Improved Method of Electric Lighting in Series and Apparatus therefor.
Year: 1891

page_text: Date of Application, 12th Oct., 1891
Complete Specification Left, 29th June 1892-Accepted, 30th July, 1892
PROVISIONAL SPECIFICATION.
Improved Method of Electric Lighting in Series and Apparatus
therefor.
.We GEORGE JOHN PARFITT and GEORGE JOHN TOM Jelley ParfitT
of The Western Counties of England Electric Light and Power Works in the
Parish of Keynsham in the County of Somerset Electrical Engineers do hereby
declare the nature of this invention to be as follows :-
The object of our invention is to prevent the extinguishing of lamps in an
installation of incandescent-lamps when they are fixed and used in series. When
lamps are arranged in simple series the entire current lighting them has to pass
through the whole number of lamps and if one of them fuses or becomes défective
that no current will pass through it then it effectually cuts off the current from the
whole number of lamps in that circuit. Now our invention is to prevent such a
mishap and to effect this we arrange our lamps in groups in parallel on the mains
but the lamps in each group we arrange in series but in a double row so that the
current will divide at the double row half going through each lot of lamps in series
and uniting again at the junction on the main.
We are well aware that even this arrangement does not provide against half the
lamps of a group being extinguished by the failure of one of the series and in order
to prevent this we place ap automatic switch to be hereinafter described in series
with each lamp and in addition thereto we metallically connect the opposite sides
of the group in such a manner that there is a "bridge" connecting the two sides of
the group before and after each switch and lamp according to the number of lamps
in the group.
While every lamp in the group remains perfect these compensating
bridges carry no current but when a failure occurs then the opposite lamp imme-
diately takes more current than before and brightens accordingly while the remainder
of the lamps retain only their normal brilliancy owing to the passage of current
through the next succeeding compensating bridge.
This extra brilliancy however lasts only for a very few seconds until in fact the
switch has felt the increased current and has acted accordingly as pre-arranged.
Upon the attraction of the armature to the poles of the electro magnet of the switch
a shunt circuit is closed in which we may place either adother lamp of a resistance
about equal to that of the lamp the particular switch is intended to protect in
which case should a failure occur the shunt circuit lamp is immediately switched
into the group circuit thereby avoiding total darkness or we may place a résistance
composed of suitable material and also abuut equal to the extinguished lamp when
perfect, leaving this lamp to be replaced by a perfect lamp at any convenient time.
This shunt immediately takes an amount of current approximately equal to that

page_text: previously absorbed by the now defective lamp so relieving the overfed one and
each lamp in the group has about the same amount of current it had before the
failure. If more than one lamp has failed the same operations take place with each
failure and the current is not cut off from the remaining lamps of the group as wo
provide a switch for every lamp and so instantaneous is the adjustment of current
to those lamps in advance of the lamp or lamps failing in any portion of the group
by reason of the compensating bridges that not a blink is observable in any one
remaining lamp. We may place any number of such groups across our mains if we
provide sufficient current for their supply. We do not bind ourselves to use any
special lamps beyond such as are known as "semes" lamps we may employ lamps
requiring a pressure of any electro.motive force using either lamps throughout the
group requiring equal pressure or we may use lamps of dissimilar voltages in the
same group taking care however to arrange them in pairs of equal voltages within
two of the aforementioned compensating bridges. Again we may use lamps
requiring any reasonable amount of current but we preferably use lamps requiring
5 ampères or thereabouts so that the whole group would take say 10 ampères or
5 ampères on each side.
In our automatic switches we provide an ordinary electro magnet round which
we cause the whole current on either side of the group to pass. The armature we
prefer to construct in such a form that when it is attracted to the magnet poles it
closes a shunt circuit in the same manner as an ordinary switch and wo provide
what is known as a rubbing contact to prevent sparking although we do not bind
ourselves to this particular form of contact. The wire of the magnet is of a gange
necessary to carry the full current required for the group while the ampère turns
are of such a value that while only 5 ampères are passing round the magnet as is
the case when every lamp in the group is perfect the armature remains unattracted
to the magnet poles but immediately more than 5 ampères passes consequent upon
a lamp becoming defective producing increased magnetism then the armature is
attracted and the switch operates.
It is obvious that we may substitute are lamps, for incandescent lamps in any
group or groups or we may run are lamps and incandescent lamps together in the
same group for the automatic switch may be so arranged as to act for both
descriptions of lamps.
Dated this 10th day of October 1891.
Improved Method of Electric Lighting in Series and Apparatus
therefor.
We, GEORGE JOHN PARFITT and GEORGE JOHN TOM JELLEY PARFItt,
of The Western Counties of England Electric Light and Power Works, in the
Parish of Keynsham, in the County of Somerset, 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 sories electric lighting.
It is well known that when a number of electric lamps are arranged in series in
a circuit if one of these lamps fails either all the lamps of the series are extinguished
or if an automatic cut-out is employed the remaining lamps burn with increased
brilliancy.
Now the object of cur invention is to provide means whereby in case one or more

page_text: of the lamps in a circuit fail it or they may be out out and a corresponding.
resistance or corresponding resistances automatically introduced without the other.
lamps in the circuit being overrun or otherwise, affected.
In carrying out our invention we form the main, circuit with two, four or other
even number of branches in which the lamps are arranged in groups and in series,
and we metallically connect the two wires of each group between each pair
of lamps.
:
In connection with each lamp we arrange an automatic switch consisting essentially
of a magnet and an armature. The coils of the magnet are so wound that the
ordinary current will pass around them without attracting the armature.: if...
however, owing to the failure of one of the lamps an extra quantity of current, flower
through the coils then the armature is attracted and switches in a resistance.equal
to that of the lamp which has failed. During the time that this is taking place
the extra amount of current which flows through the branch containing the lamp.
which has not failed passes over the bridge so that the other lamps are practically
unaffected.
To enable our invention to be fully understood we will describe the same by
reference to the accompanying drawings, in which :-
Figure 1 is a diagram shewing the main circuit divided into four branches for
two groups of lamps :
S
Figure 2 is an elevation of the automatic switch which we employ, one side of
the casing being removed:
Figure 3 is a section on the line x x, Figure 2; and,
Figure 4 is a section on the line yy, Figure 3,
Similar letters of reference indicate corresponding parts in the several figures.
a indicates the main line circuit, and b, b¹, b³, 6ª indicate four branches into
which the same is divided, the two wires b, 6' of one pair and the two wires b², b³ of.
the other pair being united at c, c whilst the wires connecting the two pairs unite.
at d,d.
e, e¹, e, e indicate the lamps of each group, and f,fare the connecting pieces or
bridges between the wires of each pair of branches. 9,',', 9 are the automatic.
switches arranged in connection with the lamps e, e, e², e' respectively, and,
h, h,,hare the resistances which the switches g, g', g³, g³ are respectively:
designed to throw into circuit in case of the failure of the corresponding lamp. It
is to be understood that in practice the lamps may be of uniform resistance or of
varying resistance (provided they are arranged in pairs in the two branches of a
pair) in order that the main current shall be sub-divided and flow equally through
all the branches.
The operation of the apparatus is as follows, that is to say, if all the lamps are
in perfect order the current will flow equally through all of them. Assume,
however, that the lamp e on the branch b, 6 should fail then an extra quantity of
current would commence to flow through the lamp e' on the branch 6', whereby the
same would momentarily brighten: as soon, however, as this current reached the
bridge fit would again divide and be equally distributed to both of the lampse, e.
Immediately that the excess of current commences to flow through the lamp e the
magnet of the automatic switch g is energized sufficiently to move its armature,
whereby the resistance is switched into the circuit so that the current then flows
partly through the lampe and partly through the resistance . If on the contrary
the lampe were to fail, the excess of current passing through the lamp & would
cause the introduction of the resistance h.
The resistance may be in the form of a lamp so that in case one lamp fails another
is substituted therefor.
The construction of the automatic switch will be understood by reference to
Figures 2, 3 and 4.
i indicates the case of the instrument, j, j indicate the coils of the magnet, and
▲ indicates the armature which is pivotted at and adapted to be adjusted
relatively to the poles of the magnet by means of a screw. Normally the current
1

page_text: flows through, say, the wire b, the coils of the magnet and the screw / connected
to the binding-post again onto the' wire 'b; · Whén; however, an excess of current
passes through the wire b and the magnet coils, the armature is attracted so that
its free end enters between the two surfaces m, n, the former of which is upon a
plate m³ in electrical connection with the screw, as shewn in Figure 4, whilst the
other is upon a plate n'in connection with a binding-post n' to which the wirem³.
leading to the resistance to be introduced is connected.
It will be noticed that when the end of the armature is between the surfaces mi n
the current is divided, part of it continuing to flow through the wire bas heretofore
and part flowing through the plate n' binding-post n³ and wire n' to the resistance'
as bereinbefore described.
It is to be understood that we may substituto arc lamps for incandescent
lamps or that we may use are lamps' and incandescent lamps together in tho
same group.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that we do not
claim generally the arrangement of circuits and lamps described in the first claim but
only when the same is used in connection with automatic switches such as referred to in
the second claim so as to provide means whereby in case one or more lamps in the circuit
fail it or they may be cut out and a corresponding resistance or corresponding resistances
automatically introduced without the other lamps in the circuit being overrun or other-
wise affected but subject to the above what we claim is :—
1. In series electric lighting, sub-dividing the main line into several branches
through which the current flows and which branches have their lamps arranged in
them in groups sand in series, the said branches being metallically connected together
in pairs in order that an excess of current passing through one part of the branch
shall be again equally divided before passing to the next lamps, substantially as
-described and subject to the above disclaiming note.
2. The employment in electrical circuits arranged as set forth in the preceding claim
of an automatic switch adapted to be operated when an excess of current passes, in
order to allow part of the current to flow to the lamps whilst the other part flows
to a resistance, substantially as described.
Dated the 29th day of June 1892.