Improvements in Controlling Devices for Electric Motors.
Year: 1899

page_text: Date of Application, 13th May, 1899 -Accepted, 3rd Feb., 1900
COMPLETE SPECIFICATION.
Improvements in Controlling Devices for Electric Motors.
We, THE BRITISH THOMSON-HOUSTON Company, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature.of this
invention (which has been communicated to us from abroad by Frank E.. Case,
residing at Schenectady, in the County of Schenectady, State of New York,
United States of America, Electrical Engineer), and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement:-
F
The present invention relates to the construction of controlling devices for
electric motors; and has for its object to devise a controller which shall be
adapted to regulate the motors from rest to highest speed when used for propul-
sion, and by turning the handle of the controller in the opposite direction, to
convert the motors into generators for use with electric brakes. This type of
controller is now well known in the art. In general these controllers embody all
the connections in a single cylinder, with the exception of the usual reversing
switch. The difficulty with this construction has been that it makes the cylinder
unduly long, so that the case of the controller is higher than is convenient for
the operator.
The connections have also been embraced in two cylindrical switches operated
by separate handles and, with the reversing switch, provided with interlocking
devices of one kind or another, such that the improper manipulation of the
various handles is prevented. While this is a good and efficient form of ap-
paratus, as is also the first one named, it is also open in some degree to the objec-
tion of making the controller unduly large, and to the further objection of having
a multiplicity of motions which must be carried out in predetermined sequence
in order to effect the purposes of the device. The objections to this, while in
some degree known, are not fully appreciated until the car is actually manipu-
lated. While the device operates readily enough under all ordinary conditions,
the operator having a number of handles to think of, some of which must be
brought to one position before the others can be operated, is apt to become con-
fused in moments of emergency.
In all manner of controlling devices it is now customary to employ contacts
for changing the resistance of the motor circuit, by cutting in or out sections
of dead resistance, so called, either at transition points of the controller or in
making minor graduations of speed between those which are effected by chang-
ing the grouping of the motors. It has therefore been found unnecessary in
a braking controller to use more than one resistance switch, inasmuch as the
resistance employed to regulate the motor speed may well be employed to regulate
the output of the motors as generators, and therefore the braking effect. By
availing ourselves of this fact, we are enabled to construct a brake and power
controller in more compact form than it has hitherto taken, by using the motor
resistance switch as the switch for operating the brake circuits, and employing
another switch which so shifts the connection that the motors are coupled in the
proper way to act as braking generators; while of course the trolley, or other
current supply is cut off. The brake switch, as it is preferred to call it, is
mechanically connected to the motor controller, so that the great advantage of
a single handle with continuous rotation may be employed; that is to say, while

page_text: there is an off position in which none of the apparatus is operative, in the ordinary
control of the car the motorman, in making a stop, turns directly from the power
positions in which the motors are driving the car, to the brake positions in which
the motors are acting as braking generators. No special separate locking means
are necessary for the brake switch, because, being mechanically connected to
the power switch, it is locked when that is locked by the reversing switch in
the usual way. In the practical embodiment of the invention, we place the brake
switch directly beneath the reversing switch and locate all of its contacts on a
cylinder of small size, this being all that is necessary, because the switch has
only two operative positions. The mechanical connection is such that its con-
tacts are open when the power switch is brought to the off position, and before
the fixed contacts of the latter switch connect with the movable contacts, the
brake switch is brought to one or the other of its operative positions, to accord
.with the direction of movement of the operative handle. By this arrangement,
no provision need be made for sparking at the brake switch contacts, inasmuch
as it is always manipulated when the circuit is open. The usual blow-out magnet
is provided on the power switch, and as all the makes and brakes by which
current passes are made there, no damage can be done to the apparatus.
The accompanying drawings shown an embodiment of the invention; Fig. 1
being a front elevation, with the cover removed, of a controller in which it is
employed; Figs. 2, 3 and 4 are view upon an enlarged scale of the mechanical
connection between the brake switch and power switch; Figs. 3 and 4 being
plans of the operating cam and lever looking down from the line 3-4 of Fig. 2.
Fig. 5 is a diagram of the circuits. We will first describe the mechanical con-
structions shown in Figs. 1 to 4.
In Fig. 1, A is the case of the controller, B is the single operating handle of
the motor controlling mechanism and C is the handle of the reversing switch D.
E is the brake switch, and K is the controlling switch. The contacts of the
latter are not illustrated in full, because they will be better understood from
the description of the circuits as shown in Fig. 5. BM is the coil of the blow
out magnet.
The mechanical connection between the controlling switch and the brake
switch E (which, it will be seen, is upon the same line as the reversing switch D,
but is not moved by the same handle, the shafts being divided at N), is shown in
the bottom part of Fig. 1, but it will be better understood from the larger
Figures 2, 3 and 4. In these latter figures F is the shaft of the power switch,
and F that of the brake switch. Upon a stud J is mounted the cam lever I.
This is a three arm lever, the arm I carrying a pin i moving in the slot of the
crank arm L, fixed to the shaft F1 of the switch E. In Fig. 3 this is shown in
the intermediate or off position of the switch, as illustrated in Fig. 5. Another
arm I, of the cam lever carries a cam roller moving upon the upper one of
the two cams H', H fixed to the shaft of the power switch K. Another arm I¹,
of the cam lever, with its corresponding roller i moves upon the lever cam H,
of the two just referred to. The connecting web 13 strengthens the parts, the
whole of the cam lever I, with its arms and the connecting web, being cast in
a single piece, although of course it may be made in other ways. As already
explained, the switch E stands in Fig. 3, in its off position. Fig. 4 illustrates
the same parts when the switch E is turned to the power position by the partial
rotation of the power switch K. In this case, the cam roller rides upon the
concentric portion of the cam H, which it reaches by the incline shown in
dotted lines, while the cam roller rides upon the concentric portion 2 of the
cam H¹, to which it is carried by the incline 3, shown in full lines.
It will be manifest that no further change in the position of the rollers or
of the lever I will occur unless the switch K is again brought to its off position.
The movement of the parts when the switch is brought to the braking position is
unnecessary to illustrate as it is simply the reverse of that shown in Fig. 4.
In Fig. 5 we illustrate the circuits of the controller. Here T is the trolley or

page_text: other source of current. The motor armatures are marked respectively A', A³,
and their fields F1, F2, the brake shoes BS', BS, the regulating resistance R.
At R' is shown a small shunting resistance for the brake shoes which is brought
into operation at the first point of the controller, so that a small portion of the
trolley current is sent through the brake shoes to demagnetize them. We do
not claim this in the present application. The controller K is a series parallel
controller, of the well known shunt type, in which one of the motors (ar more
than one where a number of motors are employed), is shunted directly to ground
around the other, the circuit of the other motor being thus opened to effect the
parallel connection in a way well understood; these changes being carried out
by the contacts 10, 11, 116 and 12. It is to be understood that the switch E
is brought to one or the other of its two operative positions by the cam lever I
before the brushes of the switch K make contact with the switch cylinder. In
Figs. 2, etc. it will be seen that the parts working on the cam are shorter than
the lever I, so that it is geared up, the switch E moving faster than the switch K.
In the power position the row of contacts marked P of the switch E touch the
brushes, while in the brake position the row of contacts marked Q is brought
into circuit. The first circuit of the power position is as follows:-from the
trolley T to the contact 23, to 23, 24, 24, thence to the contact 1 upon the con-
troller K, and then through the various cross connections of the switch to con-
tact 7, then to the resistance R and through the last six sections of that resist-
ance (it being now well known in the art that a larger resistance is employed for
braking than for motor regulation), to the contact 35, thence to contact 36, then
to contact 15 on the reversing switch, contact 16, thence through the arma-
ture A', contact .17 on the reversing switch, contact 18, contact 34, contact 32
by the cross connection between the contact plates 34" and 32ª, thence through
the field F¹, back to the controller at contact 11, to contact 10, to contact 19
upon the reversing switch, contact 20, through the armature A³, contact 21 upon
the reversing switch, contact 22, through the field F2. After passing through
this field the current divides, part of it passing through the resistance R¹ and
from the other terminal of that resistance to the contact 28 upon the switch E.
The other path of the current is to the contact 13 on the controller, by the cross
connection to the contact 14, thence to the upper terminals of both of the brake
shoes BS, BS². After passing through BS, the current in this circuit passes
to contact 29 on the switch E, and after passing BS, current goes to contact 27
upon the switch E. Thus the two brake shoes and the resistance R¹ are con-
nected in multiple between the end of the field F and the contact plate 26ª of
the switch E. Here the paths unite and current flows by contact 26 through the
three contacts 27, 28 and 29, to the ground at G. The effect of this is, as already
pointed out, to pass current through the brake shoes, the bulk of the current
passing through the resistance R', which is of such small amount that only a
small fraction of current passes through the brake shoes. At the next step of
the controller, the contact 14 is open circuited, and by tracing the connections it
will be found that this open circuits the shoes BS, BS2. It does not open
circuit the resistance R', however, and current may still pass through this as
before to contact 28, contact 26 upon the switch E and to ground; but this
resistance is short circuited by contact 12 on the controller K, which here makes
contact with plate 12ª, providing a direct path to ground for current from the
field F through contact 13, contact 12 and the ground wire to ground at G.
The other circuits of the controller regulate the motors by changing the
amount of the resistance R in the circuit, that is, as the contact 6 touches con-
tact 6 a portion of the resistance is cut out. This occurs progressively until
when the contact 2 touches 2, all of the resistance is cut out, and the motors
at this time are in series, with no resistance in circuit, giving the usual series
arrangement with maximum torque per ampere. As the contacts 2, 3, 4 pass
off the cylinder contacts in the continued rotation of the switch, resistance is
again cut into circuit until the time when contact 11 touches both contacts 11*

page_text: and 11. At this time a shunt is thrown around the second motor, and current
passes from the end of the field F¹ to contact 11, and thence to the plus terminal
of armature A², by contact 10 and contact 19 and 20 upon the reversing switch
and so on through the field F2, contacts 13 and 12 to ground. The other or short
circuit is when 11 touches 11b and contact 12 touches at the same time 12b,
the two being cross-connected and giving a path from the contact 11 to contact 12,
and thus to ground at G. When contact 11 breaks with contact 11ª, the circuit
of armature A is opened, contact 10 at the same time passing off contact 10",
thus opening the circuit in two places. When contacts 9 and 10 touch 9b
and 10%, an independent current path to the second motor is provided from one
end of the resistance R to contact .9, thence to contact 10 and to contacts 19
and 20 upon the reversing switch, and so on through armature A², field F2, con-
tacts 13 and 12 to ground.
... Further rotation of the switch cuts out sections of resistance in this multiple
position of the motors by means of contacts 4b, etc., in the same way as already
described with reference to their series position.
Whenever the switch E is passed through its off position and is brought so
that the contacts touch the plates in the row Q, the brushes of the controller K
pass to the left and touch the contacts on that side, as shown in the development
of the cylinder.
This is the first braking position, and in this case the armatures A¹ and A²
act to supply current from their plus terminals, being connected in multiple, the
brake shoes being connected between the armatures and fields, and equalizers
being thrown across both ends of the fields and armatures.
Beginning with the armatures A¹, current passes from its plus terminal to
contact 16 upon the reversing switch, then to contact 15, (it being understood
that the contacts of the reversing switch are not shifted when the switch E is
turned, but that they still remain upon the row of contacts P). From contact 15
current passes to contact 36, which now rests on contact 36b, thence to contact 29,
thence through the brake-shoe BS, passing to the left to contact 30. Here
the current has two paths, one from contact 31, the other from contact 32.
Passing from contact 32, it goes through the field F, thence to contact 11, which
here touches contact 11. The other path from the switch E is from contact 31,
passing from the field F, and reaching the contact 13 which here touches con-
Current also passes
tact 13 on the left, being thus connected to contact 11.
from the plus terminal of the armature A2 to contact 20 upon the reversing
switch, contact 19, to contact 25, the lead beyond this contact being open-
circuited at 10 upon the controller; from contact 25 to contact 27 and thus to
contact 27, through the brake shoe BS2. It will thus be seen that the arma-
tures A1, A2, are connected in multiple, and their current is fed through the
brake shoes in multiple and the fields in multiple, each brake-shoe being con-
nected in series between the armature and field of the motor operating it, with
a connection between the leads which connect each brake shoe to the field. These
all unite at the contacts 11 and 13 of the controller. From these current passes
over the lead from the brush 12 to the ground wire. This wire is here used
like any other lead in the controller, and its being grounded has no relation to
the circuit except as a safety precaution; current passes over it to contact 26,
thence to contact 26b, contact 24b contact 24, thence to contact 1 upon the con-
troller K. The next contact in circuit on this side in the first position is con-
tact 8, which thus leads to the first section of the resistance. Current passes
therefore through all of the resistances to contact 35 on the switch E, thence
to contacts 34 and 33. From 34 current passes to contact 18 on the reversing
From 33 the
switch, to contact 17, thus to the other side of the armature A¹.
circuit is to contact 22 on the reversing switch, contact 21 and to the other side
of the armature A2. Further revolution of the controller K acts simply to cut
out sections of resistance until the resistance is all cut out, leaving the two motors
in multiple, feeding current through the brake shoes. It will be seen that some

page_text: of the contacts on the controller are broken, which indicates that they extend
around the back of the cylinder so that the same contact is used in two different
relations.
Having now particularly described and ascertained the nature of our said in-
vention (which has been communicated to us from abroad) and in what manner
the same is to be performed, we declare that what we claim is;-
-
1-The combination in a controlling device for an electrically propelled
apparatus, of a power switch and a brake-switch, with a mechanical connection
between the switches such that the movement of the power switch handle operates
both switches.
2- The combination of a power-switch with a brake-switch and with a
mechanical connection between the switches operated by the movement of the
power switch and acting to bring the brake-switch to one or other of its operative
positions, according to the direction of movement of the power switch.
3-A controlling device for electric motors capable of regulating them both
as motors and as braking generators and provided with a single operating handle,
by the movement of which in opposite directions from an intermediate or "off"
position the two different forms of regulation are effected, having a power-switch,
a brake-switch, and a mechanical connection between the switches; the move-
ment of the handle in one direction bringing the brake-switch to operative posi-
tion on one side, and in the other direction upon the other side.
4-The combination of a reversing switch, a power-switch and a brake-switch,
the power-switch acting as a resistance changer, and the brake-switch shifting
the connections so that the motors act as generators when the power switch is
moved in one direction from its off position, and as motors when it is moved in
the other direction.
5 The combination, in a controller, of three separate cylindrical switches,
two of which have a common axis, and mechanical connection between the third
switch and one of the other two moving them simultaneously.
6-The combination in a controller, of a power switch of cylindrical form, a
reversing switch and a brake-switch the axes of which are in line, and a mech-
anical connection between the power and brake switches.
7-The combination, with a motor regulating switch of combined resistance-
changing and series parallel type, of a second switch mechanically connected
thereto and having contacts by which, when the motor regulating switch is
moved in one direction from its off position the circuits are established by the
second switch for motor regulation, and when moved in the opposite direction
braking circuits are established, including the resistance-changing contacts only
of the power switch.
8-The combination of the cams on the power switch, the crank on the brake-
switch, and the connecting operating lever.
9 The combination of the cams, the crank, and the lever with a long arm
operating the crank and the shorter arms actuated by the cams, so that the crank
is geared up.
Doted this 0th day of Max 1800