Improvements in and connected with Alternating Current Electric Motors.
Year: 1897

page_text: Date of Application, 16th Nov., 1897-Accepted, 5th Feb., 1898
COMPLETE SPECIFICATION
Improvements in and connected with Alternating Current Electric
Motors.
A communication from ALEXANDER JAMES CHURCHIWARD, of Brooklyn, New York,
United States of America, Electrical Engineer.
I, WILLIAM LLOYD WISE, of No. 46, Lincoln's Inn Fields, in the County of
London, Consulting Engineer and Chartered Patent Agent, 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 a novel, simple and effective alternating current
motor designed to combine in one machine or mechanism the principle of an
alternating current synchronous motor with that of the ordinary direct current
motor or generator used for non-synchronous or starting purposes. Some of the
features of the invention relate especially to motors run from constant potential
circuits.
It has heretofore been proposed to combine two separate motors, one synchronous
the other non-synchronous or starting. It has also been proposed to furnish a
motor with two separate sets of windings, field and armature, for the same
purpose. It has further been proposed to use the ordinary direct current motor
or generator both as a synchronous and non-synchronous alternating motor, but so
far as known the plans heretofore proposed for this purpose involved the working
of the field coil in shunt to the armature under one or both conditions of working,
or else the use of commutator in the circuit of the field and armature operating at
the synchronous speed to rectify the alternating current supplied to field and
armature so as to operate the motor in effect as a continuous current motor.
One of the important features of the invention is that the series field of the motor
used in non-synchronous working is by proper switch rectifying commutator and
connections used also as a series field in synchronous working alternating currents
being at such time fed to the armature.
Another feature of the invention is that in combination with such series field
in synchronous working, a shunt or constant field excitation may be had from the
alternating current portion of the circuit.
It is not intended however to limit this case to such method of obtaining the
constant field excitation in combination with the series field, as it may be obtained
in other ways.
The invention relates also to means for controlling the action of a switch, for
throwing the motor into and out of non-synchronous working condition, and to
arrangement of circuits and devices together with other features of invention more
particularly hereinafter described and then specified in the claims.
In the accompanying drawings which form a part of the specification;
Fig. 1, diagrammatically represents the invention in its simplest application.
Figs. 2 and 3, represent its application to a multipolar motor showing respec-
tively the connections for non-synchronous and synchronous running.
Fig. 4, is a like representation of a multipolar machine showing all the windings
and their connections to the controlling switch.
Figs. 5 and 6, represent respectively a side elevation and plan of one form of con-
trolling switch.

page_text: Fig. 7, represents one mode for releasing the controlling switch to allow it to
be thrown from the position of non-synchronous working into that for synchronous
working; also the starting or non-synchronous circuits in a two pole machine.
Fig. 8, represents a controlling switch automatically operated.
Figs. 9 and 10, diagrammatically represent respectively the positions of the main
commutator brushes in starting and in synchronous working.
Fig. 11, represents in a bipolar machine, the circuits for synchronous running,
and a means for regulating the field of the machine.
With special reference to Figs. 1, 7 and 11; A, indicates the armature which
may have any of the ordinary windings of a direct current motor or generator,
and the usual form of commutator as at B, the brushes therefor being indicated
at C and D. The field poles are represented at E and F.
Upon each of these poles is wound, what, for the sake of description, will be
termed the shunt G, since in the preferred form of construction, in synchronous
operation the constant field excitation is produced by this shunt across the
brushes C and D, though it may be produced in various other ways. In addition
to the coils of the shunt circuit there is also wound upon said poles the coils of
what will be termed the series circuit which is in series with the armature both
in starting and in synchronous working.
The machine for synchronous working is further equipped by mounting the
rings I and J, and the current correcting commutator K, upon the armature shaft,
which are provided respectively with brushes, 12, 13, 14, 15. The ring I, is con-
nected by conductor 16, to armature A, the ring J, by conductor 17, to one side
of the commutator K, while the other side of said commutator is connected by
conductor 18, to the armature. The remainder of the circuits will best be described
by tracing the current over them.
The non-synchronous or starting circuit is separately outlined in Fig. 7, and
leads from the main L, to the brush C, through the armature to brush D, thence
through coils H, of the field magnets and to the main L'.
The circuits for synchronous running are separately shown in Fig. 11. The
principal circuit leads from the main L, to ring J, thence to commutator K, and
from brush 14, through series coils H, to brush 15, and from commutator K, by
conductor 18, to and through armature A, to ring I, and thence to the main L¹.
The shunt circuit extends from brush D, through coils G, and to brush C.
In order to direct the current through these circuits a switch is provided which
in one position places the circuits in starting condition and in the other places
them in synchronous working condition. Such a switch is simply graphically out-
lined in Fig. 1, wherein a bar M, is shown provided with insulated contact
plates 19, 20 and 21, for closing the starting circuit and with similar
plates 22, 23, 24, 25 and 26, for closing the synchronous circuits upon the opening
of the starting circuits. These plates engage with the pairs of contacts adjacent
thereto.
In starting the machine, the lever M, is in the depressed position and the start-
ing circuit from main L, as above outlined is completed at contact 19, through the
armature, over conductor 27, then at contact 20, over conductor 28, through series
coil H, and at contact 21, over conductor 29, to the main L¹.
Then when the machine has reached or slightly passed, synchronous speed,
lever M, is raised, breaking connection at contacts 19, 20 and 21, and making them
at contacts 22, 23, 24, 25 and 26, thereby completing the synchronous circuits from
the main L, at 22, over conductors 30 and 17, and ring J, and commutator K,
then at contact 23, over conductor 31, through series coil H, then at contact 24,
over conductor 29 and 32, commutator K, and conductor 18, to and through the
armature and ring I, and then at contact 25, to the main L¹, over conductors 33
and 29, the break in the shunt coil G, being closed at contact 26.
In the six pole machine graphically represented in Figs. 2, 3 and 4, the circuits
above described are employed and controlled in substantially the same manner as
in the two pole machine and the parts bear the same reference characters. The

page_text: field poles are represented at E, bearing the coils G and H. The circle just within
them represents the armature A, within which are the commutator B, the rings I
and J, and the current rectifying commutator K, the connections 16, 17 and 18,
between these parts appearing as indicated, while the various brushes engage their
respective parts.
In Fig. 2, only the starting circuit is indicated intact. It extends from main L,
through armature A, thence by brush D, to and through coils H, and to main L',
the coils G, of the shunt circuit being shown broken from one another.
In Fig. 3, the synchronous circuits are shown alone, the shunt circuit starting
from D, extending through coils G, and by conductor 34, to brush C, while the
series circuit starting from main L, extends to brush 13, ring J, thence by 17,
to brush 14, on commutator K, thence over 31, to and through coils H, to brush 15,
on commutator K, thence by 18, to and through armature A, and by 16, to ring I,
and off brush 12, by 33, to main L¹.
In Fig. 4, the entire wiring of a six pole machine and the switch controlling it
are indicated in like manner to that shown in Fig. 1, the lever M, however, carries
a series of contacts 26, sufficient to break the shunt circuit between the adjacent
coils G, thereof, circuits 35, leading from said coils to terminals in the paths of
contacts 26. By thus providing a break in the connection between the respective
coils G, while the motor is starting, the high electro-motive force due to trans-
former action is reduced to a minimum.
The starting circuit in this diagram is from L, through contact 19, conductor 27,
brush C, armature A, brush D), conductor 28, and contact 20, through coils H,
and conductor 29, and contact 21, to main L', the synchronous circuit being broken
at all contacts above lever M. In synchronous running, the series circuit is
from L, over conductor 30, and contact 22, to brush 13, over ring J, conductor 17,
brush 14, of commutator K, conductor 31, contact 23, conductor 28, through
coils H, over conductor 29, contact 24, conductor 32, brush 15, of commutator K,
conductor 18, armature A, conductor 16, ring I, brush 12, conductor 33, and
contact 25, to main L¹. The shunt circuit is from brush D, over conductor 34,
to coil G¹, thence to and through the successive coils G, and the intervening
conductors 35, and contacts 26, to conductor 27, and brush C.
From the description thus far given it will be seen that in starting, the winding
comprised in coils H, which as indicated is of a heavier conductor than that of
the shunt winding, is in series with the single winding of the armature (Fig. 7,)
and when connected for synchronous running (Fig. 11,) the said winding is in
series with the armature through the rectifying commutator K. The com-
mutator therefor changes the alternating current of the mains into,
direct current for the field coils H, and provides for regulating the
strength of the field magnets in proportion to the load. The shunt
winding comprised in coils G, also carries a direct current rectified from the
alternating current and collected from commutator B.
This shunt winding is especially useful at light and variable loads and may if
desired be cut out at other times for which purpose the contact 26, would be carried
by a lever independent of lever M, as in an ordinary jack-knife switch, though for
general use this winding is employed and controlled along with the series winding
as illustrated. The shunt winding may be entirely omitted when the motor is
to operate under a constant load as in driving a blower, elevator, crane or like
nechanism.
It is well known that each alternation of an alternating current varies in poten-
tial so that when rectified the continuous current produced will bo of a wavy
character instead of perfectly smooth or unvarying. In order to smooth said
current, as well as to neutralize any effort of the field to surge and of the motor
to pump and upset the circuit from which the motor is supplied, a self-inductive
shunt of any desired character adapted to absorb the varying energy and give it
out again to the circuit of the field coil and thereby act to equalize the varying
current is employed. This self-inductive shunt may be as indicated, a reactive coil,
which is by preference made adjustable, but any other devices known in the art

page_text: as having the same function in the relation described might be employed as the
self-inductive shunt as, for instance, a condenser as shown in Fig. 11.
Alternating current motors as heretofore constructed require an enormous
amount of current to start them.
Means have been devised by which this defect is remedied and which enables
this motor to be started on only a slight increase of the normal running current.
Such means is illustrated in Figs. 1 and 8, and may be termed an economy coil.
The economy coil or auto-converter as shown in Fig. 1, consists of a circular
core N, constituting a magnetic circuit, and a winding upon the same, of a series
of section or coils U. This series of coils is connected at one end with the main L,
and at the other end with the main L³, thereby forming a shunt across the main
circuit. To each coil, however, is connected a contact and to the conductor 29,
which forms a continuation of the main L', is connected a switch arm P, which
travels over said contacts and throws more or less of the coils O, into the circuit
of the motor as required. In operation supposing the normal current to the motor
to be of ten amperes and arm P, to be on the contact of the ninth coil as indicated,
then the current will flow from L, through the motor to P, then through nine-
tenths of the winding and out at L', thereby generating between P and L, ten
times the normal current at one tenth of the voltage. This will start the motor
and at the same time reduce the voltage and cut down sparking at the commutator.
Then as the motor gains speed, the arm P, is moved around towards L', until the
motor is in synchronism when the economy coil is completely cut out of the motor
circuit by arm P, resting upon contact 36.
As shown in Fig. 8, the economy coil may consist of a straight bar N¹, sur-
rounded by coils O, which are separately connected to a series of contact bars as
at Q, between which and a plate R, moves a sliding contact S, the plate R, being
diagrammatically represented as connected by conductors 29 and 27, through the
motor to the main L. In this figure also, said coil is shown as automatically
operated by the rotation of armature A, as through the agency of an ordinary ball
governor T, connected to lever U, which reciprocates rod V, and moves sliding
contact S, to successively cut out the coils O, as the armature increases in speed
up to synchronous running, when said sliding contact will make direct connection
with Li, through contact 36. The coil may be automatically controlled in various
other ways and also manually controlled as in the form shown in Fig. 1.
When necessary the strength of the field is regulated in proportion to the load
through suitable current regulating means in or acting upon the shunt winding.
One means for this purpose is indicated in Fig. 11, which consists of a rheostat
having its series of coils W, located in the circuit of the shunt winding and the
controlling magnet or solenoid X, located in series in the main L¹.
It is desirable, in a machine of this sort, that the arrival thereof at synchronism
shall be insured before the connections can be shifted from the non-synchronous
to the synchronous condition. This may be accomplished in many ways, one
especial construction for which, is illustrated in Figs. 5 and 6, wherein 37, repre-
sents a base of insulation on which are mounted the terminal contacts 38, (Fig. 1,)
in the synchronous circuits and the terminal contacts 39, in the starting circuits.
These contacts are arranged in pairs as shown and spaced apart so as to receive
between them the contacts 19-21, and 22--26 respectively, which in this form of
switch, are mounted on the arms M1, M2, of an elbow lever fulcrumed at its bend
by means of the shaft 40, journalled in suitable bearings mounted upon the
base 37.
Upon one end of the base is a magnet Y, which upon being suitably energized
acts to withdraw a catch 41, from the end of lever arm M', said catch acting during
the starting operation of the motor to hold said arm down thereby completing the
starting circuit through contacts 19-21, between terminals 39. The energization'
of this magnet may be accomplished in many ways and timed to take place at that
instant when the motor has just passed synchronism. One of these ways is shown
in Figs. 5 and 7, wherein the magnet is shown in a circuit 42, supplied with

page_text: current from any suitable source, typified at 43, and the circuit is closed by means
of a governor I, mounted upon the armature shaft and so adjusted that as the
armature reaches synchronous speed the contacts 44, will be closed, the magnet Y,
energized, and the catch 41, withdrawn from arm M².
The circuit of magnet Y, may be controlled by a relay operating upon increase
in voltage if desired. Such a relay is shown at &, in Fig. 1, connected by dotted
lines 45, to branches 30 and 33, of the synchronous circuit and acting to close
contacts 44, in circuit 42, of magnet Y. This relay is of high resistance and is in
reality in shunt across the mains when the motor is running in synchronism.
When the motor is starting, however, the relay is in circuit through the armature,
via 33, 12, 16, 18, the self-induction coil R¹, and commutator K, 17, 13 and 30,
so that the sudden rise in voltage, which occurs just as the point of synchronism is
passed, will energize magnet &, close contacts 42, energize magnet Y, and release
arm M, of the controlling lever. This sudden rise in voltage is due to the fact
that the magnet & being of high resistance and the current through the armature
during non-synchronous running being an alternating current, the current in the
circuit just described does not strongly affect the magnet prior to the point of
synchronous running, but as soon as that point is passed the sudden flow of direct
current through the armature, rectified from the alternating current by the
commutator, operates the relay.
The release of catch 41, is a signal to the attendant to throw arm M², down to
engage contacts 22-26, with terminals 38. This he may do by means of a lever 46,
which is idle upon shaft 40, and carries a projection 47, for engagement with the
arms M', and M³, a sufficient lost motion being allowed thereto to enable it to
perform other work in transit from one extreme position to the other. As this
lever is thrown over, the elevation of arm M¹, breaks the starting contacts and the
depression of arm M³, closes the synchronizing contacts. Upon the closure of the
latter contacts the lever is held in the depressed position by means of the magnet Z,
which is connected to or governed by the circuit G, in any way so as to operate
or be brought into operation by the current flowing when the circuit of G, is
closed. This magnet in holding the lever depressed does so simply by magnetic
attraction upon an armature 47, carried by the arm M. It also holds said arm
against the force of a spring as 48, which upon the weakening of magnet Z, due
to the motor getting out of step, throws up arm M², and breaks the synchronous
circuit. Then the attendant throws the lever 46, over and causes M', to close the
starting circuits. This operation of the controlling lever may be automatic if
desired as will be hereinafter described.
In the synchronous running, so long as the motor is in step a direct current
flows through the shunt winding of the field magnets and the magnet Z, but if the
circuit is interrupted long enough for the motor to get out of step, or if it is
overloaded then it ceases to deliver a direct current to magnet Z, causing it to be
de-energized and to release arm M2, thereby opening the main circuit and protecting
the motor from any possibility of burning out.
The release of the controlling lever both by catch 41, and magnet Z, may if
desired be signalled in any suitable way as by said catch striking a bell or by the
armature 47, striking a bell. The arm M², may obviously also be held down by a
catch and released in substantially the same way as arm M¹.
The switch just described may be utilized to control such adjuncts of the motor
as the economy coil N, O. For this purpose there is mounted upon a suitable
support as 49, the contacts 1-10 and 36, of said coil, and attached to the lever 46,
is a suitable brush P₁, for engaging therewith. By this means while M', is held
down, 46, may be moved to cut out section after section of the economy coil and
when it has depressed M³, be in position such that P', shall rest upon contact 36,
and so cut said coil entirely out of circuit with the motor.
This lever 46, may also operate to change the brushes C and D, from the
position for non-synchronous running indicated in Fig. 9, to that of synchronous
running indicated in Fig. 10. This may be done in any suitable way, for example

page_text: by means of an arm 50, carried by shaft 40, and moving with lever 46, with such
lost motion between it and a projection on the lower end of link 51, that, as the
arm M², closes the synchronous contacts, arm 50, will engage with said projection
on link or rod 51, and effect the desired shifting of the brushes. This link or
rod (Figs. 5 and 9) is pivoted to the brushes and depends so as to place the pro-
jection thereon (indicated by the dotted lines) in the path of arm 50.
This shifting of the brushes is of great advantage in obtaining the full efficiency
of the machine, since, when the brushes are adjusted for sparkless commutation in
synchronous running they will not, in starting, give the greatest amount of
torque. It is found that placing the brushes substantially in the relative position
to the field poles seen in Fig. 9, the greatest starting torque is obtained and that to
produce sparkless commutation when the machine is brought into synchronism,
the brushes must stand in substantially the position indicated in Fig. 10. The
mechanism above described will accomplish this shifting though any other desir-
able means may be employed. The effect of the adjustment of the commutating
devices is to change the "lead" of the brushes. As well understood in the art
the effect is produced by shifting either element, to wit: either the commutator
brushes or the commutator cylinder. While, therefore, one way of adjustment
is shown, it is to be understood that the use of the other is not excluded.
The operation of the economy coil may as above described be made automatic, so
also may the entire operation of the controlling switch. One way of accomplishing
this is seen in Fig. 8, wherein said switch is simply outlined at 38, 39, M³, M³.
To the arm M¹, is connected the rod V, as by pin and slot indicated which are so
proportioned that as the motor reaches the speed at which the synchronous circuits
should be completed, the end of the slot engages with the pin and shifts the switch.
In the position of rest the switch stands as indicated, the spring 48, insuring the
closure of the starting circuits. Then when the usual line switch is thrown putting
current to the motor, the armature gradually starts into rotation, the governor,
which may be of any form desired, moves rod V, causing S, to gradually cut out
the sections of the economy coil and just as it completes that work, to strike the pin
on arm M¹, and throw the controlling switch over so that M², will complete the
synchronous circuit or circuits. Should the motor drop out of step for any reason,
the switch will be returned to the starting position by spring 48¹.
In an alternating single phase motor the energy supplied is not of a constant
character. It is a succession of impulses. Therefore, to produce perfectly smooth
running, it is advisable to use a balance or fly wheel, which is preferably mounted
upon the armature shaft as indicated at 53, in Fig. 1.
The contacts 38 and 39, though preferably of the rubbing sort may be of any
other form. The self-induction coil across the brushes of commutator K, may also
be replaced by a condenser as indicated at R2, in Fig. 11, as the condenser would
operate in the same manner as the coil in conjunction with the rectifying com-
mutator. Obviously these and many other changes are within the invention,
which as understood is herein illustrated, for the greater part, simply diagram-
matically.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
-
1. In an alternating current motor, the combination with the starting winding
and armature wound with any suitable direct current generator or motor winding
to adapt the machine for self-starting operations, of a rectifying commutator and
switch, and connections whereby said winding may be included in series with the
armature and carry a continuous or direct current for synchronous running while
the armature carries an alternating current.
2. In an alternating current motor, a compound field magnet for synchronous
operation excited in part by continuous current taken directly from a direct or

page_text: continuous current winding of the armature adapted for self-starting and in part
by current passing through the armature and rectified.
3. An alternating current motor having the ordinary direct current armature and
commutator and series field winding for non-synchronous operation or starting, in
combination with a switch, a rectifying commutator in circuit with said series
winding between the same and the armature, and connections whereby the same
armature winding may be run in series with said field winding for synchronous
operation.
4. An alternating current motor having a series field coil and a distributed or
direct current armature winding and commutator, in combination with a switch
and rectifying commutator, whereby the machine may be run as a non-synchronous
machine for starting with field and armature circuits both alternating and in series,
or as a synchronous motor with the same field and armature circuit in series, the
armatures alternating, but the field of constant polarity.
5. The method of operating an electric motor upon an alternating circuit which
consists in passing the current through the armature and field winding in series as
an alternating current in both and afterwards through the same armature winding
as an alternating current and through the field winding in series therewith as a
rectified current.
6. In a self-starting alternating current motor, a direct current exciting coil
for synchronous operation wound to increase in strength with the increase of load,
in combination with means for placing said coil in series circuit with the armature
and with a suitable rectifying commutator between said armature and field when
the machine attains synchronism.
7. A single phase alternating current motor wound with a series coil connected
into series circuit with the armature during non-synchronous or starting condition
and carrying an alternating current, in combination with means for placing it in
series circuit with the armature during synchronous condition and rectifying the
current so as to cause the current which flows in the armature coils as an alter-
nating current to flow through the field as a continuous current.
8. The combination with an alternating current motor, of a hand switch for
changing the circuits from condition of starting or non-synchronous working to
condition of synchronous working, and means for automatically releasing said
switch when or about when the motor has reached synchronous speed.
9. The combination, substantially as described, in an alternating current motor,
of a switch for changing the circuits of the motor from starting condition to
synchronous working condition, a catch normally holding said switch in starting
position, and means responsive to an increase in speed of the motor to or near
synchronous speed for releasing said switch.
10. The combination with the controlling switch for throwing an alternating
current motor from non-synchronous or starting condition to synchronous working
condition, of means for automatically throwing said switch away from position for
synchronous working when the speed falls below the synchronous speed and opening
the main circuit of the machine.
11. The combination with the controlling switch which establishes the circuits
for synchronous working condition in an alternating current motor, of means for
holding the switch normally closed and automatically releasing the same to open
the circuit when the speed drops below synchronous speed.
12. In an alternating current motor, the combination of the field coil, an
alternating current supply main, and a rectifying commutator for rectifying the
alternating currents before they reach said coil, of a self-inductive shunt around
said field coil, as and for the purpose described.
13. In an alternating current motor, the combination with starting and synchro-
nizing coils wound on poles of said motor, of means for disconnecting said
synchronizing coils from one another during non-synchronous or "starting'
operation whereby the transformer effects are reduced.
دو
14. A single phase self-starting alternating current motor having its field

page_text: excited, when running as a synchronous motor, by two coils one of which provides
a constant field excitation, while the other carries current increasing with the load
and obtained from a commutator located, as described, between armature and field
so as to cause the alternating current supplied to the motor and flowing in coils
of the armature as an alternating current to flow through the field as a continuous
current.
15. The combination with an alternating current motor, of a switch for changing
the circuits from non-synchronous or starting condition to synchronous working
condition, and mechanism for adjusting the commutating devices simultaneously
with the change of circuits by the switch.
16. The combination with an alternating current motor, of a switch for changing
the circuits from non-synchronous or starting condition to synchronous working
condition, and mechanism having lost motion for adjusting the commutating
devices, ás and for the purpose described
17. In an alternating current motor, the combination with a starting winding
in series with an armature, the said armature being wound with any standard
distributed or direct current winding and connected to a commutator so that the
machine will be self-exciting for starting, of a rectifying commutator, and switch
and connections whereby said winding may be included in series of the armature
and carry a continuous current in proportion to the load when the motor is running
in synchronism.
18. In a self-starting alternating current motor, a compound field magnet for
synchronous operation excited in part by a continuous current taken directly from
the starting commutator, the winding on the armature being a distributed winding
connected in the ordinary way to a commutator to adapt the motor for self-starting
operation, and to supply current to excite the shunt or high resistance fields when
running in synchronism, and in part by current rectified by an auxiliary com-
mutator and passing through the armature, said auxiliary commutator and a field
winding in series.
bo 1907
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.