Improvements in and connected with Return Circuits for Electric Railways and Tramways.
Year: 1895

page_text: Date of Application, 16th Oct., 1895
Complete Specification Left, 16th July, 1896-Accented, 22nd Aug., 1896
[Communicated from abroad by Gisbert Kapp, of 3 Lindenstrasse, West End,
Berlin, in the Kingdom of Prussia and German Empire, Electrical Engineer.]
Improvements in and connected with Return Circuits for Electric
Railways and Tramways.
I, WILLIAM EDWIN HEYS of 70 Market Street Manchester in the County of
Lancaster, Patent Agent, do hereby declare the nature of this invention to be as
follows:-
In electric railways and tramways in which the rails are used as parts of the
return circuit, there commonly exists, between different parts of the track, a
potential difference which causes earth currents. The object of this invention
is to reduce these potential differences and their consequent earth currents, below
the limits which have hitherto been found possible.
According to the usual construction and arrangement of the track and circuits,
the connection between the return pole of the generator and the track is made
either at the nearest available point of the track only, or at such a near point and
a more distant point respectively, by means of conductors known as " return
feeders." Where the line is long, the return feeders are insulated cables, and
their resistance is so chosen or arranged that, for a certain distribution of ampere-
load, along the track, the potential of all the return feeding points on the track is
approximately the same, and does not materially differ from that of the earth.
This arrangement however, requires an unnecessarily large resistance in the
shortest return feeder, causing a waste of power, and a heavy weight of copper
in the longer return feeders, causing. a considerable expense. Moreover, this
arrangement is effective for the minimising of earth currents, so long only as the
distribution of ampere-load along the track remains that for which the return
feeders were designed. If certain parts of the track are more heavily, and others
more lightly loaded, differences of potential between the various return feeding
points arise, and since, in the practical working of electrical railways, the ampere-
load on any particular section of the track is subject to very large fluctuations, the
difference of potential and the consequent earth currents between any two points
of the track may become so great as to produce disturbances in telephonic circuits
and to cause damage by electrolytic action to pipes and other metallic masses laid
in the earth.
According to this invention, the shortest return feeder is made of as low a
resistance as is economically practicable, and the other feeder or feeders of such
resistance or resistances as will neither cause too great a loss of power nor involve
too great an outlay. Into such return feeders as have an appreciable resistance,
there are inserted storage batteries or dynamos acting as sources of E.M.F.,
which promote the flow of the return currents, and these E.M. forces are adjusted
in such a manner that each return feeder carries that part of the total return
current corresponding to the section of track served by it."
Where the line of the return feeder is such as to be, conveniently near to the
track at any intermediate point or points, the track and return feeder may be there
connected by a conductor or conductors of suitable resistance, so that part of the
current in the track is tapped off at each of these points.

page_text: When storage batteries are used as sources of E.M.F. it is found convenient to
arrange them in duplicate, and to make the connections between the return feeler
and the return pole of the generator in such a manner that one battery, in
promoting the flow of the return current, is discharged, whilst the other, at the
same time, may be charged or disconnected. The batteries may be interchangeable.
To vary the E.M.F. according to the ampere-load on the track, the number of
inserted cells may be varied by suitable means such as a switch which may either
be worked by hand, or by the outgoing or return current, automatically.
If auxiliary dymnings be employed as sources of E.M.F. the E.M.F. of each
dynamo may be caused to vary in accordance with the ampere-vl, on the section
of track served by it, according to either or both of the following methods:-
a. The dynamo is driven at a constant speed and its field is excited by the whole
or part of the returning or of the outgoing current, preferably by the current in
the outgoing feeder which serves the particular section of the track. The
dynamo is worked by an electro-motor which may be conveniently supplie with
current from the main generators of the power station. The excitation of the
electro-motor is so arranged that the field is slightly varied when the current in
the outgoing feeder varies thereby causing the speed and the E.M.F. of the
auxiliary dynamo to vary also. The object of either arrangement or bor both
in combination, is to automatically vary the E.M.F. of the auxiliary dynamos
within such limits as correspond to the ainpere-load on each section of track, as
to keep the potential of all return feeling points approximately equal and very
Dear to that of the earth, however much the load on different parts of the railway
or tramway may vary.
Dated this 14th day of October A.D. 1895.
W. E. HEYS & SON,
Agents for the Applicant.
Improvements in and connected with Return Circuits for Electric
Railways and Tramways.
1, WILLIAM EDWIN HEYS of 70 Market Street Manchester in the County of
Lancaster, Chartered Patent Agent, do hereby declare the nature of this invention,
and in what manuer the same is to be performed, to be particularly described and
ascertained in and by the following statement:—
In electric railways and tramways in which the rails are used as part of the
return cirenit, there commonly exists, between different parts of the track, a
potential difference which causes earth currents, The object of this invention
is to reduce these potential differences and their consequent earth currents, below
the limits which have hitherto been found possible.
According to the usual construction and arrangement of the track and circuits,
the connection between the return pole of the generator and the track is male
either at the nearest available point of the track only, or at such a near point and
a more distant point respectively, by means of conductors known as "return
feeders." Where the line is long, the return feeders are insulated cables, and
their resistance is so chosen or arranged that, for a certain distribution of ampere-
load, along the track, the potential of all the return feeding points on the track is
approximately the same, and does not materially differ from that of the earth.
This arrangement however, requires an unnecessarily large resistance in the
shortest return feeder, causing a waste of power, and a heavy weight of copper in
the longer return leeders, causing a considerable expense. Moreover, this
arrangement is effective for minimising the earth currents so long only as the
distribution of ampere-lond along the track remains that for which the return

page_text: feeders were designed. If certain parts of the track are more heavily, and others
more lightly loaded, differences of potential between the various return feeding
points arise, and since, in the practical working of electric railways and tramways,
the ampere-load on any particular section of the track is subject to very large
fluctuations, the difference of potential and the consequent earth currents between
any two points of the track may become so great as to produce disturbances in
telephonic circuits and to cause damage by electrolytic action to pipes and other
metallic musses laid in the earth.
According to this invention, the shortest return feeder is made of as low a
resistance as possible or as is economically practicable, and the other feeder or
feeders of such re-istance or resistances as will neither cause too great a loss of
power nor involve too great an outlay. Into such return feeders as have an
appreciable resistance, there are inserted storage batteries or dynamos acting as
sources of E.M.F., which promote the flow of the return currents, and these
electro-motive forces are adjusted in such a manner that each return feeder carries
that part of the total return current corresponding to the section of the track
served by it.
Where the line of the return feeder is such as to be conveniently near to the
track at any intermediate point or points, the track and return feeder may be there
connected by a conductor or conductors of suitable resistance, so that part of the
current in the track is tapped off at each of the-e points.
When storage batteries are used as sources of E.M.F., it is found convenient t▸
arrange them in duplicate, and to make the connections between the return feeder
and the return pole of the generator in such a manner that one battery in
promoting the flow of the return current, is discharged, whilst the other at the
same time, may be charged or disconnected. The barteries may be interchangable.
To vary the E.M.F. according to the ampere-load on the track, the number of
inserted cells may be varied by suitable means, such as a switch which may either
be worked by hand or by the outgoing or return current, automatically.
If auxiliary dynamos be employed as sources of E.M.F., the E.M.F. of each
yummy may be caused to vary in accordance with the ampere-load, on the section
of track served by it, according to either or both of the following methods:-
a. The dynamo is driven at a constant speed and its field is excited by the whole
or part of the returning or of the outgoing current, preferably by the current in
the outgoing feeder which serves the particular section of the track. b. The
dynamo is worked by an electro-motor which may conveniently be supplied with
current from the main generators of the power station. The excitation of the
electro-motor is so arranged that the field is slightly varied when the current in the
outgoing feeder varies, thereby causing the speed and the E.M.F. of the auxiliary
dynamo to vary also. The object of either arrangement, a or b, or both in com-
bination, is to automatically vary the E.M.F. of the auxiliary dyuamos within such
limits as correspond to the ampere-load on each section of the track, so as to keep
the potential of all return feeding points approximately equal and very near to
that of the earth. however much the load on different parts of the railway or tram-
way may vary.
In the appended diagrams, Figure 1 illustrates the arrangement employed
according to this invention when the source of additional E.M.F. is a storage battery.
G indicates the main generator, A the trolley wire or conductor supplying current
to the cars, and S pat of the rail track. Ho is the shortest return feeder and
His a longer insulated return feeder connected to the track at a more distant
point B. If the situation of the return feeder H is convenient, a nearer pint B'
of the track may be connected with it by a conductor R the resistance of which
is approximately equal to the resistance of the return feeder H, between the
points B and C. When batteries are used as herein before described to promote
the flow of the return current, it is found convenient to use two such batteries D
and E, and to connect them as shewn by the figure by means of the switches de
and. When these switches are in the positions shewn, the battery D is discharging

page_text: whilst promoting the How of the return current in II, whilst the battery E is being
charged by the full current returning to the generator G. When the battery E
is charged, it may be cut out of circuit by shifting the switch f to its contact on the
left. When the battery D is discharged, the switches d and are set to their
lower contacts—in the diagram, and the switch is set to its contact on the right.
The battery will then be charged whilst E is promoting the return current in I
and is being discharged.
Figure 2 illustrates an arrangement where the auxiliary source of E.M.F. is a
dynamo F, the field magnet of which is excited by the return current flowing out
of the track at Bo. The dynamo armature y is inserted in the return circuit II.
As the general ampere-load on the track varies, so also does the excitation of the
field magnet F, and the E.M.F. of the armature vary, so that the current flowing
through the return feeder II is approximately proportional to the total ampere-
lon on the line.
The arrangement illustrated by Figure 3 ensures a more close correspondence
between the E.M.F. in the return feeder and the ampere-load on that particular
region of the line to which the return ferder is connected. In this arrangement,
the field of the auxiliary generator is excited by the current which pisses through
the outgoing or positive feeders to a distant point, of the line; hence the E.M.F.
generated by the armature and inserted in the return feeder II, will be approxi-
mately proportional to the current required at the point o The return feeler 11
is cometel to the track in the neighbourhood of the point o, at B, whilst another
point B of the track is connected at (to the return feeder by a conductor R
having a suitable resistance as hereinhetore described with reference to Figure 1.
The
The auxiliary generators may be driven in any convenient way, for example,
by means of an electromotor which is supplied with current from the omnibus bar
in the power station. This arrangement is indicated by Figure 4 where Grepre-
sents the main generator, and P is the positive and N the negative omnibus har.
An electro-motor with field magnet, and armature m, is mechanically coupled
with the armature of the auxiliary generator, with the field magnet F. The
field F is excited by the current it the outgoing or positive feeders, which latter
is connected to the trolley wire or its equivalent at the distant point o
field of the motor is excited by a shunt coil and includes also a main coil inserted
into the feeder circuits, in such a manner that the current in the outgoing feeler
tends to demagnetise the field. The more current is required at o, the weaker
becomes the field of the motor and the greater the speed of its armature, whilst at
the same time the field of the auxiliary generator is strengthened. By this
means a considerable increase in the E.M.F. of the auxiliary generator g is
produced by an increase in the ampere-load at the distant point of the line, and
more current is drawn through the return feeder H, thus relieving the track of
current and keeping its potential very near that of the earth. It is obvious that
the arrangement shown by Figure 4 can be repeated for other more or less distant
points of the line, and for points on other branches of the rail- or tram-way.
4
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, as communicated to me
from abroad, I declare that what I claim is :-
1. In electric railways and tramways, having return circuits formed by rails and
insulated return conductors, the insertion into the return conductors of sources
of E.M.F. substantially as and for the purpose hereinbefore described with
reference to the accompanying drawings.
2. In electric railways and tramways having return circuits formed by rails and
insulated return conductors, the insertion in the return circuits of storage batteries
as sources of E.M.F., the said batteries being provided in duplicated and arranged
as shewn by Figure 1 of the accompanying diagrams, substantially as and for the
purposes herein before described.
3. In electric railways and tramways having return circuits formed by rails and

page_text: insulated return conductors, the insertion in the return circuits of a dynamo as an
auxiliary source of E.M.F., the field of the dynamo being excited by the return
current, substantially as and for the purposes herein before described with reference
to the accompanying diagrams.
4. In electric railways and tramways having return circuits formed by rails.
and insulated return conductors, the insertion of a dynamo as an auxiliary source
of E.M.F. the field of the said dynamo being excited by the current of that feeder.
which joius the trolley or equivalent wire in the neighbourhood of the point in the
track where the return feeder is attached, substantially as and for the purpose.
Hereinbefore described and as illustrated by the accompanying diagrams.
5. In electric railways and tramways having return circuits formed by rails and
insulated return conductors, and having an auxiliary generator, the method of and
means for regulating the speed and excitation of the said generator, substantially
as and for the purposes hereinbefore described and as illustrated by Figure 4 of the
accompanying diagrams.
Dated this 14th day of Lulu á D 1806
WILLIAM E. HEYS.