Improvements in Conductors for Electric Railways.
Year: 1893

page_text: Date of Application, 11th Mar., 1893
Complete Specification Left, 2nd Jan., 1894-Accepted, 3rd Feb., 1394
PROVISIONAL SPECIFICATION.
Improvements in Conductors for Electric Railways.
I, JAMES ALFRED EWING, of Laugdale Lodge, Cambridge, Professor of
Mechanism and Applied Mechanics in the University of Cambridge do hereby
declare the nature of my invention for IMPROVEMENTS IN CONDUCTORS FOR
ELECTRIC RAILWAYS to be as follows:-
My object is to avoid electromagnetic disturbance in the neighbourhood of
electric railways from the currents that are used to work the line. Such disturbance
is liable to occur even when the positive and negative conductors are both insulated,
in consequence of their not being coincident or perfectly close to one another. I
reduce this disturbance by using insulated conductors and splitting up either the
positive or the negative conductor, or both, into two or more parts, and placing
these parallel to each other in such relative positions that the resultant positive
current or axis of the positive conducting system coincides with the resultant
negative current or axis of the negative conducting system.
A simple way to carry this out is to use a single conductor for say the positive
current and to divide the other conductor into two parallel parts which share the
negative current equally between them, and to place the positive conductor midway
between the two negative conductors. At any distant point the two negative
currents are sensibly equivalent in electromagnetic effect to a single current
midway between them, and as this equivalent resultant negative current coincides
in position with the positive conductor the electromagnetic effect is nearly
neutralised.
Dated this 10th day of March 1893.
Improvements in Conductors for Electric Railways.
I JAMES ALFRED EWING of Langdale Lodge Cambridge, Professor of
Mechanism and Applied Mechanics in the University of Cambridge, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
My object is to avoid electromagnetic disturbance in the neighbourhood of
electric railways from the currents that are used to work the line. Such disturbance
is liable to occur even when the positive and negative conductors are both insulated
in consequence of their not being coincident or perfectly close to one another. ID
other electric circuits electromagnetic disturbance is often avoided by twisting the
conductors together or by making one of them hollow and placing the other within
it. These devices are not applicable to the service conductors of an electric
railway, from which current is taken to the electric locomotives by means by means
of slippers or other collectors moving in contact with the conductors, neither is it
convenient in such cases to place the conductors very close to one another.
insulated conductors placed far enough apart to allow slippers to be readily used
will give rise to electromagnetic disturbance. I reduce this disturbance to an
insignificantly small amount by dividing one or other or both of the conductors
into two or more parts and placing these parallel to each other and in such relative
Price 8d1
Two

page_text: positions that the resultant positive current, or axis of the positive conducting
system, coincides with the resultant negative current, or axis of the negative
conducting system. In other words at any cross-section the area of section of the
positive conductors taken together has its centre of gravity at the same place as
that of the negative conductors. This allows the conductors to be kept reasonably
far apart without producing serious disturbance at places near the railway.
A simple method of carrying out the invention is to use a single conductor for
(say) the positive current and to divide the other conductor into two parallel parts
which share the negative current equally between them, and to place the positive
conductor midway between the two negative conductors. At any distant point the
two negative currents are sensibly equivalent in electromagnetic effect to a single
current midway between them, and as this equivalent resultant current coincides in
position with the positive conductor the electromagnetic effect is nearly neutralised.
To ensure an equal or nearly equal division of the current between the two parts
of the divided conductor these should be made of equal or nearly equal conducting
power and should be connected together at intervals by cross-conductors.
Another method of carrying out the invention is to use four conductors, two
positive and two negative, and arrange them symmetrically in pairs with one positive
near to one negative conductor in each pair.
Only one positive and one negative conductor need be exposed to contact with
the collectors provided a sufficient amount of electrical cross-connection be
introduced between conductors of the same name to secure that the current shall
be divided between them nearly equally. It is understood that the conductors are
insulated, otherwise another class of disturbance is liable to arise from the spreading
of current through the surrounding earth. The arrangements at points and
crossings by means of which the conductors are made to pass each other and to
pass the rails need not differ materially from the arrangements which are already
used in electric railways.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The use in electric railways of a group of insulated conductors arranged so
that the external electromagnetic effect is minimised by dividing either the positive
or the negative conductor or both into two or more parts and placing these so that,
at any cross-section, the joint centre of gravity of the positive members of the
group coincides or nearly coincides with the joint centre of gravity of the negative
members.
2. The use in electric railways of three insulated conductors so placed that the
current going out along one has its electromagnetic effect nearly neutralised by
returning along the other two jointly.
3. The use in electric railways of three insulated conductors one midway
between the other two, the current going out along the middle conductor and
returning divided equally or nearly equally between the other two.
4. The use in electric railways of four insulated conductors arranged substantially
as and for the purpose described.
Dated this First day of Janu 1804
J. A. EWING.