Improvements in Controllers for Dynamo Electric Machines.
Year: 1896

page_text: Date of Application, 11th Feb., 1896-Accepted, 14th Mar., 1896
COMPLETE SPECIFICATION.
Improvements in Controllers for Dynamo Electric Machines.
I, JAMES DEVONSHIRE, Secretary of The British Thomson-Houston, Limited,
of No. 38 Parliament Street, Westminster, London, (a communication to me from
abroad by Walter H. Knight, Electrical Engineer, of Lynn, in the State of
Massachusetts, United States of America, and John W. Darley, Junior,
Electrical Engineer, of Baltimore, in the State of Maryland, United States of
America) 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 :-
The present invention consists in general in a device for changing two or more
dynamo electric machines, especially motors, from series to parallel connection;
and in this invention a resistance is provided which is included in the circuit
during the time that the successive changes in the motor connections are being
made. The purpose of this arrangement is to permit of the changes being made
without any sudden and dangerous rush of current, so that the gradations in speed
of the machines acting together are made without injury to the machines them-
selves and without discomfort to passengers by reason of unexpected shocks when
motors of this kind are used in connection with electric railway apparatus. It is
also to be noted that the present invention is especially applicable to cases where a
number of large motors are used, as in a locomotive, and that the special arrange-
ment designed permits of the same resistance being used at each period of change
in the motor connections, obviating thereby the use of a large number of separate
resistances.
Referring to the accompanying drawings,
Figures 1, 2, 3, 4, and 5 illustrate diagrammatically the manner in which four
motors are successively connected in order to pass from the series to parallel
connections.
Figure 6 is a side elevation of the controller with the side of the enclosing box
removed. Figure 7 is a plan thereof.
Figure 8 is a sectional detail showing the resistance cylinder with the contact
pieces resting thereon and the blow-out magnet adjacent thereto, and
Figure 9 is a development of the switch cylinder and rheostat contacts.
The controller consists principally of two cylinders, one of which, called herein
the switch cylinder, has a series of contact pieces thereon against which bear
brushes connected to the motor terminals so that by the rotation of the cylinder
various connections between the motors are established, while the other or
rheostat cylinder is provided with a single contact plate adapted to connect with
a series of rheostat terminals, so as to bring more or less of the rheostat into
circuit.
The two cylinders just mentioned are geared so as to rotate together, but at
different rates of speed; the rheostat cylinder making five revolutions while the
switch cylinder is making but one. By this arrangement, (as there are in the case
chosen for illustration, five distinct arrangements of motors corresponding to five
gradations in speed) the resistances controlled by the rheostat cylinder will be
brought into and out of circuit five times in succession while the switch cylinder is
rotating once to establish in succession the various groupings of the motors. The
rheostat cylinder is so adjusted relatively to the switch cylinder that the greatest

page_text: resistance is inserted in the circuit and then gradually reduced during the period
that the switch cylinder is making a change from one motor grouping to another.
After this change has been effected, there is a short movement of both cylinders
during which no change is effected in the motor connections and no resistance
remains in the circuit.
These five points corresponding to the said short spaces of movement are the
five running positions, that is, when the controller has both of its cylinders stopped
at this point, the motors will operate without any resistance in circuit and give a
definite rate of speed for as long a time as may be desirable.
Referring now to the drawings, the rheostat cylinder will first be described.
Referring to Figures 7 and 8, it will be seen that the cylinder A is mounted on a
central shaft A3 and is principally composed of non-conducting material, A2,
having upon its outside a stepped contact plate A of the shape shown in Figure 9.
This contact plate, A4, (which in Figure 9 is distinguished from the non-conducting
portion, A³, by being left white, while the latter is made black), extends the
whole length of the cylinder and is gradually reduced in width by a series of
notches or steps.
R, R, indicate a series of resistances connected at one terminal to the line 30,
and having their opposite terminals ending respectively in a series of contact
pieces b¹ to pl inclusive. These contact pieces are arranged as shown in elevation,
Figure 6, and in section Figure 8, and each consists of an angular part ³, held
firmly by an upright block of insulating material D, the contact pieces are pivoted
to the angular pieces 2, as shown in Figure 8, and pressed against rheostat
cylinder A by means of a spring 63. In order to prevent the brush 6 from dropping
on the insulating or main portion of the cylinder after leaves the contact A,
a lug extends downward into a slot in the part 62, and engages with a screw 6.
This screw 6 renders the brush adjustable for wear and is held in the position
desired by means of a set screw b. For making electrical connection with the
larger contact brushes of the series, an eye, 64, is provided into which the end of a
flexible wire may be soldered. Within the body of the cylinder A and beneath
the contact piece A', is a plate of iron A, forming an armature to the blow-out
magnet ; the pole-piece A' extends spirally from top to bottom of the cylinder,
so as to follow the receding line of the contact piece A' as the cylinder is turned,
and will always serve to complete the magnetic circuit of E, so that the latter
may act more strongly to interrupt any are that may be formed by the passage of
any of the contact pieces a¹, c¹, &c., from the conducting portions A to the
insulating portion A of the cylinder. As appears in Figure 6, the rheostat
cylinder A is mounted vertically with an enclosing frame F and is provided with
a handle G for turning it. The insulating standard D is mounted in the same
frame parallel to the cylinder so that the various contact pieces which it
carries may bear_on the surface of the latter. The magnet E as it appears
from the same Figure 6, is mounted on a board K so that the core of the
magnet is parallel to the cylinder and its poles adjacent to the series of contact
pieces. It will be seen that the three lower contact pieces are of a larger
size than the others having a multiplicity of fingers and that the blow-out
magnet E is divided into two sections the lower and shorter section E being opposite
the larger contact pieces. This arrangement is simply for the purpose of securing
greater magnetic concentration at the points when a greater current is being
carried by the contacts and broken by the passage of the contact pieces from the
conducting to the insulating portions of the switch cylinder. The rheostat
cylinder, as appears from Figures 6 and 7, is provided with a pinion H, engaging
with a gear wheel L on the switch cylinder so that the latter rotates once while
the larger rotates five times. This switch cylinder is similar in character to the
rheostat cylinder and like the latter is journalled in frame F and has a series of
contact pieces a, b, c, etc., bearing respectively on a series of contact plates on the
surface of the cylinder.
These contact pieces are connected respectively to the several line terminals and

page_text: motor terminals as shown in Figure 9 and the contact plates on the surfaces of the
cylinder are arranged as shown in the same figure.
It believed that the general construction of the controller will be clear from
the foregoing description. We will now proceed to describe the operating of the
same.
Referring especially to Figure 9, and to the diagrams Figures 1 to 5, the contact
plates on the switch cylinder are numbered from 1 to 20 and the successive
positions which the contact pieces a, b, c, &c., assume as they are moved around the
cylinder, are represented by the dotted lines from 1 to 12. Of these various positions
the running positions or those in which the controller may be left inadvertently
without injury to the apparatus in order to give a desired speed, are indicated by
the lines 2, 5, 7, 10 and 12. The other positions are those in which certain
preparatory changes are being made accompanied by an insertion of the resistance
before the controller is brought to rest at the several running positions. Assuming
now that the parts are in a position of open circuit, the various contact pieces will
rest on the insulating part of the cylinders and no current will pass. The first
movement, however, of the handle G will bring the line of contact pieces a, b, c, &c.,
into coincidence with the dotted line 1 of the switch cylinder while on the rheostat
cylinder the contact pieces a¹ and b¹ will rest against plate A. The circuit will
then be as follows:
Terminals T, contact a, plate 1, plate 5, contact b, line 31, contact a', plate A*,
contact, resistance R, magnet E, line 30, magnet El, contact k, plate 28, plate 12,
contact e, motor W, contact c, plate 8, plate 17, contact g, motor X, contact i,
plate 22, plate 14, contact f, motor Y, contact d, plate 10, plate 19, contact H,
motor Z, and to the opposite terminals S.
As the handle G continues to turn, the rheostat cylinder will rotate until the
contact pieces are forced into the position indicated by the dotted line xx and the
line of contact pieces on the switch cylinder will in the same time be moved to the
position of the dotted line 2, the result being that the resistance is gradually
and entirely short circuited, the current passing directly from the contact piece a
by the plate A to the plate p'. The motors will still be in series with no resist-
ance in circuit, and will be running at their slowest speed, assuming a constant
electro-motive force on the line. As the rheostats R are in multiple the resistance
will be greatest when one of them is in circuit and it will be reduced as they are
successively connected in multiple by the step contact plate A* until finally they
have all been short circuited as above described and will remain so while the
cylinder is turning from a position with the brushes on the line to the position
with the brushes on the insulating material A2, when the resistance again comes to
a maximum.
It has thus been shown how the motors are first connected in series with the
resistance, and the resistance then cut out, without changing the relation of the
motors, such connections being diagrammatically shown in Figure 1, position 1
and 2. It will not be necessary to trace in detail the succeeding connections as
the contacts on the switch cylinder pass into the successive positions, but it will be
sufficient to refer to Figures 2, 3, 4 and 5, wherein are shown diagrammatically
the different groupings of the motors and the resistance corresponding to the
successive positions of the contact on the cylinder. Thus, in Figure 2, it will be
seen that in position 3, four motors are in series but two of them are shunted
through resistance R; in position 4 the resistance is cut out by the rotation of
the resistance cylinder and the two motors are shunted without resistance while in
position 5, two motors are out of circuit entirely leaving the remaining two in
series to drive the locomotive. This is a running position and a second rate of
speed is thereby secured. In Figure 3 are shown the groupings corresponding to
positions 6 and 7. In the former the four motors are in parallel series, one of the
series containing the resistance while in the latter position, the resistance is cut
out and the four motors will be running in simple parallel series connection.
Figure 4 are shown the groupings corresponding to the positions 8, 9 and 10. In
In

page_text: position 8, one motor out of each series is short circuited through the resistance
and in position 9 the resistance is cut out while in runuing position 10 there are only
two motors in parallel, the other two being. out of circuit. And lastly Figure 5-
shows the groupings corresponding to positions 11 and 12. In the former position
the motors are all in parallel, but the resistance is in series with two of them while
in the latter position the resistance is cut out and the four motors are in plain
parallel connection.
The foregoing description clearly indicates the construction of the controller
and its mode of operation, whereby four machines are gradually changed from
series to parallel connection, and, by means of a single resistance which is successively
introduced into the circuit at the instants of change, it is possible to produce a
succession of increasing speeds without injury to the motors and without shock to
the passengers, assuming of course that the dynamo electric machines are used
for motive purposes and are by any desired means geared to the driving wheels of
a single locomotive. By a single locomotive is meant simply a common load upon
which the motors may act.
It has heretofore been proposed to change motors from series to parallel and to
introduce a resistance while the changes are being made, but it is believed that in
the present invention this principle is for the first time adapted to four motors,
and the particular apparatus above described by which this is accomplished is
also new.
Especial attention is called to the feature of having the switch contacts and the
rheostat contacts upon separate cylinders with a definite rate of gearing whereby
the same rheostats may be used in succession and it may also be added that the
importance of the present invention is emphasized when it becomes necessary, as in
the recent application of electric motors to large locomotive work, to employ
heavy machines demanding a large current at a comparatively high voltage
where the difficulties connected with the change in the circuit connections of such
large machines and the passing of such heavy currents through resistances are
very great.
It is believed that the controller herein described is one adapted for the
successful solution of this problem.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
from abroad, I declare that what I claim is :-
1. In a series parallel controller, the combination, with a switch for changing
the groupings of two or more dynamo electric machines, of a rheostat provided
with a set of contacts and a contact plate therefore movable at a definite different
speed relatively to the said switch, whereby the resistances are successively
introduced into and withdrawn from the circuit at periods corresponding to the
successive changes in groupings of the machines effected by the switch.
2. In a series parallel controller, the combination, with a switch for changing
the grouping of two or more dyuano electric machines, of a rheostat having a
series of contacts and a contact plate separate from the switch movable at a definite
different speed relatively to the said switch adapted to connect the sections of the
rheostat in parallel to lower the resistance, the said contact plate and switch being
connected so as to operate together and successively introduce into and withdraw
from the circuit the resistance at periods corresponding to the changes in the
grouping of the machines effected by the switch.
3. In a series parallel controller, the combination with a switch, substantially as
described, for changing the groupings of two or more dynamo electric machines, of
a rheostat and a contact therefore, adapted to connect it in series with the
machines; the switch and rheostat being connected so as to be operated at definite
relative speeds, thereby introducing the rheostat into the circuit during temporary
changes in the successive groupings of the machines and to withdraw it from the
circuit when the machines are grouped for each permanent and definite rate of speed.

page_text: 4. In a series parallel controller, the combination with a switch for changing the
groupings of two or more dynamo electric machines, of separately controlled
current-reducing means, and a mechanical connection between said switch and
current-reducing means whereby the latter is successively operated a number of
times during the operation of the former to include the resistance in series with all
or part of the machines, as set forth.
5. In a series parallel controller, the combination with a switch, of a resistance,
circuit connections between said switch and resistance, and means, separate from
the switch but operated thereby, for repeatedly introducing and cutting out said
resistance during a single operation of said switcb, to include the resistance in
series with all or part of the machines, as set forth.
6. In a series parallel controller, the combination with a contact cylinder of a
connecting plate thereon against which contact pieces are adapted to bear, a
plate of magnetic material beneath said contact plate and a magnet having its
poles in proximity to said plate whereby the effect of said magnet may be
intensified and interrupt any are which may be formed on breaking of the
connections between the contact piece and their connecting plate.
7. The method of changing a plurality of machines from series to parallel,
which consists in introducing into the circuit at the moment of change a resistance,
rapidly reducing said resistance and gradually withdrawing the same after the
change has been effected.
8. The method of changing motors from parallel series to parallel, which consists
in shunting one-half the motors from each series through a resistance, removing
the resistance, breaking the circuit of the shunted motors and finally placing them
in parallel with the other halves of the two series.
9. The method of changing motors from parallel series to parallel, which consists
in shunting part of the motors from each series, breaking the shunt, and placing
the shunted part of the motors in parallel with the other part.
Dated this 11th day of February 1896.
For the Applicant,
J. C. CHAPMAN,
70, Chancery Lane, London, W.C., Chartered Patent Agent.
J. C. CHAPMAN,
70, Chancery Lane, London, W.C., Chartered Patent Agent.