
series in said liquid including a pivoted Contact
normally biased toward closed circuit position
and locatedi-in said exhaust passage to close the
same, opening of said pivoted contact forming
aof break
said passage,
in the circuit
a relatively
fixed rigidly
contact electrically connected to said pivoted con
tact, and a movable rod contact adapted to abut
said ñxed contact, opening movement of said
rod contact causing instantly a break at said l”
fixed Contact for generating in said chamber are
pressure for opening said biased contact and
driving an arc-extinguishing liquid blast through
said passage and the arc at said first-named
6. An electric circuit breaker of the oil blast
60 mally closing "a pressure relief passage in said
casing, an intermediate relatively fixed contact ~ type comprising relatively movable contact struc
" and a second movable contact coacting with said ture adapted to form two breaks in series in an
ñxed contact, the arc pressure generated in said arc-extinguishing liquid, means ier directing the -
casing at the break between said fixed and sec
ond movable contact being utilized to open said
c5 -biased
contact and drive an arc-extinguishing
liquid blast through said passage and the arc at
that point.
2. An electric circuit breaker oi the oil blast
type comprising a pressure-confining casing con
70 taining an arc-extinguishing liquid and relatively
movable contact structure immersed in said liq
uid including a movable contact normally biased
toward closed circuit positiori,'means for gener
75 ating arc “pressure in said casing for causing'
pressure generated at one of said breaks so as to dii
cause a blast oi’ said liquid at tl'ieotlier break
for interrupting the circuit, and means for con
trolling the arc pressure at said generating break
including conducting structure substantially sur
rounding said generating break adjacent the point
of -:formation thereof sc that a heavy current are
is short cireuited in part by said conducting
structure so as to shorten said arc.
7. ¿in oil circuit breaker including relatively
movable contact structure Asepa rable in an arc
extinguishing liquid to cause generation of pres
sure for interrupting the circuit, and means for
controlling said arc pressure comprising a gen
erally cylindrical conducting structure substan
5 tially surrounding said arc adjacent the point of
initial formation thereof, said structure being
concentrically located with respect to the cen
ral axis of said contact structure s0 as to be
spaced from said arc at low current values and
short circuit the same in part` at comparatively
large current values.
8. An electric circuit breaker comprising rela
tively movable contact structure immersed in an
. arc-extinguishing liquid, said Contact structure
15 adapted to form a pressure-generating break for
causing an 'arc-interrupting liquid blast, and
means for controlling the arc pressure compris
ing a conducting cylinder electrically connected
to a part of said contact structure and substan
tially surrounding the arc at the point oi’ initial
formation thereof, said cylinder being open at
one end for receiving another part of said con
ated upon separation of said contacts being uti
lized for interrupting the circuit, and electro
magnetic means responsive to the magnitude of
the current to be interrupted for blocking the
separation of said contact structure at a prede
termined point.
13. An electric circuit breaker comprising rela
tively movable contact structure, the arc pres
sure generated upon separation of said contact
structure being utilized for interrupting the cir
cuit, and arc pressure control means including
a conductor in series with the circuit normally
positioned in the form of a compressed loop,
resilient means biasing said loop toward Said
compressed position and a member adapted to
coact with said contact structure for limiting the
degree of separation thereof, said member being
operatively connected to said loop so that ex
pansion of said loop in response to comparatively
large currents causes movement of said member
toward a position for limiting the aforesaid con
tact separation.
tact structure and being in spaced concentric
relation thereto so that said arc is short circuited
25 in part by said conducting cylinder at compara
tively large arc currents.
9. An electric circuit breaker of the oil blast
type comprising a ñxedcontact and a relatively
movable rod vcontact positioned within a pressure
confining casing and immersed in an arc-extin
guishing liquid, a conducting cylinder connected
to said fixed contact so as~to surround in con
centric relation the contact end of said rod con
tact in closed circuit `position, said cylinder hav
ing pressure relief openings and being spaced from
said Contact rod so as to short circuit the enclosed
part of the arc at comparatively heavy arc cur
10. An electric circuit breaker comprising rela
tively movable contact structure, and electromag
netic means responsive to the magnitude ci" the
current to be interrupted for determining the
degree of separation ci said contact structure.
11. An electric circuit breaker comprising nxed
and relatively movable contacts arranged to form
two breaks in series, ‘the arc pressure generated
upon separation of said contacts at one of said
breaks being utilized for interrupting the circuit
at the other of said breaks, and means coacting
with the movable contact structure at said pres
sure generating break responsive to the magni
tude of the current to he interrupted for limiting
uthe opening stroke of said Contact structure so
as to decrease the arc pressure at comparatively
high currents.
l2. An electric circuit breaker comprising rela
tively movable contacts, the arc pressure gener
14. An electric circuit breaker comprising rela
tively movable contact structure adapted to coact
in substantially non-yielding engagement for fa
cilitating quick separation thereof and means
for effecting high speed separation of said con
tact structure including an operating member
having a non-yielding operative connection with
a movable part oi said structure,means for biasing
said member to open circuit position, a tripping
device directly connected to said member for
restraining the member in closed circuit position,
actuating means for moving said member against
said biasing means to closed circuit position, and
resilient means interposed between said actuating
means 'and said member for permitting a limited
over-travel of said actuating means upon contact
l5. An electric circuit breaker comprising rela
tively movable contacts, a iloating lever opera
tively connected at one end to the movable con
tact, a tripping device coacting With the opposite
end of said lever, said lever being pivotally
mounted with respect to s'aid device and movable
contact, actuating means coacting with said lever
intermediate the ends thereof for' closing said
movable contact, a reciprocally guided resilient
connection between said lever and actuating
means, said lever having a limited lateral move
ment with respect to said guided connection for 50
permitting rotation'about said tripping device,
and spring structure for biasing said lever to
Ward open circuit`position about said guided
connection in response to actuation of said trip
ping device.
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