Electrical Road-traction Installations Worked by Means of both Alternating and Continuous Currents.
Year: 1897

page_text: Date of *pplication, 9th Mar., 1897-Accepted, '0th Apr., 1997
Electrical Road-traction Installations Worked by Means of both
Alternating and Continuous Currents.
1, MAX DERI, of 1 Reichsrath Strasse 3, Vienna, Engineer, 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 :—
Although the great advantages of the use of alternating currents, in particular
polyphase alternating currents, have been duly appreciated, both as regards
production, supply and utilisation, for the various purposes of transmission of
power, yet in the case of road traction, in particular for electric railways and
tramways, the system has as yet only been applied to a very small extent.
The cause of this lies mainly in the peculiarity of the alternate current motors,
which, although as regards construction and action are stronger and frequently
more suitably constructed than the continuous current motors, yet in view of the
variable speeds which the system of traction requires, they do not act so advan-
tageously as continuous current motors; and in addition the system is subject to
the difficulty arising in the employment of accumulators in conjunction with
alternating currents.
Lastly, considerable complications are also caused, in particular when polyphase
alternating currents are used, by the necessity of providing several conductors
arranged along the entire line.
In order to render alternating currents available for road traction, at least
indirectly, it has been repeatedly proposed to provide near the line of railway or
tramway transforming stations which convert the total electrical energy of an
alternating current supply into continuous current. These transforming stations,
consisting of alternate current motors and continuous current dynamos, are very
expensive installations, cause considerable losses of energy, and require special
care and supervision and are therefore disadvantageous in respect to due economy
in the working the line.
My invention relates to a method of operating whereby all the above mentioned
difficulties are obviated, that is to say, whereby, without the use of transforming
stations, the application of single or polyphase alternating currents with accumulators,
and the simultaneous utilisation of the advantageous properties both of alternating
current-motors and of continuous current-motors are rendered possible.
The greater part of the energy for the working is in this case supplied directly
by alternating currents, and only a small portion, namely the accumulator work, is
obtained by transformation; the economy of working is therefore greatly improved
in comparison to the existing mixed system.
According to my invention, single or polyphase alternating currents are supplied
from a central station either directly or by means of transformers, to the line of
railway or tramway, where they are passed into the line conductors. It is, for the
purposes of my invention, immaterial whether the conductors are arranged over-
head, underground, or on the ground, but it may be mentioned that it is not
necessary to arrange the conductors in a continuous manner along the line; they
may be interrupted or omitted at points where their arrangement would be difficult,
or where their existence would interfere with the traffic, for example at points and
crossings, at stations, &c.
The line-conductors supply the alternating currents to the motors on the vehicles

page_text: 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 :-
In electrical road-traction-installations, the simultaneous employment of single or
polyphase alternate current motors and continuous current motors, both descriptions
of motors being either mounted on one and the same axis, or on different axes of
the same vehicle or the same train, and the alternate current motors being supplied
with alternating currents by the line-conductor from stationary current generators,
while the continuous current motors are so connected to accumulator batteries on
the vehicle or train that these are thereby at one time charged by means of the
excess of propelling energy, while at another time they give out such stored energy
in assisting in propelling the train, or in effecting the starting and propulsion of the
train, substantially as described.
Dated this 9th day of March 1897.
ABEL & IMRAY,
Agents for the Applicant.