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Патент USA US2412247

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Dec. 10, 1946.
D. I. BOHN
2,412,247
CIRCUIT BREAKER HOLDING MAGNET AND ARMATURE
Filed July 28, 1942
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Dec. 10, 1946.
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D. |. BOHN
2,412,247
CIRCUIT BREAKER HOLDING MAGNET AND ARMA‘I'URE
Filed July 28, 1942
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INVENTOR.
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Dec. 10, 1946.
2,412,247
D. l. BOHN
CIRCUIT BREAKER HOLDING MAGNET AND ARMATURE
Filed July 28, 1942
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Dec. 10, 1946.
D. 1. BOHN
2,412,2427
CZRCUIT BREAKER HOLDING MAGNET AND ARMATURE
Filed July '28, 1942
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Dec. 10, 1946.
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D. v|. BOHN'
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CIRCUI-T BREAKER HOLDING MAGNET AND ARMATURE
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ATTORNEY. '
Dec. 10, 1946.
2,412,247
D. 1. BOHN
CIRCUIT BREAKER HOLDING MAGNET AND ARMATURE
Filed July 28, 1942
'7 Sheets—Sheet 7
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INVENTOR.
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Patented Dec. 10,1946
2,412,247
‘UNITED STATES PATENT OFFICE
2,412,247
CIRCUIT BREAKER HOLDING MAGNET AND
'
ARMATURE
Donald I. Bohn, Pittsburgh, Pa., assignor to
I. T. E. Circuit Breaker Company, Philadelphia,
Pa., a corporation of Pennsylvania
Application July 28, 1942, Serial No. 452,613
7 Claims. (Cl. 175-336)
1
2
My invention. relates to circuit breaker appa
As will be obvious, in order to secure the same
eifective armature area for a smaller weight of
armature, I may decrease the radius and corre
spondingly increase the length of the armature.
'
ratus and more particularly relates to a novel
magnetic structure controlling the closing and
opening operation or" a circuit breaker.
In recent years, the rapid expansion of mer Cl
Quite obviously, however, an armature of such
great length compared to its diameter would be
cury arc recti?er installations at 600 volts, D. 0.,
both as to the total kw. installed and the rela
entirely impractical from a mechanical and stiff
tively large number of units operated in parallel,
ness point of view.
'
has emphasized the importance of switchgear
In accordance with my invention, I carry out
in providing suitable recti?er operation In the 10 this principle of weight reduction which over
event of a back?re, the rates of current rise
comes the mechanical defects noted above
through a rectifier and its transformer windings
I have discovered that I may materially re
lie, in general, between three million and six mil
duce the mass of the armature and thereby in
lion amperes per second. ‘With large installa
crease the acceleration thereof by so arranging
tions, where 60 units of 5000 amperes each are 15 the magnetic structure of the holding magnet
operated in parallel, the ceiling value of these
that there are, in effect, a plurality of individual
currents is far above a ?gure which could be
magnets, each with its individual armature.
tolerated both from the standpoint of continuity
Inasmuch as the center of the armature which
of operation and safety to equipment.
is mechanically connected to the movable con
High speed breakers having a time of approxie 20 tact of the circuit breaker assumes the greatest
mately .5 cycle from back?re initiation to cur
share of the carrying load in operating the mov
rent limitation may permit, in some installations,
able contact and this load on the armature is
peak currents in the neighborhood of 60,000 am
gradually reduced. as the edges of the armature
peres. While such a value is appreciably below
are approached, I provide maximum thickness
that which would cause equipment damage, it 25 of metal at the center of the armature with a
is nevertheless undesirably high, in that surges
tapering armature construction toward the ends
and “sympathetic” back?res on other units often
to a substantially reduced thickness‘at the ends.
This serves to prevent any de?ection of the
result. Breaker duty and maintenance are high
er than would be the case with lower values of
‘center of the armature which might tend to
back?re current and the factor of safety is not 30 occur if the armature were of uniform cross-sec
as great as is desirable.
tion; such de?ection at the center should it occur
Application Serial No. 371,092, ?led Decem
would result in a reduction of the holding force
on the armature and hence result in a rapid pro
ber 21, 1940, now Patent No. 2,390,966, issued De
cember 11, 1945, shows in Figure 15 the current
gressive release of the armature.
path during a back?re in a six phase recti?er. 35 In order that the distribution of armature mass
in this manner from maximum thickness at the
It will be noted that the current ?owing through
the cathode breaker is supplied by other recti
center to minimum thickness at the ends may
correspond to the flux distribution, the magnetic
?ers on the bus, and that the current flowing‘
circuits are so arranged that a maximum num
through the anode breaker is the same current
plus the additional current from the other anodes 40 ber of'lines of force exist at the center and the
of the faulted recti?er.
number of lines of force is reduced towards
Under these circumstances high speed break
the edges of the armature.
'
My novel circuit breaker provides for tripping
ers are essential to insure effective interruptions.
of the breaker on de-energization of the holding
The speed with which the armature of the trip
or opening magnet functions is a material factor 45 magnet armature and permits the armature of
the magnet to be operated into engagement with
in the time of circuit breaker operation. Obvi
the pole face of the magnet while the circuit
ously, the lighter the mass of the armature, the
breaker is still in disengaged position, the actual
less its inertia and the faster it can operate.
closing operations of the circuit breaker being
On the other hand, the armature must have a
sufficiently large effective area.
50 performed by a separate power supply.
Accordingly, an object of my invention is to
The breaker of the present invention employs
provide a novel magnet having a plurality of
a magnet and armature design. reducing the ar
mature weight in a ratio of approximately 1:3,
magnetic paths, each for conducting individual ‘
as contrasted with a conventional holding mag
net.
55
?uxes ?owing through individual portions of the
armature.
aeiaarr
A further object. of my invention is to provide
a novel armature structure in which the portion.
of the armature subject to the greatest load car
ries more lines of force than other portions of
the armature which carry smaller portions of
the load.
.
Still another object of my invention is to pro
vide a novel armature, the mass of which has been
reduced to a minimum for the load it carries.
Still another object of my invention is to pro
vide a novel magnet having novel magnetic path
structures.
Still a further object of my invention is to pro
vide a novel construction of a holding magnet in
which tripping is effected by de-energization oi
the magnet armature.
Still a further object of my invention is to pro
vide a novel circuit breaker structure in which
a flexible connection extends from the armature
to the movable circuit breaker contact.
There are other objects of my invention which
together with the foregoing will appear in the
detailed description which is to follow, in con
nection with the drawings, in which:
Figure 1 is a schematic view of my circuit
breaker operating element showing the contacts
closed.
Figure 2 illustrates the open position or" the
circuit breaker in Figure 1.
Figure 3 is a view corresponding to that of Fig
ure 1 showing the movement of the apparatus
for normally opening the circuit breaker.
Figure 4 is a diagrammatic showing of a slightly
modi?ed form of circuit breakers wherein'a sole
noid closing mechanism is utilized instead of a
motor.
'
Figure 5 shows the circuit breaker of Figure 4
in closed position.
Lever 22 is pivoted for rotational movement at
23. A ?exible laminated conductor 26 is secured
in any suitable manner, as for instance, by the
bolt 25 to the lower end of the lever
and at
its opposite end is secured by the bolt 26 to the
end of the connecting bar i2.
v‘When, therefore, the circuit breaker contacts
are closed a circuit is completed from conductor
6 5' through the stationary contact 83 to the mov
able contact it through the movable contact
carryinglever 22 and the ?exible lead 2!} to the
connecting bar i2. A tension spring 38 is con
nected at one end to the ear ti on the movable
contact carrying lever 22, and at the other end.
the spring so is connected to a lug 32 mounted on
the
therefore
frame biases
of the mechanism.
the movable Tension
contact spring
carrying
lever 22'into counterclockwise rotation and hence
biases this member to open circuit position.
‘When the circuit breaker is open as seen in
Figures 2 and 3, then the movable contact lever
22 rotates counterclockwise against the stop 36,
which limits further rotational movement there
of. The said stop is, of course, a.--
‘
position as to permit the move" I
ctationary
contact to ensure proper circuit interrupting
capacity.
When closed, the contacts are normally main
tained in engagement by means
the ?exible
member 35, which may take any desired form,
such as a chain.
The chain 35 is connected at
one end to an ear 36 mounted on the contact _
lever 22 preferably approximately midway be
tween the pivot point 23 and the free end which
carries the movable contact ii. This chain
passes over the roller 37' which is mounted on
the operating crank 38. The other end of the
chain is at 39 secured to the armature Iii) which
Figure 6 is a detailed showing of a portion of
the apparatus of Figures 4 and 5.
40 is normally held in engagement with the oper
ating magnet 52.
Figure 7 is an exploded view in perspective of
The armature (it is plvotally mounted on the
the operating magnet of my circuit breaker.
lever £36 which is rotatably mounted on the pivot
Figure 8 is a view in perspective of my operat
‘ G5, which in turn is carried by lugs do associated
ing magnet in assembled position.
Figure 9 is a cross-sectional view taken on line 45 with the frame of the magnet 62.
The magnet £552 is normally energized by a con
9-4) of Figure 8.
'
stant potential direct current coil £11 which pro
Figures 10 and 11 are diagrammatic views 11
vides adequate ?ux to maintain the armature 5G
lustrating the operations of the magnet of Fig
in contact with the pole pieces against the pull
Figures 12, 13 and 14 are additional diagram 50 of the spring 30 transmitted by the chain or
?exible member 35.
matic views further illustrating the operation of
Current ?owing through the series conductor
the magnet. v
i2 a?ects the flux between the magnet and the
Figure 15 is a diagram of a composite current
armature so that under certain conditionsv of
oscillogram comparing 1/2 cycle and 1/4 cycle anode
circuit breakers employed in my invention.
55 direction and intensity of current ?ow, as here
inafter described, the ?ux through the arma
Figure 16 shows the arcing structure.
ture is inadequate to counteract the e?ect of the
Referring now to Figures 1, 2 and 3, I have here
spring to, and the circuit breaker contact is pulled
shown in schematic form the construction and
to open position.
_
operation of a circuit breaker utilizing my in
The crank 38 may be operated for the purposes
vention. The circuit breaker here shown includes 60
hereinafter described to close or to open the cir
circuit connecting members it and 02, which
cuit breaker independently of the magnet 42 and
form the terminals of the circuit breaker and are
the armature (it.
'
arranged to be connected into the external cir
A motor 59 is used to operate a multi-pole unit,
cuit.
ures 7 and 8.
An L-shaped stationary contact member 93 65 driving, through'an insulating shaft, the high
speed shaft 5! of small speed reducers 52; one
speed reducer being mounted on each pole. The
low speed shaft 58 of each speed reducer carries
on the connecting bar Ii. The stationary con
the crank 38 and its roller 3?.
tact it may be engaged by the movable contact
If the motor to is run suirlciently to drive crank
I'll which also is an L-shaped member having a 70
38 through 360° and the armature 6B is sealed
' contacting surface. It and a mounting bracket it.
against the pole face of magnet 42, the effects
A bolt 20 passes through the mounting bracket
of the chain 35 riding on the crank roller 31 is to
I9 and secures the movable contact ill to the
cause the breaker to go through an open-close
upper portion of the movable contact carrying
lever 22.
75 cycle, as shown in Figures 1 and 3.
having a contact surface 563 and a securing
bracket I5, is mounted by means of the bolt it
2,412,247
A limit switch‘ may be utilized for controlling
the motor which, with suitablebraking, ensures
to the frame of the magnet 80. The opposite end
of the lever ‘1 may be slotted, or, as is shown in
the ?gures, bifurcated at ‘H to receive the rod ex
tension 12 of the solenoid plunger ‘I! normally
that the crank and roller will stop at the proper
point in the operating cycle either for closing
or opening.
'
In Figure 2, the circuit breaker contacts are
shown in the open position, having opened auto
matically because the ?ux in the magnetic path
(a
held in the position shown by compression spring
80'. The rod 12 is arranged for engagement with
the upper surface of the lever 81 by means of the
button 15 which is secured to the upper portion
of magnet 42 and the armature 4|! was reduced
of the rod 12.
beyond the critical value necessary to counter 10 - The contact members in the present case are
balance the opening force exerted by the spring 30.
Accordingly, ‘the spring 30 has'caused the lever
22 to rotate counterclockwise, thus pulling the
chain 35 over the roller 31 and lifting the arma
ture 40 away from its magnet 42.
Figure 3 shows the ?rst necessary step for
reclosing the circuit breaker ‘after it has opened
to the position shown in Figure 2. With the
breaker contacts disengaged and armature oil“
in its uppermost position, the crank iitl is rotated
by motor
through 180° so that the armature
is permitted to ‘fall by gravity against the pole
face of magnet
and the flexible member 35
is shown completely slackened having no tension
at this particular phase of the operation. The
circuit breaker may now be reclosed by energiz
ing the coil H to assure that there is adequate
holding ?ux passing through the armature All.
The shaft 53 is then rotated by means of the
motor preferably in a clockwise direction to ro- 1
tate the crank 38 and the roller 37 so that flex
ible member 35 is drawn taut and then is effective
to pull the contacts into engagement and main
tain them in the position shown in Figure 1.
To open the circuit breaker without relying on
the automatic circuit breaker opening means, the
field coil 4i’ may be deenergized, which will result
in the release of armature to and a consequent
illustrated as bridging contact 18, which, in the
open position of the circuit breaker, bridge the
contact members ‘l1, ‘l1 and, in the closed position
.of the circuit breaker, bridge the contact mem
ber ‘l8, 18. The members 18, 18 are, of course,
the main current conductorsywhile the members
‘l1, 11 may, when bridged, energize any appro
priate relay or signalling apparatus, or any ap
propriate motor circuit or other apparatus nec
essary for effective operation or the circuit break
er when it is open.
In order to close the circuit breaker, that is,
in order to move the armature £52 from the posi
tion shown in Figure a to the position shown in
Figure 5 so that the bridging contact member
‘it? may bridge the contacts it, 78, the ?eld coil
6| is first energized by closing the circuit there“
to‘through the switch 84. Thereafter, the sole
noid coil 8b is energized by closing the switch 82,
thus connecting the current source 63 through
the leads 3% and 85 to the coil 80. The plunger
‘it is attracted downwardly thus pulling the rod
downwardly and engaging the button it with the
upper surface of the lever iii‘, and pulling the
lever Ei'i downwardly.
Thearmature s2 is normally urged into raised
position by the tension spring at ?xed at its
upper end and engaged at its lower end to the
upper portion of the rod {28 which, in turn, is
may
opening
be rotated
of the so
circuit
that shaft
breaker;
153 isor
rotated
the motor
through
40 secured to the armature 52. The attraction oi‘ the
180", thus bringing the circuit breaker to the
solenoid plunger ‘l3 downwardly by the coil Bil
position shown in Figure 3. Ineach case, the
pulls the lever ill and the armature 82 down
circuit breaker may be opened.
wardly against the force oi’ the tension spring
In the foregoing, the principle of the forma
8''! When the downward movement has been
tion of my circuit breaker has been set forth in
completed, and the armature 62 has been scaled
its simplest form.
against the pole faces of the magnet Bil, the
Either of the contacts l3 or ill may obviously
circuit breaker will normally stay closed despite
be resiliently mounted upon their respective sup
the fact that the switch 82 (which may be ‘a
ports.
spring operated switch biased toward open posi
The type of holding magnet shown in Figures . tion) now opens. That is, as long as the mag»
l, 2 and 3, is of a conventional “bucking bar”
netic flux of operating magnet 50 through the
type well known in the art. The actuating mech
armature 82 is su?icient to counteract the force
anism of the circuit breaker may, of course, be
of the spring 81, the circuit breaker will remain
e?ective with any of the well-known releasable
closed, and the contacts 18, 18 will be bridged.
holding means. The type of holding magnet
Accordingly, the solenoid plunger 12 may be
which I prefer, however, to use in the circuit
permitted
to return again to the raised position
breaker of the present type, and which also has
under the bias of, for instance, a spring mount
many additional functions and operations, is that
ed directly beneath it.
shown in Figures 4 to 14 inclusive.
In Figure 6, I have shown the position of the
However, in Figures 4, 5, and 6, I have shown a
solenoid plunger and the rod 12 with respect to
somewhat modi?ed type of circuit breaker which
the lever Bl at the moment the closing operation
may operate in the same general manner, and
has been completed and before the solenoid
which may be described in its simplest terms be
plunger [has been permitted to rise again to the
fore the exact operation of the magnet itself is
position shown in Figure 5.
set forth,
livhen, now, owing to current conditions, here
In Figure 4, the modi?ed circuit breaker is
inaiter described, which cause a decrease in the
shown having the holding magnet of my inven
holding iiui: exerted by the magnet
through
tion which is energized by the field coil 63, which
the armature G2, the holding force of the magnet
may create sufricientiiu'z: to attract and hold the
armature
The ?eld coil
may be energized 70 decreases below the pull exerted by the spring 2?,
the spring
is free to pull the armature t2 up
from any direct current source as 88, the cir
wardly and, consequently, remove the bridging
cuit to the field coil being closed by, for instance,
member ‘N3 from bridging engagement with the
the switch 813.. The armature it is pivotally
contact 78 and to bridge the contact member 1?.
mounted on the lever 6i which, in turn, is pivoted
at 38 on the member so, which is rigidly attached 75 ‘ill. The holding or operating magnet Eli and its
a
garages?
function is set forth in Figures 7 to 14 inclusive
to surface engagement on opposite sides with _
and constitutes a vital element of my invention.
Referring now to Figure ‘7, there is here shown
each of the layers.
While sheet l26 should preferably be an insu
lating non-metallic sheet, it is sumcient, how
in‘ partially exploded form the holding magnet
vention. The holding magnet, as may be seen in
ever, for purposes of operation of the holding
magnet that it merely be a non-magnetic mem
Figure 7, comprises a rectangular structure con
sisting of stacks of laminations which provide
formation and is provided with the central open
69 which constitutes a primary element of my in
spaced and interleaved pole pieces or opposite
polarity. This system provides a plurality of short
?ux paths (hereinafter described in connection
with Figure 12) through the armature and results
in an extremely quick acting release. The elec
trical and magnetic properties and the advantages
in actual operation of my holding magnet will be
more speci?cally set forth. after the following de
her.
The insulating sheet Mill is U-shaped in
ing M51; which registers substantially with the
10 central opening H5 in each of the outer plates
Hi2 and till to permit the conducting bar iii to
pass therethrough. Sheet l2£i also has openings
we, i?t to permit the insulating bushings to
pass therethrough.
'
The next group of laminations immediately
beneath, that is, layer 622 has the same form
scription of the speci?c physical arrangement
as the laminations in layer i211, but the mem
thereof.
bers are reversed with respect to each other.
The stacks of laminations are held together by
Thus, the stack Mild in layer i2? extends imme
a pair of non-magnetic frame plains till and M32. 20 diately beneath the limb 833 of stack H32 in layer
Plate lei is provided with a plurality of tapped
HM; and limb i331: of stacks Hilda in layer l22
perforations 9%, N33 to receive the ends iitil, Mill
extends immediately beneath the stack lllli in
of a plurality of studs Hi5. Studs tilt are insu
layer (122i.
.
lated from the metallic laminations hereinafter
In layer 523, the positions of the stacks are
set forth by the insulating bushings M36, M36.
again reversed so that the L-shaped stack extends
These studs we pass through corresponding open
beneath the L-shaped stack of layer 62H, and the
ings M38, ltd in each of themetallic laminations
rectangular stack of layer 023 extends beneath
as hereinafter set forth, and also pass through
the rectangular stack in layer M26.
openings in the lower plate idB-all of the open
In layer Hill, the positions are again reversed
ings in the plates and in the laminations being
so that the arrangement of the stack corresponds
in registry with each other; The lower end of
exactly to that of layer B22; and again in layer
v the studs are also threaded, and the entire as
till, the positions are reversed so that the ar
sembly is securely integrated as a. single unit by
rangement of the stacks in the layer corresponds
means of the nuts ill which are threaded onto
.to the arrangement in stacks i233 and 526.
the ends Mil oi the studs Hi5, and held in place ‘
Thus, in each adjacent layer, an L-shaped stack
by the lock washers ll la and Washers ll lb. The
is in alignment with a rectangular stack, and a
washer lllb is of insulating material to ensure
rectangular stack on the opposite side is corre
that the nuts I i l are appropriately insulated from
spondingly in alignment with the adjacent
the plate ldii.
'
L-shaped stack on either side of the layer.
A central opening M5 is provided in each of
Insulating spacing plates, i271, E28 and are, simi-'
, the plates I08 and W2 and registers with cor
lar in every respect to spacing plate 826, are
responding openings in each of the laminations
introduced between successive layers of laminated
formed by the plurality of magnetic sheets, as
stacks so that each successive laminated layer
hereinafter set forth, in order to form a cen
l2 l-—l25 is magnetically isolated from the others.
tral opening through the entire structure through
The laminated stacks, aswell understood, are
which the conducting bar it passes.
formed of magnetic material so that appropriate
In Figure 7, the plate iili and one layer of
magnetic ?uxes may be created in accordance
laminations and its associated insulating spac
with the operating characteristics hereinafter set
ing plate is shown lifted from the entire stack in
forth.
order better to illustrate the complete unit.
‘An air gap M2 is provided in each layer be
In the construction shown in Figure 7, the hold
tween the rectangular stacks and the adjacent
ing magnet is provided with ?ve layers of lami
limb I35 of the L-shaped stack in the same layer
nations Hi to H5. Each of these layers of
for purposes hereinafter described in connection
laminations is separated from the adjacent layer
with Figure 14.
, by insulating plates 826 to H29 respectively.
55
The pole pieces are formed by the limbs i355,
Referring now to layer IZI, this layer, as do
585a, 885b, i350 and Wild in the stack. Adja
each of the others, consists of two sets of lami
cent poles in adjacent layers are of opposite
nations. One of the sets or stacks l32 comprises
polarity in accordance with the structures here
sheets which are L-shaped in formation‘ with one
inafter described. Thus, should pole I35 be north,
limb I33 forming the sides of the structure and 60
then pole lliiia will be south, 53% will be north,
provided with openings not, 908 to receive the
i350 south, and l35d north. The poles of oppo
studs N35. The other limb i351 forms a mag
netic pole in the manner hereinafter described.
Layer it! comprises, in the same plane with
laminations I32, another stack or layer of lami
nations M6 which consists of a plurality of sheets
of a simple rectangular form‘ and which forms
an element of the other side of the structure.
site polarity are interleaved as shown in Figure 7
so, that they extend substantially between each.
other to provide proper terminals for the mag
netic paths through the armature in the man
ner hereinafter described. The manner in which
the poles become of opposite polarity should be
obvious upon inspection of Figure 7. Thus pole
not, me to receive the insulated bolts. An air 70 face i215 extends from the right-hand end I32
of the structure, and current induced in the lam
gap M2 is provided between the limbs M35, form
inated stack will produce a magnetic flux of a
ing a pole piece, and the end of the rectangular
speci?c direction therein.
, _
.
stack of laminations Md. The insulating plate
In layer I22, the ?uxes will be of the same
I26 is placed immediately beneath the layer' l2!
‘and immediately above the layer I22 in surface
direction, but, however, pole face l35a extends
The stack Mil is also provided with openings
2,412,247
from the left-hand side of the stack, and hence
this pole will be of a polarity opposite to that
of pole I35. Similarly, pole I35b extends once
more from the right-hand end of the stack and
pole I350 from the left-hand end so that in each
case the polarity will be opposite. The arrange
ment is followed throughout the stack so that
10
BI with terminal connection I68 (Figures 4, 5, 10
and 11) provides proper energization.
The direction and intensity of the magnetic
flux of the magnetic structure herein described is
in?uenced by two factors:
The ?rst factor is the direction of the current
?owing in the bus bar I2 which passes through
adjacent interleaved poles are of opposite polarity.
the central opening H5 in the magnetic struc
In order to complete the magnetic circuit be
ture. This flux, however, is not relied upon to
tween the ends of the laminations remote from 10 generate any holding force.
the pole pieces, a single stack of rectangular 1am
The other component of the magnetic flux in
inations I50 is provided. This stack of lamina
the magnetic structure is created by the pole
tions is secured between the end frame members
pieces I6I and- IE0 and their core I67’, which is
IOI and I02 in spaced relation to the ends of the
surrounded by the coil 5|.
.
other laminations so that an air gap I5I is pro 15
The direct current energization of the coil 5I
vided between the ends of stacks I32 and I40
produces a magnetic flux in the core I67’ and in
and the stacks I50. This is done in order to re
the pole pieces I60 and IBI through the poles I35
duce the possibility of saturating the magnetic
and I40 in each layer of the stack.
material during normal operation.
These composite actions are shown more spe
The stack I50 is maintained in position, as will 20 ciiically in Figure 10.
.
be obvious in Figure '7, by the insulated studs I05
-Thus in Figure 10 when the coil 5i is energized
which pass through corresponding registering
openings in the stacks and in the end frame
by a direct current source in a desired direction,
the magnetic ?uxes in the structure are shown by
members.
.
the arrows. The direct. current coil 6| creates a
The speci?c manner in which the studs 1 05 and 25 magneto-motive force driving the ?ux through
their insulating bushings pass through the stacks
of laminations and the end frames is shown in
the cross-sectional view of Figure 9 where the
stud and bushing passing through the register
ing perforations of the stacks I35 and I40 are
shown. From Figure 9, it may readily be seen‘
that the studs “)5 do not provide any conductive
the poles l‘u‘iJ and iGI to the edges of the stacks
of laminations.
This ?ux in the schematic showing of Figures
10 and 11 will ?ow through pole I6I through one
of the magnetic laminations I35 and then
through the armature 40 to the adjacent oppo
site pole 335a, returning through pole piece I50.
path between the stacks. Preferably, the stud
A parallel magnetic circuit is provided from pole
I05, while they may be of metal, should be of non
piece it! through laminations ltiib, armature 120
magnetic material so that undesirable flux paths 35 to laminations i35a, returning through pole piece
will not be provided.
_
i663. The ?ux ?owing in laminations i351) di
In the assembly operation, the studs I05 are
vides as shown in Figure 12, some flowing
threaded into the threaded openings 503 in the
through the armature 4b to laminations I350 and
frame member Mill. The insulating bushing £105
pole piece 556i.
is then placed thereover, and the successive 40 ’ The manner in which the flux ?ows from pole
stacks of laminations and their respective insu
to pole through the armature in each case is
lating spacers are then placed over the studs, and
shown in the schematic cross-sectional view of
the entire assembly locked in place by the nuts
Figure 12.
H l and their associated members.
Thus, the ?ux in the laminations is divided
When the various laminations and their insu
into a. plurality oi paraliel ?ux paths through
lating spacers and insulating i’rames are united
the armature, each of the paths including only
in a single unit, they then assume the form shown
its individual portion of the armature as distin
in Figure 8.
_
,
l,
guished from prior magnet structures in which
The series conductor or bus bar I2 is shown
all of the ?ux in the magnetic structure must ?ow
passing through the opening M5 in the entire 50 through the entire armature. Accordingly, for
magnetic structure. The armature 40 is shown
the same armature mass, my present structure
resting against the pole faces; and the direct cur
will conduct a considerably larger number of flux
rent energization for the magnetic structure is
lines by reason of the number or multiple mag
provided by the coil 5!, the action of which cor
netic paths than is the case of the standard mag
responds to the action of coil 6| in Figure 4 or the 55 net in which all the ?ux ?ows through the entire
action of coil 41 in Figure 1.
structure in a single series path.
‘
This direct current energization of the mag
In addition to the flux paths between I35,
netic structure is obtained by reason of a mag
l35a-I35d as will now be apparent, ?ux paths
netic interconnection between the coils and the
are provided from lamination i35 through arma
magnetic structure. For this purpose, solid iron
ture 40 to laminations M0, 835a to “0a, etc.
pole pieces I50, ISI are provided—these mem
These paths are provided by reason of the slight
bers being secured against the sides of the mag
overlaps of the armature do as shown in Figure
netic laminations by bolts I63 which pass through
10 which magnetically connects laminations I35 .
openings in the pole pieces I60 and I6! and enter
with I46 through armature 40 and similarly mag
the tapped perforations I64, I84 in the sides of 65 netically connects each of the other correspond
the frame members I0! and I02 (see Figure '7). '
ing sets of laminations.
A bolt IIi'I passes through perforations in the
‘
Consequently, the magnetic ?ux ?ows not only
opposite pole pieces I60 and I6I (Figure 8), and
from pole I35 through the stack I40 in each layer,
maintains the magnetic core in position between
but also ?ows from pole I35 to pole I35 in suc-K
these two pole pieces. This magnetic core corre 70 cessive layers-the armature 40 providing the
sponds to the member I81’ of‘ Figures 4, 5, 10 and
magnetic path between successive poles in suc
11. Although the poles I30 and ISI are shown
cessive layers. The ?ux thus provided is sum
extending to the right of the laminations I35and
cient to maintain the armature 40 against the
I40 in Figure 10, they may be reversed in direc
polgnpieces, against the bias of the spring 81
tion if desired as shown in Figure 11. The coil 75
or
.
.
atlases
.,
in
‘When current is flowing in the normal direc
tion in the bus bar it, as shown in Figure 10,
it creates a ?ux through the magnetic structure,
in the direction indicated by the arrows, which
augments that created by the current in thecoil
6i, so that the armature is even more firmly
secured in position.
.
.
l2
in the center of the armature may be de?ected.
That is, the point 8d, at which the external force
exerted by the ?exible chain 35 is exerted, may be
drawn away from the pole face owing to the rela
tively small cross section required for the arma
ture. In such a case, the slight ?exing of the
armature, which permits the center area. thereof
to be drawn away, may thus decrease the mag
As may now be seen in Figure 11, should the
netic ?ux'therethrough at the center. This de
direction of the current in the bus bar it be re
versed, a flux through the magnetic structure 10 crease in magnetic flux at the center will thus
decrease the net counteracting force exerted by
in the reverse direction will be created thus tende
ing to counteract the effect of the ?ux created ' the magnetic structure to the pull at the point
89, thus permitting the pull to be exerted more
by the coil ti. These two fluxes opposing each
strongly, thus making it possible for the center
other thus will reduce the ?ux passing through
the armature to a point where the bias of the 15 of the armature to be deflected even more, and
thereby permitting a greater portion of the arma
spring 30 or at will be sumcient to overcome the
ture to be drawn away. This successive action,
pull of the magnetic structure, and the armature
which may occur very quickly, will, owing to the
will be released to permit the circuit breaker con
?exing of the armature, permit the armature to
tact to separate.
While in Figures 8, l0, and 11, the magnetic 20 be released.
Accordingly, the armature 68 is thickened at
circuit of the shunt coil all is shown as not em:
its center portion to provide a better path for
bracing the bus bar it’, it might be advisable un
the passage of magnetic fluxes thereat, and the
der certain desired conditions to extend the pole ‘
center stack of laminations is thickened so that
pieces iBll and iti so that the magnetic ?ux in
these members will also embrace the bus bar iii. 25 the center pole face 8335b is much thicker than
the other pole faces.
,
A reversed current in the bus bar l2 will then
Similarly, the pole faces adjacent the center
not merely create a reversal of the magnetic flux
pole face, that is,'pole faces idea and tilde, while
in the magnetic structure itself, but will also set
not as thick as pole face will), are much thicker .
up a magneto motive force in the pole pieces Mid
and l?l in a direction opposite to'the magneto 30 than pole faces H36 and ld?d.
Since the stacks of laminations toward the
'motive force exerted by the coil iii, thus tend
center of them'agnetic structure have the great
ing further to diminish the net magnetic ?ux
est thickness, consequently, they also have' the
tending to maintain the armature-in position and
permitting an even quicker release of the aa
ture 4t.
7
greatest pole area and provide the largest amount
35 of ?ux flowing into the armature. The armature
-
itself, since it is thickened at the center, also
It will thus be seen from an examination of
Figures 10 and 11 that the magnetic structure , provides an appropriate path 101' this increased
amount of?ux. This flux is progressively de
and its energizing coil 6i and the magnetic force‘
creased toward the center of the armature.
exerted thereby is sumcient to hold the armature
It thus becomes possible to provide an arma
so in position, and that this holding force is ac 40
ture of a minimum weight with greater physi=
centuated when current is ?og through the
cal strength than in cases where an armature
bus bar it’ in the forward direction.
structure of uniform cross-section throughout is
When current flows in the bus bar id in a direc
used.
,
it
tion opposite due to a fault condition, this mag
Thus, in Figure 12, the poles i585, lllhb and
neto motive force is counteracted, as shown in 45
i350! and indicated as being north. Flux lines
Figure 11, and is rapidly diminished to an extent
2% ?ow from pole led into the intermediate pole
where the armature so may be released. 1
lt?a. Also, ?ux lines 2M flow from pole l85d
By reason of a plurality of poles which are
into the intermediate pole l35c. Flux lines 2&2
thus provided, I have found that a very small
armature, weighing approximately of the order 50' and 203 ?ow from the central pole 83Gb into the
intermediate poles 835a and l85c. In each case,
of .55 pound, is all that is needed to maintain
closed contact position of. the circuit breaker.
The weight of the armature may thus materially
the magnetic circuit is completed from pole to
be reduced. I The inertia of the parts, which‘must
be brought into motion upon the occurrence of
a condition which makes it necessary that the
the core lB‘i'.
0n the occurrence of reverse current condi
tions in the bus bar if, as shown in the dia
pole through the pole pieces I68 and it! through
grammatic sketch of Figure 11, the ?ux tend
circuit breaker open, is also greatly reduced and
ing to hold armature All in place against the
the opening time of the circuit breaker is corre
force of the counteracting spring is reduced so
spondingly decreased. The armature need only
be su?icient to provide an appropriate path for 60 that the armature is permitted to move away
from the magnetic structure. As armature d0
the magnetic ?uxes, asshown in Figure 12, and
need only be physically strong enough to support
moves a slight distance away from the magnetic
the chain or fiexiblemember 35 which is secured
structure, as shown in Figure 13, thus creating the
air gap 2 i ll, then, under normal or steady current
conditions, the introduction ‘of such an air gap
will cause the building up of the leakage between
the adjacent poles so that the flux passing into
the armature is so rapidly reduced that the pull
exerted by the magnetic structure becomes sub
at 38 to the armature.‘
_
,
In Figure 12, I have shown a cross-section
through the magnetic pole'pieces and the arma
ture along approximately the center line. Again,
since the armature need only be of su?lcient
thickness and strength to carry the ?ux be
tween adiacent pole pieces, .and thus is, in e?ect, 70 stantially zero at a very small air gap 25c, and
the armature may then be drawn away from the
a plurality of small armatures bridging separate
magnetic structure very quickly.
air gaps, the cross section of the armature may
During practical operating conditions in some
become so small in respect to the physical force
existing that in an armature of uniform cross
section, an effect may very well be created where
installations, ‘a fault current may increase in
75 value at an exceedingly high rate. There are
2,412,247
13
.
.
installations in which the rate 01' rise in cur
rent may be increased at ten million amperes
per second. Under such conditions, it is essen
tial that the speed of movement of the arma
ture and the rate of rise of the ?ux in the air
14
In order to further reduce the mass of the
armature, a V~shaped groove is cut therein as
shown at I'H in Figure 8, since the magnetic
paths are such that substantially no lines of
force would be ?owing through this portion of
gap be so arranged that there shall be no tend
the metal.
This is better shown and more evident from
an examination of Figure 12, which shows por
circuit breaker.
,
tions of the metal between the lines of force
While the condition shown in Figure 13 rep 10 202 and 203 which perform no usefulfunction
resents a leakage flux from one pole piece to an
in carrying magnetic lines of force.
adjacent one, which will occur during normal
This same principle may be carried out in other
operating conditions, high rate of rise may
portions of the armature, if desired.
change this action. At a very high rate of cur
The blow-out structure which I have found
rent rise, the flux increases correspondingly. 15 operating satisfactorily with the present circuit
I have found that rapidly changing ?ux will
breaker is shown in Figure 16.
flow normally parallel to the plane of the lami
With the previous breaker, the current reached
nations, and that they are so guided by the
a value under a certain set of test conditions of
outer laminations that the cross leakage is sub
30,000 or 35,000 amperes when arcing was in
ency for the armature to be drawn back against
the pole piece and so prevent the opening of the
stantially zero. Any flow of this flux of rapidly 20 itiated, whereas, with this higher speed breaker,
changing value normal to the plane of the lami
arcing may be initiated at appreciably less than
nations would tend to create eddy currents which
would tend to oppose the cross ?ow.
As a re
sult of this condition, the situation shown in
Figure 13, would not exist during a fault in
volving a very high rate of rise in current, and
half this value. As a consequence, satisfactory.
speed of arc travel during the early formation of
the arc with the ‘prior arc extinguisher was un
satisfactory, resulting in distress and delayed
current limitation.
for this reason, it is necessary to provide, as
The structure of Figure 16 employs a strength
shown in Figure 14, a relatively narrow air gap
ened primary blowout responsible for initial arc
between the ends of a pole I35 and the rectangu
motion and the transfer to the secondary blow
lar stack M0. This air gap will provide a leak 30 out is made much earlier.
‘
age for the flux produced by a current changing
any value of rate of rise so that the tendency
to draw the armature back against the pole pieces
is eliminated.
From the above, it will now be clear that the
While I have here described my invention in
connection with preferred, successful embodi
ment thereof, many variations in the actual
form of the interleaved pole pieces, and many
variations in the form and construction of the
magnetic path for ?uxes ?owing through the
armature and of the circuit breaker itself, as well
as many variations in the “bucking bar” arrange
pole piece M60 is distributed through the lami
ment and in the exciting coil and other elements
nations iii to H5. Because of the variation in
of my invention, will now be obvious to those
the number of laminations in section i2i as com
pared to the next section I22 and I23, less lines 40 skilled in the art. Accordingly, I prefer to be
bound not by the speci?c disclosures herein but
of force will flow in the laminations i2 i, a greater
only by the appended claims.
amount of ?ow in I22 and still a greater amount
I claim:
in I23. The lines of force ?owing in laminations
1. In a holding magnet, a plurality of magnetic
I35 of layer iZl will in turn divide themselves, a
conductors of one polarity a common magnetic
larger proportion of such ?uxes ?owing from the
path for all of said magnetic conductors; a plural
lamination i35.to lamination i35a through the '
ity of magnetic conductors of an opposite po
portion of the armature bridging I35 and 93511
larity; said magnetic conductors being arranged
as shown at 200 in Figure 12.
in a stack parallel to each other, the magnetic
A smaller proportion of such fluxes ?ows ‘from
lamination i35 through the armature which 50 conductors of one polarity being interleaved be
tween the magnetic conductors of the opposite
bridges the gap M2 to the layer Mil. This is due
polarity and spaced from each other; and an
to the fact that the reluctance of the smaller
armature having a face simultaneously engage
path to the armature from layer H35 to H9 is
able with each of said magnetic conductors and
greater than the reluctance of the much larger
path provided by the armature from layer i35 55 completing a plurality of magnetic paths between
adjacent magnetic conductors, the adjacent mag
to NM.
netic conductors providing leakage paths between
Moreover, the lines of force ?owing in the mag
each other when said armature moves away from
netic structure are greater than the lines of force
said conductors.
which could be carried by the armature cross
section at this point which further determines 60 2. In a holding magnet, a plurality of magnetic ,
conductors of‘ one polarity a common magnetic
the distribution of lines of force.
path for all of said magnetic conductors; a
In general, the distribution of magnetic lines
plurality of magnetic conductors of an opposite
of force is as illustrated in Figure 12. A rela
polarity; said magnetic conductors being arranged
tively small number of lines ?ows from lamina
tion I35 to i3_5a through the armature of re== 65 in a stack parallel to each other, the magnetic
conductors of one polarity being interleaved be
duced cross-section. A much larger number of
tween the rnagnetic conductors of the opposite
lines 202 flows through laminations i851; and
i351) through the armature of greater cross-sec
polarity and spaced from each other; and an
armature having a face simultaneously engage
tion at this point. Thus, the portion of the
, armature which is subjected to greatest load also 70 able with each of said magnetic conductors and
completing a plurality of magnetic paths between
has the greatest mass of material and carries
the largest number of lines of force and the
adjacent magnetic conductors; said magnetic
portion of the armature which carries the least
conductors having a different cross-sectional area;
load is of the least cross-section and carries
the cross-sectional area of the armature opposite
the minimum number of lines of force.
‘
76 each magnetic conductor being correspondingly
2,412,234?
i5
id 1
5. In an electromagnet, a magnetic structure
comprising a pair of pole pieces, an armature, a
istering with thicker magnetic conductors.
magnetic conductor extending from each of said
3.v In an electromagnet, a magnetic structure
pole pieces and means for providing a magnetic
comprising a pair of pole pieces, an armature
operable to an energized and de-energized posi
path from one to the other of said pole pieces
try-passing said armature, said armature engag
tion-means for providing a closed magnetic path
ing said conductors to provide a closed magnetic
through said magnetic structure and said
path to said pole pieces of less reluctance
armature and for providing a magnetic path hy=
than said icy-pass and said armature introducing
passing said armature, the magnetic path through
said armature when said armature is in its 10 an air gap connection in the magnetic path in
energized position providing a, lower reluctance
cluding said armature having a greater reluctance
edil?erent, thicker portions of the armature reg
magnetic path than said by-pass and said
than said by-pass as soon as said armature breaks
the contact connection to said magnetic path.
t. In an electromagnet, a magnetic structure’
to its second position providing a greater re
luctance magnetic path than said by-pass.
15 comprising a plurality of pole pieces, an armature,
a magnetic path through said pole pieces and said
4. In an electromagnet, a magnetic structure
armature, and a magnetic path through said pole
comprising a pair of pole pieces, an armature, a
plurality of magnetic conductors extending from
pieces and by-passing said armature, said "in:
ature presenting a closed iron magnetic circuit
each of said pole pieces, said armature being in
physical contact withisaid conductors when said 20 of less reluctance than said by-pass when said
magnet is energized and completing a magnetic
electromagnet is energized and said armature
presenting an air gap connection in its magnetic
circuit from one of said magnetic conductors ex
tending from one of said pole pieces to one of said , path having a greater reluctance than said bik
magnetic conductors extending from the other of
pass as soon as said armature moves on de
'
said'pole pieces, one of said magnetic conductors 25 energization of said electromagnet.
from one of said pole pieces being closely posi~=
7. In an electromagnet, a, laminated magnetic
structure, an armature having an energized and
tioned to the end of said armature, means for
providing a magnetic path completing said ?rst - a de-energized position, means for providing a
mentioned magnetic path and presenting a large
magnetic path through said magnetic structure
surface area to one of said magnetic conductors 30 and said armature, and means for providing a
extending from the other of said pole pieces and
netic path by-passing said armature, the
spaced therefrom to produce a, high reluctance by
magnetic path through said armature when said
pass magnetic connection relative to said
armature is in one of its positions providing a
armature path, said armature immediately on
lower reluctance magnetic path than said byspass
its ?rst disengaging movement away from said 35 and said armature as soon as it starts to move to
' conductors providing a greater reluctance mag
its second position providing a greater reluctance
armatureas soon as said armature starts to move
netic path than said magnetic path by-passing
said armature.
'
-
. magnetic path than said by-passr -
DONALD 1. some
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