Improvements in Controlling Switches and Apparatus for Electric Motors.
Year: 1898

page_text: Date of Application, 11th Oct., 1898-Accepted, 3rd Dec., 1898
COMPLETE SPECIFICATION.
Improvements in Controlling Switches and Apparatus for Electric
Motors.
I, REESE HUTCHISON, Electrical Engineer, of Mobile, Mobile County, Alabama,
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 ascer-
tained in and by the following statement:
It is well understood that when an electric motor generates no counter electro-
motive-force, it is customary to introduce into circuit artificial adjustable
resistances and the connections of the motors with respect to each other and to
the source of current are varied also, thus guarding against the flow of excessive
current as well as modifying the speed and power of the motors. For this pur-
pose it is common practice to employ multiple contact switches, that is, switches
having a series of fixed contacts and one or more movable contacts by which
variations in the amount of resistance in the motor circuit and the connections
of the motors with respect to each other and to the supply circuit are quickly
and accurately made; these switches have a number of contact positions and in
successively moving from one position to another the effective strength of
current in the car circuit is varied in two ways, first, by the arrangement of the
resistances and the connections of the motors, and second, by the counter-electro-
motive-force due to variations in speed of the motor or motors. It is well known
to be wasteful of energy and dangerous to the useful life of the apparatus to
suddenly and abruptly move the controlling switch from one contact point to
another in succession without permitting the necessary time to intervene to allow
the effective strength of current to reach its normal or predetermined safe point.
My invention consists in the arrangement of a locking device so that the moy-
ing element of the controlling switch is caught and held in each contact position,
successively in connection with this locking device I employ an electro-magnetic
device, (such as an electro-magnet or a solenoid) adjusted to respond to a pre-
determined strength of current only, and this magnet will only free and release
the locking device when such predetermined strength of current is present or not
exceeded in the motor circuit. By this means it is made impossible to change
the multiple contact switch from one contact position to another until the pre-
determined safe strength of current has been established, and thus economy and
safety are guaranteed at all times.
To provide for emergencies I provide two simple switches for cutting my con-
trolling magnet out of circuit, the first contact of each switch is connected to one
terminal of the magnet, the second contact of each switch is connected to the
opposite terminal of the said magnet, the arrangement being such that when
either pair of contacts is closed the magnet is cut out of circuit. One of these
switches forms part of or is operated by the usual motor reversing switch, the
other switch is independently located in operative proximity to the controller and
normally held in an open position by a seal or severable section, as a section of
soft metal wire which can be broken by the motorman under proper conditions,

page_text: :
but when broken will serve as a "tell tale" device to indicate that the switch
has been operated and an explanation will be called for.
The accompanying drawings illustrate my invention.
Fig. 1 shows my improvement applied to the multiple contact switch with
reversing switch constituting essential parts of the well-known car controller;
Fig. 2 is a diagram arranged to show the electrical connections with a single
motor; Fig. 3 is a diagram arranged to illustrate the electrical connections of
my improvement applied to the well-known series-multiple motor controller in
which two motors are employed; and Fig. 4 shows the application of my inven-
tion to a wheeled vehicle, such as a street railway car.
Referring to Fig. 1, S, is a supply circuit; this may be either stationary with
an overhead or underneath conductor or it may be a source of electricity carried
on the vehicle; in the case of a stationary generator there is employed a traveling
contact, like T. C, is a multiple contact switch; R, is a reversing switch having
its contact points connected with the motor coil terminals and with the terminals
of the motor circuit, arranged to reverse the direction of current in the motor;
the controller C, has a rotary operating handle h; the reversing switch has
an operating handle ; the switches C, and R, are usually placed under one
enclosing case, like B, and there is one on each platform of a car. In the con-
troller C, there is a vertical cylinder y, carrying a series of electrical contacts of
varying extent, like 50 to 54, and there is a series of fixed contacts registering
with the movable contacts, like 19 to 23; there is also an artificial resistance X,
divided into sections connected at their terminals, 30 to 33, with screw posts 24
to 27, the latter being electrically connected with the fixed contacts 19 to 23 of
the controller, respectively. The reversing switch R, has a vertical rotary
cylinder z, and a series of contacts variously grouped and positioned, as shown at
55 to 58, and there is a series of fixed contacts registering with the movable con-
tacts; as shown at 34, 35, 40 and 41. M, is a motor, its terminals 37 and 38 are
connected with the binding posts 36 and 39, the latter points being electrically
connected to the fixed contacts 35 and 40. F', is the field coil of the motor; its
terminals are connected to the binding posts 28 and 29; the post 29, is con-
nected to the fixed contact 34, of the switch R, and the post 28, is connected
through the resistance X, with the binding post 27, and point 20, in the con-
troller C. The fixed contact 41 of the switch R, is connected with binding post 42,
and by conductor 43, with the ground or return circuit at W.
By varying the radial position of the handle h of the switch C, the resistance X
may be all included in circuit with the motor, or one or more coils thereof may
be included in circuit with the motor, as desired; in this way the strength of
current coming from the supply conductor S, is varied in the motor circuit; when
current is first admitted the motor is idle and offers no counter-electro-motive-
force, all the resistance X, is included in circuit to diminish the strength of cur-
rent, the motor starts into action, its counter-electro-motive-force rises, the
effective strength of current in the motor circuit decreases, and additional
resistance is then removed. Theoretically, and to secure the best results, the
described decrease of resistance should be at a rate commensurate with the rise
of the counter-electro-motive-force, but a careless and inefficient motorman for
selfish reasons or from ignorance will rapidly move the controlling handle to
withdraw artificial resistance faster than the compensating counter-electro-
motive-force can be developed, the result of this misuse approximates the result
due to introducing the full strength of current from the supply circuit to the
motor when no resistance and no counter-electro-motive-force is present. My
invention renders this action impossible; the mechanism I prefer to employ is
arranged as follows:-On the shaft of the cylinder y, I fix a toothed wheel w,
shown in each figure of the drawings; the number of teeth in this wheel is at
least equal to the number of contact positions of the handle h. As shown in
Fig. 2, there are four contact positions, 20, 21, 22 and 23; the wheel w, has
four teeth, 70, 71, 72 and 73. D, is a dog pivoted at d, its free end engages the

page_text: teeth of the wheel w. m, is an electro-magnetic device, preferably in the form
of a solenoid located in a vertical position; m, has a core c, under control of a
helical conical spring s, the retractile force of which is adjustable by means of
a screw and nut, like n. One end of the dog D, is mechanically connected with
the core c, and the reciprocation of the core c, causes the free end of the dog D,
to engage and disengage with the teeth of the wheel w. In a single motor
equipment the magnet m, is included in the motor circuit at a point between the
multiple contact switch C, and the source of supply D', current passing from the
supply conductor S, via T, 10, 11, 12, 13, m, 14, 15, 18, 19, 50, 51, 20, 27, X, 24,
28, F, 29, 34, 55, 35, 36, 37, 38, 39, 40, 56, 41, 42, 43 to W, and return; the
course of this circuit is shown in Fig. 2, with some of the unessential parts omitted
for clearness and brevity. When the handle h, is in this last-described position,
the car is assumed to be starting and no counter-electro-motive-force apparent,
the strength of current is assumed to be such that the core c, is attracted, over-
coming the force of the spring s; the wheel w, is locked by the dog D; as the
counter-electro-motive-force rises the effective strength of current drops, mag-
net m releases the wheel w, and the handle h, can be moved to the second notch
or position, shown at 21; this establishes new conditions in the motor circuit
because more current can flow from the supply circuit, the magnet m, responds
and again locks the wheel w, but as the counter-electro-motive-force rises by the
increased speed of the motor due to the increased current from the supply circuit
a counter-electro-motive-force is almost immediately generated which causes the
predetermined effective strength of current to be again established in the motor
circuit when this occurs the magnet m releases the wheel w, the handle h, is
unlocked and the motorman can proceed to move it to a third position; this
same operation is repeated for each contact position of the handle h, and for each
corresponding locking position of the dog D, and wheel w. The effect of this
automatic control is to obviate the possibility of changing from one contact
position to another at any interval when the effective strength of current in the
motor circuit exceeds a predetermined maximum which is determined by the
adjustment of the retractile springs, for any particular case or condition.
pre-
It is necessary. to provide for emergencies such as that when the motor is upon
a car under headway and an accident is about to happen, to avoid which the
motorman would naturally reverse the motor. The locking device would not
allow him to move the controlling handle unless the conditions were of the
determined character. To provide for such occasions I connect a simple switch
mechanically to the reversing switch or so arrange this switch that the reversal
of the handle h', will deprive the magnet m, of its control during the time that
the handle h, is in reverse position; for this purpose I place upon the cylinder,
of the reversing switch a movable contact 60, and I add two fixed contacts 61
and 62, the contact 61 is connected by the wire 16, with one terminal of the
solenoid m, and the contact 62 is connected by the wire 17, with the opposite
terminal of the solenoid magnet m. As shown in Fig. 1, the handle, is in
position to propel the motors forward; upon shifting h¹, so that the contact 60
engages, with the contacts 61 and 62, a short circuit is formed around the solenoid
magnet m which is temporarily put out of use.
There is another emergency of not infrequent occurrence when the unlimited
use of current is permissible under satisfactory explainable circumstances and
this often occurs at a time when the reversing switch is not called into operation;
the occasion referred to would be presented where a car is crossing an inter-
secting street and a fire-engine or other vehicle practically out of control is
approaching; the car must be spurted ahead to avoid collision; another occasion
would-be where the car has been derailed at one end and it was desirable to pull
it back on the track by its own motive power regardless of the expense in power
or material involved. For this purpose I provide a simple circuit-breaking
switch E, shown in Figs. 1 and 2; there is a movable reciprocating contact 63,
upon a lever pivoted at 66, and there is a fixed contact at 65, these contacts are

page_text: preferably of a knife-edge and spring-jaw pattern. The movable contact 63,
is electrically connected by the wire 64, with one terminal of the magnet m, and
the fixed contact 65, is similarly connected by the wire 67, with the opposite
terminal of the magnet m, these connections being practically identical with
those described for the contacts 61 and 62 in the reversing switch R. The
movable contact 63, is normally held against a backstop by means of a severable
seal or tell-tale device t; this preferably consists of a short section of soft metal
wire suitably identified, one end of which is connected with the movable part
of the switch E, while the opposite end is connected with a fixed point v.
When
the abnormal conditions described are presented and it is desired to relieve the mul-
tiple contact switch from the control exercised by the electro-magnetic device m,
sufficient manual force applied to the handle of the switch E, will break the seal
and bring the contacts 63 and 65 together, the magnet m, is thus short-circuited
and the multiple contact switch can be used without restraint.
In Fig. 3 I have diagrammatically illustrated a suitable connection for the
electro-magnetic device m, in cases where two motors are employed in connection
with a switch which permits of introducing and withdrawing resistance as well
as connecting the motors in series and in parallel circuit. Where the motors
are placed in parallel circuit the effective strength of current at some time equals
at least twice the strength of current taken by one motor or by both motors in
series and the controlling magnet m, must be placed in position where the pre-
determined strength of current permissible for one motor will control its
operation.
M and M', are the two motors referred to, the controller C, operates substan-
tially like that heretofore described and the locking device, with the controlling
magent m, is arranged similar to that heretofore described. The diagram shows
in full line the artificial resistance and the two motors in series with the magnet,
current passes from the supply circuit via the conductor 10, to the handle h,
thence via 107, through the resistance 106 to 103, 102, 101, m, 100, M, 109,
insulated contact point 111 on the arm h, fixed contact 108, 110, motor M³, to
the return circuit. With the handle shifted to the dotted line position, current
will pass via conductor 10, handle h, where it divides passing thence via 107, 209,
212, 213, 101, m, 100, M, 109, 111, 207, and 208 to the return conductor; the
second branch being via h, 206, 203, to M¹, and return conductor; this places
the motors in parallel circuit with more or less resistance in each branch accord-
ing to the position of the handle h, but the magnet m, is always in series with
one motor, and when the motors are in parallel circuit, the magnet m, is in series
with one motor and in parallel circuit with the other, so that assuming GO
amperes passing to the two motors, each motor taking one-half thereof, and 30
amperes being the predetermined strength of current which it is permissible
to establish for one motor, the magnet m, may be adjusted to respond to this pre-
determined strength of current only, and the motors either or both will always
be protected from abnormal changes and abnormal strengths of current.
In Fig. 4, I have shown the application of my invention to a wheeled
vehicle V, the controller C, placed in a case B, with the controlling magnet m,
is located one upon each platform, and the motors M and M¹, are each mechani-
cally connected with a wheel W, or axle to propel the car.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what I
claim is:
1. The combination of a supply circuit and two or more electric motors in
separate branches, a suitable controlling switch for the motors, a locking device
for said switch, and an electro-magnet having its coils in one of said branches,
operating to automatically control the locking device.
2. The combination of a moving vehicle, two electric motors to propel said
vehicle, a source of electricity, separate branches for each motor, an artificial

page_text: resistance, a suitable motor controlling switch, a locking device therefor, and a
magnet to automatically control said locking device operated by the current
passing to one motor substantially as set forth.
3. The combination of two electric motors, an electrical circuit, a controlling
switch to connect said motors in series and in parallel, a locking device for the
switch, and an electro-magnet operated by a predetermined strength of current
said magnet coil being connected in series with one motor and in parallel with
the other motor.
4. The combination of two electric motors, an electric supply circuit, a con-
trolling switch for the motors, a locking device for the switch, an electro-magnet
having its coil in series with one motor and in parallel with the other motor,
and one or more cut out switches connected to opposite sides of the magnet coil
as shown and described.
5. The combination of two electric motors, a supply circuit, a controlling
switch for the motors a locking device for said switch, an electro-magnet in
circuit with a motor to automatically control said locking device, a switch con-
nected in circuit at opposite sides of said magnet coils and a severable mechanical
connection to hold said switch at rest as shown and described.
Dated this 28th day of September 1898
REESE HUTCHISON.
W. P. Thompson & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.