Improved Method of and Apparatus for Indicating Potential in Systems of Electrical Distribution.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improved Method of and Apparatus for Indicating Potential in
Systems of Electrical Distribution.
1, RALPH DAVENPORT MERSHON, of 120, Broadway, in the City and State of
New York, U.S.A., Electrical Engineer, do hereby declare the nature of this
invention to be as follows:--
My invention relates to systems of distribution for alternating electric currents,
and more particularly to means employed for indicating at the generating station
or other desired point the potential at the load in such systems.
The object of my invention is to provide a method and a means whereby the
potential at the load may be substantially indicated at the power station or at any
other desired point, whatever may be the ohmic or inductive drop in the line, or
other disturbing effect or effects tending to vary the potential at the load from
that at the generator end of the line.
Means are known whereby the potential at the load in an alternating current
circuit may be either exactly or approximately indicated, where there is either an
inductive or ohmic drop in the line, or where both the ohmic and the inductive
resistance of the line cause a variation between the effective potential at the load
and that at the generator or power station. In these cases there are many
possible arrangements of circuits and connections for securing an accurate indica-
tion of the potential at the load, and such systems give substantially correct
results when used in connection with transmission lines delivering all of the
power to a more or less definite and limited location on the line.
Where, however, the conditions are such that the power or current taken from
the line, instead of being taken at one definite place, is distributed at various
places along the line, the methods and means hitherto used will not give accurate
indications.
The condition last mentioned is present in long transmission lines where there
is more or less current due to, first, capacity effects; second, to loss between wires
through the air and over insulators, and third, where power is delivered at
various points along the line.
For convenience of description I shall hereafter refer to the first of the effects
above enumerated as line capacity, to the second as line leakage, and to the third
as distributed load.
The conditions of line capacity and line leakage exist in all transmission lines,

page_text: and though they are not ordinarily of sufficient prominence to be noticeable or
to effect the working of the system they may assume such prominence in long
transmission lines carrying high voltages or in short transmission lines where
there exists what would be ordinarily considered abnormal conditions.
By employing a suitable combination of apparatus it is possible to indicate at
any desired point the voltage existing at any other desired point of the line when
the three specified conditions or any one or two of them are present, provided
that where there is distributed load, namely, a load located at two or more different
points in the line, the power taken at the several distributed points is constant
at each point. If the power is not constant, the indication will be approximate
only, whereas, if line capacity and line leakage exist without distributed load,
the indication secured may be substantially accurate. I will first describe the
method that I have devised for indicating the voltage when either line capacity
or line leakage, or both exist, and the third condition of distributed load is not
present.
In describing this method I will first assume that the indicating means is
located at the power station and that the point the voltage of which it is desired
to indicate is at approximately the end of the line where I will also assume that
the power is delivered.
In the accompanying drawing Figures 1, 2, 3, 4, 5, and are diagrams of
circuits and apparatus adapted for practising my invention, a separate and detailed
description of each of which will be more conveniently given in connection with
the detailed description of the structure and operation of the invention.
In each of the figures the generator supplies the transmission circuit a-b
with the electrical energy to be utilized by translating devices s located at a more
or less distant point. This loads may comprise any kind of electrical translating
devices or a variety of such devices connected in any known way to the circuit
either directly or by means of step-down transformers. It will also be understood,
of course, that a step-up transformer may be used between the main generator
and the transmission line where the distance of transmission is so great that the
generator voltage is not sufficiently high for the purpose.
In each of the figures of the drawing the primary of a transformer c is connected
across the main circuit --b at or near the generator r, and the secondary of this
transformer is included in a local circuity in order to impress upon the local
circuit an electro-motive force that is representative of the main line impressed
electro-motive force. In each figure the local circuit -y also contains other
devices and apparatus so constructed and arranged as to insure the production
in such local circuit of the conditions corresponding to those of the main line,
in order that the volt meter also included in each local circuit shall correctly
indicate the line voltage at the load. The details of construction other than those
above specified vary in the different figures and will be considered separately.
Referring now particularly to Figures 1 and 2 which illustrate the means
employed for indicating the voltage when line capacity and line leakage both
exist to such a degree as to make it necessary or desirable that they be taken
into account, the resistance coil and non-inductive resistance employed to re-
present the inductive and ohmic resistance of the line are subdivided and the
subdivisions of the reactance coil are made to alternate in the local circuit
with the divisions f of the ohmic resistance. Connected between the middle point
of each ohmic resistance division f and each reactance coil division and the
opposite side of the local circuit in parallel are a condenser k and a resistance /
of suitable capacity. The resistance may be either reactive or ohmic, or a
combination of the two, as may be required in any particular case.
It will be seen the subdivisions g of the reactive coil and subdivisions f of
the ohmic resistance, in combination with the condensers and the resistances
represent in miniature the reactance, resistance, distributed capacity and dis-
tributed loss between the wires in the main or transmission line, and that this
resemblance may be carried to any desired degree of accuracy by sufficiently sub-

page_text: dividing the reactance coil and the resistance and at the same time suitably
subdividing the capacity devices or condensers.
It will also be understood that the reactance and ohmic resistance elements
may be combined as a single element having both reactance and resistance, and
that the condensers and resistance in parallel therewith may be attached at various
points along this combined element, as is indicated, for example, in Figure 5
of the drawings, this figure being in all respects like Figure 1, except that the
ohmic and inductive resistances in the local circuit have been combined into a
single element t.
It will also be understood that if the ohmic and inductive resistance be combined
in this manner, or if they be sufficiently subdivided and the subdivisions alternated,
as indicated in Figures 1 and 2, a single condenser of suitable capacity and a
single resistance of proper construction and proportions may be attached at the
proper point and employed in lieu of the plurality of small condensers and
resistances shewn in Figures 1 and 2. This modification is illustrated in Figure 6
of the drawing, this figure being a reproduction of Figure 2, except that a single
condenser and a single resistance are employed in lieu of the plurality of
these devices, as in Figures 1 and 2.
In each of Figures 1, 3 and 5, the representation in the local circuit of the
main line current is effected by means of a converter d, while in each of Figures 2,
4 and 6 this result is effected by connecting the local circuit directly to the main
line.
The valves of the capacity or condenser elements and of the resistances in
parallel therewith will, of course, depend upon and be fixed by the capacity of
the line and the loss between the line wires, etc., but the combination thus far
described will not accomplish the desired end, for the reason that there is already
passing through the miniature reactance and resistance a current proportional t
and in step with that component of the line current which is due to distributed
capacity and loss between the wires, that is, line capacity and line leakage, con-
sequently, the effect of this current on the reactances and resistances must be
neutralized. This is accomplished by means of a converter e which includes in
its secondary circuit a suitable condenser or capacity device h, and a suitable
resistance, the two being in parallel with each other and in series with the
resistances f and reactances g. The connections are also such that the current
through the reactances g and resistances of due to the converter is in the reverse
direction to that component of the current originally flowing through the re-
actances and resistances by reason of the existence of the line capacity and line
leakage.
In Figures 1 and 2 the effects of line capacity and line leakage are represented
as distributed instead of as concentrated at the end of the line, the former being
the condition which exists in the transmission circuit.
It is apparent that if line capacity only of the three disturbing elements herein-
before mentioned exists, then the resistances may be omitted and the condensers k
only may be used.
If line leakage only exists, then the condensers may be omitted and the
resistances only may be used.
When, in addition to neutralizing the line current component in the reactances
and resistances, it is necessary to neutralize it in the converter c, the connection
of converter e, instead of being made at the point p, should be made at the
point
o so that the current from the converter e shall pass through converter c.
This connection for the conditions last mentioned I have indicated by broken
line no in Figures 1 and 5.
Converters cand e may be combined in one piece of apparatus, if properly
designed, one of the conditions of such design being the employment of two
secondary windings corresponding respectively to the secondaries of converters e
and e as shewn in the drawing.
Reference may now be had to Figures 3 and 4, which shew another method

page_text: of and means for accomplishing the end desired; that is, the correct indication
of the potential at the load in the main circuit when line capacity but not line
leakage is present in the main circuit. In this case the neutralization, instead
of being effected by means of a converter c, is effected by means of a reactance
coil m so adjusted that its current is equal to that which would exist in the
reactances and resistances f, if such a coil were not connected.
Since a reactance coil takes a current displaced 180° from that of a condenser,
and since the component of current which it is desired to neutralize is a capacity
current, a proper adjustment of the reactance coil m will accomplish the desired
purpose.
The statement made above as to the angular displacement between the current
taken by a reactance coil and one taken by a condenser is made upon the assump-
tion that the condenser and reactance coil are theoretically perfect in operation,
that is, such as have no loss. Since by assumption the condenser has no loss, and
since the condition of no loss can be very closely approximated in a reactance coil
of suitable design, the statement holds good in this case and in practice can be
made to hold good with a sufficiently close approximation for practical purposes.
The arrangement of apparatus shewn in Figures 3 and 4 is open to the objection
that if the coil m is properly adjusted for one frequency, it will not be for
another, hence if the speed of the generator changes materially the voltmeter
will not give a correct indication. However, where fairly good speed regulation
obtains, the error due to this cause will be small.
We will now consider the question of obtaining proper indication when the load
is distributed at various points along the transmission line.
It is evident that if the component of current due to distributed load is constant,
the distributed load may be represented similarly to the representation of line
leakage in Figures 1 and 2, the resistances i and I. As the resistance represents
a distributed cause, it is subdivided in order to approximate the condition of such
distribution. If the line load is not distributed, the resistance / must be located
in the local circuit at such a point as corresponds to the actual location of the
load on the working line and a suitably designed shunt must be provided for
the resistance i.
If the distributed load, and, therefore, the current due to it, are not constant,
then an approximate indication may be obtained by representing such load by a
resistance or by resistances properly located and taking the current the value of
which is proportional to the average value of the compound of current due to the
distributed load.
It is, of course, to be understood that when the distributed load is represented
by a combination similar to resistances 1, the combination must be such as to
take a current proportional to and in step with that taken by the distributed load.
This can be accomplished by making the representative of such load a suitable
combination of resistance, reactance, and, if necessary, capacity.
If line capacity, line leakage and distributed load do not all exist in the line,
but only one or two of them, those elements corresponding to the cause or causes
not present may be obviously omitted.
Throughout the foregoing description, the term resistance as applied to the
element has been used rather loosely. While the term resistance is ordinarily
construed to mean ohmic resistance or dead resistance, when used without qualifi-
cation, the resistance / may be either reactive or ohmic or a combination of the
two.
As an example of the value of my present invention where the load is not all
located at any one point, say, at the end of the transmission line, let us suppose
that we have a line in which capacity and leakage both exist and that the main
load located at the end of the line is one for which special regulation is not
necessary, that is, it can stand a considerable variation in voltage. At another
point, say midway between the generator and the main load is a group of
translating devices, such, for example, as electric lights, which require good

page_text: regulation and which constitute what has been heretofore designated as the
distributed load, then the load at approximately the middle of the line will be
represented at the generating station by a resistance which takes a current
proportional to and in step with the average current at such load and which is
located half way along the combination of reactance and resistance, that is,
the miniature reactance and resistance in the local circuit. Since the lighting
load is half way along the transmission line, that is, half way between the gene-
rator and the main load, the voltmeter connected half way along the combination
of reactance and resistance will approximately indicate the voltage at such
midway load, and if the main load is large with reference to this midway load,
the indication may be quite accurate. Indeed, if the main load be very large
with respect to the lighting load, the representation of the latter in the local
circuit may be omitted and the voltmeter attached half way along the combination
of miniature reactance and resistance.
When the effect of capacity current in the generating station is neutralized
by a reactance coil connected across the main line beyond the miniature local
circuit or by raising transformers beyond the miniature local circuit which take
a large magnetizing current, as may be done, it is evident that the converter e.
with its resistance i, and condenser may be omitted from the circuit shewn in
Figures 1 and 2.
While I have, for convenience, assumed that the potential indicating apparatus
is located at the main generating or power station, as will usually be found
desirable in practice, I desire it to be understood that the said apparatus may be
located at any other desired or convenient point in the line.
Modifications of apparatus and circuits other than those specially illustrated and
described may be made without departing from my invention, and I therefore
desire it to be understood that the invention is not intended to be circumscribed
by the specific disclosure herein before made.
Improved Method of and Apparatus for Indicating Potential in
Systems of Electrical Distribution.
I, RALPH DAVENPORT MERSION, of 120, Broadway, in the City and State of
New York, U.S.A., Electrical Engineer, do hereby declare the nature of this
invention and in what manner the same is to be performed to be patricularly
described and ascertained in and by the following statement:—
My invention relates to systems of distribution for alternating electric currents,
and more particularly to means employed for indicating at the generating station
or other desired point the potential at the load in such systems.
The object of my invention is to provide a method and a means whereby the
potential at the load may be substantially indicated at the power station or at any
other desired point, whatever may be the ohmic or inductive drop in the line, or
other disturbing effect or effects tending to vary the potential at the load from
that at the generator end of the line.
Means are known whereby the potential at the load in an alternating current
circuit may be either exactly or approximately indicated, where there is either an
inductive or ohmic drop in the line, or where both the ohmic and the inductive
resistance of the line cause a variation between the effective potential at the load

page_text: and that at the generator or power station. In these cases there are many
possible arrangements of circuits and connections for securing an accurate indica-
tion of the potential at the load, and such systems give substantially correct
results when used in connection with transmission lines delivering all of the
power to a more or less definite and limited location on the line.
Where, however, the conditions are such that the power or current taken from
the line, instead of being taken at one definite place, is distributed at various
places along the line, the methods and means hitherto used will not give accurate
indications.
The condition last mentioned is present in long transmission lines where there
is more or less current due to, first, capacity effects; second, to loss between wires
through the air and over insulators, and third, where power is delivered at
various points along the line.
For convenience of description I shall hereafter refer to the first of the effects
above enumerated as line capacity, to the second as line leakage, and to the third
as distributed load.
The conditions of line capacity and line leakage exist in all transmission lines,
and though they are not ordinarily of sufficient prominence to be noticeable or
to effect the working of the system they may assume such prominence in long
transmission lines carrying high voltages or in short transmission lines where
there exists what would be ordinarily considered abnormal conditions.
By employing a suitable combination of apparatus it is possible to indicate at
any desired point the voltage existing at any other desired point of the line when
the three specified conditions or any one or two of them are present, provided
that where there is distributed load, namely, a load located at two or more different
points in the line, the power taken at the several distributed points is constant
at each point. If the power is not constant, the indication will be approximate
only, whereas, if line capacity and line leakage exist without distributed load,
the indication secured may be substantially accurate. I will first describe the
method that I have devised for indicating the voltage when either line capacity
or line leakage, or both exist, and the third condition of distributed load is not
present.
In describing this method I will first. assume that the indicating means is
located at the power station and that the point the voltage of which it is desired
to indicate is at approximately the end of the line where I will also assume that
the power is delivered.
In the drawings accompanying my Provisional Specification, Figures 1, 2, 3,
4, 5 and 6 are diagrams of circuits and apparatus adapted for practising my
invention, a separate and detailed description of each of which will be more con-
veniently given in connection with the detailed description of the structure and
operation of the invention.
In each of the figures the generator r supplies the transmission circuit a-b
with the electrical energy to be utilized by translating devices s located at a more
or less distant point. This loads may comprise any kind of electrical translating
devices or a variety of such devices connected in any known way to the circuit
either directly or by means of step-down transformers. It will also be understood,
of course, that a step-up transformer may be used between the main generator
and the transmission line where the distance of transmission is so great that the
generator voltage is not sufficiently high for the purpose.
In each of the figures of the drawing the primary of a transformer c is connected
across the main circuit - at or near the generator r, and the secondary of this
transformer is included in a local circuit -y in order to impress upon the local
circuit an electro-motive force that is representative of the main line impressed
electro-motive force. In each figure the local circuit -y also contains other
devices and apparatus so constructed and arranged as to insure the production
in such local circuit of the conditions corresponding to those of the main line,
in order that the volt meter also included in each local circuit shall correctly

page_text: indicate the line voltage at the load. The details of construction other than those
above specified vary in the different figures and will be considered separately.
Referring now particularly to Figures 1 and 2 which illustrate the means
employed for indicating the voltage when line capacity and line leakage both
exist to such a degree as to make it necessary or desirable that they be taken
into account, the reactance coil and non-inductive resistance employed to re-
present the inductive and ohmic resistance of the line are subdivided and the
subdivisions of the reactance coil are made to alternate in the local circuit
with the divisions f of the ohmic resistance. Connected between the middle point
of each ohmic resistance division f and each reactance coil division y and the
opposite side of the local circuit in parallel are a condenser and a resistance
of suitable capacity. The resistance / may be either reactive or ohmic, or a
combination of the two, as may be required in any particular case.
It will be seen the subdivisions g of the reactive coil and subdivisions f of
the ohmic resistance, in combination with the condensers k and the resistances
represent in miniature the reactance, resistance, distributed capacity and dis-
tributed loss between the wires in the main or transmission line, and that this
resemblance may be carried to any desired degree of accuracy by sufficiently sub-
dividing the reactance coil and the resistance and at the same time suitably
subdividing the capacity devices or condensers.
It will also be understood that the reactance and ohmic resistance elements
may be combined as a single element having both reactance and resistance, and
that the condensers and resistance in parallel therewith may be attached at various
points along this combined element, as is indicated, for example, in Figure 5
of the drawings, this figure being in all respects like Figure 1, except that the
ohmic and inductive resistances in the local circuit have been combined into a
single element t.
It will also be understood that if the ohmic and inductive resistance be combined
in this manner, or if they be sufficiently subdivided and the subdivisions alternated,
as indicated in Figures 1 and 2, a single condenser of suitable capacity and a
single resistance of proper construction and proportions may be attached at the
proper point and employed in lieu of the plurality of small condensers and
resistances shewn in Figures 1 and 2. This modification is illustrated in Figure 6
of the drawing, this figure being a reproduction of Figure 2, except that a single
condenser and a single resistance are employed in lieu of the plurality of
these devices, as in Figures 1 and 2.
In each of Figures 1, 3 and 5, the representation in the local circuit of the
main line current is effected by means of a converter d, while in each of Figures 2,
4 and 6 this result is effected by connecting the local circuit directly to the main
line.
The valves of the capacity or condenser elements and of the resistances in
parallel therewith will, of course, depend upon and be fixed by the capacity of
the line and the loss between the line wires, etc., but the combination thus far
described will not accomplish the desired end, for the reason that there is already
passing through the miniature reactance and resistance a current proportional to
and in step with that component of the line current which is due to distributed
capacity and loss between the wires, that is, line capacity and line leakage, con-
sequently, the effect of this current on the reactances and resistances must be
neutralized. This is accomplished by means of a converter e which includes in
its secondary circuit a suitable condenser or capacity device h, and a suitable
resistance the two being in parallel with each other and in series with the
resistances and reactances g. The connections are also such that the current
through the reactances g and resistances f due to the converter e is in the reverse
direction to that component of the current originally flowing through the re-
actances and resistances by reason of the existence of the line capacity and line
leakage.
In Figures 1 and 2 the effects of line capacity and line leakage are represented

page_text: as distributed instead of as concentrated at the end of the line, the former being
the condition which exists in the transmission circuit.
It is apparent that if line capacity only of the three disturbing elements herein-
before mentioned exists, then the resistances i may be omitted and the condensersk
only may be used.
If line leakage only exists, then the condensers may be omitted and the
resistances only may be used.
When, in addition to neutralizing the line current component in the reactances
and resistances, it is necessary to neutralize it in the converter e, the connection
of converter e, instead of being made at the point, should be made at the
point o so that the current from the converter e shall pass through converter c.
This connection for the conditions last mentioned I have indicated by broken
line no in Figures 1 and 5.
Converters and e may be combined in one piece of apparatus, if properly
designed, one of the conditions of such design being the employment of two
secondary windings corresponding respectively to the secondaries of converters c
and e as shewn in the drawing.
Reference may now be had to Figures 3 and 4, which shew another method
of and means for accomplishing the end desired; that is, the correct indication
of the potential at the load in the main circuit when line capacity but not line
leakage is present in the main circuit. In this case the neutralization, instead
of being effected by means of a converter e, is effected by means of a reactance
coil m so adjusted that its current is equal to that which would exist in the
reactances g and resistances f, if such a coil were not connected.
Since a reactance coil takes a current displaced 180° from that of a condenser,
and since the component of current which it is desired to neutralize is a capacity
current, a proper adjustment of the reactance coil m will accomplish the desired
purpose.
The statement made above as to the angular displacement between the current
taken by a reactance coil and one taken by a condenser is made upon the assump
tion that the condenser and reactance coil are theoretically perfect in operation,
that is, such as have no loss. Since. by assumption the condenser has no loss, and
since the condition of no loss can be very closely approximated in a reactance coil
of suitable design, the statement holds good in this case and in practice can be
made to hold good with a sufficiently close approximation for practical purposes.
The arrangement of apparatus shewn in Figures 3 and 4 is open to the objection
that if the coil m is properly adjusted for one frequency, it will not be for
another, hence if the speed of the generator changes materially the voltmeter
will not give a correct indication. However, where fairly good speed regulation
obtains, the error due to this cause will be small.
We will now consider the question of obtaining proper indication when the load
is distributed at various points along the transmission line.
It is evident that if the component of current due to distributed load is constant,
the distributed load may be represented similarly to the representation of line
leakage in Figures 1 and 2, by the resistances i and 1. As the resistance / represents
a distributed cause, it is subdivided in order to approximate the condition of such
distribution. If the line load is not distributed, the resistance / must be located
in the local circuit at such a point as corresponds to the actual location of the
load on the working line and a suitably designed shunt must be provided for
the resistance .
If the distributed load, and, therefore, the current due to it, are not constant,
then an approximate indication may be obtained by representing such load by a
resistance or by resistances properly located and taking the current the value of
which is proportional to the average value of the compound of current due to the
distributed load.
It is, of course, to be understood that when the distributed load is represented
by a combination similar to resistances 1, the combination must be such as to

page_text: take a current proportional to and in step with that taken by the distributed load.
This can be accomplished by making the representative of such load a suitable
combination of resistance, reactance, and, if necessary, capacity.
If line capacity, line leakage and distributed load do not all exist in the line,
but only one or two of them, those elements corresponding to the cause or causes
not present may be obviously omitted.
Throughout the foregoing description, the term resistance as applied to the
element has been used rather loosely. While the term resistance is ordinarily
construed to mean ohmic resistance or dead resistance, when used without qualifi-
cation, the resistance may be either reactive or ohmic or a combination of the
two.
As an example of the value of my present invention where the load is not all
located at any one point, say, at the end of the transmission line, let us suppose
that we have a line in which capacity and leakage both exist and that the main
load located at the end of the line is one for which special regulation is not
necessary, that is, it can stand a considerable variation in voltage. At another
point, say midway between the generator and the main load is a group of
translating devices, such, for example, as electric lights, which require good
regulation and which constitute what has been heretofore designated as the
distributed load, then the load at approximately the middle of the line will be
represented at the generating station by a resistance which takes a current
proportional to and in step with the average current at such load and which is
located half way along the combination of reactance and resistance, that is,
the miniature reactance and resistance in the local circuit. Since the lighting
load is half way along the transmission line, that is, half way between the genera-
tor and the main load, the voltmeter connected half way along the combination
of reactance and resistance will approximately indicate the voltage at such
midway load, and if the main load is large with reference to this midway load,
the indication may be quite accurate. Indeed, if the main load be very large
with respect to the lighting load, the representation of the latter in the local
circuit may be omitted and the voltmeter attached half way along the combination
of miniature reactance and resistance.
When the effect of capacity current in the generating station is neutralized
by a reactance coil connected across the main line beyond the miniature local
circuit or by raising transformers beyond the miniature local circuit which take
a large magnetizing current, as may be done, it is evident that the converter e,
with its resistance i, and condenser h may be omitted from the circuit shewn in
Figures 1 and 2.
While I have, for convenience, assumed that the potential indicating apparatus
is located at the main generating or power station, as will usually be found
desirable in practice, I desire it to be understood that the said apparatus may be
located at any other desired or convenient point in the line.
Modifications of apparatus and circuits other than those specially illustrated and
described may be made without departing from my invention, and I therefore
desire it to be understood that the invention is not intended to be circumscribed
by the specific disclosure herein before made.
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 method of indicating at any point the potential at any other point in
an alternating current circuit which consists in reproducing in miniature in a
local circuit the main line impressed and counter electro-motive forces and the line
capacity, leakage and distributed load or such of the latter as it is desired to take
into account and then observing the resultant difference of potential in said loca!
circuit at a point corresponding to the point in the main circuit.
2. An electrical installation provided with a local circuit in which the main

page_text: line impressed and counter electro-motive forces and the line capacity, leakage
and distributed load or such of the latter as it is desired to take into account are
reproduced in miniature for the purpose specified.
3.. The various arrangements for indicating at any point the potential at any
other point in an alternating current circuit substantially as described with
reference to the drawings.
Dated the 18th day of April 1900
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham.