Improvements in Electric Traction.
Year: 1896

page_text: Date of Application, 24th Jan., 1896-Accepted, 21st Mar., 1896
COMIDLEID DI BUIFICATION.
Improvements in Electric Traction.
I, DESIRE KORDA, of 64 Rue Caumartin, Paris, in the French Republic,
Electrician, do hereby declare the nature of this invention aud in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
This invention relates to improvements in electric traction.
The invention
enables alternating currents to be used for the propulsion of vehicles on a
permanent way as will be described in the following Specification reference being
made to the accompanying drawings in which-
Fig. 1 is a diagrammatic view of a track and connections to illustrate the
invention.
Fig. 2 is a similar view of a modified arrangement of same.
Fig. 3 is a cross section of a part of the track on an enlarged scale, and
Fig. 4 is a longitudinal section of same.
Instead of providing the vehicle with a rotary electric motor driving the axle by
means of gearing or other convenient mechanism it is propelled by a combination of
an inductor and a part induced thereby one of these being fixed and the other
carried by the moving vehicle. As one method of carrying this arrangement into
effect I suspend from tubes bb Fig. 1, surrounding the axles of the vehicle, a
structure of convenient form tending to preserve the requisite distance between the
axles of the carriage, and which supports a long piece a, the under surface of which
almost touches the road bed. This piece a is provided with a suitable winding.
It may be considered as an armature of a non synchronous polyphase motor
developed in a straight line. The field of the motor d also developed in a straight
line is placed parallel with and between the two track rails r, r, on which run the
wheels c, c, of the carriage. It is thus evident that a permanent way and a carriage
of the above described construction constitute, as it were, a non-synchronous motor;
the permanent way acting as the field of an infinitely great radius of curvature, the
carriage constituting a portion of the armature or moving part of the motor.
course it is not necessary to state that the armature may also be attached to
specially arranged small trucks in order to maintain a fixed distance between the
parts d and a; in other words in order to maintain constant the air gap notwith-
standing the deterioration of the permanent way, an object which may be.
accomplished by means of suitable regulating mechanism attached to the piece a
and which may be operated from the carriage itself.
Of
The field d, does not need to be continuous, that is to say, it may consist of
sections uniformly spaced. With lengths of sections of say 4 metres, and say
4 metres intervals between each section, the carriage will be always over one
section of the field, the action of which will cause the carriage to pass to the section
in advance, provided that a section of the armature a is mounted at each end of the
carriage or vehicle.
Fig. 1 also shows the arrangement of the circuits, A, being the power station
developing three phase currents, B, a sub station with transformers adapted to lower
the voltage, and d a section of the field with a properly arranged three phase
winding, well insulated and securely fixed to cross ties or directly imbedded in the
earth.
The magnetic field developed in these several sections d, resulting from the
proper combination of the three phase currents in the winding, will be characterized
by poles moving always in the saine direction, for instance in the direction indicated
by the arrow in Fio i

page_text: The result of the action of this moving magnetic field would be the development
of currents in the winding of the piece or armature a attached to the carriage,
whenever the latter is situated above one of the sections of the field d.
The mutual action of the moving magnetic field and the induced currents will
give rise to the movement of the carriage exactly as the rotating field of a three
phase motor sets in movement its armature.
By suitable combinations of the sections of the winding of the piece or
armature a attached to the carriage, that is to say, by coupling the sections in
series, in opposition, in parallel or by introducing suitable resistances, it is possible
to obtain the desired speeds and torque as well as the starting and stopping of the
carriage. The sections d as well as the piece or armature a may be provided with
ring, (but preferably with drum) winding. This latter form of winding is shewn
in the Figs. 3 and 4. In these figures two chaunel irons of U form serve to hold
firmly in place, by means of rivets g partially insulated, the laminations of the core
of the sections of the field d.
The electrical conductors united by appropriate end connections, may be of
iron or copper well insulated.
When once the winding of these sections has been completed the channel section/
is filled with an impermeable insulating material 4, and if deemed advisable, the
upper surface of the laminations of the sections d may be covered with a layer of
asphalt i or with a sheet of zine of 1 millimetre in thickness, the surface of which is
kept clean by a brush. k attached to the earriage and placed directly before the
armature a. In order to avoid a great loss of energy due to the hysteresis in the
laminated or solid parts of the cores of the sections of the field d, as well as to
diminish to the smallest amount possible the Wattless exciting current circulating
through the several sections of the fixed field d, it is necessary that the current
should not pass through the sections d except at the moment of the passage of the
vehicle or carriage. To this end the so called neutral points of the winding of each
'section d should not be united to the ground return or to similar points of the
other windings of the section except during the passage of the carriage. At all
other times the three ends 1, m and n of the three phase winding Fig. 1 should
beither be in contact with each other nor in contact with the earth return. To this
end they are hermetically sealed in a small box o, closed by an elastic conducting
sheet which during the passage of the carriage or vehicle, is pressed down by a
.projecting edge of the armature, and which consequently establishes, during the
passage of the car, a contact between the three ends of the windings in question
and the earth. The box o containing the contacts is situated near the rail for this
purpose. In certain cases for this arrangement may be substituted an automatic
switching device situated near the transformers B, for the purpose of maintaining
the primary circuit of the transformer open during the periods of time in which
cars or vehicles are not to be found on the section of the line fed by this transformer.
In order to move the car or vehicle backwards and also in order to provide an
electric brake without in any manner modifying the nature of the winding of the
field sections d there can be arranged a second series of field sections d parallel
with the section d, wound in such a manner that their magnetic fields move in the
opposite direction to those of the section d (as shown in Fig. 2). In this case the
car or vehicle should be provided with a second armature a' fixed in a position
parallel to the other armature a. If the carriage is moving in a given direction
due to the influence of the field sections d upon the closed circuit of the armature a
it will only be necessary to open the circuit of the armnature a and to close that of
the armature a' in order that the sections d' shall act in the first place as a brake,
and afterwards to reverse the direction of the movement of the car.
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 1
claim is :-
1. The improvement in electric traction by means of polyphase currents which

page_text: consists in the combination of an inductor, and a part induced thereby, one of these
being fixed and the other carried by the vehicle substantially as and for the
purpose described.
2. The improvement in electric traction by polyphase currents which consists in
the employment of an inductor or field forming a part of the permanent way and a
part or armature induced thereby attached to the vehicle in such a manner that
unovement is given to the vehicle by a direct propulsion due to the action of
the magnetic field of the fixed inductor on the part induced substantially as
described.
3. The improved arrangement of parts constituting a system of electric traction
substantially as and for the purpose described and illustrated in Fig. 1.
4. The improved arrangement of parts constituting a system of electric traction
substantially as and for the purpose described and illustrated in Fig. 2.
ou da of Innuant 1006
PHILIP M. JUSTICE,
55 & 56 Chancery Lane, London, Chartered Patent Agent,
For the Applicant.