IMPROVEMENTS IN ELECTRICITY
Year: 1884

page_text: THE DISTRIBUTION
OF
I, SYDNEY PITT of Sutton in the County of Surrey, Solicitor do hereby declare
the nature of my invention for "IMPROVEMENTS IN
ELECTRICITY." (a communication to me from abroad by Theodore Benedict Edward
Turrettini of Geneva in the Republic of Switzerland, Engineer) to be as follows:-
The appliances now in use for the distribution of electricity on a large scale
show-1. That there is an advantage from the point of view of diminishing the
section of conductors in employing high electric tensions, but these high tensions
present in practice the drawback of serious danger a danger which prohibits the
use of electricity at high tension for domestic purposes.-2. That in the applications
of high tensions to incandescent lighting difficulty is encountered in the lamps
when the tension is higher than 100 to 150 volts. 3. That the employment of low
tensions such as are necessary for incandescent lamps requires conductors of a
section so that the capital absorbed limits to a few hundred metres the distance
from the electric source to which the electricity can be carried.
By the present invention the advantages from the employment of high tensions
are realized whilst the inconveniences are avoided.
The invention consists in introducing into the circuit of a dynamo machine
constructed for high tensions groups of accumulators of which the number will
vary according to the fall of potential which it is wished to utilise at a given
point and to lead a current to each pole of each group of accumulators, so that all
the lamps or electro motors placed upon the derived circuit going from one pole to
the other to one of the groups shall be subjected only to the difference of electro
motive power corresponding to the groups of accumulators on which they depend.
When a group of accumulators shall have been charged it will be put out of
circuit either by hand or by the automatic apparatus.
Figure 1 shews a plan of the principal conductor in my new system. It
represents an urban district which has to be lighted divided into 20 centres of
distribution from each one of which radiate say 10,000 pairs of wires terminating
in 10,000 lamps. The principal conductor starts from the positive pole of the
battery of dynamo machines at the works, it goes first to the positive pole of

page_text: the accumulator battery of the number one centre. From the negative pole of the
battery 1 the principal conductor goes to the positive pole of the battery 2 and so
on
From the negative pole of the accumulator battery N° 20 the conductor goes
back to the negative pole of the battery of dynamo machines at the works.
As compared with the parallel arc system it may be said in round figures that
for an equal sacrifice of work this system permits of dividing the weight of metal
employed by the square of a number of centres of distribution.
Let me remark besides that the production and the distribution of a current of
say 40,000 ampères would be realised with difficulty at present, whilst the supply
of 2000 ampères with a tension of 2000 volts which is sufficient by this system to
do the same work is well within the present resources of electrical industry.
In this system it is necessary to connect the two poles of the battery cut out, or
else the charging will be interrupted everywhere. The connection of these two
poles at the proper time is a very simple affair.
I cause it to be done by a hand commutator or an appropriate automatic
commutator may be employed.
Cutting out or inserting a battery diminishes or increases the difference of
potential between the two terminals of the battery of dynamo machines in the
works. It it thus useful that this battery should be provided with an automatic or
hand regulator; which maintains its output almost constant.
It will be necessary then to regulate approximately the intensity of the charging
current in place of regulating precisely its current. This system is characterized,
1. By the employment of a series of accumulator batteries connected in tension
by a main conductor so that the charging current coming from the works returns
there after having passed through all the accumulator batteries.
2. By the employment at each centre of distribution of a hand or automatic
commutator of which the function is to put one of the poles of the accumulator
battery in communication either with the charging pole of the same sign when the
battery is to be charged, or with the charging pole of the contrary sign when
the battery refuses the charge.
3. By the substitution of the system of charging at an almost constant intensity
and variable tension for the system of constant tension and variable intensity in
use up to the present time with the parallel arc system.
Dated this 24th day of December 18QA

page_text: "
COMPLETE SPECIFICATION.
I, SIDNEY PITT, of Sutton, in the County of Surrey, Solicitor do hereby
declare the nature of my invention for "IMPROVEMENTS IN THE DISTRIBUTION
OF ELECTRICITY (a communication to me from abroad by Theodore Benedict
Edward Turrettini of Geneva in the Republic of Switzerland Engineer) and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:
The object of this invention is to provide a system of distribution of electricity
for lighting large towns by the use of high tensions in the main circuits and low
tensions in the secondary circuits by which the lamps are fed--the system is based
on the use of groups of accumulators traversed successively by the high tension
current.
This system of distribution is more especially adapted for the lighting of com-
paratively large towns in which the distances are such that the lighting by
incandescence from one central point would necessitate too great an expense of
copper conductor.
The system is arranged in the following manner :—
1st There is established at some point in or near the parts to be lighted a central
station for the production of electricity, provided with motors and generating
dynamos for supplying a current of high tension 500 to 700 Volts for example.
2nd There are formed a certain number of secondary distributing stations at each
of which there are groups of accumulators so arranged that the current coming
from the central station feeds in succession these groups of accumulators and then
returns directly to the central-station.
In this way the principal current goes and returns directly to and from the
central station to each of the secondary stations. This is a preferable arrangement
to causing the current to feed the several secondary stations in succession one after
the other as it effects a considerable saving in the dimension of cable required.
The lamps within the circle or district surrounding each secondary station are fed
from secondary circuits led off from the groups of accumulators at that station-
the number in each group being such as to reduce the potential to that required for
incandescent lamps.
I will now describe more fully the various parts of the system of installation.
1° The central station.
The central station A sheet 1 contains not only as above stated apparatus for
producing currents of high tension but also apparatus for regulating its intensity.
The motive power may be obtained from steam or water or from other source.
The mode of production of the electricity may also be either from primary
batteries or from magneto or dynamo machines. In this description I will assume
that dynamo machines are employed.
The number of dynamos used at the central station will vary according to the
number of secondary stations fed from it. One dynamo should not be used for
simultaneously feeding several secondary stations as the resistance of the circuit in

page_text: each secondary station may vary from one moment to another according to the
number of groups of accumulators introduced into the principal circuit.
It is therefore necessary that each secondary station should be independently fed
with electricity. The central station can however be so arranged that any one or
more of the dynamos may be used for feeding any one or other of the secondary
stations.
The dynamos should be so made as to give a charge of constant intensity and
variable tension instead of constant tension and variable intensity as usual in the
ordinary systems of distributing electricity. To obtain this result the inductors of
the dynamos may be excited by one or more special dynamos in such manner that
the magnetic field may be independent of the speed of the dynamo or of the tension
of the current which it generates.
The central station should contain indicators to show the conditions of the
principal currents both as to Ampères and to Volts. Each dynamo should in
addition be separately furnished with two special apparatus the object of the first
of which is to cut off all communication between the dynamo and the circuit going
to the groups of accumulators in the secondary station so soon as the tension given
by the dynamos is lower than the static tension of the accumulators.-This is
required to prevent all discharge from the accumulators to the dynamo which
would result in loss of electricity and injury to the collection of the dynamo if not
to an accident of a more serious nature.
The cut off may be effected either by hand by removing a plug as soon as it is
seen that the hand of the Ampère meter measuring the intensity of the current of
the dynamo has passed beyond the zero point or it might be by automatic
apparatus.
An apparatus of this latter kind might be based upon the following (see sheet 2).
The needle of an Ampère meter on the principal circuit is made as it passes
beyond the zero point (which corresponds with equilibrium between the tension of
the dynamo and that of the secondary station) to break the primary circuit by
liberating mechanism to effect the interruption.
A lever L carrying a spring contact is retained by a catch D in a position such
that it closes the circuit A B (see sheet 2). The catch can be released by the action
of an electro magnet E so as to allow the lever to drop and consequently break the
circuit A. B. An Ampère meter whose needle is so arranged as to close a circuit fed
by a primary battery or otherwise closes the said circuit at the moment when the
needle arrives at zero. The circuit passes through the coils of the electro magnet
and so causes the circuit A B to be broken.
The other apparatus used in connection with each dynamo is shewn on Sheet 3.
It is to effect the reverse operation that is to say it has on the starting of the
dynamo to close the circuit between the dynamo and the secondary station so soon
as the tension of the dynamo comes up to the total static tension of the groups of
accumulators in the secondary station.
Thus no return current from the accumulators can pass to the dynamo as it is
only in communication with the accumulators when the tension of the current
which it produces is greater than the static tension of the charge of the accumu-
lators in the circuit. This second apparatus is very similar to the preceding and is
formed as follows:
:-
A lever L carrying the contact to close the circuit CD is retained by a catch in
such a position that the circuit C D remains open until the catch releases the lever
which then falls by its own weight and closes the circuit C D.
The catch is worked by an electro magnet E actuated by a primary battery.
Two Volt meters are placed one by the side of the other with the axis of the
needle of one a prolongation of the axis of the needle of the other.-One of the Volt
meters measures the tension of the dynamo machine the other measures the tension
of the charge of the accumulators. The needle of the Volt meter of the dynamo
machine carries an arm so formed as to come into contact with the needle of the
other Volt meter as soon as the two needles indicate the same tension. The contact

page_text: of the two needles closes the circuit of the electro magnet and immediately the catch
is drawn back and the circuit C D is closed.
2. Secondary stations marked B on sheet 1.
As above stated each secondary station contains a certain number of groups of
accumulators, each group being composed of a number of accumulator cells connected
in tension so as to obtain during discharge a sufficient tension to obtain the normal
light required from the incandescent lamps.
To effect this the number of accumulators in each group which are placed in
tension should be greater than the number required theoretically for obtaining the
requisite tension. The additional accumulators should be introduced from time to
time during the discharge so as always to obtain a constant tension in spite of the
accumulators becoming partially exhausted-to do this a sort of commutator is used
so formed that it can vary at will the number of accumulators in a group either
during the charge or discharge.
On Sheet No 4 is shown a group of accumulators arranged so as to be able to
regulate at pleasure, on the one hand by means of the commutator A the number of
accumulators that are being charged and on the other hand by the commutator B
the tension of the discharge circuit which feeds the lamps.
Each element of the accumulator may be itself formed of several accumulators
placed in parallel so that a group of accumulators giving for example a tension of
120 volts (the tension of each cell or element being 2 volts) would contain 60 cells
in tension, or there might be in each element 10 parallel accumulators so that the
group would consist of 600 accumulators. If the secondary station contained
5 such groups it would then be formed of 3000 accumulators and the tension
required to charge the 5 groups would be 600 volts.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The distribution of electricity by the establishment of a central generating
station feeding accumulators at one or more secondary stations by currents of high
tension passing and returning directly from the central station to a secondary
station, these currents of high tension being changed into currents of low tension
by the groups of accumulators at each secondary station substantially as herein
before described.
2. In such a system of distribution of electricity the employment of apparatus at
the central station whereby injury to the dynamos is prevented by the fact that
the dynamos are only in the circuits to the secondary stations at the time when the
tension in the dynamos is greater than in the accumulators.
3. The employment in the secondary stations of regulating apparatus or commu-
tators always allowing the tension of charge and discharge to be regulated by
introducing or cutting out of the primary circuit or from the lamp circuit a certain
number of accumulator cells.