Improvements in Apparatus for Automatically Switching Loop Circuits out of or into the Main Electric Circuits.
Year: 1889

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Automatically Switching Loop
Circuits out of or into the Main Electric Circuits.
I, ELMER AMBROSE SPERRY 1007 Opera House Block, Chicago, Illinois, United
States of America, mechanical engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:—
My invention is with some of its uses illustrated in the accompanying drawings.
Figure 1 is a view of a duplex switch as used in my system upon the main line of
an electric light circuit for the purpose of changing the electrical connections from a
service loop to a short loop.
Figure 2 shows its adaptation for an incandescent circuit.
Figure 3 shows a switch in which the differential action serves to change the
contacts of the switch onto a new loop in which translating devices are located.
Figure 4 shows a varied form of Figure 3 in which two service and one short loop
are used.
Figure 5 shows a varied form of Figure 1, in which the switch is controlled by
the equal magnetic effect of separate electro-magnets which are in the main circuit
in the path of each switch arm.
Similar letters of reference indicate like parts in the different figures.
A represents a generator of electricity. B B the wires of the "main line."
CC the switch arins, D D the normally used service loop terminals, D' D₁ the short
loop terminals, D' D* fig. 4 the terminals of the second circuit.
The lamps are
indicated by crosses. E shows an electro-magnet wound by two sets of conductors
and so adjusted as to each other that when the same current traversos each in opposite
directions, there is no magnetic effect from the same upon the common core. These
two coils in the main line form the path for the circuit as it goes into and comes from
the loop or branch.
Findicates the armature of said magnet.
The switch arms are connected by an insulated strip G, pivoted to each for the
purpose of simultaneous movement. An upward projection G' of this strip engages
the armature and serves to retain the contact arms upon one set of contact pieces or
loop terminals; the spring H serves to move the switch when the armature releases
the same.
A handle is provided at I to facilitate the movement of the switch arm.
J, K and K' indicate loop circuits in which various translating devices may be
arranged.
The construction of the oppositely projecting lateral retaining contacts in figure 4
is such that as the armature F is raised it breaks contact with G' but engages
with G; when the armature again drops or returns to its former position it engages
the stop G³ which holds the switch arms upon the circuit K₁ until the armature Fis
again drawn upward, when a still further movement of the arm takes place and the
loop J is brought into circuit. The varied form shown in figure 5 may be described
as follows: a centrally pivoted armature F¹ is provided with a centralizing spring L
and a laterally projecting stop F at the extremity of a projection as shown; this
stop engages an opposite laterally prejecting stop G' upon the strip G which may
be released by a movement of the stop in either direction, upward or downward from
the central position.
The letter M, figures 1 and 3, indicates the outside view of a loop switch working
upon the same main circuit which may be like or unlike the first.
When the loop or branch is in a normal working condition the path of the
current is upon the main line throughout one coil of the helix to the switch arm to
the loop thence around the loop circuit to the other terminal, thence to the other
switch arm through the other coil of the magnet upon the main line. In practice I

page_text: prefer to wind the magnet in each switch with two strands simultaneously, the first
ends of which are attached to the outer main lines and the last ends to the switch
arms or vice versa; in this way the currents are opposite and the magnetic effects
are equal.
Referring now to figure 1, it will be considered that the current flows from the
generator A through the circuit B in the direction of the arrows point, the lower
terminal of B maintained at a higher potential than the upper one; in its progress it
traverses one of the coils upon the magnet E, thence through the switch arm to the
loop, and around the same, energizing the various translating devices therein, thence
to the other switch arm, through the remaining and opposing coil upon the
magnet E, thence out upon the main circuit. The spring H is given a tension by
the movement of the arms to the right in which position the system is retained by the
catch upon the underside of-the-armature which armature is placed before the core of
the magnet E and which is attracted by the same when ever-there-is-any appreciable
difference between the incoming and outgoing currents. Suppose a contact or ground
to exist between the wire of loop K and the iron of the building at any point upon
said loop as X or Y, as yet there is no interference with the normal operation of the.
system, but should any other contact or "ground" occur upon the outside circuit or
any of its loops, or even in the generator A, the current will then divide part passing
between the two points of "ground as from X to X¹ or Y to Y¹ leaving only a
part of the normal circuit to flow through one of the coils upon the magnet E; the
current intensity in the other will remain or even rise above the normal, owing to
the decreased resistance exterior to the generator; the differential magnetizing
effect-thus-obtained_serves to energize the core, attract the armature F releasing the
stop Gand thus allow the spring H to draw-the-contact points over onto the other
set of terminals--11 D', thus removing from circuit altogether the faulty or grounded
loop.
It will readily be seen from the foregoing that the differential action of the
ingoing and the outgoing- currents, to change the line connectors to a new loop
circuit may be utilized in various ways. To open or switch-out an incandescent
loop as in figure 2. To switch from one service loop to another as in figure 3.
To switch from one service loop to another and then to a short loop as in figure 4.
The alternate form shown in figure 5 illustrates an alternate form of differential
magnetic devices. Two magnets are so adjusted as to act equally and opposedly
upon a common armature centrally pivoted and so organized that when a movement
takes place in either direction from this central position the switch mechanism will
be released.
This is accomplished by a laterally projecting finger G³ and an opposite
laterally projecting catch F connected with the armature.
It is important that the operating magnet should be constantly in the main
circuit in order that its action may continue long enough to break any current
which might arise from the switching out of the loop.
A duplex switch is a two arm switch.
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 1
claim is;
1. Combination with a double switch adapted to be operated by a spring or
equivalent, a catch organized to oppose said spring and an electro-magnetic core
wound with two coils of equal magnetizing effect, which are placed one in the
circuit with each switch arm, said magnet placed so as to contact and operate the
catch substantially as and for the purpose specified.
2. An electrical switch provided with two simultaneously moving arms, a
retracting device previously energized, an armature operating a catch to retain
said arms in opposition to said retracting device and differential electro-magnet in
circuit with each of the two arms of said switch adapted to control the said catch as
and for the purpose specified.

page_text: 3. In combination with the main circuit, a duplex switch forming a connection
between said main circuit and a loop or branch circuit, a differential magnetic
system, the opposing helices of which are in electrical connection one with each arm
of the switch and an actuating mechanism, said magnet placed so as to control and
operate the actuating mechanism and the latter to operate the switch, substantially as
and for the purpose specified.
4. In a duplex switch the combination with simultaneously moving switch arms,
a retracting device, a catch to hold the same, a magnet operating said catch having
two helices one. in circuit with each switch arm, substantially as and for the purpose
specified.
5. Two loop or branch circuits terminating each in two electrical contacts in
combination with a duplex switch the arms of which are adapted to operate in
connection with said contacts and which are in connection with the main circuit
through two electro-magnetic helices which oppose each other and connecting
mechanism consisting of the catch and spring or its equivalent for operating said
switch, said magnet placed so as to control and operate the catch, substantially as and
for the purpose specified.
6. The duplex switch, substantially such as described, in combination with two
differentially acting electric helices the circuits through which being those passing
the arins of the switch, said magnets being located between said switch arms and the
points of production of the electrical currents upon the circuit; substantially as
specified and shown.
7. The combination of a main line with a service loop thereon, a duplex switch
whose arms complete the connections with the main line, a differential magnet through
which the loop current passes in opposite directions, a retracting spring connected
with such switch, a catch to hold such switch, said catch controlled by the magnet
so as when released to release the switch and permit the loop to be cut out of the
main line.
S. The combination of a main electric circuit with a loop circuit therefrom a duplex
switch connecting the two, a switch to controll such connections and a switch con-
trolling electric device in the main circuit:
9. The application of a differential switch to switching a short or loop circuit out
of and a similar loop into a main electric circuit when both the main circuit and the
first loop circuit are grounded.
ייים
FREDERIC PRINCE,
1, Quality Court, Chancery Lane, London, W.C., Agent for Applicant.