Indicating Lamp Failures in Electric Lighting Circuits, and Apparatus therefor.
Year: 1894

page_text: Date of Application, 5th July, 1894
Complete Specification Left, 5th Apr., 1895--Accepted, 11th May, 1895
PROVISIONAL SPECIFICATION.
Indicating Lamp Failures in Electric Lighting Circuits, and
Apparatus therefor.
1, GEORGE JOHN TOM JELLEY PARFITT, of The Avenue, Keynsham, Bristol,
in the County of Somerset, Electrical Engineer, do hereby declare the nature of
this invention to be as follows:-
:-
My invention has for its object to provide means whereby the failure of an
electric lamp in an electric lighting circuit and the position of the lamp failing
shall be indicated at the central station.
In carrying out my invention I arrange in conjunction with the lighting main
what I term a pilot circuit which may be a metallic circuit or partly a metallic
and partly an earth circuit. This pilot circuit is provided with a battery, a bell
and an ainmeter. In connection with each of the lamps I arrange a closing device
having an electro-magnet the armature of which is in the pilot circuit and is
normally in position to retain the pilot circuit open, but which in the case of
a lamp failing serves to close the pilot circuit and ring the bell at the station
so as to indicate to the attendant that a lamp has failed. The attendant can
then by switching the bell out of circuit and the ammeter in circuit ascertain the
position of the lamp that has failed, the resistance indicated by the ammeter being
inverse to the distance of the defective lamp.
When my invention is used in conjunction with the electric lighting system
described in the Specification of Letters Patent No. 17324 of 1891, the electro-
magnetic closing device arranged according to this invention is placed in the circuit
containing the resistance in such a manner that when the resistance is thrown into
circuit owing to the failure of the corresponding lamp the pilot circuit will be
closed. In the case also of lamps in series circuit an electro-magnetic closing device
is placed in the usual shunt circuit around each lamp.
When my invention is used in connection with lamps in parallel circuit the
closing device for each lamp is placed in the shunt carrying the lamp and is
maintained open so long as the current passes freely through the said shunt, a
spring in connection with the armature of the closing device serving to move the
said armature to close the pilot circuit in case the current ceases to flow through
the shunt.
Dated this 5th day of July 1894
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
Indicating Lamp Failures in Electric Lighting Circuits, and
Apparatus therefor.
1, GEORGE JOHN TOM JELLEY PARFITT, of The Avenue, Keynsham, Bristol,
in the County of Somerset, Electrical 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 :-
My invention has for its object to provide means whereby the failure of an

page_text: electric lamp in an electric lighting circuit and the position of the lamp failing shalk
be indicated at the central station.
In carrying out my invention I arrange in conjunction with the lighting main
what I term a pilot circuit which may be a metallic circuit or partly a metallic and
partly an earth circuit. This pilot circuit is provided with a battery, a bell and
an ammeter. In connection with each of the lamps I arrange a closing device
having an electro-magnet the armature of which is in the pilot circuit and is
normally in position to retain the pilot circuit open, but which in the case of a
lamp failing serves to close the pilot circuit and ring the bell at the station so as to
indicate to the attendant that a lamp has failed. The attendant can then by
switching the bell out of circuit and the ammeter in circuit ascertain the position
of the lamp that has failed, the resistance indicated by the ammeter being inverse
to the distance of the defective lamp.
When my invention is used in conjunction with the electric lighting system
described in the Specification of Letters Patent No. 17324 of 1891, the electro-
magnetic closing device arranged according to this invention is placed in the circuit
containing the resistance in such a manner that when the resistance is thrown into
circuit owing to the failure of the corresponding lamp the pilot circuit will be
closed. In the case also of lamps in series circuit an electro-magnetic closing device
is placed in the usual shunt circuit around cach lamp.
When my invention is used in connection with lamps in parallel circuit the
closing device for each lamp is placed in the shunt carrying the lamp and is
maintained open so long as the current passes freely through the said shunt, a
spring serving to move the armature to close the pilot circuit in case the current
ceases to flow through the sbunt.
To enable my invention to be fully understood I will describe how it can be
carried into practice by reference to the accompanying drawings, in which
Figure 1 is a diagram shewing my invention applied to an electric lighting
circuit in which the main line is sub-divided into four branches for two groups
of lamps in accordance with the Specification of the said Letters Patent No. 1732
of 1891:
Figure 2 is an elevation of one of the circuit closing devices which serve to close
the pilot circuit :
Figure 3 is an elevation of one of the circuit closing devices serving to cut out
the failing lamps which device is arranged on the opposite side of the plate which
carries the device shewn in Figure 2:
Figure 4 is a side view shewing the two devices so arranged:
Figure 5 is a diagram illustrating the use of my invention in connection with
lamps arranged in parallel circuit:
Figure 6 is an elevation of the circuit closing device for use therewith:
Similar letters in all the figures indicate similar or corresponding parts.
I will first describe my invention by reference to Figures 1 to 4.
a indicates
the main line circuit and b, bare the pilot circuits one of which I arrange in
conjunction with each group of lamps; c, e are the batteries, d, d the bells and
e, the ammeters with which the pilot circuits bare provided, a', a are fuse boxes;
ffare the pilot circuit closing devices one of which is arranged in connection with
each of the lamps g; h is the electro-magnet thereof and i is the armature which is
in the pilot circuit b and serves to close the same and ring the bell d when a lamp
has failed. k, kare the switches whereby the attendant cuts the bells d, d out of
circuit and brings the ammeters e, e in circuit so as to indicate the position of the
lamp that has failed.
The circuit closing device f is placed as shewn in the circuit containing the
resistance of the lighting system described in the Specification of the said Letters
Patent so that when the resistance is thrown into circuit owing to the failure of
the corresponding lamp the current will flow from the circuit closing device ; of
such resistance through the wire m and energize the magnet whereby the

page_text: armature i will be attracted so as to electrically connect the wires n and o of the
pilot circuit belonging thereto and sound the bell d of the same.
In the arrangement for lamps in parallel circuit the closing devices f, fare placed
in the shunts p, p carrying the lamps g, y. In this case so long as the lamps are
intact the current passes freely through the shunts p and flowing through the
electro-magnet h of the closing device Figure 6 of each lamp will attract
the armature i thereof which is carried by a counteracting spring 7. Should,
however, one of the lamps g fail the armature of the device corresponding with
such lamp will be no longer attracted by its electro-magnet h and the spring
thereof will make contact with the terminal thereby establishing electrical
connection between the wires s and t in the pilot circuit .
In all other respects
the arrangement is similar to that hereinbefore described with reference to
Figures 1 to 4.
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 I
claim is :-
1. In an electric lighting circuit the combination with a main circuit of means
whereby the failure of an electric lamp and the position of such lamp in the
circuit shall be indicated at the central station, substantially as hereinbefore
described.
2. Apparatus for indicating lamp failures in electric lighting circuits comprising
the combination with a main circuit of a pilot circuit, a battery, a bell and an
ammeter in such pilot circuit, a circuit closing device in connection with each lamp
such device having an electro-magnet the armature of which is in the pilot circuit
and a switch for switching the bell out of the circuit and the ammeter in circuit the
whole operating substantially in the manner and as herein before described and
illustrated in the accompanying drawings.
Dated the 5th day of April 1895
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.