in the Means of Distributing Electrical Energy, and in Dynamos and other Apparatus therefor.
Year: 1893

page_text: Date of Application, 3rd Feb., 1893
Complete Specification Left, 4th Dec., 1893-Accepted, 20th Jan., 1894
PROVISIONAL PRA
nprovements in the Means of Distributing Electrical Energy, and
in Dynamos and other Apparatus therefor.
I, JOHN AUGUSTINE KINGDON of 29 Marlborough Hill, St. John's Wood in
e County of London, Electrical Engineer do hereby declare the nature of this
vention to be as follows:-
My invention in its simplest form consists of an improved means of working what
known as the "three wire system" of electrical distribution, but it may also be
pplied to more complicated multiple series systems worked with continuous
urrents.
As generally carried out the three wire system consists of two main conductors
f large sectional area, which may be distinguished as the positive and negative
nains and of an intermediate conductor of comparatively small sectional area known
s the third or middle wire; the function of which is to carry the excess of current
lowing through one main over that flowing through the other main back to the
source of electricity.
According to one system now in use, two dynamos connected in series are
employed and the third wire is connected with the connection between them.
According to my present invention instead of using two dynamos connected in
series I may employ but one dynamo of a new or improved type, and furnished in
addition to the ordinary positive and negative poles with a third pole, which is at a
potential intermediate between that of the other two.
I may construct my improved type of dynamo with four field magnet poles but
instead of arranging the field poles to be alternately north and south, I make two
adjacent field poles say both north and the remaining two adjacent field poles both
south.
The brushes which make contact with the commutator between the north and
south field poles are the positive and negative poles of the dynamo and have the
full potential difference of say 200 volts."
The potential of the third and fourth brushes which are placed respectively one
between two north fields and the other between two south fields, is intermediate
between the potentials of the positive and negative brushes and differs from them
by, in the case supposed, about 100 volts.
The positive main is connected with the positive pole of my improved dynamo,
and the negative main with the negative pole; the third wire is connected with
the middle pole which is connected with the intermediate brushes. The third wire
thus conducts the excess of current flowing through one main over that flowing
through the other main back to the dynamo thus equalising the voltage of the two
groups of lamps or other electrical appliances connected respectively with the
positive and negative mains.
In the arrangement of two dynamos connected in series, the four brushes of the
two dynamos all collect the large currents passing in the positive and negative
O mains, whereas in my improved method of working the three wire system, the main
currents are collected only at two brushes, the positive and negative, the current
collected at the intermediate brushes being merely the difference between the main
currents, which is generally comparatively small.
Besides the saving of expense and simplification of apparatus involved in the use
5 of one dynamo instead of two, I have the additional advantage that there is less wear
and tear of commutator and brushes.

page_text: Any number of twin field dynamos of my improved type may be connected in
parallel the positive poles being all connected to one omnibus bar, & the negative
poles to another omnibus bar. The intermediate brushes may some or all be
connected with the third or middle wire. One or more ordinary dynamos without
the middle pole may be connected in parallel with the twin field dynamos.
Instead of employing a dynamo with four field magnet poles, I may employ a
machine having two twin field magnet poles of the same magnetic polarity and a
third field of the opposite polarity and having a polar area approximately equal to
the sum of the areas of the two twin fields. In this case there is but one middle
brush, collecting current at a point on the commutator intermediate between the
two twin fields.
According to another method of carrying out my invention instead of carrying
back the third wire to the generating station for the purpose of connecting it with
the middle pole of my improved dynamo, I may employ at any convenient place, or
places, it may be at a distance from the generating station, one or more dynamos
of my improved type, to equalize the voltage on the two sides of the middle wire.
The positive and negative mains are connected with the positive and negative poles
respectively of this equaliser. The third wire is connected with the middle pole.
The equaliser is not driven by a steam engine or other motor but is allowed to
rotate as a motor taking very little current when the currents on the two sides are
equal. When the current passing from say the positive main through the lamps or
other appliances connected therewith which I will call the lamps A, exceeds the
current passing from the negative main through the lamps connected with it which
I will call lamps B, the equaliser acts as a continuous current transformer, taking
current from, in the case supposed the negative side of the middle wire and giving
out current as a generator to the lamps A.
It is obvious that as these equalisers may be placed anywhere at a distance from
the station a considerable saving may be effected in the cost of the third wire.
The magnet coils of iny improved dynamo and equaliser may be shunt, series or
compound wound.
The regulation may be effected by varying the exciting current in any known
manner or by shifting the brushes or otherwise and this may be done automatically
or by an attendant.
Any adjacent pair of magnet poles of like polarity may have a common magnet
core or a common exciting coil or coils.
Accumulators may be used in connection with my improved system of distribution.
According to another method of carrying out my invention I may use one or
more of my improved dynamos at the generating station and connect the third wire
with the middle poles. At any convenient place or places, as for example where
the inequality between the currents in the two mains is likely to be considerable,
I may place equalisers which may be disconnected from the mains when the currents
are nearly equal. The sectional arca of the third wire may according to this
method be reduced and expense saved.
Automatic apparatus may be employed in this or in the previous method to
connect with or disconnect the equalisers from the mains.
I have hereinbefore explained the application of my invention to the particular
case of multiple series distribution in which only two groups of lamps or other
appliances are connected in series, but it may also be extended to systems in which
more than two groups of lamps are worked in series. For the application of my
invention to systems having any number of groups of lamps in series I may construct
dynamos in a similar manner to that herein described having a suitable number of
poles arranged in groups of the same magnetic polarity, and a suitable number of
electric poles to which are connected the equalising wires.
Instead of using equalisers I may use continuous current transformers constructed
in the same manner as my new type of dynamo, to transform currents of high
pressure say 1000 or 2000 volts to currents of low pressure say 200 volts suitable
for incandescent lamps and a three wire system. According to my invention

page_text: I construct the transformer with two poles connected with the high pressure mai
with the primary part of the armature. The secondary or low pressure part of the
armature may have two main poles connected with the low pressure mains and one
or more intermediate poles connected with the equalising wires.
COMPLETE DIEUT
mprovements in the Means of Distributing Electrical Energy, and
in Dynamos and other Apparatus therefor.
I, JOHN AUGUSTINE KINGDON, of 29 Marlborough Hill, St. John's Wood, in
he County of London, Electrical Engineer, do hereby declare the nature of this
avention and in what manner the same is to be performed to be particularly
escribed and ascertained in and by the following statement :-
My invention in its simplest form consists of an improved means of working what
3 known as the "three wire system " of electrical distribution, but it may be applied
more complicated multiple series systems worked with continuous currents.
According to my invention, instead of using two dynamos connected in series as
proposed by Dr. J. Hopkinson in his Patent Specification No. 3576 of 1882, for
working a multiple series system with three conductors, I employ a dynamo of a
new or improved type and furnished in addition to the ordinary positive and
negative poles or terminals with a third pole or terminal which is at a potential
intermediate between that of the other two terminals.
One form of my improved dynamo is illustrated in Fig. 1 of the accompanying
drawings. It has four field magnets, but instead of arranging the poles of the four
magnets to be alternately north and south, as has usually been the case with four
pole dynamos, I make two adjacent poles N north and the other two adjacent
poles S south. Fig. 2 is an illustration of the well known arrangement of poles in
an ordinary four pole dynamo having its poles alternately north and south. The
magnetic circuits are different in the two figures. In Fig. 1 they are indicated by
lines M and M' with arrow heads.
Four brushes are provided in the dynamo Fig. 1, two B1, B2, make contact with
the commutator C in such a position that they serve as the ordinary positive
and negative poles, and have the full potential difference such, for example, as
200 volts..
The brush B' is connected with the positive main P, and the brush B² is connected
with the negative main Q.
The third and fourth brushes 61 and 62 are so situated on the commutator that
they are at the same or nearly the same potential differing from the potentials of
the brushes B1 and B2 by a less amount say for instance about 100 volts.
The brushes b¹ and b² are connected with the third wire or conductor R.
If the currents in the mains P and Q are equal, the conductor R carries no
current. But if there is more current in one main than in the other the third
wire R conducts the excess back to the dynamo, thus equalising the voltage of the
two groups of lamps G1, G2 or other electrical appliances connected respectively
with the positive and negative mains.
If, instead of the arrangement of Fig. 1 I employ the ordinary arrangement of
four poles as shewn in Fig. 2 the two opposite brushes B' and B2 may be arranged
to have potentials differing from the potentials of 61 and 62 by say 100 volts.
B¹ and B³ may consequently be connected together, as well as b¹ and b². I may
therefore convert a dynamo connected as in Fig. 1 for say 200 volts and
100 amperes into one connected as in Fig. 2 for say 100 volts and 200 amperes.
Suitable switches may be employed for reversing the exciting current in two of the
field magnet coils and for connecting the brushes.

page_text: In Fig. 3 is illustrated Hopkinson's arrangement of two dynamos connected in
series and with the three conductors P, Q and R. It will be seen that all the
brushes collect large currents, as all the currents in the main P passes both the
brushes of the dynamo D¹ and all the current in the main Q passes both brushes of
the dynamo D².
The intermediate brushes 6' and 6 connected with the conductor R in general
have considerable currents passing in them. In my improved dynamo illustrated
in Fig. 1, the intermediate brushes and 63 collect no current when the currents in
P and Q are equal and when the currents in P and Q are unequal, they collect
only the excess of the current in the one main over that in the other main.
Hence in my improved dynamo in addition to the advantage of substituting one
dynamo for two, I have the advantage that there is less wear and tear of commu-
tator and brushes.
A dynamo constructed as in Fig. 1 with adjacent poles of the same polarity may
be termed a twin pole dynamo. The two electrical pressures of a twin pole dynamo
may be regulated independently by introducing resistances into the circuits of the
field coils. For this purpose, the coils K' and K2 enclosing the magnetic flux M
may be connected in series, and resistances may be introduced into or cut out of
their circuit so as to regulate the potential difference between the brush B' and the
brushes and 12.
The coils of K³ and K' enclosing the flux M' may be similarly connected and
the current in them may be adjusted by means of separate resistances so as to
regulate the potential differences between the brushes &¹ and 62 and the brush B2,
independently of that between 13' and ' and b².
The regulation may be effected automatically or by hand or by compound
winding the magnets of the twin pole dynamo with coils connected in series with
the brushes B and 132 and wound round the coils K' and K2 in the first case and K³
and K in the second case.
Any number of the twin field dynamos described may be connected in parallel,
the positive poles being all connected to one omnibus bar and the negative poles
to another omnibus bar, the intermediate brushes being connected with the third
or middle wire. One or more dynamos without the middle pole may be connected
in parallel with the twin field dynamos.
Instead of employing a dynamo with four field magnet poles I may employ a
machine having two twin field magnet poles of the same magnetic polarity and a
third field of the opposite polarity having a polar area approximately equal to the
sum of the areas of the two twin fields. In this case there is but one middle brush
collecting current at a point on the commutator intermediate between the brushes
for the two twin fields.
The
According to another method of carrying out my invention, instead of carrying
back the third wire to the generating station for the purpose of connecting it with
the middle pole of the twin dynamo, I may employ at any convenient place or
places, it may be at a distance from the generating station, one or more twin
dynamos to equalise the voltage on the two sides of the middle wire. The positive
and negative mains are connected with the positive and negative brushes respectively
of this equaliser. The third wire is connected with the middle brush.
equaliser is not driven by external power, but is allowed to rotate as a motor
taking very little current, when the currents in the two mains are equal or nearly
So. When the current passing from the one main exceeds the current passing from
the other main, the equaliser acts as a continuous current transformer, taking
current from the latter main and giving out current as a generator to the former
main, thus acting as an equaliser.
As the equalisers may be placed anywhere at a distance from the station, a
considerable saving may be effected in the cost of the third wire.
The magnet coils of dynamos such as I have described may be shunt, series, or
compound wound.
The regulation may be effected by varying the exciting current in
any known

page_text: manner or by shifting the brushes or otherwise, and this may be done automatically
or by an attendant. Any adjacent pair of magnet poles of like polarity may have
a common magnet core or a common exciting coil or coils.
Accumulators may be used in connection with the system of distribution above
described.
According to another method of carrying out my invention, I may use one or
more of my improved dynamos at the generating station and connect the third
wire with the brushes of the middle poles. At any convenient place or places, as
for example where the inequality between the currents in the two mains is likely to
be considerable, I may place equalisers, which may be disconnected from the mains
when the currents are nearly equal. The sectional area of the third wire may
thus be reduced with proportional saving of cost.
By applying an electromotor to drive a dynamo such as I have described using
one double wound armature and one set of field magnets I can form a continuous
current transformer to transform currents of high pressure say 1000 or 2000 volts
to currents of low pressure say 200 volts having two or more different pressures
suitable for incandescent lamps and a three wire system.
The transformer in this case has two terminals connected with the high pressure
mains and with the primary winding of the armature. The secondary or low
pressure winding has two main brushes connected with the low pressure mains and
one or more intermediate brushes connected with the equalising wires.
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. A continuous current dynamo having two pairs of magnetic poles, the two of
each pair of like polarity and having three or more brushes arranged to collect
currents of different pressures, substantially as described with reference to Fig. 1.
2. In a dynamo having two pairs of poles arranged as in the preceding claim,
three or four brushes so arranged that the potential difference between one pair of
the brushes is greater than the potential difference between either of these brushes
and the other brush or brushes, substantially as described.
3. In combination with a dynamo of the kind above referred to, conductors
arranged on the three wire system of electrical distribution.
4. The construction of a continuous current transformer giving two or more
secondary electrical pressures by combining an electromotor with a dynamo such
as is above referred to, substantially as described.
Dated this 4th day of December 1893.
ABEL & IMRAY,
Agents for Applicant.