Year: 1898

page_text: Date of Application, 15th Oct., 1898
Complete Specification Loft 12th Aug 1899-Accented 14th Oct
1809
We, JAMES FERGUSON, of 18, Cambridge Street, Glasgow, Electrician, and JAMES
WHITE, Scientific Instrument Makers, of 18, Cambridge Street, Glasgow, North
Britain, do hereby declare the nature of this invention to be as follows:--
The object of this invention is to obtain an automatic maximum or minimuni
current breaker.
To break an electric circuit when the current exceeds a certain amount we use
the well known method by which an electro-magnet whose winding forms part of
the circuit and whose armature is attracted towards the poles when the current
for which it is adjusted is attained. This armature, when attracted, releases a
catch holding on the switch for making and breaking the current, and the brush
is pulled off the contacts by springs to break the circuit.
A link carrying the catch is pivoted to a loose arm carrying the handle by
which the switch is put to the "on" position and engages with an arm rigidly
attached to the switch spindle, and by which the position of the switch is con-
trolled. If, on moving the handle so that the circuit is completed at the switch
and from any cause the current passing attains the ** maximum," the armature
will be attracted upwards, will strike the link and release the switch arm allow-
ing the springs to pull the switch to the " off" position. It is therefore impos-
sible to hold the switch on when the arranged maximum current is attained.
"
If the current on making the circuit is not sufficient to raise the armature,
the switch can be pushed to its full on position when a notch on the link
attached to the setting handle will engage with another notch on a link attached
to the base of the apparatus thus forming a coupling holding the switch on the
66 on
or working position. When the cut out is set in this position should the
current attain the predetermined maximum, the armature in rising will engage
with and throw up the link attached to the setting handle, disengaging the
catches and allowing the switch to be pulled off by the springs. By hinging the
link attached to the base and withdrawing the part on the link holding switch
in "on
position which engages with the armature when it rises, and providing
on the hinged link attached to the base a projection to engage with the armature
in its lower position the apparatus will break the current when a predetermined
minimum is reached.
"
In this case the working position for the armature is at the top, it being held
there till the electro-magnetic effect due to the current is not sufficient to sup-
port it, when it falls releasing the catch and allowing the circuit to be broken.
A simple lock or wedge is provided having a suitable handle for fixing the link
hinged to the base rigidly for use as a "maximum" current breaker, or loose för
use as a minimum current breaker.
it

page_text: Improvements in Automatic Means of Breaking Electric Circuits.
We, JAMES FERGUSON, of 18, Cambridge Street, Glasgow, Electrician, and JAMES
WHITE, Scientific Instrument Makers, of 18, Cambridge Street, Glasgow, North
Britain, 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:-
The object of this invention is to obtain an automatic maximum or minimum
current breaker.
To break an electric circuit when the current exceeds a certain amount we use
the well known method by which an electro-magnet whose winding forms part of
the circuit and whose armature is attracted towards the poles when the current
for which it is adjusted is attached. This armature, when attracted, releases a
catch holding on the switch for making and breaking the current, and the brush
is pulled off the contacts by springs to break the circuit.
A link carrying the catch is pivoted to a loose arm carrying the handle by
which the switch is put to the "on" position and engages with an arm rigidly
attached to the switch spindle, and by which the position of the switch is con-
trolled. If, on moving the handle so that the circuit is completed at the switch
and from any cause the current passing attains the maximum," the armature
will be attracted upwards, will strike the link and release the switch arm allow-
ing the springs to pull the switch to the off" position. It is therefore impos-
sible to hold the switch on when the arranged maximum current is attained.
65
وو
وو
If the current on making the circuit is not sufficient to raise the armature,
the switch can be pushed to its full on position when a notch on the link
attached to the setting handle will engage with another notch on a link attached
to the base of the apparatus thus forming a coupling holding the switch on the
on or working position. When the cut out is set in this position should the
current attain the predetermined maximum, the armature in rising will engage
with and throw up the link attached to the setting handle, disengaging the
catches and allowing the switch to be pulled off by the springs. By hinging the
link attached to the base and withdrawing the part on the link holding switch
in " on" position which engages with the armature when it rises, and providing
on the hinged link attached to the base a projection to engage with the armature
in its lower position the apparatus will break the current when a predetermined
minimum is reached.
In this case the working position for the armature is at the top, it being held
there till the electro-magnetic effect due to the current is not sufficient to sup-
port it, when it falls releasing the catch and allowing the circuit to be broken.
A simple lock or wedge is provided having a suitable handle for fixing the link
hinged to the base rigidly for use as a "maximum" current breaker, or loose for
*6
use as a minimum current breaker.
In order that our invention may be properly understood and readily carried
into effect we have hereunto appended two sheets of drawings, of which,
Figure 1 is a front view and Figure 2 an end view of a maximum and minimum
current breaker.
Figures 3, 4, 5, 6, 7, and 8 show various details.
A, A are the brushes for making and breaking the current, which are carried
on a spindle. This spindle has an arm B rigidly attached and also a handle
bar C which is loose on the spindle. Near the top of the handle bar there is a
cross piece c for the purpose of engaging with the arm B when the brushes are

page_text: to be turned to make the current. When the current is to be made the handle
is turned round and carries with it the arm B and turns the brushes on to the
contact pieces and thus the circuit is completed. The handle bar has a quad-
rant c, having a notch cut on the upper surface, which, when the handle
is lifted up to complete the circuit, passes through a hole d in the piece D and
the notch engages with the upper edge of the hole and the handle holds the
arm B with the switch in the "on" position. The piece D is shown in Figure 8
and has a horizontal arm and vertical arm and is pivoted to the framework so as
to have freedom for a slight rocking motion. The electromagnet E acts as a
maximum current breaker. When the current attains the maximum the arma-
ture e is attracted and in rising comes in contact with the cross piece d¹ on the
piece D and releases the quadrant attached to the handle. The spiral springs F, F,
cause the spindle carrying the brushes to turn round and the circuit is broken.
The electromagnet G may be used either as a minimum or a maximum current
breaker. When used as a minimum current breaker the armature is kept
attracted to the electromagnet, as shown in Figure 6, while the current Hows, but
when the current falls to the minimum the armature is released and falls on to
a knob on one end of a pivoted arm H, the other end h of which then comes in
contact with the horizontal arm of the piece 1) and lifts it up and releases the
quadrant attached to the handle. It will be observed that in Figure 6 the piece 1)
is tilted so that when the armature is attracted by the electromagnet G it does not
come in contact with the cross piece d'. When this electromagnet is used as a
maximum current breaker the piece D is turned so that the cross piece d' is hori-
zontal as shown in Figure 7 and when the maximum current is attained and the
armature attracted it comes in contact with the cross piece d' and raises it up and
releases the handle as described with reference to the electromagnet F.
mechanism for accomplishing this will now be described with reference to
Figures, 3, 4, and 5.
The
The piece D is pivoted at Figure 8 to a fork I as shown in Figure 4
which can be turned on a pivot i in the framework of the apparatus. Attached
to or being an extension of the fork I there is an arm J Figures 3 and 4 having
a fork at one end in which an eccentric cam K works. This cam is attached to
the spindle L on which the arm H is pivoted. By turning the spindle L the
piece D and arm H can be turned so as to be in the position shown in Figure 6
for minimum current breaker, the act of turning the spindle L causing the
arm H to lift the armature g to its position for minimum current breaker, or in
the position shown in Figure 7 for maximum current breaker.
To prevent sparking semi-circular discs A', A³, A³, A4, formed of thin asbestos
are provided, two of which are mounted on the spindle carrying the brushes A, A,
and move with them, and the other two are fixed.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
The maximum and minimum current breaker substantially as described.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicants' Patent Agents.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicants' Patent Agents.