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Патент USA US3054882

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Sept. 18, 1962
J. D. woon ETAL
3,054,876
MAGNETIC AssTsTs FOR Low CURRENT ARcs
Filed Deo. 24, 1958
2 Sheets-Sheet 1
INVENTORS
Sept. 18, 1962
3,054,876
J. D. WOOD ETAL
MAGNETIC ASSISTS FOR LOW CURRENT ARCS
Filed Deo. 24, 19.58
2-Sheets-Sheet 2
United States Patent Otiâce
1
3,054,876
Patented Sept. 18, 1962
2
addition to the conventional magnetic blowout means, for
the interruption of low current arcs.
Still another object is to provide assistance means for
the interruption of low current arcs which does not require
3,054,376
MAGNETIC ASSISTS FÜR LÜW CURRENT ARCS
Joseph D. Wood, Wayne, Philip G. Smith, Hatboro, and
William A. Carter, Chester, Pa., assignors to I-T-E Cir
cuit Breaker Company, Philadelphia, Pa., a corporation
of Pennsylvania
Filed Dec. 24, 1958, Ser. No. 782,751
10 Claims. (Cl. 200-147)
additional mechanical opening forces to be available in
the breaker operating mechanism.
A fur-ther object is to provide an assist means for the
interruption of low current arcs which is substantially ín
stantaneously by~passed when the circuit breaker in
The instant invention relates to air magnetic circuit 10 terrupts high current arcs.
breakers and more particularly to «magnetic assist means
A still further object is to provide an assist means which
for arc interruption at low currents.
is only operated during circuit breaker operation which
Air magnetic circuit breakers usually include an arc
results in the interruption of an arc.
extinguishing means which operates in conjunction with
Yet another object is to provide »a longitudinally split
magnetic blow-out means to eiiect a rapid interruption 15 arc runner construction for the insertion and withdrawal
of the arc drawn between the parting contacts of the cir
of the magnetic assist means.
cuit breaker when the circuit breaker interrupts a cur
These as well as other objects of the instant invention
rent carrying circuit. The extremely low magnetic force
produced by the magnetic means for movin's an arc of
low current magnitude makes it necessary to provide an
assist device to aid the arc extinguishing means in the
interruption of low'current arcs.
Prior art devices have provided assists for the inter
ruption of low current arcs which comprised a light blast
of air directed to blow the arc into the arc chute, forming 25
the arc extinguishing means, as the arc was formed when
the breaker contacts parted. The light blast of air was
usually supplied from a chamber and plunger assembly
shall become readily apparent after reading the following
description of the accompanying drawings in which:
FIGURE l is a schematic illustrating a circuit inter~
rupter including a novel magnetic assist means constructed
in accordance with the instant invention.
FIGURE 2 is a schematic similar to FIGURE l illus
trating a modiiication of the invention.
`FIGURE 3 is a schematic illustrating still another
modification of this invention.
FIGURE 4 is a iront elevation of the longitudinally
split arc runner of FIGURE 3 looking in the direction of
with either the plunger or chamber being actuated by some
arrows 4ä4.
moving component of the breaker. IThe blast of air is 30 lNow referring more particularly to FIGURE 1, circuit
created by the displacement of air in the chamber by the
breaker lil comprises a lower terminal stud 11 insulated
plunger.
and spaced from an upper terminal stud 12 whereon sta
This type of arrangement made it necessary to increase
tionary main 13 and arcing 14 contacts are mounted.
the amount of opening force in the operating mechanism
Conducting bridge y15 is pivotally secured and electrically
of the breaker to compensate for the opposition from the 35 connected to lower terminal 11 at pivot ‘16. Movable
displacement of air by `the plunger. Further, the air
main 17 and arcing 18 contacts are mounted to bridge 15
assist devices are operated each time the breaker operates,
and operatively positioned for engagement with stationary
even when no current is being interrupted as well as to
interrupt high current arcs, thereby resulting in unneces
sary wear to the plunger and chambers well as tto asso
40
main 13 and arcing 14 contacts, respectively, when the
circuit breaker is closed. Movable arcing contact 18 is
pivotally secured to bridge 15 in a manner well known to
the art which enables main contacts 13, 17 to part, upon
t
The device of the instant invention includes a specially
opening of the circuit breaker, before the parting of arcing
designed magnetic circuit separate and distinct from the
contacts 14, 18 and upon closing of the circuit breaker,
main magnetic blow-out means of the interrupter, and in
zarcing contacts 14, 18 will engage before main contacts
addition thereto, to assist in the interruption of low cur~ 45 13, 17 are brought into engagement.
rent arcs. The coil of the magnetic assist is energized
Rear arc runner 2t) extends upwardly in the region
only by the arc after fthe arc is formed by the parting of
above stationary contacts d3, 14 `while front runner 21 is
the breaker contacts.
spaced from rear runner 20 and extends upwardly from
Means are provided whereby the magnetic assist coil
the position occupied by bridge 15I when circuit breaker
ciated parts.
is energized only during predetermined conditions of the 50 10 is open. Jump gap 22. is disposed between stationary
arc. That is, the magnetic assist coil is by-passed when
the arc current exceeds a predetermined value or after
the arc has been driven into the arc chute a sufficient
distance so that it is under the strong iniluence of the main
magnetic circuit. The coil of the magnetic assists com
prises a large number of turns to obtain the necessary
flux to produce a strong magnetic held when only a low
magnitude of current is flowing. Relatively small diam
arcing Contact 14 and the bottom of rear runner 20.
A
plurality of spaced parallel plates 23 forming arc chute
24 generally of the type described in U.S. Patent 2,390,735
are disposed between parallel portions of the rear 20 and
55 front 21 runners.
A main blow-out structure comprising main blow-out
coil 30 and main iron circuit 31 associated therewith is
operatively positioned to urge arcs drawn between the
eter Wire may be used in the assist coil since this coil will
parting contacts 14, 18 into the region of plates 23
be required to carry current for only a short interval of 60 thereby elongating the arcs so that they may be eiîectively
time.
Accordingly, a primary object of the instant invention
is to provide an air magnetic circuit breaker having novel
cooled, by plates 23, for the rapid extinguishing thereof.
One end 33 of coil 30 is electrically connected «to rear
runner 20 while the other end 34 of coil 30 is electrically
means for low current arc interruption.
connected to upper terminal stud 1‘2.
Another object is to provide a magnetic assist means, in 65 Circuit breaker 10‘ also includes a magnetic assist
3,054,876
3
4
means comprising magnetic assist blow-out coil 40 and
its associated iron circuit 41 positioned in the region of
«the contacts 14, 13, 17, 18. One end 42 of coil 40
is electrically connected to »front runner 21 while the
other end 43 is electrically connected to return connection
32 which electrically connects front runner 21 to lower
terminal stud 11. Front runner 21, in the region shunted
.
coil 40 is lconnected to »return connection 32. A gap
52, deñned by edges 50 and 51, is formed in front runner
60 in the region above curved portion 61. A jumper 63
is connected to front runner 60 above gap edge 51 and
extends to assist blow-out coil terminal 43.
When circuit breaker 100 is utilized to interrupt a cur
rent carrying circuit magnetic assist blow-out coil 40 is
by magnetic assist blow-out `coil 40, includes a gap 44
for a purpose to be hereinafter explained.
energized at the moment the portion D of the are is ex
Interruption of an arc by circuit breaker 10 proceeds
as follows: with the circuit breaker in the closed, position,
that is, with movable contacts 17, 18 in engagement
with stationary contacts 13, 14 lbridge 15 is moved clock
wise about pivot 16 by any one of the operating mecha
iron circuit 41 forces the are upwardly toward arc chute
24. When the arc is in the path designated E magnetic
assist blow-out coil 40 is still energized. However, as
the arc continues to travel upwardly the end thereof ter
minating at front runner 60 will pass ‘from one side of
gap 52 to the other side. With the arc in lthe position
deiined by path F the arc current will ilow through
nisms well known to the art.
Initially, `an arc is drawn A
directly between the sta-tionary 14 and movable 18 arcing
contacts and occupies the arc path A. As arcing contact
18 proceeds to the right, a portion of the arc is extin
guished by jump gap 22 and the arc then assumes the
path B between rear runner 20 and movable arcing con
tact 18 with the arc current ñowing through main blow
out coil 30.
Continued movement of arcing Contact 18 to the right
results in further elongation of the arc until it occupies
the path C between the closest portions of the rear 20 and
front 21 runners in the lower regions thereof and the
path D between the front runner 21 and movable arcing
tinguished.
The ilux ‘generated in the magnetic assist
jumper 63 thereby passing magnetic assist blow-out coil
40.
When circiut breaker 100 is called upon to interrupt a
circuit carrying a high magnitude current, the arc will
travel 4upwardly into chute 24 at a very rapid rate so
that the arc current will only pass through the magnetic
assist coil 40 -for an extremely short interval of time.
This enables coil 40 -to be constructed of many turns of
fine wire with the resistance of the wire providing a
measure of self protection in that the current magnitude
is limited by the resistance.
Still another embodiment of the instant invention is
illustrated in FIGURES 3 and 4. Circuit breaker 200
contact 18. Further movement of movable arcing con
tact 18 to the right causes the portion of the arc at path
D to be extinguished. At this time the current path 30 comprises a lower 201 and an upper 202 terminal stud to
which external circuit connections are made. Conductive
between upper terminal 12 and lower terminal 11 com
prises return connection 32 through assist blow-out coil
40, the arc along path C to rear runner 20 and through
main blow-out coil 30.
If `the arc current is of a rela
tively high magnitude the voltage between the ends 42,
43 of assist blow-out coil 40 will be sufficient to break
down the air in gap 44 and the arc current of path C will
bridge gap 44 so as to by-pass magnetic assist blow-out
coil 40.
bridging member 203, pivoted -to lower stud 201 at pivot
204, bridges the gap between current studs 201 and 202
when the circuit breaker is in the closed position illus
trated in FIGURE 3.
Contact block 205 is mounted to the end of upper stud
202 and carries stationary main contact 206 and station
ary auxiliary arcing contact 208.
Stationary auxiliary
arcing contact 208 is mounted to lthe foot of L-shaped
Thus, it is readily seen that with an arc current of rela 40 member 236 whose arm is pivotally mounted at 237 to
contact block 205. Torsion spring 235, interposed be
tively low current Ithe current through assist blow-out
tween member 236 and block 205, biases member 236
coil 40 will cause a ñux to be generated in the magnetic
in a counterclockwise direction about pivot 237 for a
assist iron circuit 41 which is operatively positioned to
reason to be hereinafter explained. These stationary
force the arc upwardly into `arc chute 24 where it may
contacts 206 and 208 are engageable by movable main
be efñciently acted upon by the main iron circuit 31 by
contact 207 and movable auxiliary arcing contact 209,
main blow-out coil 30. If the arc current is of a high
magnitude it will flow through assist blow-out coil 40
gîäaectively, both of which are secured directly to bridge
for only a short time during which the potential across
Insulating member 212 which is positioned above con
gap 44 will build up to a break down voltage at which
tact block 205, and another contact block 213 is posi
time assist coil 40 will be shunted so ythat only main
blow-out coil 30 will be energized.
`
With this novel arrangement, magnetic assist coil 40
may be comprised of many turns of tine wire so that the
tioned above insulating member 212 with stationary
arcing contact 214 being secured to conductor block 213.
Movable arcing contact 215, which cooperates with sta
tionary arcing contact 214, is mounted to conducting
even though «the current is of a low magnitude. When 55 member 216 pivotally mounted at 217 to bridge 203 and
is biased in a counterclockwise direction about pivot 217
the current through assist blow-out coil 40 exceeds a
by means of tension spring 233.
predetermined value the current is shunted through gap
flux in the assist circuit 41 will be of a high magnitude
Rear arc runner 220 is a longitudinally split member
44.
comprising a first longitudinally extending conducting
The invention as illustrated in FIGURE l comprises a
portion 221, on the right with respect to FIGURE 4, and
device wherein the arc current is caused to by-pass the
magnetic assist blow-out coil 40 when the arc current 60 a second longitudinally extending portion 222 with a
longitudinally extending insulator 223 being interposed
exceeds a predetermined value. The modification of the
inveniton illustrated in FIGURE 2 is directed to a con
struction whereby the arc current by-passes the magnetic
assist blow-out coil 40 when the arc has reached a pre
determined position in `arc chute 24.
between conducting portions 221, 222. It is to be noted,
that conducting portion 221 includes an offset portion ex
ending below the lower end of conducting portion 222,
with the insulator 223 having an offset portion 224 to in
v Now referring more particularly to FIGURE 2, circuit
sulate the lower end of portion 222 from portion 221.
breaker ’100 comprises essentially the same elements as
circuit breaker 10 of FIGURE l. For the sake of brevity
and clarity, like reference numerals are utilized to iden
One terminal 225 of main blow-out coil 226 is elec
trically connected to upper current stud 202. The other
terminal 227 of main blow-out coil 226 is connected to
one terminal 228 of magnetic assist coil 229 whose other
terminal 230 is connected to conducting block 213 upon
which stationary arcing contact 214 is mounted. Blow
out coil terminals 227 and 228 are connected by jumper
75 248 to conducting portion 222 of rear runner 220. Con
tify identical elements in both iigures.
`Circuit breaker >100 includes a front arc runner 60
having an inwardly curved portion 61, the lower end of
which is connected to end 42 of magnetic assist blow-out
coil 40 while the other end 43 of magnetic assist blow-out
5
3,054,8-7ë
ducting portion 221 of rear arc runner 220 is connected
to conducting block 213. Y
Upper iron circuit 231 is associated with main blow
out coil 226 and is energized thereby while lower iron
circuit 232 is associated with assist blow-out coil 229 and
is excited thereby. It is noted that although separate iron
circuits 2_31, 232 have been illustrated for blow-out coils
226, 229, respectively, a single iron circuit excited by
said ñrst and second means being isolated from said co
operating contacts when said contacts are in an engaged
position; a rear runner at one side of said arc chute and
a front runner at the other side; one of said contacts
being movable and the other of said contacts being sta
tionary; said rear runner being positioned in the region
of said stationary contact; said movable contact being
movable from a ñrst position in engagement with said
both coils 226 and 229 may be utilized.
stationary contact, toward said front runner to a second
The upper portion of front arc runner 2‘33 is positioned 10 position wherein said contacts are disengaged; said front
in spaced parallel relationship with respect to rear arc
runner including a gap therein; said second means com
runner 220 and the lower end of front arc runner 233 is
prising a second coil connected in electrical parallel with
connected by return jumper 234 to lower current stud 201.
said gap; said gap being constructed to be arced over
ì When bridge 203 is pivoted clockwise about pivot 204,
when current through said second coil exceeds a predeter
from the circuit breaker closed position of FIGURE 3, to 15 mined value thereby by-passing said current around said
bring circuit breaker 200 to the open circuit position,
main contacts 206, 207 are lirst to part since spring 235
urges conducting element 208 to the right with respect to
FIGURE 3. Continued clockwise movement of bridge
-203 brings about the disengagement of auxiliary arcing 20
contacts 208, 209.
Since the current path through auxiliary arcing con
second coil through said gap to prevent damage to said
second coil.
2. A circuit breaker including a pair of cooperating
contacts, an arc chute operatively positioned to receive
an electric current arc drawn between said contacts upon
parting thereof, iirst means associated with said arc chute
energizeable by said arc for urging said arc deeply into
said arc chute, `and second means energizeable by said
parallel path through arcing contacts 214, 215. This
are; said second means being operatively positioned in
parallel path comprises main blow-out coil 226 and assist 25 the region of said contacts and being constructed to urge
blow-out coil 229 in electrical series. The current
an arc of low current magnitude toward said ñrst means;
through the two blow-out coils 226, 229 produces a volt
said iirst and second means ‘being isolated from said co
age drop which appears across auxiliary arcing contacts
operating contacts when said contacts are in an engaged
208, 209. This voltage attempts to maintain an arc at
position; a rear runner at one side of said arc chute and a
contacts 208, 209 but this arc impinges on the insulating 30 front runner at the other side; one of said contacts being
member 212 thereby extinguishing this arc.
movable and the other of said contacts being stationary;
Arcing contacts 214, 215 then part forming an arc
said rear runner being positioned in the region of said
which is free to move up the right hand portion 221 of
stationary contact; said movable contact being movable
rear arc runner 220. At this time, the voltage drop
from a iirst position, in engagement with said stationary
across the magnetic assist blow-out coil 229 is across longi
y contact, toward said front runner at a second position
tacts 208, 209 has now been broken, the current selects a
tudinal extending insulating member 223. At low values
of current, there is a low voltage drop between the por~
wherein said contacts are disengaged; said front runner
including a gap therein; said second means comprising
tions 221, 222 of arc runner 220 so low that the arc re
a second coil connected between said gap and said mov
mains on the right hand portion 221 and is driven far
able contacts; current conducting means connected in
into arc chute 250 due to the high iield produced by mag 40 electrical parallel across a series combination including
netic assist blow-out coil 229 which comprises many
said gap and said second coil; said gap being operatively
turns. At high values of current, a high voltage drop is
positioned to cause arc current heretofore ñowing through
developed between portions 221, 222 of arc runner 220
said second coil to be shunted through said current con
so that the arc jumps the insulating barrier 223 thereby
ducting means when said arc has reached a predetermined
deenergizing the magnetic assist blow-out coil 229.
45 position in said arc chute thereby preventing damage to
The arc is still driven upwardly in the chute 250 due to
said second coil.
the magnetic iield produced by the main blow-out coil
3. A circuit breaker comprising cooperating contact
226 since a high current is flowing through this coil 226,
means, an arc chute operatively positioned to receive an
even though this coil 226 is comprised of a fewer number
electric current arc drawn between a iirst set of contacts,
of turns than assist coil 229. The transfer of the arc 50 of said contact means, upon parting thereof, tirst means
to the left hand portion 222 of arc runner 220 prevents
associated with said arc chute energizable ‘by said arc for
magnetic assist blow-out coil 229 from being destroyed
urging said arc deeply into said arc chute, second means
by excessive heating and/ or mechanical forces.
also energizable by said arc; Said first and second means
Thus, we have provided a circuit breaker including
being isolated from said cooperating contacts when said
novel magnetic means for assisting in the interruption of 55 contacts are in an engaged position; said second means
low current arc.
The magnetic means does not include
any movable parts which will wear out after repeated
operations of the breaker. Further, the magnetic means
does not require additional mechanical opening forces to
be provided for the circuit breaker.
Although we have here described preferred embodi
ment of our novel invention, many variations and modi
iications will now be apparent to those skilled in the art,
and we therefore prefer to be limited, not by the specific
disclosure herein, but only by the appending claims.
We claim:
1. A circuit breaker including a pair of cooperating
contacts, an arc chute operatively positioned to receive
an electric current arc drawn between said contacts upon
parting thereof, ñrst means associated with said arc chute
energizable by said arc for urging said arc deeply into
said arc chute, and second means energizable by said arc;
said second means being operatively positioned in the
region of said contacts and being constructed to urge an
arc of low current magnitude toward said first means; 75
being constructed to urge an arc of low current magnitude
into said arc chute; said second means being yautomatical
ly deenergized `when said arc attains a predetermined char
acteristic; said arc chute including a longitudinally split
arc runner; said arc runner including a iirst and a second
longitudinally extending conducting portion, an insulat
ing means interposed between said first and said second
conducting portion; said insulating means and said con
ducting portions being operatively connected to said tirst
and said `second means to cause deenergization of said
second means when said arc is of said predetermined
characteristic.
4. A circuit breaker `comprising cooperating contact
means, an arc chute operatively positioned to receive an
electric current arc drawn between a itirst set of contacts,
of said contact means, upon parting thereof, iirst means
associated with said arc chute energizable by `said arc for
urging said arc deeply into said arc chute, second means
also energizable by said arc; said ñrst and second means
being isolated from said cooperating contacts when said
8,054,876
7
8
contacts are in an engaged position; said second means be
ing constructed to urge an arc of low current magnitude
into said arc chute; said `second means being automatically
deenergized when said arc attains a predetermined charac
teristic; said arc chute includingT a longitudinally split arc
coil being electrically connected between said first and
runner; said arc runner including a first and a second
portion and `said stationary Contact of said second pair
longitudinally extending conducting portion, an insulat
ing means interposed between said first and said second
conducting portion; said insulating means and said con
of cooperating contacts; said first pair of cooperating con
tacts being constructed to open after the opening of said
and said second means to cause deenergization of said
second means when said arc is of said predetermined
said second coil being comprised of a greater number
of turns than said first coil.
7. In combination, a pair of cooperating contacts, an
are chute having a pair of arc runners operatively posi
said second arc runner portions with said first portion also
being electrically connected to said stationary contact of
said first pair of cooperating contacts; said first coil being
electrically connected between said second arc runner
second pair of cooperating contacts upon operation of
ducting portions being operatively connected to said first 10 .said circuit breaker from its closed to its open position;
characteristic; said first conducting portion being longer
than said second conducting portion; said first portion
including at a first end thereof an offset portion positioned
opposite a first end of said second portion.
tioned to receive an arc drawn between said contacts
5. A circuit breaker comprising cooperating contact
said arc chute for urging said arc into said arc chute,
means, an arc chute operatively positioned to receive an
electric current arc drawn between a first set of contacts,
of said contact means, upon parting thereof, first means
auxiliary blowout means positioned in the region of said
associated with said arc chute energizable by said arc for
urging said arc deeply into said arc chute, second means
also energizable by said are; said first and second means
having a gap, said auxiliary blowout means being con
nected across said gap for developing a voltage drop across
upon separation thereof, main blowout means housed in
cooperating contacts for urging said arc in the direction
of said main blowout means, one of said arc runners
said gap during circuit interruption whereby the voltage
drop urges the arc to jump said gap.
8. in combination, first and second cooperating con
contacts are in an engaged position; said second means 25
tacts, an arc chute operatively positioned to receive an are
being constructed to urge an arc of low current magnitude
being isolated from said cooperating contacts when said
into said arc chute; said second means being automatically
deenergized when said arc attains a predetermined charac
teristic; said arc chute including a longitudinally split arc
drawn between said contacts upon separation thereof,
main blowout means housed in said arc chute, auxiliary
blowout means positioned in proximity to said contacts
runner; said arc runner including a first and a second 30 for urging said are in the direction of said main blowout
longitudinally extending conducting portion, an insulating
means, a pair of arc runners housed in `said arc chute,
one of said runners having a spark gap which splits said
means interposed between said first and said second con
arc runner into an upper and lower portion, said auxiliary
ducting portion; said insulating means and said conduct
blowout means being connected between said first contact
ing portions being operatively connected to said first and
and the upper portion of said split arc runner, the lower
said second means to cause deenergization of said second
portion of said split arc runner being connected to said
means when said arc is of said predetermined charac
first contact whereby the voltage developed by said aux
teristic; said first means comprising a first coil and said
iliary blowout means during circuit interruption causes
second means comprising a second coil; said contact means
the spark gap to draw an arc between the halves of said
comprising a first and a second pair of cooperating con
tacts, with each of said pairs of contacts including a 40 split arc runner causing the lower half of said split arc
runner to by-pass said auxiliary blowout means.
stationary contact; another insulating means interposed
9. A pair of cooperating contacts, an arc chute op
between said stationary contacts; said second coil being
eratively positioned to receive an arc drawn between said
electrically connected ‘between said first and said second
contacts upon separation thereof, said are chute including
arc runner portions with said first portion also being elec
trically connected to said stationary contact of said first 45 a front and a rear arc runner and first and second blowout
means, said first blowout means being connected to said
pair of cooperating contacts; said first coil being elec
trically connected between said second arc runner portion
front arc runner for urging said arc deeply into said arc
and said stationary contact of said second pair of co
chute when said arc is transferred from said cooperating
operating contacts.
contacts to said arc runners, said second blowout means
6. A circuit breaker comprising cooperating contact 50 positioned in the immediate area of said cooperating con
means, an arc chute operatively positioned to receive
an electric current arc drawn between a first set of con
tacts, of said contact means, upon parting thereof, first
means associated with said arc chute energizable by said
arc for urging said arc deeply into said arc chute, second
means also energizable by said arc; said first and second
means being isolated from said cooperating contacts when
said contacts are in an engaged position; said second
tacts and connected to said front arc runner for urging
said arc in the direction of said first blowout means when
said arc is drawn between said arc runners, said front arc
runner having a gap for deenergizing said second blowout
means when the current drawn by said second blowout
means attains a predetermined magnitude, said first and
second blowout means being isolated from said contacts
when said contacts are in an engaged position.
l0. A pair of cooperating contacts, an arc chute op
magnitude into said arc chute; said second means being 60
eratively positioned to receive an arc drawn between said
automatically deenergized when said arc attains a prede
contacts upon separation thereof, said arc chute including
termined characteristic; said arc chute including a longi
means being constructed to urge an arc of low current
tudinally split arc runner; said arc runner including a first
a front and a rear arc runner `and first and second blowout
and a second longitudinally extending conducting portion,
means, said first blowout means being connected to said
an insulating means interposed between said first and said 65 front are runner for urging said arc deeply into said arc
second conducting portion; said insulating means and said
conducting portions being operatively connected to said
chute when said arc is transferred from said cooperating
contacts to said arc runners, said second blowout means
first and said second means to cause deenergization of said
.positioned in the immediate area of said cooperating con
second means when said arc is of said predetermined
tacts and connected to said rear arc runner for urging
characteristic; said first means comprising a first coil 70 said arc in the direction of said first blowout means when
and said second means comprising a second coil; said con
said arc is drawn between said arc runners, said rear arc
tact means comprising a first and a second pair of co
runner having a gap for deenergizing said second blowout
operating contacts, with each of said pairs of contacts
means when the current drawn «by `said second blowout
including a stationary contact; another insulating means
interposed between said stationary contacts; said second 75 means attains a predetermined magnitude, said first and
3,054,876
second blowout means being isolated from said contacts
when said contacts are in an engaged position.
References Cited in the file of this patent
UNITED STATES PATENTS
1,533,251
2,381,637
Johnston ____________ __. Apr. 14, 1925
Bohn ________________ _- Aug. 7, 1945
410
2,554,547
Zajîc ________________ __ May 29, 1951
2,822,449
2,918,552
Thommen ____________ __ Feb. 4, 1958
Fust ________________ __ Dec. 22, 1959
215,899‘
Great Britain ________ __ Ma)r 22, 1924
837,964
1,042,712
France ______________ __ Nov. 28, 1938
Germany ____________ _.. Nov. 6, 1958
FOREIGN PATENTS
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