IMPROVEMENTS IN APPARATUS USED IN THE DISTRIBUTION OF " ELECTRICAL ENERGY
Year: 1882

page_text: LETTERS PATENT to John Perry, B.E, of 14, Talgarth Road West
Kensington, in the County of Middlesex for an Invention of
"
IMPROVE-
PROVISIONAL SPECIFICATION left by the said John Perry at the Office.
of the Commissioners of Patents on the 5th January 1882.
JOHN PERRY, B.E. of 14 Talgarth Road, West Kensington in the County of
Middlesex IMPROVEMENTS IN APPARATUS USED IN THE DISTRIBUTION OF
"
ELECTRICAL ENERGY."
In the distribution of electrical energy from a central source it is very important
that any person to whose premises conducting wires are laid should get a supply
which quite independent of the demand from and supply to other consumers of
power.
That is, a person who is using an electric light or is driving a machine by means
of electricity supplied to him from some central source ought not to have his supply
interfered with by other consumers lighting their lamps or working their machines.
That this may be the case it is necessary that the difference of electrical potential
between the main cable from which every person takes his supply and the earth
or return cable should be maintained constant. We assume that each consumer
has a wire or wires connecting the main cable and the earth or return cable so
that the supply wires to consumers are all in parallel arc.
Various inethods have been designed to enable this to be effected. Some depend
upon automatic regulators at the central station acting in such a way that any
increase or diminution in the above mentioned difference of potentials shall cause an
electrical instrument to diminish or increase the supply of steam to the steam engine
and so diminish or increase the speed of the Dynamo Machine which supplies the
electricity. M. Deprez uses two distinct circuits which have no connexion with each
other to cause the field magnets of his dynamo machine to have a constant current
flowing round them besides the ordinary or main current, and in this way by creating
a new kind of electrical machine he effects the purpose. Our method is to use one or
more magneto-electrical machines or some other form of electrical machine or battery

page_text: which will produce in a circuit an electromotive force which is constant and inde-
pendent of any other electromotive forces in the same circuit, And in addition to
this we have in the same circuit one or more Dynamo-electric Machines.
The independent electromotive force which we thus introduce into the main
circuit is arranged to be equal to the constant electromotive force which ought to
exist between the supply cable of any consumer and the return cable or earth.
The Dynamo Machines ought to get constant speeds, being driven by Engines with
good governors and these speeds ought to be what have been termed the critical
speeds. That is, the speed of each dynamo machine ought to be such that the
electromotive force created in it by its motion ought to be proportional to the
current circulating in the coils of its field magnets.
In scientific language the intensity of the magnetic field in which the armature
circulates ought to be proportional to the main current. It is evident that one
large dynamo machine is preferable to two or more smaller ones in such a case and
it will be better to employ larger field magnets than are usual in dynamo machines. -
But to use the dynamo machines now in use will not introduce much discrepance
from the conditions required and we find that we can readily employ for our
method one or more of any of the Dynamo Machines now in use, whether large or
small As an example-If there is only one Dynamo Machine and if the resistanco
of the main cable, return cable and machines, in fact that part of the total circuit
which is supposed to be constant, be, let us suppose 3 ohms, then the Dynamo
Machine ought to be run at such a speed that the electromotive force in Volts
produced in its moving part is three times the current in Amperes which flows
through the field magnets.
This speed can readily be found by experiment-Suppose the constant electro-
motive force of the Magneto-Machine to be 50 Volts; its resistance 0.3 ohms and
the resistance of the Dynamo Machine and other unchanging part of the circuit
2. 7. ohms And suppose that the speed is that at which the electromotive force
produced by the rotating armatine of the Dynamo is 3 times the current. Now,
let there be a consumer's resistance of 2 ohms, the total resistance is 5 ohms-
Evidently the electromotive force produced in the Dynamo is 75 Volts and the total
electromotive force in the circuit is therefore 125 Volts and as total resistance is
5 ohms the current is 25 Amperes giving an electromotive force of 50 Volts between
the ends of the consumers part of the circuit-Now if consumers resistance
increases to 12 Ohms by some of them ceasing to use their circuits there is an
instantaneous alteration of the electromotive force produced in the Dynamo to
12 Volts or 62 in the whole circuit and 624 divided by 15 gives 4 Amperes,
and this means 44 multiplied by 12 or 50 Volts as before, between the ends of the
consumers' part of the circuit.
Instead of using the Dynamo Machine of the ordinary type, that is, with its field
magnets forming part of the main circuit, I sometimes use it in the form in which
the field magnets act as a shunt. The Magneto Machine or other source of
constant electromotive force may be introduced either in the shunt which includes
the field magnets or in the part called A later on in this Specification the armatine
part but I do not so much approve of this. When using a Dynamo Machine of
the Shunted field magnet type I prefer to place my magneto machine or other source
of constant electromotive force in a part of the circuit which is quite outside the
machine, that is, in the main circuit, so that the current passing through it is that
which goes to the supply cable. The speed may be determined which will produce
the desired result.
For so far, we have considered the lamps or machines which are supplied with
electricity to be "in parallel are." When however the lamps or machines to which
electricity is given are "in series;" that is, the same current is to go through them
all; What we effect is that they shall all receive the same current of electricity
however the resistance of one or more of them may vary-This is effected by
using instead of ordinary Dynamo electric Machines, one or more Dynamo Machines
constructed so that their field magnets are a shunt between their brushes or the

page_text: binding screws connected with their brushes combined with one or more Magneto
Electric Machines or some other form of electrical machine or battery which will
produce an independent electromotive force.
For simplicity take the case of one Dynamo Machine and one Magneto Machine.
Let the shunt part of the Dynamo be called M whether it contains merely the
wire of its own magnets or has the Magneto Machine inserted in it.
Let the part of
the Dynamo which contains the wire of the revolving Armatine be called A and let
us be able to insert a Magneto Machine in this portion of the circuit if we please―
Now the two ends of A and the two ends of M are the same, and these may be
called the binding screws of the machine-If these binding screws are joined to the
two ends of any external wire or cable or system of lamps in Series which we may
call the external circuit being really the part of the whole circuit which is external
to the machine; then if we introduce a Magneto-electrical Machine in the part A or
in the part M, or if we have a Magneto Machine in A and another in M we can by
giving a certain constant speed to the machine deliver a constant current of
electricity through the external circuit however the resistance of that circuit
may vary The constant current we find to be that which the Magneto Machine
or Machines would produce in a circuit whose total resistance is equal to the
resistance of A.
Thus if a Magneto Machine or other constant source of electromotive force
producing a constant electromotive force of 100 Volts is inserted in A. and if its
internal resistance is 0-3 Ohms, and if another Magneto Machine whose constant
electromotive force is 160 Volts and internal resistance is 2 Ohms be inserted in M-
and if the resistance of the revolving part of the Dynaino (from brush to brush) if
it were working in the ordinary way) be 0.5 Ohms; then when joined up to an
external circuit in the manner described and run at constant speed the current in
the external circuit will be the sum of 100 and 160 divided by the sum of 0.5 and
0-3 or 325 Amperes or else it will be the difference of 100 and 160 divided by the
sum of 0-5 and 0.3 or 75 Amperes; the latter case being one in which the Magneto
machines oppose each other's actions-But in either case the current in the external
circuit will not alter although its resistance be altered-The constant speed at
which the Dynamo Machines should be run, may be determined by experiment and
calculation The speed should be such that the electromotive force produced in
the Armatine by rotation is equal to the current in M which includes the field
magnets multiplied into the sum of the resistances of A and of M. It is possible,
by running even an ordinary Gramme Machine at lower speeds than usual, to get
the electromotive force produced in the Armatine to be proportional to the current
in the field magnets.
Both in the first and second cases described in this Specification namely,
distribution of electrical power to persons who consume it in parallel are and
distribution of electrical power to lamps or machines which are joined up in series
in one circuit.
I have spoken of the constant speed at which a Dynamo Machine
must be run. To make my meaning clear, I give an example-Suppose I find by
calculation that it is necessary to run a Dynamo machine at such a speed that the
electromotive force in Volts produced in the revolving armature is equal to the
Amperes or current passing in the field Magnets multiplied into 2 Ohms Make an
experiment letting a current of 20 Amperes pass through your field magnets and
let them be disconnected from the Armature Circuit-Revolve your Armature at a
speed of 200 revolutions per minute and let us suppose that you find that an
electromotive force of 100 Volts is produced by the rotation-If the Machine is a
suitable one for your purpose so that the proportionality of electromotive force to
the product of field magnet current and number of revolutions, holds, then the
constant speed required is 2 multiplied by 200 and by 20 divided by 100 or 80
revolutions per minute.
In the process of Electro plating we bave exactly the same condition as there is
in the distribution of electrical power when the consumers' connections are in
parallel arc; that is, in an electro plating bath there ought to be maintained a

page_text: constant difference of electrical potentials between the two sides of the bath,
however few or many objects may be undergoing the electroplating process.
Instead therefore, of employing a single dynamo machine which is the common
plan at present, I employ in the circuit one or more Magneto electrical Machines or
other electrical Machine or battery which will produce a constant and independent
electromotive force as well as one or more Dynamo-Machines.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Perry in the Great Seal Patent Office on the 5th July
1882.
JOHN PERRY, Bachelor of Engineering of 14 Talgarth Road, West Kensington
in the County of Middlesex. "IMPROVEMENTS IN APPARATUS USED IN THE
DISTRIBUTION OF ELECTRICAL ENERGY."
In the distribution of electrical energy from a central source, it is very important
that any person to whose premises conducting wires are laid, should get a supply
which is quite independent of the demand from and supply to other consumers
of power. That is, a person, who is using an electric light or is driving a machine
by means of electricity supplied to him from some central source, ought not to
have his supply interfered with by other consumers lighting their lamps or
working their machines. That this may be the case, it is necessary that the
difference of electrical potential between the main cable from which every person
takes his supply and the earth or return cable should be maintained constant,
We here assume that each consumer has a wire or wires connecting the main
cable and the earth or return cable, so that the supply wires to consumers are all
in parallel arc. Various methods have been designed to enable this to be effected.
Some depend upon automatic regulators at the central station acting in such a
way that any increase or diminution in the above mentioned difference of potentials
shall cause an electrical instrument to alter the supply of steain to the steam
engine, and so diminish or increase the speed of the Dynamo Machine which supplies
the electricity. M. Deprez uses two distinct circuits, which have no connection
with each other to cause the field magnets of his Dynamo Machine to have a
constant current flowing round them besides the ordinary or main current, and in
this way by creating a new kind of electrical machine he effects the purpose.
Others obtain a constant supply of electrical energy by arranging that any
diminution or increase automatically cuts out or introduces resistance in the main
circuit or automatically increases or diminishes the efficiency of the dynamo by
moving the brushes or by introducing resistance in the field magnet circuit or by
displacing an iron armature near the pole piece of the poles of the field magnets
If the lamps or motors are in series, that is, the same current passes through them
all then the constancy of electric supply requires that the current in this circuit

page_text: As an
shall be constant no matter how many or how few lamps or motors there may be
in this circuit. And methods similar to those already described have been used by
various people to accomplish the same result. Our method on the other hand consists
in combining with our Dynamo machine or machines, one or more Magneto Electric
Machines or other form of electrical machine or battery which will produce in a circuit
an electro motive force which is constant and independent of any other electro-
motive forces in the same circuit. First. When the consumers wires are arranged in
parallel are we usually employ a "series" dynamo and in that case we introduco
into the main circuit a magneto electric machine or battery or other apparatus
producing a constant electromotive force equal to the electromotive force which
ought to exist between the supply cable of any consumer and the return cable or
earth. The Dynamo machines ought to get constant speeds being driven by engines
with good governors and these speeds ought to be what have been termed the
critical speeds. That is the speed of each dynamo machine ought to be such that
the electromotive force created in it by its motion ought to be proportional to
the current circulating in the coils of its field magnets. In scientific language
the intensity of the magnetic field in which the armature rotates ought to
be proportional to the magnetising current. It is evident that one large Dynamo-
Machine is preferable to two or more smaller ones in such a case, and it will be better
to employ larger field magnets than are usual in Dynamo Machines. but to use the
dynamo machines, at present in use will not introduce much discrepancy from the
conditions required and we find that we can readily employ for our method one or
more of any of the dynamo machines now in use, whether large or small.
example if there is only one Dynamo machine and if the resistance of the main
cable, return cable, and machines, in fact of that part of the total circuit which is
supposed to be constant, be, let us suppose, 3 ohms, then we find that the Dynamo
machine ought to be run at such a speed that the electromotive force in volts
produced in its moving parts is three times the current in ampères which flows
through the field magnets, consequently this speed can readily be found by
experiment. Suppose the constant electromotive force of the magneto machine to
be 50 volts; its resistance 0.3 ohms, and the resistance of the Dynamo machine and
of the other unchanging parts of the circuit 27 ohms, and suppose that the speed
is that at which the electromotive force produced by the rotating armature of the
Dynamo is 3 times the current. Now let there be a consumers resistance of
2 ohins, the total resistance is 5 ohms. Evidently the electromotive force produced
in the Dynamo is 75 volts and the total electromotive force in the circuit is,
therefore, 125 volis and, as the total resistance is 5 ohms the current is 25 ampères
giving an electromotive force of 50 volts between the ends of the consumers part
of the circuit. Now if the consumers resistance incrcases to, say, 12 ohms by some
of the consumers ceasing to use their circuits, there is an instantaneous alteration of
the electromotive force produced in the Dynamo to 12 volts or 62 volts in the
whole circuit and 624 divided by 15 gives 44 ampères; and this means ++ multiplied
by 12 or 50 volts as before between the end of the consumers part of the circuit.
Instead of using the Dynamo machine of the ordinary type that is with its field
magnets forming part of the main circuit, I sometimes use it in the formn in which in
which the field inagnets act as a shunt. The Magneto machine or other source of
constant electromotive force may be introduced either in the shunt which includes the
field magnets or in the part which contains the wire of the revolving armature, called A
later on in this Specification, but I do not so much approve of this.
When using
a Dynamo machine of the shunted field magnet type I prefer to place my magneto
machine or other source of constant electromotive force in a part of the circuit
which is quite outside the machine; that is in the main circuit so that the current
passing through it is that which goes to the supply cable. The speed may be
determined from which will produce the desired result. Second-So far we have
considered the lamps or machines which are supplied with electricity to be "in
parallel arc." when, however, the lamps or machines to which electricity is given
are in series" that is when the same current is to go through them all, what we
15

page_text: effect is that they shall all receive the same current of electricity however the
resistance of one or more of thein may vary. This is attained by using instead of
an ordinary "Series " Dynamo electric machine-one or more Dynamo machines
constructed so that their field magnets are a shunt between their brushes, or the
binding screws connected with their brushes, combined with one or more magneto
electric machines or some other form of electrical machine or battery which will
produce an independent electromotive force. For simplicity take the case of one
Dynamo machine and one Magneto machine. Let the shunt part of the Dynamo
be called M. whether it contains merely the wire of its own inagnets, or has the
magneto machine inserted in it. Let the part of the dynamo which contains the
wire of the revolving armature be called A. and let us be able to insert a magneto
machine in this portion of the circuit if we please. Now the two ends of A, and
the two ends of M are the same, and these may be called the binding screws of
the machine. If these binding screws are joined to the two ends of any external
wire or cable or system of lamps in series, which we may call the external circuit
being really the part of the whole circuit which is external to the machine, then if
we introduce a magneto electric machine in the part A or in the part M, or if we
have a magneto machine in A and another in M we can by giving a certain
constant speed to the machine deliver a constant current of Electricity through the
external circuit, however the resistance of that circuit may vary. The constant
current we find to be that which the magneto machine or machines would produce
in a circuit whose total resistance is equal to the resistance of A. Thus if a
magneto machine or other constant source of electromotive force producing a
constant electromotive force of 100 volts is inserted in A, and if its internal
resistance is 03 ohms, and if another magneto machine whose constant electro-
motive force is 100 volts and internal resistance is 2 ohms be inserted in M,
and if the resistance of the revolving part of the Dynamo (from brush to brush
if it
were working in the ordinary way) be 0.5 ohms, then when joined
up to an external circuit in the manner described, and run at constant speed
the current in the external circuit will be the sum of 100 and 160 divided
by the sum of 0.5 and 0.3, or 325 ampères, or else it will be the difference
of 100 and 160 divided by the sum of 05 and 03 or 75 amperes; the latter
case being one in which the magneto machines oppose cach others actions.
But in either case the current in the external circuit will not alter although its
resistance be altered. The constant speed at which the Dynamo machine should be
run may be determined by experiment and calculation. The speed should be such
that the electromotive force produced in the armature by rotation is equal to the
current in M which includes the field magnets multiplied into the sum of the
resistances of A and of M. It is possible by running even an ordinary Gramme
machine at lower speeds than usual to get the electromotive force produced in the
armature to be proportional to the current in the field magnets. But in the first
and second cases described in the Specification, namely distribution of electrical
power to persons who consume it in parallel arc, and distribution of electrical power
to lamps or machines which are joined up in series in one circuit, I have spoken of
the constant speed at which a Dynamo Machine must be run.
To make my
meaning clear I give an example, suppose I find by calculation that it is
necessary to run a Dynamo machine at such a speed that the electromotive force in
volts produced in the revolving armature is equal to the ampères of current
passing in the field magnets multiplied into 2 ohms. Make an experiment letting
a current of 20 ampères pass through your field magnets, and let thein be
disconnected from the armature circuit. Revolve your armature at a speed of, say,
200 revolutions per minute and let us suppose that you find that an electromotive
force of 100 volts is produced by the rotation. If the machine is a suitable one for
your purpose, so that the proportionality of electromotive force to the product of
field magnet current and number of revolutions holds, then the constant speed
required is 2 multiplied by 200 and by 20, and divided by 100, or 80 revolutions per
minute. In the process of Electroplating we have exactly the same conditions as

page_text: there are in the distribution of electrical power when the consumers' connections
are in parallel arc; that is, in an electroplating bath there ought to be maintained
a constant difference of electrical potentials between the two sides of the bath
however few or many objects may be undergoing the electroplating process.
Instead therefore of employing a single dynamo machine, which is the common
plan at present, I employ in the circuit one or more magneto electric or other
electrical machines or batteries, which will produce a constant independent electro-
motive force, as well as one or more Dynamo machines. In the process of charging
Accumulators the current that should pass through each cell depends on the size and
weight of the Accumulator, but not at all on the number of Accumulators to be
charged. When then we desire to vary at will the number of Accumulators to be
charged, we arrange them partly in series and partly in parallel circuit, and use
either our first or second system of supplying constant electric energy to each
Accumulator. With our first arrangement when it is desired to increase or diminish
the number of Accumulators charging, we increase or diminish the number in
parallel circuit, leaving the total number in series unaltered. On the other hand,
when our second arrangement for supplying constant electric energy to each
Accumulator is employed, and it is desired to increase or diminish the number
charging, we increase or diminish the number in series, leaving the number in
parallel circuit unaltered.
My meaning may be made clearer by the use of algebraic formulac. Thus in the
first case where we want a constant difference of electric potential a established at
the two ends of a resistance r, if R is the resistance of a magneto machine or
battery and dynamo-machine and any other unchanging part of the whole circuit;
then let the constant electromotive force produced by the magneto machine be a and
we know that we can have the electromotive force produced by rotation of the
armature of the Dynamo machine proportional to c the current, say that it is equal
to n b C where n is the number of revolutions per minute, and b is a constant
number which can be determined by experiment. Then the whole electromotive
force of the arrangement is a + n b C; but by Ohm's law this must be equal
to RC+r C. If now we make n b equal to R it is obvious that C must always
be equal to a, however and C may vary. Again, in the second case, where we
want a constant current C to flow through the external circuit of a shunted Dynamo
machine. Let there be a magneto machine, or battery of constant electro-motive
force inserted in the armature circuit of the Dynamo Machine, and let the current
in the armature be c, in the magnets c¹ and let the electromotive force e produced by
rotation of the armature be en be. Then we know that the following statements
are true R being resistance of dynamo armature from brush to brush, R¹ being
resistance of magneto machine 7, being the resistance of the shunt circuit of Dynamo,
being variable resistance of outside circuit. eta - (RR¹) cr¹ c₁ = r C and
c = c + C It follows from this that C { (R + R¹) (r + r¹) ÷ r r¹ − n br} = a r¹.
Hence if R + R¹ + r¹n b = 0 then C =
Again, in the second case, if the constant source of electromotive force is
inserted in the magnet circuit, we have e = nbc¹, e
RC =
(r¹ + R') c' 1a=
=r C, c = c + C. It follows from this that C { Rr + R (R¹ + r¹) + r (R¹ + r¹)
|– nbr} a (nb R) so that if n b = RR x r' we must have C = I>
that is the coustant current produced in the outside circuit of the slunt dynamo
is the current which the constant electromotive force of the inagneto machine or
battery is capable of producing through a total resistance equal to that of the
armature circuit of the Dynamo machine. In the above mathematical demonstration
I have only spoken of resistance in the outside circuits as varying; it is obvious
that when we work motors or charge secondary batteries, these exert back electro-
motive forces which may vary and such varying electromotive forces will enter
into the calculations as if it were the resistances that varied.
R+R'
-
-
and is therefore constant.
a
Having now described the nature of the said Invention and the manner in which

page_text: it may be performed, I would have it understood that what I consider to be novel
and original and therefore claim as secured to me under these Letters Patents, is--
(1). For the supply of electric energy to lamps or electric motors, or secondary
batteries, or other apparatus in parallel arc, the use of one or more magneto electric
machines or other machines or batteries which are capable of producing a constant
electromotive force, in series with one or more Dynamo-electric machines, the
constant speed or speeds of these Dynamo electric machines being determined by
experiment and calculation, for the purpose of maintaining a constant difference of
electric potential between the terminals of the lamps or motors or secondary
batteries or other apparatus where they are connected with the supply and return
cables substantially as heretofore described.
(2). For the supply of electric energy to lamps or electric motors or secondary
batteries or other apparatus placed in series, the use of one or more magneto electric
machines, or other machines or batteries which are capable of producing an
independent constant electromotive force in the armature or in the magnet circuit
of a shunt dynamo electric machine or machines, the constant speed or speeds of
this or these dynamo machines being determined by experiment and calculation, for
the purpose of maintaining a constant current of electricity through these lamps
or motors or secondary batteries or other apparatus, however the resistance or
internal electromotive force of each or all of them may vary, substantially as
hereinbefore described.
In witness whereof I the said John Perry have hereunto set my hand
& seal this Fifth day of July in the year of our Lord One thousand eight
hundred and eighty two
JOHN PERRY (L.S.)