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Патент USA US3096423

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July 2, 1963
Filed Nov. 24, 1958
5 Sheets-Sheet 1
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July 2, 1963
Filed Nov. 24, 1958
3 Sheets-Sheet 2
July 21 1953
Filed Nov. 24, 1958
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yieldable material. However, the material is suiliciently
Carl E. Gryctko, Haddon Heights, NJ., and Kenneth
Ball, Philadelphia, Pa., assignors to I-T-E Circuit
Breaker Company, Philadelphia, Pa., a corporation of
Filed Nov. 24, 1953, Ser. No. 775,862
2 Claims. (Cl. 20G-S8).
Our invention relates to circuit breakers in general and
is more particularly directed to a novel construction for
an actuating means for the shunting means which by
passes the bimetal 'time delay trip element of the circuit
breaker upon the occurrence of a severe overload con
Molded case circuit breakers are provided with a
time delay trip unit usually in the form of a bimetallic
element and an instantaneous trip element which is in
the form of a yoke armature combination.
Patented July 2, 1963
resistant to deliection ‘to prevent contact rebound and
maintain contact pressure sutlicient to establish a low
resistance juncture.
Thus, in choosing the material of the shunt it becomes
necessary to comprise between the rrigi-dity necessary to
prevent rebound and maintain contact pressure, and the
yieldability necessary to prevent reverse deflection. This
compromise has often resulted 4in excessive arcing at the
shunt circuit contacts leading to a high resistance junction
which introduces a high impedance into the shunt circuit.
The instant invention maintains the shunt circuit con
tact junction at `a low impedance by providing a mag
netic means associated with the bimetal and its protective
shunt. The shunt comprises a yieldable member and
the magnetic means urges the shunt member toward
the bimetal upon the occurrence of an over-current.
Once the contacts of the shunt path have been closed,
On the
the magnetic means exerts a closing force to hold the
occurrence of an overcurrent, the deflection of the mi 20 contacts closed and help prevent contact blow-olf due to
metal will be effective to delatch the cradle mechanism
current flow through these contacts.
and on the occurrence of la fault current the magnetic
Accordingly, a primary object of the instant invention
yoke will be sufficiently energized to attract its armature
is to provide a novel shunting circuit for the thermal
time -delay tripping element of a circuit breaker.
to effect contact disengagement.
Another object of »this invention is to provide a directly
It has been found that the bimetal will be perman
heated thermal time delay trip element and a shunt
ently deformed if it is subjected to excessive currents.
therefor which are both mechanically independent of the
Some circuit breakers of the prior art have included
instantaneous trip device although both act on the same
circuits which shunt current so as to by-pass the bi
common tripper bar.
metal upon the actuation of the instantaneous trip unit. 30
Still another object is to provide a bimetal actuated
In this way ythe bimetal is protected from excessive cur
bimetal shunt, including associated magnet means, for the
rent from the moment that the armature is attracted by
directly heated bimetallic element of an instantaneous
the yoke. However, the armature is of a substantial
trip unit of a molded case circuit breaker.
mass so that its operating time is not instantaneous.
These as well as other objects of the instant invention
thereby resulting in delatching of the cradle mechanism
lIt has also been found that upon Ithe occurrence of a 35 shall become readily apparent after reading the following
short circuit condition the bimetal shunt circuit is not
description of the accompanying drawings in which:
Aactuated by the instantaneous trip unit in a sufficiently
FIGURE l is a top view of a three pole circuit
short interval of time so as to prevent burn-out or
breaker, including my novel bimetal actuated bimetal
distortion due to excessive heating in the case of a directly
bypass, with the cover removed.
heated bimetal. The problem is particularly severe in 40
FIGURE 2 is a side sectional view of the circuit
circuit breakers having a low continuous current rating,
breaker taken along line 2-2 of FIGURE l, and illus
hence a high resistance bitmetal.
trates the operating mechanism after the circuit breaker
This problem has in part been solved by providing
a shunting circuit which is actuated by the bimetal itself
has been tripped due to an overcurrent.
FIGURE 3 is a perspective view illustrating the me
as fully explained in copending application Serial No. 45 ohanical independence of the time delay bimetal 'and
its shunt from the instantaneous trip unit.
740,041 filed June 5, 1958, now Patent No. 2,989,605,
FIGURE 4 is ian end View of the overcurrent device.
entitled “Bi-metal Actuated Bi-Metal Shunt” with J. H.
Leonard as inventor and assigned to the assignee of the
instant invention. In the circuit breaker of the aforesaid
FIGURE 5 is a side view of the novel bimetal actuated
bimetal shunt.
copending application, the free end of the bimetal carries 50
FIGURE 6 is a view taken in the direction of the
arrows 6-6 of FIGURE 5.
a contact which upon suñicient deflection of the bimetal,
'engages a contact in a shunt circuit which is completed
FIGURE 7 is a side elevation of the bimetal of the
when the two contacts are in engagement. The shunt
center phase and its associated shunt.
Vcircuit is not complete during normal heating of the
FIGURE 8 is a cross-section taken through line 8-8
bimetal but is closed when there is :over-heating at a 55 of FIGURE 7 looking in the direction of arrows 8-8.
time before burn-out or distortion set in. Thus the
FIGURE 9 is a side elevati-on similar to FIGURE 7
illustrating a variation of this invention wherein a magnet
shunt does not carry current for an extended period of
is mounted to the shunt las well as ytoi the bimetal.
time but merely for some time less than it takes the
FIGURE l0 is a cross-section taken through line 10
circuit breaker to open after being hit by a short circuit
or severe fault condition. The bimetal actuated shunt, 60 10 of FIGURE 9 (looking in the direction of arnows
in addition to its superior electrical qualities over that
of the instantaneous trip operated shunt, offers the ad
vantages of compactness and fewer number of parts.
The shunt comprises a member which is securely
fastened `at one end and extends parallel to thc bimetal.
A contact is secured to the shunt at its free end'and is
At the outset it is pointed out that the circuit breaker
10 to be hereinafter described is a three phase unit having
substantially identical electrical elements for each phase.
Thus, Ifor »the sake of brevity and clarity only the center
phase will be described so that a reference numenal fol
lowed by a capital letter such as B means that there is
positioned to be engaged by a contact carried by the
a corresponding element in the other two phases.
bimetal, at the free end thereof, when the deflection of
Referring first to FIGURES l and l2 showing a three
the bimetal reaches a predetermined point. In order to 70 pole embodiment of a `circuit breaker in which our inven
prevent a reverse delleotion of the bimetal under extreme
tion can be adapted, the housing 20 of the circuit breaker
ly high current conditions, the shunt is constructed of a
1t) is preferably made of a plastic substance and is pro
vided with appropriate openings 21B and 22B through
the latch 147B-152B to thereby elîect disengagement of
the cooperating contacts 77»85.
wlhich the circuit breaker terminals 25B and 26B, respec
tively, are substantially brought out of housing 20 to be
engaged by the line terminals of the line to be protected.
This circuit breaker may be of the type shown 'in U.S.
Patent 2,673,9081to I . C. Brumñeld entitled “Instantaneous
Trip Circuit” and assigned to the assignee orf the instant
The housing 20 :consists of two sections, a base 20a
which is a section of the housing 20 on which the vanious
llt will be noted that the movement of the armature 211
when attracted by the magnetic pole 200 is completely
independent of the movement of the bimetal v38B and
hence, clockwise rotation thereof will result in a hammer
blow on the proitrusion 60B of the common tripper bar
65 to eñîect contact disengagement. The portion 66B
of the common tripper bar 65 is positioned in alignment
with the `adjustment »screw 43B of the thermal element
components of the circuit breaker 10 are mounted as here
inafter described and a cover 20b Which completely closes
38B. Thus, on the occurrence of an overcurrent, the bi
the circuit breaker 10 by tightly engaging the base 20a.
Considering then this center phase B of the three pole
manner as seen in FIGURE 2, to thereby engage the por
tion 66B and cause counterclockwise rotation of the
circuit breaker 10, the circuit breaker terminal 25B rests
against .an extending shoulder 28B of molding 20a. Shoul
der 20B is perforated to receive threaded insert 29B ywhich
eventually receives a bolt (not shown) to secure the line
terminal (not shown) to circuit breaker terminal 25B. As
previously mentioned, circuit breaker terminal 25B ex 20
common tripper bar 65. It will be noted that when the
circuit breaker `is tripped due to «the occurrence of an
overcurrent condition, the bimetallic element 38B will de
ñect to the right and Iits movement willl be independent
tends through opening `21B into base 20a. Circuit breaker
terminal 25B lis shaped like an angle, one side 30B of the
angle being used .to receive a line terminal (not shown),
metal 38B will deflect to the right in the conventional
and unaffected by ythe .instantaneous magnetic »trip means
The common tripper bar 65 provided at phase B as
above noted has an extending member having portions
60B and 66B which are respectively engaged by the por
tion 216 of the armature 211 and the adjustment screw
while the other side 31B is soldered or Áin any other
way connected to a pigtail or conductor 35B.
25 43B of the bimet'al 38B.
Pigtail 35B is rigidly #secured t0 cross member 300B
mounted to bimetal 38B at the calibration screw 43B.
As best seen in FIGURES 3 through 6, the L-shaped
thermal responsive means 38B has one lleg thereof posi
The pigtail 52B to the fault current responsive means
38B and 211 is electrically connected to the arm 71B
at the end 70B thereof. Movable contact arm 71B is
pivoted by means of the pivot pin 72B engaging aligned
tioned on top of the substantially U-shaped magnetic yoke 30 openings 73B of the metallic f-rame or support 75B.
Contact arm 71B is provided at its other end with a
200. A screw 201 is passed through the leg of íixed «shunt
member 301B, through one leg of the bimetal 38B through
magnetic yoke 200 into the molding 20a. Tlhus, the screw
tact slab 77B made of good conducting material is
201 secures both the bimetallic element 38B and the mag
rigidly secured to contact arm 71B by means of a rivet
substantially rectangular shaped contact slab 77B. Con~
78B or in any other suitable way.
netic yoke 200 to [the base molding 20a and also serves
Stationary contact 80B consists of a rectangular sec
to electrically connect the terminall 48B Ito the bimetallic
tion metallic member 81B having at the end nearer to
element 38B. P'igtail 52B is soldered or otherwise secured
contact arm 71B a stationary contact slab 85B rigidly
to the diagonally extending tip 48B «of shunt member
secured to member 81B. Member 81B is secured to
301B. Thus, a complete current path is provided ffrom the
pigtail 52B to the terminal 48B and out the pigtail 35B 40 housing 20a of the circuit breaker through a screw 86B
and a washer 87B. Stationary contact 80B is also pro
to thereby form a single turn for the energization of the
vided with a terminal extension 26B an integral part
magnetic yoke 200.
of metallic member 81B, which extends for a portion 901B
A pivotally mounted shaft 203 mounted in bearings
out of housing 20a to permit by means of screw means
204, 205 contains wire spring 206. A barrier plate 209
positioned Within appropriate recesses ot the groove in 45 (not shown) for the connection of a line terminal to
circuit breaker terminal 26. Stationary contact 80B is
base molding 20a for the overcurrent device serves as a
further provided with an anc extinguishing chamber 95B
stop for one end of lthe wire spring 206.
or are chute having a number of arc extinguishing plates
The ‘armature 211 is secured to the rotatably mounted
96B so that at the opening operation of the circuit break
shaft 203 at the area which contains the wire spring 206
er the arc existing between contact slab 77B `and con
and serves as a stop for the opposite end of this wire
tact slab 85B is extinguished before producing damage
spring. It will be noted that the wire spring 206 may be
to the contact slabs 77B and 85B.
mounted on either side of the armature 211 rather than
The operating mechanism of the circuit breaker, which
being mounted yin the center as shown in FIGURE 3.
forms no part of my present invention, is -described in
With «only one end of the spring 206 engaging rthe arrna
ture 211, it will not be necessary to reduce the cross 55 the aforementioned U.S. Patent 2,673,908.
T-member 120B is provided at its upper portion 122B
sectional area of the ‘shaft 203 to mount the spring. Thus,
with a substantially rectangular extension 131B. Upper
as best seen in FIGURE 5, the armature 211 is biased in
portion 122B of T-member 120B is slotted in its mid por
va counterclockwise direction around the shaft 203 due to
tion and provided with raised member 132B cut out from
the Wire spring 206. The bottom ledge of the barrier 209
the upper portion 122B of T-member 120B which serves
serves as a stop to elimit the counterclockwise rotation of 60
to be engaged by a plastic operating handle 135B for man
the armature 211.
ually opening and closing the circuit breaker, as herein-af
rIl‘ne enlarged magnetic section 213 of the armature 211
ter described. One leg `155B of the V-shaped cradle 145B
is positioned above the prole faces 214 yand 215 of the
is shaped as shown in FIGURE 2 to engage a latch 147B.
magnetic yoke 200. On the occurrence of a faullt current,
Latch l147B is provided with a slot 148B engaged by pin
the single turn comprising the current How through the 65 150B around which latch 147B can rotate and can also
bimetal 38B will sufficiently energize the magnetic yoke
200 so that the portion 213 of the armature 211 will be
attacted toward the pole faces 214 and 2-15. That is, the
armature 211 will be rotated in a clockwise direction
have translational motion. Latch 147B is provided with
a pointed end 151B latched under normal conditions by
a latch surface 152B on the tripper bar 65.
Latch surface 152B is composed of a thin strip of
vmaterial on tripper bar 65 supporting the latch 147B.
The leg 157B of V-shaped member 145B is provided with
a cylindrical hole engaged by a pivot pin 160B secured to
the protrusion 60B of .the common tripper bar 65.
the raised portion 165B of frame 75B. Leg 157B of V
As willl be apparent, the countercl'ockwise rotation of
'the common tripper bar 65 will effect disengagement of 75 shaped member 145B is provided at the bottom of the
against the bias oit the wire spring 206. The protrud
ing portion 21B of the armature 1211 will then be against
V wi‘th a shoulder extension 166B. Raised portion 165B
of frame 75B is provided with an opening :through which
will be parted before shunting contacts 302B, 303B
become engaged.
The spacing between magnet350B and armature 351B
passes contact slab 77B of movable Contact ,arm 71B and
provides a stop for V-shaped cradle 145B.
is such that the energization of magnet 350B by a fault
current flowing through bimetal 38B will not attract
armature 351B since instantaneous trip means 200-211
will act before any appreciable deflection of bimetal 38B.
Near the end 70B of movable contact arm 71B at
which pigtail 52B is connected, an essentially rectangu
lar section bar 180 is rigidly secured to movable contact
arm 71B in any suitable way.
Shaft or tie bar 180* is
Upon the occurrence of a short circuit or other severe
common to all three phases A, B and C `of the three
fault, instantaneous trip means 20G-211 will act before
pole circuit breaker, being rigidly secured to the ends 10 screw 43B has engaged tripper bar 65. However, cir
70 of the movable con-tact arm 71 of every phase so that
cuit interruption is not instantaneous so that bimetal 38B
one movable contact, for example 71B, is moved wheth
is deflected beyon‘d the point where screw 43B engages
er opened or closed, the other two movable contact arms
tripper bar 65 under mere overcurrent conditions. Bi
71A and 71C will `simultaneously perform the same
metal 38B will continue to deflect until movable shunt
movements. The circuit breaker 10 is also provided,
contact 303B engages fixed shunt contact' 302B and the
in the vicinity of arc chute 95B, with an insulation 185B
major portion of the circuit current now passes through
for completely insulating arc chute 95B.
shunt 301B rather than bimetal 38B. The spacing be
Thus, it will be seen that when either the time delay
tween shunt contacts 302B `and 303B is such that they
or instantaneous overcurrent means rotates the common
will lbe engaged before burn-out or distortion of bimetal
tripper bar 65, in a clockwise direction, both the latch 20 33B can take place.
147B and 187B will be released and hence, spring 118
Under these severe fault conditions magnet 350B will
will drive the contacts 77~85 to the disengaged position.
be sufficiently energized, even before contacts 302B,
As heretofore noted this trip of the circuit breaker
303B engage, to attract armature 351B resulting in a
to the position indicated in FIGURE 2 by the release of _ more rapid closing of contacts 302B, 303B thereby re
»the two latches can be achieved by either and overcur 25 ducing arcing at these contacts. Once contacts 302B,
rent which will cause deflection of the bimetal 38B to
303B are engaged, the attraction between armature 351B
'the right and result in engagement of the adjustment
and magnet 350B serves to maintain contact pressure
screw 43B with the protrusion 66B to cause counter
`and prevent blow-off.
clockwise rotation of the tripper bar 65 or due to a fault
In addition the utilization of the magnetic means 350B,
current condition wherein the single turn of the bimetal 30 351B
in conjunction with the bimetal shunt results in a
38B will sufficiently energize the magnetic pole 200* to
construction Iwhere-in it is no longer necessary to com
thereby rotate the armature 2111 in a clockwise direction
promise the rigidity of shunt 301B, as formerly required
to prevent rebound, with the yi‘eldability required to pre
against its bias 206 thereby bringing its extension 216
into engagement with the protruding portion 60B to
vent bimetal distortion.
rotate the tripper bar in a counterclockwise direction.
It ‘is permissible to mount the magnet to fthe shunt and
Thus, it will be seen that with the novel overcurrent
the armature to the bimetal in which event the magnetic
device of our invention, the instantaneous trip means
means will not assist -the bimetal in closing the shunt
comprising the armature 213 and the magnetic yoke 200
circuit contacts but once these contacts engage, the mag
are mechanically independent of the time del-ay thermal
means 38B and hence, the occurrence of a faul-t current 40 netic means will maintain the shunt circuit closed until
such time as current through the circuit breaker falls to
or an overcurrent will result in a blow or force in one
a value which will not injure the bimetal.
direction on the tripper bar `65 to result in the tripping
In the embodiment illustrated in FIGURES 9 and l0,
of the circuit breaker.
armature 351B of FIGURES 7 and 8 has been replaced
Fixed shunt 301B is -a resilient generally L-shaped
by magnet 370B. The same reference numerals have
member with the upwardly extending arm thereof being
been utilized in FIGURES 7-10 to indicate identical
positioned generally parallel to the upwardly extended
leg of bimetal 38B when it is not deflected. A ñxed
With the arrangement of FIGURES 9 and l0, when
shunt contact 302B is secured »to the upper end of shunt
shunt contacts 302, 303B are brought into engagement
member 301B and is positioned for engagement by
magnet 370B will be energized by the high value of cur
movable contact 303B carried by the bimetal cross~mem50 rent flowing through the shunt. Thus, the Iforce of tw'o
ber 300B.
magnets 350B, 370B will now act to maintain contact
When shunt contacts 302B and 303B are engaged a
complete current path between pigtails 43B and 52B
which by-passes bimetal 38B is formed. This current
path- extends from pigtail 35B, through cross-member
300B, through shunt contacts 302B and 30GB, through
In the foregoing, we have described our invention only
in connection with preferred embodiments thereof.
55 Many variations and modifications of the principles of
low resistance fixed shunt 301B to pigtail 52B. Current
flow is vshunted through this path since ñxed shunt 301B
is of a much lower electrical resistance than bimetal 38B.
In order to prevent rebound and also to produce ad
ditional force to hold contacts 302B and 303B closed 60
against blow olf forces due to curren-t flow through »these
contacts a magnetic means comprising magnet 350B
our invention within lthe scope of the description herein
are obvious. Accordingly, We prefer to be bound not by
the specific disclosure herein but only by the appending
We claim:
l. A circuit breaker including a pair of cooperating
contacts and a bimetallic means connected in electrical
series with one of said cooperating contacts; means op
eratively connected to `one of said cooperating contacts
350B is secured to bimetal 38B by means of rivet 352B
with insulating sheet 353B and other insulation (not 65 and actuated by said bimetallic means upon deflection
thereof to a first predetermined position to thereby sepa
shown) insulating magnet 350B from bimetal 38B.
rate said cooperating contacts; a normally open shunt
Armature 351B is secured to shunt 301B by means of
circuit actuated by said bimetallic means upon a deflec
rivet 354B and is positioned opposite magnet 350B.
tion thereof to a second predetermined position; said
Iusulating sheet 355B is secured to the face of armature
70 shunt circuit when actuated being operatively connected
to said bimetallic means to prevent deflection thereof be
Upon the occurrence of a mere overload condition
yond said second predetermined position and to provide
and cooperating armature 351B are provided. Magnet
the upper end of bimetal 38B will slowly deflect to the
la conductive path shunting said bimetallic means to
right until adjusting screw 43B engages portion 66B of
thereby prevent burn-out and distortion thereof; mag
tripper bar 65 and the cooperating contacts 77B, 85B 75 netic means associated with said bimetallic means and
said shunt circuit; said magnetic means being operatively
cuit ‘and thereafter maintain said shunt circuit actuated
until> such time as current flow through said circuit breaker
positioned and -constructed to assist said bimetallic means
in actuating said shunt circuit :and thereafter maintain
is reduced to a value which will not cause injury to said
bimetal; said bimetallic means having a first shunt contact
said shunt circuit actuated until such time as current
ñow through said circuit breaker is reduced to a value
which will not cause injury to said bimetal; said mag
lnetic means |being adapted to enable said shunt circuit
to lbe rapidly urged toward said bimetal; said shunt cir
cuit comprising la conductive shunt member; said shunt
member ‘being highly «ñexible along its entire length to
at the free end thereof; said shunt circuit including a
shunt member having a second shunt contact engageable
by said first shunt contact when said bimetallic means
has deflected to said second position; said magnetic means
comprising a ñrst electro~magnet mounted to said bi
10 metallic means and a second electro-magnet mounted to
enable rapid movement of said shunt member towards
said shunt member and being energized upon the engage
ment of said shunt contracts; said magnetic means being
adapted to enable said shunt circuit to be rapidly urged
toward said bimetal; said shunt member being highly
contac-ts and a bimetallic means connected in electrical 15 ñexible along its entire length to enable rapid movement
said >bi-rnetallic element and to eliminate contact bounce
between said |bimetallic element and said shunt circuit.
2. A circuit breaker including a pair of cooperating
series with one of said cooperating contacts; means opera
tively connected 4to one of said cooperating contacts and
actuated by said bimertallic means Iupon deñect-ion thereof
to A,a first predetermined position to thereby separate said
cooperating contacts; la normally open shunt circuit actu, 20
ated by said bimetallic means upon a deflection thereof
to a second predetermined position; said shunt circuit
when actuated being operatively connected to said bi
metallic means to prevent deflection thereof beyond said
of said shunt member towards said bimetallic element
and to eliminate Contact bounce between said bimetallic
element and said shunt circuit.
References Cited in the tile of this patent
Howard _____________ __ June 23, 1943
and distortion thereof; ‘magnetic means associated with
said lbimetallic means and said -shunt circuit; said mag
Von Hoorn _________ __ Aug.
M-iddendorf __________ __ July
Brumñeld ____________ __ July
Walker et al. ____ ______ June
netic means being operatively positioned and constructed
ì 2,989,605
Leonard ____________ __ June 20, 1961
Walker et al. ________ __ June 20, 19611
second predetermined position to thereby prevent burin-out 25
to assist said bimetiallic means in actuating said shunt cir
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