Improvements in Supplying Electrical Energy to Motor Vehicles on Electric Railways and to Electromotors on Vessels by Means of Alternate Current Transformers.
Year: 1893

page_text: Date of Application, 28th July, 1893
Complete Specification Left, 27th Apr., 1894-Accepted, 2nd June, 1894
PROVISIONAL SPECIFICATION.
[Communicated, from abroad by Messrs. SIEMENS & HALSKE, of Berlin, in the
German Empire, Electrical Engineers.]
Improvements in Supplying Electrical Energy to Motor Vehicles on
Electric Railways and to Electromotors on Vessels by Means of
Alternate Current Transformers.
We, SIEMENS BROTHERS & Co. Limited, of 12 Queen Anne's Gate,
Westminster, in the County of Middlesex, Electrical Engineers, do hereby declare
the nature of this invention to be as follows:-
Electric railways as heretofore constructed have almost always been worked by
means of continuous currents.
This method of working suffers from the disadvantage that it can only be
employed with comparatively short lines, as a continuous current of very high
voltage such as would be necessary for the economical working of long lines of
electric railways, cannot be produced either directly nor by transformers.
Our foreign correspondents have in consequence hereof already in the year 1886
proposed the application of alternating currents in place of continuous currents for
this purpose, as by this means currents of high voltage could be conveyed to long
distances and be converted by transformers to the requisite low voltage at the
motors of the trains.
Such an arrangement was described in the Specification to Patent No. 10,926
of 1886. This arrangement however suffered from the defect cominon to all distri-
bution installations worked by high tension alternating currents, in which the
consumption of energy varies considerably, that during the time that the trans-
formers are not loaded they cause very considerable losses of energy owing to the
continued reversal of the magnetism of their core.
According to the present invention this defect is avoided by applying to the
working of electric railways and the electric propulsion of vessels on water,
the construction of transformers for working with varying loads described in the
Specification to our application for Letters Patent No. 19,821 of 1892. The
essential feature of this construction of tranformers consists in so arranging
the primary and secondary coils thereof that the number of windings is increased
during the time when the load is diminished, without changing the ratio of
conversion, or the windings, being arranged in sections, are connected in parallel
when the load is great, and in series when the load is small. When the latter is
effected, the core is only weakly magnetised and consequently does not wastefully
consume energy in the continued reversal of its magnetism.
This arrangement possesses, among other obvious advantages, the following:
Firstly, as in the case of railways supplied with continuous current, there is
available at all times and at all parts of the line the full supply of power.
Secondly, the switches and connections required for the transformers are rendered
so simple and are so little subject to disturbance, that the whole system, in addition
to its economy, affords an hitherto unknown degree of reliability. The actuation of
the switches of the transformers can be rendered entirely independent of the direct
action of passing trains.
It is only necessary for this purpose to include in the secondary winding of each
transformer a solenoid which, as soon as the current passing through the winding

page_text: exceeds a certain value, draws inwards an iron core acted upon in the contrary
direction either by gravity or by a spring, so that it will be drawn outward again
when the strength of current decreases to a certain extent. This motion of the
iron core is utilised for simultaneously actuating switches by the motion of which
the primary and secondary windings of the transformer are increased or decreased,
according to whether the load is small or great.
Thus when a vehicle with an electric motor approaches a particular transformer,
the current given off therefrom increases, and the switches are actuated so as to
reduce the windings and enable the transformer to supply the full current. As the
vehicle passes away, the current taken off diminishes and the switch apparatus is
moved so as to increase the windings in such manner that the iron core will only be
weakly magnetised.. A number of the transformers constructed as above described
are arranged at about equal distances along the line of railway, the circuits of the
secondary coils, including the solenoids, being connected in parallel to the rails, or
to the separate conductor if the rails do not act as such, while the primary coils of all
the transformers or of a group thereof, are connected in parallel to the circuit of the
electric generator at the central station.
All the transformers work with the same secondary potential, so that if there is
no motor vehicle on the line, none of the transformers give off current.
When a
motor vehicle is travelling along the line they are successively actuated as above
described. Should by accident one of the transformers be thrown out of action,
which owing to the simplicity of the construction, is very remote, the working of
the line is in no way interrupted as all the transformers being connected to the
continuous conductor of the line, the transformers contiguous to the one that is
thrown out of action will supply current to the section of the conductor to which it
is connected and will thus enable the vehicle to proceed even though it be 'at a
diminished speed.
This advantage is gained by the fact that the conductor of the line does not
require to be divided into separate sections. Should it however, not be required to
avail oneself of this advantage the conductor may of course be divided into separate
sections each of which would be supplied by one or more transformers.
The system is applicable either with single or polyphase alternating currents.
It will be evident that it may also be used for supplying conductors arranged along
waterways for supplying current to electromotors on vessels.
Although it is preferred to actuate the switches of the transformers automatically.
'as described, yet they might also be worked by hand by the attendants on the
line, or by the passing train through the medium of any suitable known pedal
arrangement.
Dated this 28th day of Lule 1902
ABEL & IMRAY,
Agents for the Applicants.
Improvements in Supplying Electrical Energy to Motor Vehicles on
Electric Railways and to Electromotors on Vessels by Means of
Alternate Current Transformers.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate,
Westminster, in the County of Middlesex, Electrical Engineers, 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:―
Electric railways as heretofore constructed have almost always been worked by
means of continuous currents.
This method of working suffers from the disadvantage that it can only be

page_text: employed with comparatively short lines, as a continuous current of very high
voltage such as would be necessary for the economical working of long lines of
electric railways, cannot be produced either directly nor by transformers.
Our foreign correspondents have in consequence hereof already in the year 1886
proposed the application of alternating currents in place of continuous currents for
this purpose, as by this means currents of high voltage could be conveyed to long
distances and he converted by transformers to the requisite low voltage at the
motors of the trains.
Such an arrangement was described in the Specification to Patent No. 10926
of 1886. This arrangement however suffered from the defect common to all
distribution installations worked by high tension alternating currents, in which the
consumption of energy varies considerably, that during the time that the trans-
formers are not loaded, they cause very considerable losses of energy owing to the
continued reversal of the magnetism of their core.
According to the present invention this defect is avoided by applying to the
working of electric railways and the electric propulsion of vessels on water, the
construction of transformers for working with varying loads described with reference
to lighting installations in the Specification to our Letters Patent No. 19821
of 1892. The essential feature of this construction of transformers consists in so
arranging the primary and secondary coils thereof that the number of windings is
increased during the time when the load is diminished, without changing the ratio
of conversion, or the windings, being arranged in sections, are connected in parallel
when the load is great, and in series when the load is small. When the latter is
effected, the core is only weakly magnetised and consequently does not wastefully
consume energy in the continued reversal of its magnetism.
This arrangement possesses, among other obvious advantages the following:
Firstly, as in the case of railways supplied with continuous current, there is
available at all times and at all parts of the line the full supply of power.
Secondly, the switches and connections required for the transformers are rendered
so simple and are so little subject to disturbance that the whole system, in addition
to its economy, affords an hitherto unknown degree of reliability. The actuation
of the switches of the transformers can be rendered entirely independent of the
direct action of passing trains.
It is only necessary for this purpose to include in the secondary circuit of each
transformer a solenoid which, as soon as the current passing through the winding
exceeds a certain value, draws inwards an iron core acted upon in the contrary
direction either by gravity or by a spring so that it will be drawn outward again
when the strength of current decreases to a certain extent.
This motion of the iron core is utilised for simultaneously actuating switches by
the motion of which the primary and secondary windings of the transformer are
increased or decreased, according to whether the load is small or great.
Thus when a vehicle with an electric motor approaches a particular transformer,
the current given off therefrom increases; and the switches are actuated so as to
reduce the windings and enable the transformer to supply the full current. As the
vehicle passes away, the current taken off diminishes and the switch apparatus is
moved so as to increase the windings in such manner that the iron core will only be
weakly magnetised.
Fig. 1 of the accompanying drawings shews a transformer for variable loads
arranged with an automatic switch apparatus as above described.
The primary and secondary windings are divided into groups Wi Wi W: 'W'
which can be connected either in parallel or in series by the switch apparatus.
s is the solenoid introduced into the secondary circuit, is the iron core acted
upon by the coil. The core is attached to a spring that tends to withdraw it
from the solenoid, and it is connected in any suitable manner, such as by the
bars G to the switch levers H. When these are moved into the position shown in
fill lines by the attraction of the core by the solenoid, the sections of the trans-
former windings are connected in parallel and when they are moved into the
.**.

page_text: position in dotted lines by the withdrawal of the core by the spring f, the sections
are connected in series, so as to increase the windings.
Fig. 2 shews a diagram of the arrangement of several of such transformers
connected to the supply conductors of a line of railway. D is the central station
alternate current generator, the current from which is supplied in parallel to the
primary coils of the several transformers T1 T2 T3 T the secondary coils of which
are connected in parallel to the supply conductors a a'; all the transformers work
with the same secondary tension, so that when no vehicle is on the line no current
is delivered from any of the transformers.
If however there is a motor vehicle on the line, it will take up current from the
conductors a and al; this current will mainly be supplied from the nearest trans-
former. U indicates the before described automatic switch apparatus of the
transformer.
Experience has shown that on the reversal of the transformer switches there is
practically no sparking, so that the switch apparatus is maintained in good order
for a long time.
These switch apparatus can, as will be seen from the drawing, be of so simple a
construction that there is practically no risk of their getting out of order. Should
however one of them become inoperative, the working of the line is in no way
interrupted.
As all the transformers are connected to the continuous conductors, in the event
of one of them being thrown out of action, the contiguous transformers will supply
current in its place, and effect the propulsion of the vehicle, train or boat taking
current from the conductors, even though it be at a somewhat diminished speed.
This last named advantage is mainly attained by the fact that with this arrangement
it is not necessary to divide the working conductors a a¹ into separated sections,
each of which is provided with its own transformer or transformers.
If it is not desired to utilise this advantage the conductors a a' may also be
divided into separated sections, each having its own transformer or transformers.
The system is applicable with either single or polyphase alternating currents.
It will be evident that it may also be used for supplying conductors arranged
along waterways for supplying current to electro-motors on vessels.
Although it is preferred to actuate the switches of the transformers automatically
as described, yet they might also be worked by hand by the attendants on the line
or by the passing train, through the medium of any suitable known pedal
arrangement.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what
we claim is :-
1. The use for supplying electrical energy to electric railways and electrically
propelled vessels, of transformers constructed and operating as described in the
Specification to Patent 19,821 of 1892, and arranged at distances apart along the
conductors supplying the electrical energy to the vehicles or vessels with which
conductors the secondary circuits of the transformers are connected in parallel,
while the primary circuits are connected in parallel to the conductors from the
current generator, these circuits being so controlled by a switch apparatus that
when the consumption of energy is small or ceases, the extent of the primary and
secondary windings of the transformer is increased, without altering the ratio of
conversion, for the purpose of reducing the magnetising work of the transformers
during the time when they have little or no load, substantially as described.
2. In alternate current transformers such as are referred to in the preceding
claim, effecting the automatic reversal of the switches that control the windings of
the transformer, by means of a solenoid included in the secondary circuit thereof
and having a moveable core connected to the switches, so that when the current in
the circuit increases beyond a certain amount the core in being attracted by the
solenoid moves. the switches so as to decrease the primary and secondary windings,

page_text: while when the said current decreases again, the core is withdrawn from the
solenoid by a spring or by gravity and thereby moves the switches so as to increase:
the primary and secondary windings, substantially as described.
Dated this 26th day of April 1894.
ABEL & IMRAY,
Agents for Applicants..