Improvements in Automatic Magnetic Circuit Breakers.
Year: 1897

page_text: COMPLETE SPECIFICATION.
Improvements in Automatic Magnetic Circuit Breakers.
I, WILLIAM MAXWELL SCOTT, of 108, Johnson Street, Germantown, in the City
and County of Philadelphia, State of Pennsylvania, United States of America,
Electrical Engineer, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be particularly described and ascertained,
in and by the following statement :-
My invention relates to automatic magnetic circuit breakers and the object of
my improvement is to provide a circuit breaker which will be actuated to open the
circuit or circuits either upon a predetermined maximum or minimum flow of
current having convenient means of exact adjustment, means of introducing into the
device current or currents in various ways either to actuate it or to be affected
by its actuation, with means for increased efficiency in actuation.
In the accompanying drawings Fig. 1 is a front view of one form of my circuit
breaker showing two jacketed coils side by side; Fig. 2 is a side view of same in
part section; Fig. 3 is a top view of same; Fig. 4 is a front view of another form
of my circuit breaker having double poles and showing but one solenoid coil and
movable core with an electro-magnet placed over the core having a pivoted arma-
ture; Fig. 5 is a side view of same in part section; Figs. 6 to 13 are diagrams
showing various arrangements for introducing currents into the device either to
actuate it or to be affected by its actuation; Fig. 14 is a view in perspective of
a portion of switch arm and hub thereon.
In Fig. 1, 6 is the base block of non-magnetic material upon which are mounted
two magnetic jackets 7 and 8 each containing a solenoid coil 9 and 10 respectively,
each coil surrounds a non-magnetic tube which contains at its upper end a fixed
magnetic core and below the fixed magnetic core a movable core. The fixed core 11
has passing through it longitudinally a movable magnetic pin 12 adapted to commu-
nicate the impact of core,13 to latch 14; the ends of the fixed and movable cores.
being so shaped that a portion of one is adapted to overlap a portion of the other so
that the shortest distance between the two is less than their axial separation. The
fixed core 15 has passing through it longitudinally the movable non-magnetic rod 16
secured to the movable core 17 and is provided with a head 18 adapted to engage
with lever 19. The section of one or both of these cores immediately at point of
contact may be reduced to obtain increased pull. The switch bridge 20 is mounted
upon arms 21. The contacts of the switch bridge are at 22 adapted to engage with:

page_text: the switch jaws 23 best shown in Fig. 3. The movable core 13 is provided at its
lower end with plate 24 slotted at either side so as to ride on guides of frame 25
which carries on its lower side the set screw and lock nut 26 adapted for adjust-
ment of the core. This plate 24 has marked upon it a point or line by means of the
relation between which and marks placed upon the vertical portion of the fraine 25,
adjustment may be ascertained. To the switch bridge 20 is pivoted at 27 a block
supporting a handle 37 having a limited pivotal movement. Near the upper end of
this block is loosely seated one end of a pin 28 kept under the control of said block
by stop pin 34 driven into the block and projecting into a detent in said pin 28.
When the handle 37 is pushed forward in the operation of closing the switch it
presses pin 28 forward to engage lever or cam 29, which I shall hereafter designate
as cam to more readily distinguish it from lever 19. Cam 29 is pivoted at 30 and is
actuated to press upon the end of lever 19 which is pivoted at 33 causing it to
engage with head 18 of the pin 16 and to lift the movable core 17 to its highest
position in the coil and at the same time latch 14, being spring actuated, engages
the lower edge 35 of the bridge holding the switch closed against the action of the
springs 36 wound around the pivots of arms 21. The slot 38 in cam 29 into which
projects stop pin 39 fixed upon latch 14 permits of such further movement of
the cam 29 after the closing and latching of the switch as may be necessary to allow
lever 19 to fall away from head 18. When handle 37 is released it falls back to the
limit of its pivotal movement which may be regulated by the pin 28 having an
enlarged head to prevent it from being drawn through the bridge. The said pin 28
is drawn backward by the weight of handle 37 away from cam 29 so that lever 19
falls away from head 18 leaving the movable core 17 free to fall at the moment of
interrupted current or predetermined underflow. Upon the fall of core 17 the
head 18 will again contact with lever 19 causing the edge of slot 38 to contact with
stop 39 actuating latch 14 to release the switch arm.
Adjustment of core 17 may be secured by any suitable means of limiting the
distance which the core may be drawn upward into the coil. A non-magnetic
washer may be used to prevent the sticking of core 17 to fixed core 15. Another
form of adjustment for cores 17 and 15 is to have core 15 in two parts as shown in
Fig. 1, that is, 15 being the fixed core and 151 being the adjustable core adapted to
move to and from core 15 for the purpose of changing flow, thereby altering the
pull between 15 and 17 without changing the distance between them.
The arms 21 are pivoted at some distance from their lower ends so that portions
of the arms rotate about the opposite side of their pivots from that of the switch
bridge and are adapted to engage with spring clips or jaws 40 to gradually arrest
their motion until they come in contact with stop plates 41 to finally arrest them.
The hubs upon the arms provide adequate bearing for the arms upon their pivots
and determine the position of the arms in their supporting lugs independently
of the springs 36 which actuate them. The carbons 55 are yieldingly attached to
the support of the contact jaws 23 to contact with carbons 56 attached to switch
blades or arms 21 to prevent arcing at the main contacts.
The binding posts as shown in Fig. 1 are at 43 and 44. 43 is connected with one
of the contact jaws 23, the other contact jaw 23 being connected with one end of
coil 9 and the other end of the coil 9 connected through the underload-coil 10 with
the binding post 44 as shown in diagram in Fig. 6. The following means may be
employed for the actuation of the switch by the cumulative or differential effect of
two or more coils, the same being either in series with the switch or in a circuit or
circuits independent of it, either in whole or in part.
The overload coil may be in two sections so connected as to mutually assist each
other, one section being on each side or leg of the circuit as shown in diagram in
Fig. 7, or the coil may be in shunt to the circuit in which the switch, to be operated
upon, is placed, as shown in Fig. 8, or the coil may be in a circuit entirely indepen-
dent of the switch, as shown in Fig. 9. The winding of the underload coil may be
varied in a similar manner either when used independently or in combination with
any of the above arrangements, as for instance, said coil may be in two sections so

page_text: connected as to mutually assist each other, one section being on each side or leg of
the circuit as shown in Fig. 10; or it may be in shunt with the main circuit as
shown in Fig. 11, where a single pole switch is employed and in Fig. 12 where a
double pole switch is employed; or it may be in a separate circuit from that to be
opened by it as shown in Fig. 13. Additional binding posts are added to the base
as means for introducing into the device one or more currents either to affect or be
affected by the actuation of the device as above described.
Supposing the switch to be closed in the position shown in Fig. 2 upon the occur-
rence of a predetermined overflow, the magnetic core 13 is drawn upward to impact
the pin 12 to actuate the latch 14 thus opening the circuit, or instead of the over-
flow, upon the occurrence of an interrupted or a sufficiently below normal current,
the movable core 17 is permitted to fall and actuate lever 19 to actuate through
cam 29 the latch 14 to release the switch. Where it is desired to have a double
pole switch the bridge 20, instead of being the conducting medium between the
contact jaws 23 as above described, may be insulated from the arms 21, said arms
being adapted to act as bridges to contact the contact jaws 45 with 46 and 47
with 48 as shown in Fig. 4.
It will be noticed that instead of these connecting bridges being horizontal as the
bridge shown in Fig. 1 they are in a vertical position when closed and move in
vertical planes parallel with each other and the jaws of opposite polarity are thus
separated by a greater distance than otherwise would be available in the limited
space, and the bridges of opposite polarity move in different planes separated from
each other.
Instead of having two coils and movable cores as shown in Fig. 1, I may have a
single jacketed coil and movable core as already described for the overflow actuation,
with an electro-magnet 50 as shown in Fig. 4 fixed over the latch which holds the
switch bridge and armature 51, pivoted at 52, adapted to be held by the magnet
either against the force of gravity or spring actuation during the normal flow of
current and upon the interruption of the current or predetermined below normal flow
to leave the magnet and strike latch 14 actuating it to release the switch bridge.
The knob 37 is mounted on the plate 53 attached to switch bridge and having a
certain amount of play.
The upper part of this plate 53 protrudes over the switch bridge and is adapted
when forced forward by the hand in the operation of closing the switch to engage
with the armature forcing it against the electro-magnet where it is held during the
normal flow of current and upon releasing the hand the plate falls away from the
armature leaving it free to fall upon the interruption of the current to actuate
the latch. By having the core of the electro-magnet in two parts one fixed and the
other movable, the movable one may be threaded through the end plate and provided
with a knurled head so that adjustment may be obtained by regulating the distance
between the ends of the movable and fixed cores.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. In an automatic magnetic circuit breaker the combination with a switch and
contacts of a spring adapted to actuate the switch, a latch adapted to restrain the
switch against the action of the spring, two coils, each provided with a movable core,
one core adapted to be actuated by a predetermined magnetic flux to rise in the coil
and a pin adapted to communicate the force of the core's movement to the latch to
release the switch, the other core adapted to be held within its coil during normal
magnetic flux and to fall upon the occurrence of an interrupted or predetermined
subnormal magnetic flux and a rod attached to the core, a lever adapted to be
actuated thereby and a cam adapted to be actuated by the lever to actuate the latch
to release the switch.
2. In an automatic magnetic circuit breaker the combination with a switch and

page_text: contacts of springs adapted to actuate the switch, a latch adapted to restrain the
switch against the action of the springs, two coils, each provided with a fixed and
movable core, one movable core adapted to be actuated by a predetermined magnetic
flux to rise in the coil and a pin adapted to cominunicate the force of the core's
movement to the latch to release the switch, the other movable core adapted to be
held within its coil during normal magnetic flux and to fall upon the occurrence of
an interrupted or predetermined subnormal magnetic flux and a rod attached to the
core, a lever adapted to be actuated thereby and a cam adapted to be actuated by the
lever to actuate the latch to release the switch.
3. In an automatic magnetic circuit breaker the combinaton with a switch and
contacts of springs adapted to actuate the switch, a latch adapted to restrain the
switch against the action of the springs, a coil provided with a movable core, a rod
attached to said core, a lever adapted to actuate and to be actuated by said rod, a
cam adapted to actuate and to be actuated by said lever and also adapted to actuate
the latch, a resetting handle pivoted on the switch arm with limited movement
adapted to actuate the cam to actuate the lever to raise the movable
simultaneously with the closing and latching of the switch.
core
4. In an automatic magnetic circuit breaker the combination with a switch and
contacts of a coil and movable core, a rod attached to the movable core, a lever
adapted to engage with the rod to actuate the rod and to be actuated by the rod, a
cam adapted to engage with said lever to actuate and to be actuated by said lever,
a resetting handle pivoted to the switch arm adapted to actuate the cam to actuate
the lever and a latch adapted to be actuated by said cam upon its being actuated by
the movement of the core communicated to it through the rod and lever to release the
switch arm.
5. In an automatic magnetic circuit breaker the combination with a switch and
contacts of a coil and a core vertically movable therein, said core adapted to be held
within the coil during normal flow of current through the coil but to fall by force of
gravity upon an interrupted or predetermined below-normal flow, a rod attached to
the movable core, a lever adapted to engage with the rod and to be actuated by the
rod, a cam adapted to engage with the said lever and to be actuated by it and a
latch adapted to restrain the switch and to be actuated by the cam upon the
movement of the movable core communicated to it through the rod and lever to
release the switch.
6. In an automatic magnetic circuit breaker the combination with a switch and
contacts of a coil having a movable core, switch arms provided with hubs as means
of adequate bearings on their pivots and guards to maintain each arm at a fixed
distance from either side of its pivot lug to afford space for the springs actuating
said switch arms, spring jaws attached to each of said lugs as means of receiving the
projecting ends of the switch arms to check, and stop plates back of the spring jaws
to finally arrest, the pivotal movement of the switch arms.
7. In an automatic magnetic circuit breaker the combination with a switch and
contacts of a coil having a fixed and movable core, a latch adapted to engage with
the switch, springs adapted to actuate the switch arms, contact jaws adapted to
receive portions of the switch arms, an electro-magnet and a pivoted armature
placed above the latch, said armature adapted upon interrupted or predetermined
below-normal flow of current to leave the electro-magnet and impinge the latch to
actuate it to release the switch, the movable core adapted to be actuated by a
predetermined overflow of current, the pin movable through the fixed core adapted
to communicate the movement of the movable core to the latch to actuate it to
release the switch arins and drive them from contact.
8. In an automatic magnetic circuit breaker the combination with a switch and
contacts of a coil, a fixed and movable core, an electro-magnet and a pivoted
armature, a latch adapted to engage with the switch, the pivoted switch arms and
contact jaws for same, the plate nounted on switch-bridge having a limited movement
thereon and having its upper part protruding over the front of the switch-bridge
adapted when forced forward by the hand in the operation of closing the switch to

page_text: engage with the armature of electro-magnet to force it against the magnet and upon
releasing the hand the said plate adapted to fall away from the said armature to leave
it free upon interrupted or predetermined underflow of current to leave the magnet
and impinge the latch to actuate it to release the switch arms.
Dated this Tante anvanth day of Contambor 1907
WILLIAM M. SCOTT.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.