Year: 1888

page_text: County of Alleghany, State or rennsylvania, United States of America, Engmeer.
I, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, & 6 Bank Street Manchester, both
in the County of Lancaster, & 323; High Holborn in the County of Middlesex,
Civil 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 :-
The invention relates to the class of apparatus employed for detecting accidental
short-circuits or ground connections in systems of electric circuits.
The object of the invention is to provide means for detecting and locating faults in
conductors employed in systems of alternate-current electric distribution, and it
relates especially to the circuits wherein metal-covered underground conductors
are used.
The invention consists generally in placing two electric converters in circuits which
may be completed from the respective poles of a generator or lines leading therefrom,
with the earth, and in applying to each an indicating, device, such for instance as an
incandescent electric lamp included in their respective secondary circuits. In case
there is a ground connection with one of the lines, the converter connected with the
corresponding line will be short-circuited, and the consequent variation in the light
operated by the converter will indicate that such false connection is made.

page_text: The accompanying drawing is a diagram illustrating the general organization of
apparatus.
Referring to the figure, A' and A³ represent two alternate-current electric generators.
The generator A¹ is provided with conductors L' and L³ leading from its respective
poles, and likewise conductors L' and L lead from the poles of the generator A². The
conductors L³ and L* are here represented as being covered by a sheathing c of metal,
such for instance as lead, and when the conductors are underground, these outer
sheathings will, it is evident, be in electrical connection with each other as indicated
by the conductor c¹.
The conductor I is connected by a conductor 1 with a switch point e¹, and the
line L³ is connected by a conductor 2 with a switch-point e³. Switches S¹ and Sare
respectively applied to these points and these switches are connected by conductors 5
and 6 respectively through the primary coils of electric convertors or inductoriums B
and B. The conductors, after traversing the coils of the converters, are united with
a conductor 7 leading through a switch or circuit-closing device S to the earth at G.
The secondary coils of the converters B' and B2 are respectively connected through
translating devices, such for instance.as.incandescent electric-lamps d'and d².
It is evident when the generator A' is operating and the lines L'and L' are properly
insulated, a current will traverse the conductors 1 and 2, and therefore the lights d'
and d will be equally illuminated. Should, however, one of the lines, L' for instance,
be in any manner connected with the earth, as indicated at G' by the conductor 8,
then the converter B₁ will be shunted while.an.increased current, the amount of
which is dependent upon the resistance of the earth connection, will traverse the
primary coil of the converter B' and thus increase the illumination of the device d'.
Had the ground connection been made with the conductor L', then the illumination
of d¹ would have been increased. This affords a ready means for determining
in which line the fault occurs.
In case the lines. leading from the generator are for instance, lead-covered cables,
-placed underground, then the operation will be in the manner now to be described
with reference to sther generator A. Conductors 3.and 4lead respectively from the
lines L and L to switch-points and applied to the switch arms S1 and S2. By
moving the switches into contact with these points, connections will be made from the
lines: Land L-through..the..converters, Bl and,B respectively. As already seen. the
outer casings of the conductors Land L' are at all times.connected with the earth, as
is diagrammatically indicated by the conductor 9 leading to the earth at G². In
practice it is found that the coverings of the conductors act in connection with the
conductors themselves, as condensers, and that therefore in an alternate-current
system; there will be a flow of current-through an indicator-connected in the ordinary
Away from either conductor to the earth, even when there are no faults and the
#conductors themselves are well.insulated from the earth.
In the organization described; however, the equilibrium of the indicating devices d¹
and is not altered by the condenserueffect; since they are similarly related to both
conductors and to the earth, so long as no earth connection occurs on the circuits.
Should, however, an earth connection be made, then the corresponding converter will
-be shunted as before; and the translating device connected with the other converter
will give the proper indication for showing with which conductor the ground connection
has been made.
When the apparatus is not required the switches' S₁ and S² may be moved upon
their resting contact-points s, s, or the switch Smay be opened.
Having now particularly_described and ascertained. the nature.of.the, said invention,
and in what manner the same is to be performed, as..communicated.to.me by
my foreign correspondent, I declare that.what. I. claim.is :-
1. The combination with a source of alternating electric currents and lines leading
therefrom, of two electric converters, conductors derived from said lines respectively and
including such converters and leading to the earth, and an indicating device connected
in the secondary circuit of each of said converters.

page_text: 2. The combination with a source of alternating electric currents and underground
metal-covered lines leading from the respective poles thereof, of two electric converters,
means for placing the same in circuit between the respective lines and the earth, and
indicating devices connected in the secondary circuits of the respective converters.
3. A fault detector for alternate-current systems of electric distribution, consisting
of the converters B1 and B2 adapted to be connected between the respective poles
of the source of electricity and the earth, and indicating devices operated by the
currents induced in the secondary circuits of the respective converters.
Dated this 98th day of May 1888
WM. P. THOMPSON & Co.,
Agents for the Applicant.