Improvements in Automatic Circuit-breakers."
Year: 1897

page_text: Date of Application, 9th Nov., 1897-Accepted, 18th Dec., 1897
[Communicated from abroad by THE CROCKER-WHEELER ELECTRIC COMPANY,
Manufacturers, a corporation organized under the laws of the State of New
Jersey, U.S.A., and having its principal office at 39 Cortlandt Street, New
York, State of New York, United States of America.]
65 Improvements in Automatic Circuit-breakers."
I, WALLACE FAIRWEATHER, C.E., of 62 Saint Vincent Street, in the City of
Glasgow, Chartered Patent Agent, do hereby declare the nature of this invention
and in what manner the same is to be performed, as communicated to me, to be
particularly described and ascertained in and by the following statement: -
This invention consists broadly in providing means for magnetically short-
circuiting the magnetic field employed to keep the circuit closed, and thereby
causing the circuit to be broken, whenever the current exceeds any desired limit
of strength.
In the accompanying sheet of drawings whch forms a part of this specification,
the figure shows a perspective view of the invention.
The line E E includes the coil of the circuit-closing magnet A, the armature B
and the contact brush F. The circuit is closed by moving the armature B up
to the magnet and remains closed so long as the current is constant within desired
limits. If the current falls below the desired lower limit the armature B falls
back and breaks the circuit. A brass or other non-magnetic adjusting screw J,
prevents the armature from actually touching the magnet and permits regulation
so that it shall fall back by gravity when the current drops below any desired limit.
In order to cause the circuit to be broken when the current exceeds a definite
limit, a second armature C is provided which normally rests against an adjust-
When-
ing screw D but can be drawn up into contact with the magnet as shown
ever the current exceeds a limit regulated by setting the screw D, the armature C
is drawn up and short-circuits the field of force which includes the armature B.
This causes the armature B to fall back by gravity and opens the circuit. There
are a certain number of lines of force through the magnet core and the armature B
under normal conditions, but the area of the magnet core is not sufficient to
supply magnetism for both armatures B and C together. When the current
increases, armature C which has heretofore been held off by a spring, is attracted
and brought into intimate contact with the pole pieces. As the capacity of the
magnet core will not permit the magnet to hold both armatures, it will hold the
armature C which is in most intimate contact, or subject to the least mechanical
retractile force, and the other armature being insufficiently attracted, will fall
away.
It will be clear that many changes can be made without departing from th>
spirit of this invention. Thus, for example, the invention is not limited to any
particular number of coils on the magnet as these may be one or several. Nor is
it limited to employing the force of gravity to operate the parts, since springs
or other desired means may be employed. Nor is it limited to any particular
construction and arrangement of the parts. This invention is believed to be

page_text: cadly novel and of great importance because, no matter how great the inrush
of current, provided it exceeds the predetermined limit the circuit-breaker is
sure to act, and the greater the inrush of current the more quickly it acts.
my
Having now particularly described and ascertained the nature of said
invention, and in what manner the same is to be performed, I declare that what I
claim is:
The combinatin of a source of electric energy, a magnetic field created thereby,
a circuit-breaker controlled by the magnetic field, and means for short-circuiting
the field and breaking the circuit when the current exceeds a certain strength,
substantially as described.
T
1
01 1
1
100-
WALLACE FAIRWEATHER.