Improvements in Controllers for Electric Motors.
Year: 1896

page_text: Date of Application, 24th Mar., 1896-Accepted, 9th May, 1896
COMPLETE SPECIFICATION.
Improvements in Controllers for Electric Motors.
1, JAMES DEVONSHIRE, Secretary of the British Thomson-Houston,
Limited, of 38 Parliament Street, Westminster, London (a communication from
abroad by Edward D. Priest, Electrical Engineer, of Schenectady, in the 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:-
My invention relates to controllers for electric motors, particularly to railway
motors; and has for its object to provide a controller reliable in action, so that it
will be practically impossible for it to operate improperly; simple in design, 80
that it may not confuse the operator, and permit of the least possible amount of
injury from attempt at improper inanipulation in case the operator becomes
confused; in which the power may be turned off quickly; which will control
the motors with the greatest possible economy and power and in such a way
that maximum traction may always be obtained when desired; convenient in
operation, requiring a minimum amount of power to operate; and in which the
injury either to the controller or to the motors by constant handling will be reduced
to a minimum.
In carrying out the objects of my invention, I adopt the well known series-parallel
system of control; but in the same controller, without introducing undue complica-
tion, I use the straight rheostatic control of the old types of controller; or in other
words, I combine in one controller the two methods of control which may be called
"maximum efficiency" and the "maximum traction" methods. For ordinary
running, it is of course most efficient to start the motors in the series position,
but when the track is slippery, or when, for any other reason, it is desirable to
have the maximum amount of power, it sometimes happens that only one set of
wheels would slip and the revolving motor would cut down the current furnished to
the other motor in series with it, so that very little power would be obtained. In
such cases it is desirable to start the motors in multiple with a resistance in series
with them, and I have arranged my controller to provide for this combination.
Briefly, the arrangement consists in an operating handle for the resistance, which
is arranged upon & reciprocating cylinder, as in my British Patent No. 2913, dated
February the 9th, 1895, and is also connected to a series-parallel switch of simple
construction, more fully described hereafter. Geared to this bandle is a dial
revolving once for every two revolutions of the operating handle, one-half the dial
representing the series position of the motors, the other half the multiple. I also
so arrange my improved controller, that in whichever direction the handle is turned,
the current can only be turned on through resistance, it being understood that the
handle may be freely operated in either direction of motion. In one direction the
motors are coupled in series or "maximum efficiency" relation, and the combination
changes, as hereinafter pointed out, to the multiple position, by continuous rotation;
while in the other direction they may be directly thrown into the multiple or
"maximum traction" combination. In neither case can the train be started with a
jerk; as the current can be turned on only through the resistance and this resistance
is arranged especially for the series combination, the car will start less quickly, if
anything, (the current dividing between the two motors), when the handle is turned
to the multiple position. So also in turning off the current; this can only be done
through resistance. By preference, the system which I employ in masking the

page_text: changes is the so-called "open-circuit" system; in other words, the circuit is opened
between the trolley and the motors before each change of motor relation, and
only closed after the change is effected. As in my Patent above referred to, I
prefer to open the circuit always upon the resistance cylinder, which I provide
with a blow-out magnet; thus there is no sparking at the contacts of the series-
multiple switch, and the change of motor relation may be effected easily.
The accompanying drawings show an embodiment of my invention,
Fig. 1 being a front elevation, partly broken away, of my improved controller;
Figs. 2 and 3 are side elevations showing the detail of the reversing switches;
Fig. 4 is a top plan view of the top of the controller with parts of the mechanism
'shown in dotted lines;
Fig. 5 is a plan view, with the top removed, partly in section;
Figs. 6 and 7 show details of the series-parallel switch and reversing-gear
interlock;
Figs. 8 to 20 are diagrams of the motor combinations preferred, and
Fig. 21 is a general diagram of the circuits.
A is the body of the controller; B is the front or cover, in the case illustrated
made of wood, although it may be of other material; C is the handle, of which
Cis the crank; it is provided with a latch e' controlled by a spindle c in the handle;
D is the segment upon which the handle latch operates, it being provided with
notches d, d indicating the positions of the controller. As indicated, the handle is
free to move in one direction, but each step in the opposite direction must be made
by raising the latch or dog c¹ by means of the spindle c, before the handle can be
operated. By this means any carelessness of the motor-man in turning on the
power too rapidly is checked, while he can turn off the power at once, should it be
desired. At EI indicate the pole-piece of the blow-out magnet, provided with its
coil E. The form of this device is substantially like that shown in British Patent
of James Devonshire, dated March the 18th, 1896, No. 6048, although other
forms may be employed if desired. F is the series-parallel switch, a face view of
the contacts of which is shown in Fig. 21 in diagram. It is provided with two
sets of co-operating fixed contacts ff, and according as it is upon one side or the
other of its central position, makes the change from series to parallel relation of the
motors. G is the handle of the reversing switch. I provide two reversing switches,
(as will be fully explained in referring to Figs. 2 and 3), which are operated by
a single handle and connected by the rod H. I, 1 are the cut-out switches by
which a disabled motor may be removed from circuit and the apparatus operated
with a single motor. At K is a bracket cast upon the top of the controller and
affording a bearing for the operating shaft. N is a lever arm affixed below the
bracket to the operating shaft and working a connecting rod P by which the
rod O is also operated, as will be more fully explained by reference to Fig. 4. A
similar bracket K' furnishes an upper bearing for the parts. The shaft of one of
the reversing switches is indicated at Q, the resistauce cylinder at R and its
co-operating fixed contacts at r, r respectively.
Referring to Figs. 2 and 3, I show the detail of the reversing switches, Fig. 2
being a view of the switch contacts upon the inside of the case, and Fig. 3 showing
the means of operating them situated upon the outside of the case. The handle G
is loosely connected to the cam G2, and moves over the sector G¹, which is partly
broken away to show the construction. A latch g is pivoted upon a lug projecting
from the cam G2, and co-operates with a notch in the sector G¹ so that the reversing
switch may not be accidentally displaced. Lugs g', g* prevent the removal of the
handle G except in one position of the cam G³, that in which the circuit is broken
upon the reversing switches, the lug g' also operating to press the latch g into the
notch before the handle G can be removed. His the rod or link connecting
the two switches, or more accurately, connecting the cam G with the lever Hi
operating the lower switch. The detail of the contacts shown in Fig. 2 is
readily understood. The switch consists of plates G³, G making contact with the
fixed contacts g³ to y respectively. When the contacts g³, g are joined by the

page_text: plates G, and . g by the plate G, the circuit of the motors is in one direction,
while, as will be manifest, when the plate G connects the fixed contacts g, y, and
the plate G³ connects g and 9, the circuit will be in the other direction. The
lower switch provided with its contact-plates G, G, co-operates with its fixed
contacts in the same way, and, as will be manifest from an inspection of its connec-
tions, the lever H' and the rod or link H will be simultaneously operated with the
upper switch by means of the handle G.
Referring now to Fig 4, the operation of the switching mechanism will be
understood from an inspection of the mechanism shown in dotted lines; the
segment O, operated by the rod P connected to the lever N affixe.l to the
lower part of the shaft of the operating handle, operates the resistance cylinder R,
the segment being provided with teeth meshing with those of a piuion upon the
cylinder. At the same time a small gear L' upon the main shaft of the
operating handle, is turned by the rotation of that handle, operating another
gear L affixed to a central shaft L, and thus rotating the cams F2, F shown in
dotted lines. These cams are fixed to studs on the under side of the top or cover
of the apparatus. A fuller understanding of the operation will be derived from an
inspection of Figs. 5, 6 and 7, taken in connection with Figs. 1 and 4.
Referring first to Fig. 7; when the shaft L rotates, the cams F, F also rotate
and operate the cam roller F affixed to the lug N at the back of the case, thus
reciprocating the series-parallel switch F so that it makes contact with either one
or the other of the sets of fixed contacts f, f, its position determining the relation
of the motors; when thrown to the right in the figure, the motors being in parallel,
and when thrown to the left, being in series.
In Figs. 5 and 6 is also shown an interlocking mechanism between the reversing
switches and the series-parallel switch. Upon the shaft L is also fixed a roller or
dise having a notch F with which co-operates the toe of the pawl M' operated
by the lever M connected to the reversing switch handle. For greater certainty
of action the spring M is affixed to the pawl M' so that unless it is positively
engaged with the notch F4 in the roller F, it is withdrawn so that the roller may
rotate freely.
The means for effecting this withdrawal is shown on the right in Fig. 5. The
cam G, operated by the handle G, has at its ends cut-away portions g', 9 co-operating
with the bar M. When the cam is in such position that one of these portions
registers with the end of the bar, the spring M' may withdraw the pawl M' from
the notch F in the roller F, and leave the shaft L³ free to rotate; but in any
intermediate position, the pawl engages with the notch and locks the shaft against
rotation. It is understood that the same lever operates the reversing switches
at both ends of the car, but one lever being provided, so that, if there be two
controllers, the act of withdrawing the lever from one locks it in the open-circuited
position so that it cannot be tampered with while the motorman is at the other end
of the car.
In Fig. 5, the resistance cylinder is shown in plan and one of the fixed contacts
or fingers is also shown enclosed in a chute of insulating material attached to
the pole-piece E of the magnet. In Figs. 8 to 20, I show the motor combinations
which I prefer to employ. In this I have employed the notation R for the
resistance, M F, MA for the field and armature respectively of the first
motor, MF, MA' for the same parts of the second motor, and Gr for ground. It
will be observed that in Fig. 8, which is the first position of the controller, and that
in which the handles may be removed, and at which it is designed that the controller
shall be left when not in use, the circuit is open between the resistance and the
first motor and between the two motors. In Fig. 9, the two motors are coupled
in series but are not yet in circuit with the resistance, as the circuit is open
between the resistance and the first motor. In Fig. 10 this gap is closed and
the motors are in the first running position, indicated by the letters R P.
The second running position is that shown in Fig. 11 in which the resistance
is cut out. The transition steps between Figs. 12 and 15 are indicated in

page_text: the respective figures, in Fig. 12 the resistance being again cut in, in Fig. 13 the
first break in the circuit being made, and in Fig. 15 the motors being in multiple or
parallel, but with a gap between the resistance and the first motor; in Fig. 16 the
third running position is made, and this latter gap is closed, the circuit being through
the resistance in series with both of the motors which are in multiple. In Fig. 17
the final running position is found, differing only from Fig. 16 in having the
resistance short-circuited. The steps from Figs. 17 to 20 are the reverse of those
just noted, that is, in Fig. 18 the motors are in multiple with the resistance included
in series; in Fig. 19 the first break is made, and in Fig. 20 the motors are separated
from each other and from the resistance in the same way as in Fig. 8.
By the term "running position," I mean those positions in which no injury will
be done by allowing the motors to remain; although the term more strictly applies
only to those positions in which the resistance is entirely cut out of circuit.
Fig. 21 illustrates the circuits of my improved controlling apparatus. Therein
T represents the trolley or source of current; .the lightning arrester, the main
switch and the fuse (or circuit breaker of any other type), are indicated diagram-
matically by the rectangles following the trolley. The resistances are arranged in
multiple and lettered R to R", though other numbers of resistance may be used;
it being understood that the rotation of the resistance cylinder R brings a greater
number of resistances into circuit, so that the total resistance is reduced, not by
cutting out portions of resistance and thus diminishing its carrying capacity, but by
cutting in resistances in multiple, thus increasing the carrying capacity of the total.
The resistance brushes or fixed contacts are lettered, as before, . At there is a
'final or short-circuiting contact, the path of the current then being from the trolley
direct to the contact and the motors, cutting out all of the resistances
simultaneously. The other parts of the diagram have been referred to in describing
the apparatus. The circuits are as follows:
The current entering at the trolley and passing through the resistances, comes
out to the final permanent contact Ra, which is arranged to be in circuit, no matter
in what position the cylinder may be. The current then passes around the blow-
out magnet coil E¹ and to the cut-out switch I. If the switch F be thrown to the
left, as in the first position of the motors it would be, then the lead to the lower
half of the switch is open-circuited, and the only path of the current is across the cut-
out switch I'; it then passes through the reversing switch by the plate G, the
motor armature M A', through the other side of the reversing switch by the
plate G, through the motor field M F¹ to the series-multiple switch F,
the contacts f, to the cut-out switch I, through the reversing switch by the plate G³,
the motor armature M A2, through the other side of the reversing switch by the
plate G, through the motor field M F and to ground. When the series-multiple
switch is in the right hand position, however, making contact with the brushes f, fa,
the current is from the cut-out switch I' in two directions; first, as before, across
the cut-out switch to the reversing switch, and by the plate Go through the motor
armature M A', through the reversing switch by the plate G, through the motor
field M F1, to the series-multiple switch, to the fixed contacts fi and thence directly
to ground; the other path of the current is from the cut-out switch I' directly to
the series-inultiple switch F, thence to the contacts fa, thence to the cut-out
switch I, through the reversing switch by the plate G³, through the motor
armature M A³, through the reversing switch by the plate G, to the motor field M F
and to ground.
Referring now to Fig. 4, it will be observed that the pinion L meshing with the
gear L, and the sector O meshing with the pinion upon the resistance cylinder R,
are so related that the rotation of the handle C acts first to throw the series-
multiple switch F to the left, thus putting the motors in series by means of the
cams F, this closing the circuit between the motors, but not closing the circuit
between the trolley and the first motor; then closing the circuit between the
trolley and the motors through the resistance, the upper brush r (Fig. 21), making
contact. with plate 1 upon the resistance cylinder R and the next two brushes

page_text: serving to connect that plate with plate 2; further rotation then couples in more
of the resistance in multiple, as more and more of the brushes r touch the plate 2,
until the resistance is all cut out.
In passing through the entire series of operations necessary in the controller,
during which the handle makes two revolutions, the operation would be as follows:
Turning from the position in Fig. 4 marked "off" to 180°, the first "on" position,
or position in series, is reached, the indicator upon the dial pointing to the series
position. Continuing 180°, the current is cut off and then the handle is at the off
position; another 180° turn, the current is again on and the handle is at the
multiple position, as indicated by the dial. Another 180°, and the current is again
cut off, the handle standing at the off position. For the straight rheostatic control,
the handle is turned 180° from the first off position in the opposite direction. The
motors are thus connected in multiple with the rheostat in series which is thus cut
out without going through the series position. The current may then be cut off by
turning the handle 180° in either direction. By this arrangement, the handle is
always at the off position when it stands at the left, and always in the on position
when on the right of the controller, in a diametrically opposite position. In
whichever direction the handle is turned, these conditions always' obtain; the
operator does not need to read the dial to know when the current is turned off or on,
but has only to see or feel that the handle is pointing to the proper position. In
order to effect the motion of the series-parallel switch at the proper point, the
current is turned off, not after the handle has moved the full 180°, but when it has
moved about 130°; the rest of the half circle after the circuit is broken being
required to change the combinations from series to parallel, or parallel to series, as
the case may be."
A peculiar advantage which I have found in the arrangement pointed out, over
the controllers in which the handle is always moved in one direction to turn the
current on, and in the opposite direction to turn the current off, is that by going
directly into the multiple position, maximum traction may be obtained under all
conditions; and another, and perhaps still more important advantage is that the
wear on the controller and the tendency to break down the insulation in the motors
from inductive reaction when the circuit is broken, is only one half what it is in
breaking the circuit by returning through the series position. A further advantage
is that since at all times current can be turned directly on or off from either series
or multiple position without going through the position not in use, it follows that
it may be turned off quickly and without further accelerating the train, as when
the current is turned off from a multiple position by going through that in series.
Furthermore, the motors are always handled alike, each doing its full share of the
work and taking advantage of the entire weight on the driving wheels. As no
change in the combination of the motors can take place except when the circuit is
broken, all arcing is confined to the rheostatic cylinder, and the interlocking
mechanism does not permit the reversing switch to be thrown when the current is
on; while the removable handle is so arranged, as already pointed out, as to lock
the controller when not in operation.
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. A controller for electric motors comprising means for connecting the motors
in series or parallel and varying the resistance in circuit to suit the conditions of
running, such means being operated by movement of the controller-handle in, one
direction from a position in which the circuit is open, and means for controlling the
motors by the rheostat alone, such means operated by the movement of the handle
in the opposite direction from its open-circuit position.
2. A controller for electric motors comprising a reciprocating resistance switch,
a separate reciprocating series-parallel switch, and permanently connected means
for operating the two switches simultaneously from a single handle.

page_text: 3. A controller for electric motors, comprising a cylindrical reciprocating
resistance switch, a separate reciprocating series-parallel switch, and permanently
connected means for operating the two switches simultaneously from a single
handle.
4. A controller for electric motors, comprising a reciprocating resistance switch,
a separate reciprocating series-parallel switch, means for operating the switches
from a single handle, reversing switches for the motors, and interlocking means
between the operating handle and the reversing switches, whereby the operation
of the reversing switches is prevented except when the circuit is broken.
5. A controller for electric motors comprising a reciprocating resistance switch,
a separate reciprocating series-parallel switch, an operating handle, and means for
operating the two switches from the one handle, comprising gearing between the
operating handle and the series-parallel switch, whereby the handle makes a
revolution for each reciprocation of the series-parallel switch in opposite directions
from a central position in which the circuit is broken.
6. A controller for electric motors, comprising a reciprocating resistance switch,
a separate reciprocating series-parallel switch, and operating handle, means for
operating the two switches from one handle, comprising gearing between the
operating handle and the series-parallel switch, whereby the handle makes a
revolution for each reciprocation of the series-parallel switch in opposite directions
from a central position, and means connected to and operated by the handle and
arranged to indicate the series and parallel positions of the series-parallel
.switch.
7. A controller for electric motors, comprising a reciprocating resistance switch,
a separate reciprocating series-parallel switch, and operating handle having an off
and an on position at opposite sides of the controller, and connecting mechanism
between the operating handle and the two switches, whereby the handle may take
the same positions for off and on in both the series and the parallel positions of the
series-parallel switch.
At out 1 L M 1000