An Improved Method of and Apparatus for Controlling Electro-motors.
Year: 1895

page_text: Date of Application, 9th Feb., 1895-Accepted, 27th Apr., 1895
COMPLETE SPECIFICATION.
An Improved Method of and Apparatus for Controlling
Electro-motors.
I, JAMES DEVONSHIRE, Secretary of The British Thomson-Houston Limited,
of 38 Parliament Street, Westminster in the County of Middlesex, (a com-
munication to Edward D. Priest of Schenectady, County of Schenectady, State of
New York, 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 :--
This invention relates to controllers for electric motors and especially to those
operated by the now well known "series-multiple" or "series-parallel" system, in
which the motors are first put in series to develop the greatest torque at low speed,
and afterwards are thrown into various combinations of series-multiple and multiple
to get higher speeds; and has for its object to provide an apparatus of the kind
described which shall operate with ease and efficiency and in which the rotation of
the commutating switch shall be continuous in one direction if desired; that is to
say in which from the highest speed to the off position shall be only a single step,
thus rendering it unnecessary for the engineer to reverse the action of the con-
troller under ordinary circumstances. The apparatus is particularly designed for
the control of motors in trunk line railway or long distance work, but I do not by
this statement mean to exclude from its scope ordinary tramway or surface railway
work, as it is well adapted to this purpose also.
Briefly stated, the apparatus consists of two cylinders, one of which, the
commutating or controlling cylinder for the motors, is adapted to revolve
continuously in either direction, while the other, which is used as a switching
cylinder for the resistances in ways well understood, does not revolve, but reciprocates
about its axis; the two cylinders are geared together, and the relation of the
gearing is such that the reciprocating cylinder makes a complete stroke, that is,
from one side to the other, or from a position where all of the resistance is in
circuit to one in which it is cut out and back again, during a partial revolution of
the commutating cylinder; and by a slightly greater movement of the commutating
cylinder, the circuit is opened upon the resistance switching cylinder, or the
resistance cylinder, as it will be hereafter called. By this combination of apparatus
a method of control of electric motors is obtained which I believe to be novel, and
which consists in the main in the fact that by this arrangement it is always possible
to open the circuit upon the resistance cylinder; it is further possible to always
open the circuit when the resistance is included therein, and lastly, the changes of
the motor combinations are effected during the time that the circuit is thus opened,
and when the circuit is again closed, the resistance is in and no injurious jump or
shock to the motors is experienced. To state the method somewhat more fully,
before changing the combination of the motors a resistance (by preference a some-
what high resistance) is introduced into the circuit and then the circuit is opened;
the changes in the motor combinations are then made and with the resistance still
in, the circuit is closed again, the resistance is cut out, and the motors are operated
in their new combination so long as may be desirable. This method is pursued
even when the controller is rotated backwards; it may become necessary to stop
the train or car before it has attained full headway, and under such circumstances
the shortest way may be to turn the controller handle backwards; but by the

page_text: arrangement which has been designed of having the resistance cylinder make a
complete reciprocation with every change in running position of the motors, the
same result will be attained whether the controlling handle be turned forward or
back that is to say, the resistance will be in circuit whenever the circuit is being
opened and whenever the circuit is being closed, being only out of circuit when toe
controller is in a running position.
It is also aimed to employ novel methods of combining the motors, which will
be more fully pointed out in the claims annexed to this Specification.
The accompanying drawings show an embodiment of the invention, Figure 1.
being a plan partly broken away of the improved controller; Figure 2 a front
elevation partly in section of a portion thereof; Figure 3 a development of the
two cylinders, and Figure 4 a series of diagrams showing the motor combinations.
In Figures 1 and 2, A is the controller or commutating cylinder, B the resistance
cylinder, C is a bar connecting the handles of the two cylinders, G, H are gears,
one of which is mounted at the axis of the crank N of the commutating cylinder
and the other upon that cylinder itself. By the proportioning of these two gears
the engineer determines what part of the contact shall pass under the brushes
during a single revolution of the crank N. Fis a similar crank attached to the
segment D meshing with a pinion E upon the resistance cylinder B. I is a handle
turning the crank N. An examination of the parts just described will show that
with every revolution of the crank N the bar C draws the crank F from left to
right in Figure 1, and as the crank N returns to its original position, the bar C
thrusts the crank F back again; and thus the segment D is reciprocated, rotating
the cylinder B first in the direction of the arrow, and then back again. Thus for
every revolution of the crank N this action is repeated and during each such
revolution a determinate part of the contacts upon the cylinder A passes under the
brushes.
Referring now to Figure 3, a development of the cylinders is shewn, the
connections being indicated diagrammatically. The two cylinders are shown with
the brushes out of contact. No change in the circuit relations of the motors takes
place during the revolution of the commutator cylinder from the time the brushes
make contact until it has rotated as far as the dotted line Q, Q; but the contact
brushes, upon the resistance cylinder B progressively touch the short circuiting
plate B2 (for which may be substituted short-circuiting contacts of any kind, for
instance, parallel strips cross-connected, as indicated in Figure 2). The resistance
is gradually reduced by connecting up a greater number of resistances in multiple
until, when the brush M touches the plate B2, it is short-circuited. At all times
when there is liability of sparking, as when any of the brushes / break contact
with the short-circuiting plate B2, the path of the current is around the blow-out
magnets B3, B4, indicated in dotted lines, and the only time they are out of circuit
is when both of the brushes L M are upon the short-circuiting plate B2. Although
series magnets are shewn it is not essential that they should be in the main circuit,
but they may be in shunt. These magnets are preferably located within the
resistance cylinder, and in order to reduce the resistance and self induction of the
windings, they may be arranged in multiple either by placing the entire coil of
each magnet in multiple to its mate, or by having multiple circuits through the
coils. Inasmuch as the circuit is never opened upon the commutating cylinder, it
is unnecessary to have such magnets for that cylinder.
The paths of the current in the various combinations are as follows; starting
with the trolley K, the current enters by the brush L upon the resistance cylinder,
thence to brush 1, through the magnet B³, thence through the resistances, thence
through the magnet B to the lead O and by this lead to the brush a upon the
commutating cylinder, to contact-plate 1, (assuming the brushes to have just made
contact), by cross-connection to contact-plate 6, to the brush d, through the
motor 1 to brush b to contact-plate 3, by cross-connection to contact-plate 10, to
the brush f, through the motor 2 to brush h, to contact-plate 14, by cross-connection
to contact-plate 8, to brush e, through the motor 3 to brush c, to contact-plate 5,

page_text: by cross-connection to contact-plate 12, to brush y, through the motor 4 and out at
ground. This corresponds to the first or series position shown in diagram 1,
Figure 4.
When the brushes a, b, &c., reach the dotted line QQ, the resistance cylinder B
will have completed the entire reciprocation, and the brushes will be again out of
contact after all the resistance has been cut in, thus opening the circuit; while the
circuit is thus broken, the brushes momentarily span the gaps between the contact-
plates 7 and 8, 13 and 14, and the combinations are set up as in diagram 5 of
Figure 4, diagrams 2, 3 and 4 showing what takes place as the cylinder comes to
the position of diagram 5; that is, the resistance is first cut out leaving the motors
all in series as in diagram 2, and then preparatory to opening the circuit the
resistance is again inserted as in diagram 3, after which the circuit is opened as in
diagram 4. The position shown in diagram 5 with the brushes bridging the breaks
in the contact-plates, throws a shunt around each of the groups of two motors, and
thus prevents any destructive spark which would ensue if the contacts were opened
upon the commutating cylinder. The circuits are as follows, omitting in this case
the resistance cylinder, as its action is identical in all the positions of the com-
mutating switch; the current entering at contact-plate 1, goes by cross-connection
to contact-plate 6, to brush d, through motor 1, to brush b, contact-plate 3, by
cross-connection to contact-plate 10, brush f, through motor 2 to brush h, contact
plate 14, by cross-connection to contact-plate 8, brush e, through motor 3, brush c,
contact plate 5, by cross-connection to contact-plate 12, brush g through motor 4
to ground; this being the series circuit, as before traced.
The second circuit starting from contact-plate 1, goes to contact-plate 6 by
cross connection, through motor No. 1 to contact-plate 3, contact-plate 10, thence
through motor No. 2 to brush which at this time is bridging the break between
the contact plates 13 and 14, thence to contact-plate 13, by cross-connection to
contact-plate 15, brush i, and out at ground, thus forming a shunt circuit around
motors 3 and 4; the shunt circuit around the motors 1 and 2 being from contact-
plate 1 to contact-plate 6, by cross-connection to contact-plate 7, to brush e bridging
the break between 7 and 8, and thence, as before, through the motors 3 and 4 to
ground. In this position there is also a path direct from contact-plate 1 to ground
as follows; from contact-plate 1 to contact-plate 6 by cross-connection, by another
cross-connection to contact-plate 7, by the brush bridging the break from the
contact-plate 7 to contact-plate 8, by cross-connection to contact-plate 14, by the
brush to contact-plate 13, by cross-connection to contact-plate 15 and out at
ground.
The position illustrated in diagram 6, Figure 4, occurs when the brushes have
passed the breaks between contact-plates 7 and 8, and 13 and 14, and is as follows:
The current entering at contact-plate 1, passes by cross-connection to contact-
plate 6, through motor No. 1, to contact plate 3, thence by cross-connection to
contact-plate 10, through motor No. 2 to contact-plate 13, by cross-connection to
contact-plate 15, and thence to ground; the path through motors 3 and 4 is
from contact-plate 6 to contact-plate 7 by cross-connection, thence through
motor No. 3 to contact-plate 5, by cross-connection to contact-plate 12, through
motor No. 4 to ground. In this position the brush L is just about to touch the
plate B2 upon the cylinder B and when it does touch, the position is that illustrated
in diagram 7 of Figure 4, that is, with the resistance in series and the motors in
two groups in multiple of two each; the positions illustrated by diagrams 8, 9
and 10 are the same as to motor combinations and vary only in that while the
brushes a, b, &c., are passing from the line Q-Q to the line Q-Q, the resistance
cylinder changes first by cutting out the resistance leaving the motors as in
diagram 8, second by reinserting the resistance as in diagram 9, and then breaking
the circuit with the resistance all in, as in diagram 10, which is the preparatory
step to throwing the motors all in multiple. The position illustrated in diagram 11,
is the first step in this latter process. In diagram 11, the brushes are upon the
line QQ, and bridge over the breaks between the contact-plates 2-3, 4-5, 9-10,

page_text: and 11-12. In this position each of the motors has a shunt around it preparatory
to throwing it in multiple with the others. The circuit is traced from contact-
plate 1 to contact-plate 6, thence through the motor 1 to contact-plate 3, by the
brush to contact-plate 2, by cross-connection to contact-plate 15 and to ground.
Starting again from contact-plate 3, by cross-connection to contact-plate 10, then
to brush through the motor 2, to brush h, to contact-plate 13, to contact-plate 15
by cross-connection and thence to ground. Another circuit leads from contact-
plate 1, by cross connection to contact-plate 6, by another cross-connection to
contact-plate 7, to the brush e, through the motor 3, to the brush c, to contact-
plates 4 and 5 at the break, thence by cross-connection from contact + to contact-
plate 15, and out at ground; again starting from contact-plate 5, by cross-
connectiour to contact-plate 12, thence through motor 4 to ground; the other path
through the motor 4 being from contact-plate 1 to contact-plate 6, by cross-
connection to contact-plate 11, and thence through the motor 4 to ground. In this
position, that is, as indicated in diagram 11 of Figure 4, there are also two paths
to ground directly from the contact-plate 1, as follows: By cross-connection to
contact-plate 6, by cross-connection to contact-plate 9, by the brushes bridging
the break to contact-plate 10, by cross-connection to contact-plate 3, by the brush
to contact-plate 2, by cross-connection to contact-plate 15 and out at ground; the
second direct path being, by cross-connection to contact-plate 6, by cross-connection
to contact-plate 11, by the brush to contact-plate 12, by cross-connection to
contact-plate 5, by the brush to contact-plate 4, by cross-connection to contact-
plate 15, and out at ground. When the brushes have crossed the line Q'Q', the
circuits are all in multiple through the motors and are as follows: From contact-
plate 1 to contact-plate 6, through the motor No. 1, to contact-plate 2, contact-
plate 15 and out at ground. Starting again from contact-plate 1, the circuit
passes to contact plate 6, thence by cross-connection to contact-plate 9, through
motor No. 2, to contact-plate 13, contact-plate 15, and out at ground. The circuit
for motor No. 3 is from contact-plate 1 to contact-plate 6, by cross-connection to
contact-plate 7, thence through motor No. 3 to contact-plate 4, cross-connection to
contact-plate 15 and out at ground; and that for motor No. 4 is from contact-
plate 1 to contact-plate 6, to contact-plate 11, through the motor and out at ground.
The position thus described corresponds to diagrams 12, 13, 14, 15 and 16, and
does not change upon the commutating cylinder after the brushes pass the
line QQ, the changes in the relations of the resistance and the motors being
effected solely upon the resistance cylinder. The next step after the motors
have been thrown in multiple, as in diagram 12, is to complete the circuit
through the resistance, as in diagram 13, the resistance being then cut out, as in
diagram 14, leaving the motors in their last running position. To proceed from
this running position to the off position preparatory to throwing the motor in series,
the resistance is again inserted, as in diagram 15, and the circuit is then opened as
in diagram 16. Between diagrams 16 and 17 the brushes a, b, &c., are upon the
insulated portion R of the cylinder A with the circuit open; and the next step is
when these brushes again touch the contact-plates at 1, 3, &c., thus changing the
combination of the motors from multiple to series as in Figure 17, the circuit
however, being still open. By this arrangement it is possible to pass at once from
the final running position at highest speed back to the off position without going
through all of the intermediate steps.
The resistances in the various combinations of motors are indicated diagram-
matically by triangular figures, the apex of the triangle pointing in the direction
in which the resistance diminishes; for instance, in diagram 1, the resistance is
diminishing preparatory to its being cut out in diagram 2, while in diagram 3 the
resistance is increasing in amount preparatory to the circuit being opened, as in
diagram 4. A comparison of the various diagrams in Figure 4 will illustrate the
fact pointed out in the statement of invention that the resistance increases to a
maximum immediately before the circuit is opened, in whichever direction of
rotation the controller is being operated; and it also exemplifies a peculiarity of

page_text: the controller which is believed to be of great value; that is, that there is an off
position adjacent to each running position so that at whatever speed the vehicle on
which the motors are is being propelled, the circuit may be broken by a single
motion of the operating handle without waiting to run the controller through all
of its various speeds as in some forms of so-called "unbroken circuit" controllers
now in use.
Changes may easily be devised in the arrangements which are illustrated without
departing from the principle of the invention. Other motor combinations, for
instance, might be chosen, and the principle might be extended to a greater or less
number of motors than the four illustrated; but all such changes I regard as formal
and aim to embrace apparatus embodying them in the scope of the claims appended
hereto.
With the apparatus described herein may be combined any suitable step-by-step
device, such as the star-wheel and friction roller now often employed; or the
position of the contacts may be indicated merely by a pointer or index upon a dial
but all this forms no part of the invention, and is well understood in the art, so
that it is not considered necessary to illustrate or describe such parts of an
operative apparatus.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that
what I claim is :-
1. In a series parallel controller for electric motors a switch for the motors
arranged to connect them in various combinations, in series, multiple series or
multiple, and a reciprocating resistance switch adapted to cut in resistance and open
the circuit before each of such changes of combination.
2. In a series parallel controller for electric motors, a switch adapted to connect
the motors in various combinations, series, multiple series or multiple, and a
reciprocating resistance switch arranged to open the circuit through a resistance
before each such change of combination and to close the circuit through a resistance
after each combination is effected.
3. In a series parallel controller for electric motors, a switch adapted to connect
the motors in various combinations, series, multiple series or multiple, and a
reciprocating resistance switch geared to the commutating switch and arranged to
open the circuit through a resistance before each change of combination, and to
close the circuit through a resistance after each combination is effected.
4. In a series parallel controller for electric motors, a commutating device or
cylinder adapted to couple the motors in series or parallel at will, and a
reciprocating resistance cylinder geared to such commutating cylinder and making
a complete reciprocation for a definite arc of movement of the commutating
cylinder.
5. The method of controlling electric motors herein set out, which consists in
closing the circuit through a resistance with the motors in series, then cutting out
the resistance leaving the motors in series in a running position, then reinserting
the resistance, then opening the circuit, then changing the motors to a multiple
series relation by first shunting a part of them and then closing the circuit through
a resistance with the motors in multiple series, and then cutting out the resistance.
6. The method of operating electromotors herein set out, which consists in closing
the circuit through a resistance with the motors in multiple series, then cutting out
the resistance leaving the motors in multiple series as a running position, then
reinserting the resistance and breaking the circuit, then changing the motors from
series multiple to multiple by first shunting each motor with the circuit still open,
then closing the circuit through a resistance, and then cutting out the resistance,
leaving the motors all in multiple as their running position.
7. The method of operating electric motors herein set out, which consists in
closing the circuit through a resistance, with the motors all in multiple, then
breaking the circuit with the motors still in multiple then changing the motors to a

page_text: series position with the circuit still broken, and then closing the circuit through a
resistance with the motors in series, and then cutting out the resistance.
8. The method of operating electric motors herein set out, which consists in
closing the circuit through a resistance with the motors in series, then cutting
out the resistance leaving the motors in series, then reinserting the resistance, then
opening the circuit with the motors still in series then throwing the motors into
multiple series with the circuit still open by shunting some of the motors, then
closing the circuit through a resistance with the motors in multiple series, then
cutting out the resistance, then reinserting the resistance and opening the circuit,
then shunting each of the motors, then throwing them all in multiple, then closing
the circuit through a resistance, and finally cutting out the resistance, leaving the
motors all in multiple.
9. The method of operating electric motors herein set out, which consists in
closing the circuit through a resistance with the motors in series, then cutting out
the resistance leaving the motors in series, then reinserting the resistance, then
opening the circuit with the motors still in series, then throwing the motors into
multiple series with the circuit still open by shunting some of the motors, then
closing the circuit through a resistance with the motors in multiple series, then
cutting out the resistance, then reinserting the resistance and opening the circuit,
then shunting each of the motors, then throwing them all in multiple, then closing
the circuit through a resistance, then cutting out the resistance leaving the motors
all in multiple, then reinserting the resistance, then opening the circuit, then changing
the motor combination to series, as herein set out.
Dated this 8th day of February 1895.
JAMES DEVONSHIRE.