Improvements in Resistance Apparatus for Regulating Electro- motors.
Year: 1898

page_text: Date of Application, 27th Apr., 1898-Accepted, 11th June, 1898
COMPLETE SPECIFICATION.
Improvements in Resistance Apparatus for Regulating Electro-
motors.
We, SIEMENS BROTHERS & CO. LIMITED, of 12, Queen Anne's Gate, Westminster,
S.W., in the County of London, Electrical Engineers, do hereby declare the nature
of this invention (as communicated to us from abroad by Siemens & Halske Aktien-
Gesellschaft, of Markgrafen-Strasse, No. 94, Berlin, S.W., in the Empire of
Germany, Electrical Engineers), and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:
The starting of electromotors and the regulation of the speed thereof, in
particular of those used for railway or tramway cars, is generally effected in such
manner that, with series motors, in order to pass from a slow speed to quick speed,
the resistance introduced in series with both the field magnets and the armature, is
cut out, after which a second resistance is introduced in shunt to the magnet
windings.
With shunt motors the above operation is effected by first cutting out the
resistance in series with the armature, after which a second resistance is intro-
duced in series with the magnet windings. In both arrangements the said
operations always occur consecutively, and the present invention is based upon
this fact. It consists in employing in either case in place of two sets of resistances,
only a single set, which is used consecutively for starting the motor and for sub-
sequently weakening the magnetic field. We will describe the arrangements
employed for this purpose with reference to the accompanying drawing in which
Figure 1 shews a diagram of the arrangement employed for applying the invention
to series motors.
M represents the field magnet windings and W the one set of resistances.
The contacts from which leads pass to the corresponding resistance stages, are,
for the sake of clearness, shewn to the right of the resistances for the regulation of
the main current, and to the left thereof for the regulation of the shunt current,
and two corresponding switch levers are shown. The positions of the switches and
the action of the motor resulting therefrom are as follows:
-
1. The left hand switch is on cut-out contact 0; the right hand switch is on
cut-out contact 01; the motor is stationary.
2. The left hand switch is on cut-out contact 0; the right hand switch is
moved gradually upward from cut-out contact 0¹.
The motor is thus started and the speed gradually increases until the right hand
switch arm arrives on the top contact 7, where it remains.
3. The right hand switch is on contact 7; the left hand switch is moved from
the cut-out contact 0 gradually upward. The speed still increases until the left
hand switch arrives at the top contact 10, when the motor will have attained its
greatest speed.
By the gradual movement of the right hand switch as stated at (2) the resistance
inserted in the main circuit series with the motor is gradually diminished to zero,
while by the movement of the left hand switch as at (3) the same resistance is

page_text: utilised for being connected in parallel with the circuit of the field magnet-
winding, thus producing the above described action of the motor.
Fig. 2 shews the arrangement for shunt motors. M and W represent as before
the magnet windings and the set of regulating resistances.
The arrangement of the connections is somewhat different from that of Fig. 1,
corresponding to the different type of motor, otherwise it is the same as above
described, as will be readily seen from the drawing.
The positions of the switches and the actions produced thereby are as follows: -
1) The left hand switch is upon contact A (negative pole); right hand switch
is on the cut-out contact 01; the motor is stationary.
2) The left hand switch is upon contact A; the right hand switch passes
gradually from cut-out contact Of upward; the motor is started and the speed is
gradually increased until the right hand switch arrives at the top contact, where
it remains.
3) The right hand switch is on contact 7, the left hand switch passes gradually
from contact A downwards. The speed further increases until the left hand switch
arrives on the lowest contact 10, when the motor will have attained its highest
speed.
In the positions described under (2) the resistance inserted in the main circuit
in series with the motor is gradually reduced to zero, while the field magnets remain
fully excited; with the positions at (3) the magnetic field is gradually weakened
by means of the same resistances whereby the described action of the motor is
obtained.
With the present invention the manner in which the same set of resistances are
employed for regulating the series, and shunt circuit is quite optional, and has to
be determined for each particular case. Thus for example it is not absolutely
necessary that two switches should be employed; all the contacts 1 to 10 might
be arranged upon a drum which is turned in one and the same direction by a
crank handle, for effecting consecutively the several commutations above described.
From the above description it will be seen that the set of resistances employed
for regulating the one circuit may be only a part of the set of resistances employed
for regulating the other circuit.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
1. In electromotors, the use of resistances for regulating the action of the motor
so arranged that one and the same set of resistances is employed consecutively for
regulating the armature current and the field magnet currents, substantially as
described.
2. In resistances operating as set forth in the first claim, the arrangement
whereby the entire set of resistances is employed for regulating the one motor
circuit and only part of such set for regulating the other motor circuit, sub-
stantially as described.
Thaind this 97th day of Anmil 1898.