An Improved Automatic Electric Switch and Cut-out.
Year: 1885

page_text: An Improved Automatic Electric Switch and Cut-out.
We, HENRY HARDINGE SAMUEL CUNYNGHAME, of the Inner Temple, in the City
of London, Barrister at Law, OTWAY EDWARD WOODHOUSE, and FREDERICK
LAWRENCE RAWSON, both of Number 11 Queen Victoria Street, in the City of
London, Electrical Engineers, do hereby declare the nature of our invention for
AN IMPROVED AUTOMATIC ELECTRIC SWITCH AND CUT OUT," to be as follows:-
Our invention relates to the control of electrical circuits, and consists of an
apparatus for severing an electrical circuit when the current exceeds a desired
amount.
It comprises two parts, the regulating part and the operating part or switch.
The regulating part consists of an electro magnet placed near an armature retained
back by a spiral or other suitable spring, which may be adjustable or otherwise,
and the distance between the armature and electro magnet may be regulated by a
screw stop or other suitable adjusting device.
The operating part consists of a metallic switch through which the current to be
controlled passes, and which is pushed by hand between two brushes or clips of
suitable metal on the main circuit against the force of a somewhat powerful spring,
thus completing the circuit, the switch being normally retained in that position by
means of a catch or detent.
The operation of the instrument is as follows:-
As soon as the current reaches the amount for which the instrument has been
set, by means of the spring or screw adjustment before mentioned, the magnetic
force of the electro-magnet becomes sufficient to overcome the resistance of the
spiral spring acting against this magnetic force, and the armature is thus drawn
towards the electro magnet. One end of the said armature, or a suitable projection
thereon, strikes, like a hammer, against the catch or detent holding the switch in
the normal position of closed circuit, and releases the switch, which, then, by means
of the spring, is torn from between the brushes or clips or other switch arrange-
ments used, to any required distance, such as will entirely break the circuit and
prevent "arcing."
The instrument can also be actuated by hand for an ordinary "cut-out; " or can
be used for severing currents at a distance by actuating the electro-magnet as before

page_text: described by means of a current from a distant source, instead of by sending the
current to be severed through the electro-magnet.
Sometimes, instead of a spring to withdraw the switch or bolt, we use the force
of gravity, or the combination of the force of gravity, and a spring..
FELL & WILDING,
Agents for the Applicants.
COMPLETE SPECIFICATION.
An Improved Automatic Electric Switch and Cut Out.
We, HENRY HARDINGE SAMUEL CUNYNGHAME, of the Inner Temple, in the City
of London, Barrister at Law, OTWAY EDWARD WOODHOUSE, and FREDERICK
LAWRENCE RAWSON, both of No 11 Queen Victoria Street, in the City of London,
Electrical Engineers, 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 :—
Our invention relates to the control of electrical circuits, and consists of an
apparatus for breaking an electrical circuit by hand when desired or automatically,
when the current exceeds a determined amount. It comprises two parts, the
regulating part and the operating part or switch. The regulating part consists of
an electro magnet acting upon an armature held back by a spiral or other suitable
spring, which may be adjustable or otherwise, and the distance between the
armature and electro magnet may be regulated by a screw stop or other suitable
adjusting device.
The operating part consists of a switch through which the current to be controlled
passes; this is conveniently made of two brushes or clips insulated from each other
and forming a break in the circuit with which they are in connection; between
these brushes a metallic or other conducting switch block is pushed by hand against
the force of a somewhat powerful spring, thus completing the circuit, the switch.
block being normally retained in that position by means of a catch or detent.
The automatic operation of the instrument is as follows:-
As soon as the current in the electro-magnet coils (which in this case are in the
same circuit as the switch contacts) reaches the strength for which the instrument
has been set by means of the spring or screw adjustment before mentioned, the
attractive force of the electro-magnet becomes sufficient to overcome the resistance
of the spring holding back the armature, and this is then drawn towards the electro
magnet. One end of the said armature, or a suitable projection thereon, strikes
like a hammer, by reason of the largely increasing momentum it attains in its
approach to the electro magnet pole, against the catch or detent, and so releases

page_text: the switch block, which is then by means of the spring attached to it drawn from
between the brushes or clips, or other contact arrangements used, to such a distance
as will entirely break the circuit, and, by reason of the quickness of the break,
prevent "arcing."
The instrument can also be actuated by hand for an ordinary "cut-out" or
switch by simply moving the detent, and if this is the only use for which the
instrument is intended, the electro magnet is dispensed with. Or again, the instru-
ment may be used for breaking circuits at a distance by sending an independent
current through the coils of the electro magnet instead of the current to be stopped
by the action of the instrument.
Sometimes, instead of a spring to withdraw the switch or bolt, we use the force
of gravity or the combination of the force of gravity and a spring. For instance,
instead of a balanced armature and a spring, a suitably weighted armature may
be used, and instead of a spring to withdraw the switch piece, a weight may be
employed or a combination of a spring for one duty and a weight for the other
duty.
It will be seen that by this device a very delicately pivotted armature will act
very accurately at a determined strength of current, for it has no friction retarding
it save that at its pivots; and as it moves towards the magnet, its momentum
becomes sufficient to always overcome the variable friction of the detent.
Having thus described the essential features of our invention we will now proceed
to describe a suitable method of carrying out the same.
In referring to the drawings accompanying this specification the letters given
will indicate corresponding parts in different forms of our invention. In these
drawings the electro-magnet coils are shown as being in the circuit that is to be
broken by the action of the instrument, and it will be easily understood that by
taking the ends of these coils to separate terminals, the apparatus may be actuated
from any desired distance as herein before stated.
Three forms are shown in the drawings.
Figure 1 is a plan of the apparatus with a balanced bar armature.
Figures 2 and 3 are section and plan showing a saddle armature, and
Figures 4 and 5 are section and plan of an instrument in which the magnet forms
the guide for the sliding switch rod.
A is the electro magnet, B the balanced armature pivotted at M, C regulating
spring, D adjustable stop to armature, E scale marked with current values at which
the armature will be attracted, F moving switch block or piece attached in figure 1
to a rod G sliding in guides as shown, and drawn from between the contact brushes
or clips K K by the spring H, unless held in position by the detent J. P and Q
are terminals. In figures 2 and 3 the switch piece F is attached to a bent lever G,
pivotted at M in the same axial line as the armature, and is drawn from between
the contact clips K K by the spring H acting on the short arm of the bent lever
rod R. When this rod is in the position shown, the spring H also keeps the step J
in R behind the guide bracket, and so prevents the circuit from being broken until
the armature descends by reason of the attraction of the magnet, and knocks down
and releases the rod R. In figures 4 and 5 the magnet is cylindrical and bored
through its axis to form a guide for the switch rod or tube G. The spring H is placed
inside this tube and is attached to it by a pin through F its other end being held
by a pin through the magnet flange working free of the tube in slots as shown.
The balanced armature B is attracted, when the current becomes strong enough, to
the magnet pole, and strikes the pin L which releases the catch J from the plate N,
and so allows the spring H to break the circuit by drawing the piece F from
between the contact brushes K. . The switch tube can be released by depressing
the plate N against the force of the spring O by the knob at the top; and in the
case of figures 2 and 3, the circuit can be broken by hand by depressing the rod R.
The switch is reset and the circuit completed by pushing the knob S until the
catch holds it.

page_text: 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
1st The construction and use of instruments for breaking electric circuits by
means of a delicately pivotted armature controlled by a spring or weight which
attains sufficient momentum on being attracted by an electro magnet to move a
catch or detent, and so to release a switch controlled by a spring or weight,
substantially as described.
2nd The combination of such an instrument for breaking electric currents with
a system of circuits by which a main circuit can be broken at distance by an
independent current through the electromagnet coils, substantially as described.
3rd The construction and use generally of the instruments, substantially as
hereinbefore described.