Improvements in Automatic Magnetic Circuit Breakers.
Year: 1898

page_text: Date of Application, 12th Apr., 1898-Accepted, 29th Oct., 1898
COMPLETE SPECIFICATION.
Improvements in Automatic Magnetic Circuit Breakers.
I, WILLIAM MAXWELL SCOTT, of 108, Johnson Street, Germantown, in the City
of Philadelphia and 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 invention is to afford improved means of breaking the circuit either auto-
matically upon a predetermined condition of the current or arbitrarily by the
application of manual force.
I accomplish this object by the mechanism illustrated in the accompanying draw-
ings in which Fig. 1 is a side elevation in part section of my device; Fig. 2 is a
similar view showing modified means of communicating the thrust of the movable
core to the switch arm.
In Fig. 1 the switch arm 1, carrying the movable contacts and the handle 24
for manual operation, is pivoted at 2 to the magnetic jacket 3. One of the
stationary contacts is indicated at 4, the other not shown, the movable contact
engaging therewith is indicated at 25, the bridge supporting the movable contacts
is shown in section at 5. The piston 6 and the spiral spring 7 adapted to actuate
it to exert its force against the upper part of switch arm 1, are enclosed in cylinder 26
shown in section. This cylinder is provided with a slot 27 in its lower portion to
receive the projection 28 of piston 6 and the upper member 12 of latch 8. The
piston 6 is adapted to be forced against the thrust of the spring 7 into engagement
with the latch by the movement of arm 1 in closing the switch. The latch 8
is pivoted at 18 to the upper part of the magnetic jacket 3 and is adapted to be
actuated by the force of the movement of the core 9 movable in the solenoid coil 10.
The force of the movement of the core is communicated to the latch through the
extension pin 11. Upon the actuation of the latch as described the piston 6 is
released and driven forward against the switch arm 1 driving it outward to cause
An additional impetus
the separation of the movable from the stationary contacts.
is given to the piston after its release by the impact upon it of the upper member 12
of the latch 8 proportioned to the energy with which the movable core is actuated
thus securing an efficiency of operation in direct proportion to the amount of current
causing its actuation.
It will be noted that heretofore in circuit breakers of this class the restraining
means have usually been connected directly with the switch arm or movable con-
tact part, while in my invention I apply the restraining means to the spring-
The said arm is adapted
actuated opening means independently of the switch arm.
to be normally held in a closed position by the friction between the stationary
and movable contacts as in the case of an ordinary knife switch and is adapted to
be manually operated to cause the separation of the stationary and movable contacts
independently of the operation of the spring-actuating means.
In circuit breakers used with currents of high potential it is desirable to provide
against injurious arcing by securing a quick opening when manually operated as

page_text: well as when automatically operated. I secure this end by providing the lever 13
pivoted at 17 to the switch arm 1, said lever having a catch at its free end adapted
to engage with pin or projection 14 in the upper part of latch 8. The lug 15 of
said lever 13 is adapted to be encountered by the pin or projection 16 to limit the
pivotal movement of the lever 13. Upon the manual operation of the switch arm
outwardly towards an opening position, the lever 13 engages the projection 14 on
latch 8 actuating the latch 8 to release the piston 6, which thereupon impinges
the switch arm 1 assuring a positive and quick separation of the movable from the
stationary contacts.
1
I may modify my device by omitting the spring to actuate the piston 6 rely-
ing upon the thrust communicated to said piston by the member 12 of latch S to
cause the opening of the circuit breaker: or, I may dispense with the upper
member 12 of the latch and rely solely on the spring actuation of the piston upon
its release.
I may
further modify my device by substituting for the piston 6 the lever 19
shown in Fig. 2. This lever may be pivoted at 20 to the magnetic jacket 3 and
provided at its free end with an anti-friction wheel 21 adapted to communicate
with the curved surface 22 of the movable switch arm 1, said curved surface 22
being in the arc of a circle of less diameter than that described by the outer
extremity of the lever 19. Upon the upward movement of the pin 11 the lever 19
is raised and the wheel 21 caused to impinge the curved surface 22 because of its
said movement in the line of the arc of a circle of greater diameter than that of
said curved surface thereby imparting a thrust to the switch arm 1 causing the
separation of the movable contacts carried thereon from the fixed contacts."
;
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. In an automatic magnetic circuit breaker having stationary and movable
contacts the combination of automatic means of effecting the separation of the
movable from the stationary contacts, means of restraining the operation of said
separating means independently of the switch arm until actuated to permit the
same, substantially as described.
2. In an automatic magnetic circuit breaker the combination of automatic means
of effecting the opening of the circuit breaker, means of normally restraining the
operation of the said opening means independently of the part supporting the
movable contacts until actuated to permit the same and automatic magnetic means
of actuating the restraining means upon the occurrence of a predetermined flow
of current, substantially as described.
3. In combination with a manually operative switch, spring actuated means
of opening the same, means of normally restraining the spring actuated means
independently of the switch, and automatic magnetic means of actuating the
restraining means to release the spring actuated means, substantially as described.
4. In combination with a manually operative switch, spring actuated means of
opening the same, means of normally restraining the spring actuated means
independently of the switch, automatic magnetic means of actuating the restrain-
ing means to release the spring actuated means, and additional means of actuating
the restraining means to release the spring actuated means upon the manual
operation of the switch substantially as described.
5. In combination with a manually operative switch, automatic magnetic means
of opening the same with a force proportionate to the amount of current causing
its actuation, substantially as described.
6. In a circuit breaker having stationary and movable contacts, the combination
of automatic magnetic means of actuation, a pivoted lever intermediate the said
automatic means and the movable contacts adapted to be actuated by the said auto-
matic means to cause the separation of the movable from the stationary contacts,
substantially as described.

page_text: 7. In a circuit breaker having stationary and movable contacts, the combination
of movable contact member having a curved inner surface, a pivoted lever adapted
to encounter the curved surface of the movable contact member in the line of the
arc of a circle of greater diameter than that of said curved surface, and automatic
magnetic means of actuating the pivoted lever to cause the actuation of the movable
contact member, substantially as described.
WILLIAM M. SCOTT.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.