-electric Generators.
Year: 1885

page_text: Dynamo-electric Generators.
I THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex Patent Agent do hereby declare the nature of this Invention for
"IMPROVEMENTS IN AND RELATING TO ELECTRO-DYNAMIC MOTORS AND DYNAMO-
ELECTRIC GENERATORS" a communication to me from abroad by Frank Julian
Sprague of New York in the County of New York and State of New York,
United States of America, Electrical Engineer, to be as follows:-
This invention relates to a new method of regulation for electro-Dynamic motors
whereby the power and speed and direction of rotation of a motor may be varied.
at will, either by hand or automatically and with great exactness and precision : or
the motor may be made to run at one or another determined constant speed with
a constant current or constant potential under varying loads; or the power may
be maintained constant at different speeds.
The invention is applicable to series or shunt or differentially wound motors and
to motors employed on a constant potential or a constant current circuit; and some
features are also adapted to the regulation of Dynamo-electric generators.
The main feature of the invention is the use of a continuous field circuit wound
in a manner to be presently described, in connection with means for changing the
connection of the terminals of the supplying circuit from one part of such field
circuit to another whereby the effective magnetic moment of such field coils is
varied in any desired progression and direction.
The field coils are wound sectionally in layers, the coils of each section of a series
being wound upon the whole length, of the core or of that portion of the core
which is enclosed by the series, and the sections are connected together so as to
form a continuous and unbroken series of coils. Connections from the bights of
these coils are brought to suitable contact blocks on which travel arms which form
the inlet and exit terminals of the supplying circuit. By shifting these arms the

page_text: current may be inade to enter and leave the field sections at any desired points
whereby the current may be reversed in any desired number of sections while
remaining direct in others, and any magnetic effect or moment, up to the maximum
of either polarity may be obtained at will.
My foreign correspondent is aware that in the specification to Letters patent
granted to Marcel Deprez A.D. 1883 N° 3074 a closed external field circuit with.
movable supplying terminals is set forth. Deprez's arrangement is however totally
distinct from the present invention, as will be now explained.
In Deprez's arrangement the sections are wound side by side upon the core, and
the reversing of the current in a section changes the polarity of that particular
part of the core enclosed by that section: by reversing the sections successively
the position of the magnetic poles is changed, and thus the effect on the armature
is varied. This is fully set forth in the specification to the said patent. In this
invention, however, each section affects all that part of the core enclosed by the
series, and the reversing of current in the sections instead of shifting the poles,
changes the magnetic condition of the whole core.
In regulating the field according to this invention there is no material change in
the resistance of the field circuit, which is a closed circuit offering two paths to the
passage of the current and there is no breaking of the circuit.
It is evident that the closed field circuit may be used in parallel circuit, or in
series with the armature of a motor, or two such field circuits may be used in a
differential motor, one being a shunt to the armature alone or to the armature
and the other field circuit; or the continuous closed field circuit may be used as
the shunt field circuit of a differential motor in connection with an ordinary series
field circuit.
The resultant action in the motor is not the same in all these cases: and it is
different in any form according to whether the motor is used on a eircuit of
constant potential or of constant current.
Since with a constant current the speed and power of a given motor, depend
upon the strength of the field, and its direction of rotation upon the polarity of the
field, by the use of this invention the speed and power may be varied as desired
from zero to maximum, or the motor may be reversed at will, or by suitable
automatic devices a constant speed may be maintained under varying loads.
Also a given power may be developed under different speeds.
With constant potential circuits the speed power, and direction of rotation of a
motor may be varied or constant speed under varying loads may be maintained
automatically or different speeds may be attained under the same load.
The invention is particularly effectivo in regulating the speed and power of
differential wound motors having two sets of field coils one in series the other in
shunt relation with the armature, designed to work with a constant potential or
a constant current; and to maintain a constant speed under varying loads without
any automatic shifting of contacts but by an electrically automatic regulation of
the field strength due to its particular winding.
By the invention herein set forth the relation between the shunt and series coils
may be changed at will so as to maintain whatsoever ratio may be desired.
A motor may be constructed whether for a constant current or a constant potential
which can be set to run at certain predetermined constant speeds under varying
loads. The same principles are applicable to generators designed to furnish a
constant current or a constant potential.
In the differential form of motor the magnetic field is due to the difference in
the effective ampere turns of the shunt and the series sets of field coils, the former
predominating, and the latter being differential The shunt may be to the armature
alone or to both armature and series field sets, and in one form of motor means
are provided for shifting one of the supplying terminals of the shunt circuit, inside
or outside the main field circuit terminals. It is evident that if any ratio exists
between the effective ampere turns in the two sets of field coils, by employing the
method of regulation above set forth, the total of such effective ampere turns may

page_text: be altered while maintaining their ratio constant or the ratio may be changed
without changing the total, or both the total and the ratio may be changed.
While the above changes may be effected without any change in the resistances
of the series and shunt field coils, my said foreign correspondent also desires to be
able to vary the resistance of either, and at the same time retain the power of
varying the effective ampere turns. This is done by short circuiting a greater
or less part of the closed field circuit.
Another feature of the invention relates to the use of the closed field circuit
with movable supplying circuit terminals and movable armature circuit terminals.
With the supply circuit terminals in position so that the magnetic moment of all
the coils is similar a shifting of the armature terminals will vary the potential
existing at these terminals from maximum to zero, and from zero to the reverse
maximum.
No matter where the supplying terminals are, however, it is evident that the
arinature terminals may be reduced from maximum to zero potential and the
reverse by shifting the terminals from the line terminal contacts to positions
electrically equidistant from these Also with any fixed position of the armature
circuit terminals, like changes of potential may be made to take place by shifting
the supply terminals.
One peculiarity must be noticed.
If the supply terminals are shifted into any other than what may be called the
normal position, there is a differential magnetic moment, and the field may be
weakened to zero, and then reversed, and if the armature be in a certain position
removed from the position of maximum and zero polarity for its brushes with any
particular differential position of the supply terminals, we have a motor with a
new arrangement of circuits, namely two series differential field coils the armature
between the two and two sets of shunt field coils, one of which is in shunt to the
armature and one series differential field set and the other in a shunt to
the armature and the other series differential field.
If the armature circuit terminals be now moved certain direct coils may be
added to the series differential without changing the general arrangement of the
series and shunt circuits with regard to each other and the armature, so that
the differential effect may be increased or lessened or made to entirely disappear.
The reversal of armature or field or both the weakening and strengthening of the
field and high and low speeds and power are thus obtained with great celerity.
The armature terminals being movable upon the field coils my foreign corre-
spondent is enabled further by shifting one or both of such terminals to introduce
the armature gradually into circuit.
Another part of the invention relates to means for gradually introducing the
resistance of the field coils of a series or shunt wound motor into circuit while
maintaining a zero field.
The line terminals being separately movable it is evident that if they are both
connected at the same point of the continuous closed field circuit there will be no
field resistance and no magnetizing effect. If they are moved away from each
other each being moved over the same number of contacts portions of the field
resistance will be placed in circuit but the current flows equally in both directiqus
through such portions and there is still no effect on the core.
The terminals may
thus be shifted until the full resistance of the field is in circuit while the field
magnet still remains entirely quiescent.
If the terminals are then moved in the same direction around the circuit the
direction of the current is changed in some of the coils, remaining the same in
the others as previously explained and so any magnetic effect is reached without.
changing the resistance.
It is evident that the foregoing methods of field regulation are also highly
effective when used with dynamo-electric generators.
The mode of winding the sectional field which is preferred is to take several
strands of wire and wind them together in one layer from one end of the core to

page_text: the other. Each strand forms one section and similar layers of sections are wound
successively upon the core an end of each strand being connected to that of the
next so that a continuous series is formed and from between the sections
connections are made to the contact blocks of the adjusting commutator.
For automatically carrying out the invention a speed governor connected with
the shaft of the regulated motor or generator may be employed whose movements
shift the field commutator arms so as to properly vary the field to compensate for
changes in speed; or an electro-magnetic device affected by changes in current
may be similarly employed.

page_text: Dynamo-electric Generators.
I, THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex, 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 new method of regulation for electro dynamic motors
whereby the power and speed and direction of rotation of a motor may be varied
at will, either by hand or automatically and with great exactness and precision:
or the motor may be made to run at one or another determined constant speed
with a constant current or constant potential under varying loads; or the power
may be maintained constant at different speeds.
The invention is applicable to series or shunt or differentially wound motors and
to motors employed on a constant potential or a constant current circuit; and some
features are also adapted to the regulation of dynamo-electric generators.
The main feature of the invention is the use of a continuous field circuit wound
in a manner to be presently described, in connection with means for changing the
connection of the terminals of the supplying circuit from one part of such field
circuit to another whereby the effective magnetic moment of such field coils is
varied in any desired progression and direction.
The field coils are wound sectionally in layers, the coils of each section of a
series being wound upon the whole length of the core or of that portion of the core
which is enclosed by the series, and the sections are connected together so as to
form a continuous and unbroken series of coils. Connections from the hights of
these coils are brought to suitable contact blocks on which travel arms which form
the inlet and exit terminals of the supplying circuit. By shifting these arms, the
current may be made to enter and leave the field sections at any desired points
hereby the current may be reversed in any desired number of sections while
remaining direct in others, and any magnetic effect, or moment, up to the maximum
of either polarity may be obtained at will.
"
My foreign correspondent is aware that in the specification to Letters patent
granted to Marcel Deprez A.D 1883 N° 3074 a closed external field circuit with
movable supplying terminals is set forth. Deprez's arrangement is however totally
distinct from the present invention, as will be now explained.
In Deprez's arrangement the sections are wound side by side upon the core, and
the reversing of the current in a section changes the polarity of that particular part
of the core enclosed by that section: by reversing the sections successively the
position of the magnetic poles is changed, and thus the effect on the armature is
varied. This is fully set forth in the specification to the said patent. In this
invention, however, each section affects all that part of the core enclosed by the
series, and the reversing of current in the sections instead of shifting the poles
changes the magnetic condition of the whole core.
In regulating the field according to this invention there is no material change in
the resistance of the field circuit, which is a closed circuit offering two paths to the
passage of the current and there is no breaking of the circuit,

page_text: It is evident that the closed field circuit may be used in parallel circuit, or in
series with the armature of a motor, or two such field circuits may be used in a
differential motor one being a shunt to the armature alone, or to the armature and
the other field circuit; or the continuous closed field circuit may be used as the
shunt field circuit of a differential motor in connection with an ordinary series field
circuit.
The resultant action in the motor is not the same in all these cases: and it is
different in any form according to whether the motor is used on a circuit of
constant potential or of constant current.
Since with a constant current the speed and power of a given motor depend
upon the strength of the field, and its direction of rotation upon the polarity of the
field, by the use of this invention the speed and power may be varied as desired
from zero to maximum or the motor may be reversed at will, or by suitable
automatic devices a constant speed may be maintained under varying loads. Also
a given power may be developed under different speeds.
With constant potential circuits, the speed, power and direction of rotation of a
motor inay be varied or constant speed under varying loads may be maintained
automatically or different speeds may be attained under the same load.
The invention is particularly effective in regulating the speed and power of
differential wound motors having two sets of field coils one in series the other in 1
shunt relation with the armature, designed to work with a constant potential or a
constant current, and to maintain a constant speed under varying loads without
any automatic shifting of contacts but by an electrically automatic regulation of
the field strength due to its particular winding.
By the invention herein set forth the relation between the shunt and series coils
may be changed at will so as to maintain whatsoever ratio may be desired.
A motor may be constructed whether for a constant current or a constant potential
which can be set to run at certain predetermined constant speeds under varying
loads. The same principles are applicable to generators designed to furnish a
constant current or a constant potential.
In the differential form of motor the magnetic field is due to the difference in
the effective ampère turns of the shunt and the series sets of field coils, the former
predominating, and the latter boing differential. The shunt may be to the
armature alone, or to both armature and series field sets and in one form of motor
means are provided for shifting one of the supplying terminals of the shunt circuit,
inside or outside the main field circuit terminals. It is evident that if any ratio
exists between the effective ampère. turns in the two sets of field coils, by
employing the method of regulation ahovo set forth, the total of such effective
ampère turns may be altered while maintaining their ratio constant or the ratio
may be changed without changing the total, or both the total and the ratio may
be changed.
While the above changes may be effected without any change in the resistances
of the series and shunt field coils, my said foreign correspondent also desires to be
able to vary the resistance of either, and at the same time retain the power of
varying the effective ampère turns. This is done by short circuiting a greater or
less part of the closed field circuit.
Another feature of the invention relates to the use of the closed field circuit
with movable supplying circuit terminals and movable armature circuit terminals.
With the supply circuit terminals in position so that the magnetic moment of all
the coils is similar, a shifting of the armature terminals will vary the potential
existing at these terminals from maximum to zero, and from zero to the reverse
maximum.
No matter where the supplying terminals are, however, it is evident that the
armature terminals may be reduced from maximum to zero potential and the
reverse by shifting the terminals from the line terminal contacts to positions
electrically equidistant from these. Also with any fixed position of the armature

page_text: circuit terminals, like changes of potential may be made to take place by shifting
the supply terminals.
One peculiarity must be noticed.
If the supply terminals are shifted into any other than what may be called the
normal position, there is a differential magnetic moment, and the field may be
weakened to zero, and then reversed, and if the armature be in a certain position
removed from the po-ition of maximum and zero polarity for its brushes with any
particular differential position of the supply terminals, we have a motor with a
new arrangement of circuits, namely, two series differential field coils, the armature
between the two, and two sets of shunt field coils one of which is in shunt to the
armature and one series differential field set, and the other in a shunt to the
armature and the other series differential field.
If the armature circuit terminals be now moved, certain direct coils may be
added to the series differential without changing the general arrangement of the
series and shunt circuits with regard to each other and the armature so that the
<differential effect may be increased or le-sened, or made to entirely disappear.
The reversal of armature or field or both, the weakening and strengthening of the
field, and high and low speeds and power are thus obtained with great celerity.
The armature terminals being movable upon the field coils my foreign corre
spondent is enabled further by shifting one or both of such terminals to introduce
the armature gradually into circuit.
Another part of the invention relates to means for gradually introducing the
resistance of the field coils of a series or shunt wound motor into circuit while
maintaining a zero field.
The line terminals being separately movable it is evident that if they are both
connected at the same point of the continuous closed field circuit, there will be no
field resistance and no magnetizing effect. If they are moved away from each
other, each being moved over the same number of contacts portions of the field
resistance will be placed in circuit, but the current flows equally in both directions
through such portions and there is still no effect on the core. The terminals may
thus be shifted until the full resistance of the field is in circuit while the field
magnet still remains entirely quiescent.
If the terminals are then moved in the same direction around the circuit, the
direction of the current is changed in some of the coils, remaining the same in the
others, as previously explained, and so any magnetic effect is reached without
changing the resistance.
It is evident that the foregoing methods of field regulation are also highly
effective when used with dynamo electric generators.
The mode of winding the sectional field which is preferred is to take several
strands of wire and wind them together in one layer from one end of the core to
the other. Each strand forms one section, and similar layers of sections are wound
successively upon the core an end of each strand being connected to that of the
next, so that a continuous series is formed, and from between the sections
connections are made to the contact blocks of the adjusting commutator.
For automatically carrying out the invention a speed governor connected with
the shaft of the regulated motor or generator may be employed whose movements
shift the field commutator arms so as to properly vary the field to compensate for
changes in speed; or an electro-magnetic device affected by changes in current may
be similarly employed.
:
And in order that the said Invention may be perfectly understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the accompanying sheets of drawings, the same letters of
reference indicating corresponding parts in all the figures.
Figures 1 to 1e of the accompanying drawings are diagrams illustrating the most
simple application of the invention to a shunt wound motor.
Figures 2 to 2e show the simple application to a series motor.

page_text: Figures 3 and 3ª are diagrams of a differential motor with differential coil inside
the terminals of the armature and main field shunts.
Figures 4 and 4a diagrams of a differential motor with differential coil outside
the terminals of the armature and main field shunts.
Figure 5, a diagram of a compound motor having a switch for changing the
connection of the differential coil.
Figure 6, a view of the same motor with its switch.
Figures 7 to 7b diagrams illustrating the gradual throwing in of the field rosist-
ance in a shunt-wound motor.
Figures 8 to 8b show the same in a series motor.
Figures 9 to 98 are diagrams illustrating a different way of connecting the
continuous closed field circuit whereby all the different changes may be most
conveniently inade.
Figure 10 is a diagrammatic view of the motor wound in this way with the field
commutator shown diagrammatically.
Figures 11 to 11° illustrate one mode of gradually throwing in the armature.
Figures 12 to 12' illustrate another mode of varying the armature current.
Figures 13, 14 and 15 illustrate different automatic methods of regulation which
may be employed in carrying out the invention.
Figures 16 and 16 are diagrams illustrating the short circuiting of part of the
closed field circuit.
Figure 17 represents a commutator for this purpose.
Figure 18 is a vertical transverse section of a commutator which is employed in
some cases.
Figure 19 a vertical longitudinal section of the same.
Figures 20 and 21 are views of motors embodying the invention; and
Figure 22 illustrates the preferred mode of field winding.
In the motor diagrams contiguous sectional winding is shown, the sections being
arranged longitudinally with relation to one another, but it is to be clearly under-
stood that the actual winding of the sections is in layer form and each section
extends the full length of the core: The diagrams are simply for clearness of
explanation.
A is the motor armature, B the main or regular field coils, and 1, 2, are the .
terininals of the supplying circuit for the field.
These may be terminals of a derived or multiple are circuit or of the direct main
conductor. In all cases the direction of the current is indicated by the arrows.
Referring first to figures 1 to 1° the armature coils A are in shunt relation to the
field coils B. It will be seen that such field coils are arranged in a single continuous
closed circuit. In figure 1 the terminals are connected at such parts of this circuit
that the current has two paths in the same direction, the whole current acts to
magnetize the cores directly and the resistance of the circuit is that of these two
parallel or multiple arc paths.
But if the terminals are shifted to the position seen in figure 1ª it is evident that
the current is reversed in part of the coils as indicated by the arrows, while it
remains the same in the rest and consequently the field is weakened; while the
current has still two paths of the samo resistance as before.
Now if the movement is still continued when the terminals reach the position
shown in figure 1b, the coils in which current is reversed are equal to the direct
coils. Hence the opposing magnetizing effects are equal and the field strength is
at zero.
A further shifting as shown in figure 1°, reverses the current in a still greator
number of coils, the reverse effect predominates over the direct and the polarity of
the field and direction of rotation of the motor are changed. Shifting to the
position in 1d reverses the whole field and gives the maximum reverse strength.
It will be seen that all these changes have been effected without any change in
the resistance of the field, and with no change in the direction of the armature
current.

page_text: It is to be understood that the field is weakened to produce an increase in speed
or power and strengthened to produce a decrease, if working on a circuit of constant
potential.
Figure 1e shows the motor with commutator and connections for accomplishing
the field regulation just described. The field magnet C is wound in sections, all
the sections being connected in a continuous closed circuit, and each section has a
connection to a contact block of the circular commutator D, on which bear two
pivoted arms a a¹ each forming a terminal of the supplying circuit. By moving
these arms into contact with the different blocks, the line connections are changed
from one part of the field coils to another and the changes above described are
produced.
Figures 2 to 2d show a motor with the armature and field circuit in series.
The connections of the field coils are changed to vary the strength of the field
magnet in the manner above set forth and as indicated by the arrows.
In this motor the reversal of motion can be accomplished by reversing the field,
either with a constant potential or constant current circuit.
Figure 20 represents the series motor, the connection from the arm a¹ being to a
commutator brush, thus bringing both armature and field coils into the direct
circuit.
Referring to Figures 3 and 3ª E is a set of differentially wound field coils in the
armature shunt.
In figure 3, the full number of regular field coils B are in direct circuit and also
the full numbers of opposing coils E. There is thus a magnetizing effect and a
field strength due to the number of turns in coils B multiplied by the ampères of
current in the field shunt, less the number in coils E multiplied by the ampères in
the armature shunt, and the motor runs at a certain speed. But in figure 3ª the
terminals are changed so as to reverse the current in some of the direct field turns,
and in a different number of the opposing field turns. The relation of the ampère
turns is therefore changed and a different magnetizing effect is produced and a
different speed, there being a constant potential at the armature shunt terminals or
a constant current on the line.
Now, as either the direct or the opposing field magnetisms may be varied to any
desired extent, it is evident that this gives a great range of field variation, each
different relation of the ampère turns having its particular effect on the cores.
Further, the total number of effective ampère turns can readily be altered
without altering their ratio by changing the direct and differential field coils to the
same extent, or both the total and relative numbers may be changed if desired.
In figures 4 and 4ª the differential coils E. are outside the terminals of the
arinature shunt.
Figure 5 illustrates the differential motor provided with a switch for changing
the connections of the differential coil to either side of the armature shunt terminal.
The connection is changed at switch b and the dotted lines indicate the changing
of terminals from one part of the field to another.
Figure 6 is a view of the differential motor. In addition to commutator D to
which the main field sections are connected as already explained, a commutator F
is provided to which the differential coils E are similarly connected.
By throwing switch b to the rigl t, the differential coils are placed outside of the
armature shunt terminals and throwing the switch to the left places the said coils
within the shunt.
It will be observed that the arrangements illustrated in Figures 3 to 6 embody
the combination in an electro-dynamic motor of main field magnet coils in shunt
relation to the armature with differential field magnet coils in series with the
armature, the magnetizing effect of both of which sets of field coils is variable.
Although however it is preferable to provide means for varying the magnetizing
effect of both sets of field coils, yet it is obvious that I may in some cases substitute
for the variable series field coil an ordinary series field coil as before mentioned ;
and, similarly, on the other hand, where the variable series field coil is used, I may
.

page_text: substitute for the variable shunt coil an ordinary shunt coil. Further, it is not
essentially necessary that the variation in the magnetizing effect of either the shunt
or the series field coils in the differentially wound motor should be effected in the
manner shewn in the drawings as any known method may be adopted for the
purpose and comes within the scope of this Invention.
In figures 7 to 7b the gradual throwing in of the field coils is illustrated in a
shunt motor and in figures 8 to 8b in a series motor.
In the position shown in figures 7 and 8 it will be seen that the field coils are
entirely cut out of circuit and the field strength is zero. Shifting the terminals
equal distances along the parallel sides of the field to the positions shown in 7ª
and 8° a certain resistance is thus in circuit, but the reverse flow is equal to the
direct, and the field strength is still zero. At the positions of 7b and 8b the whole
resistance of the field is in circuit but the direct and reverse effects are still equal
and the field strongth still zero. Thus the resistance of the field circuit has been
gradually introduced while the magnet has remained perfectly inactive.
This is of great value in series systems, where the sudden throwing in of the
whole field circuit resistance would produce an effect which might not be instan-
taneously compensated for in the generator. After the full resistance is introduced
the strength of the field may be gradually brought up to the desired point.
This feature is further illustrated in figures 9 to 98 in which the continuous
closed field circuit is connected in such a way that all the operations of changing its
resistance without changing its magnetizing effect and of changing its magnetizing
effect without affecting its resistance, may be most readily performed.
Here the two parallel ranges of sections are connected diagonally from one end
of each to the farther end of the other, and the two ranges are wound or connected
to oppose each other.
At the position of the terminals scen in figure 9, such terminals are close together
electrically, the field coils are all short circuited, and the field magnet has no
resistance and no magnetic strength. On shifting the terminals as in 9, portions
of the field coils are brought into circuit, forming two paths for the current, one of
which is of low resistance, but those coils in which current is reversed, equal those
in which it is direct, the coils being oppositely wound, and thus while the resistance
is increased the magnetic effect is still zero. In figure 9b the full resistance is in
circuit there being two paths of equal resistance but the direct and reverse coils
are still equal and the field still zero.
Having now the full resistance in circuit, by shifting the terminals as at 9° the
positively acting coils predominate over the negative, though the two paths are
still of equal resistance and the field is of a certain strength. In 9d all the coils
act directly, and the field has its full strength, the resistance remaining the same.
In ge the reversely acting coils exceed the direct coils, and the direction of
rotation is changed. In 9' the field has its full reversed strength, the resistance of
the coils being still unchanged.
Figure 9 illustrates these adjustments. The field coils have sectional connections
as shown. The ends of contact arius forming line terminals and inovable singly
or together, are represented by 11. At the position shown the effect is the same
as in 9b; and it is evident that by the movement of the contact arms any of the
other effects above described may be produced. This form of connection is of
course as well applicable to shunt wound as to series motors.
Figure 10 is a view of the motor connected as just described. One diagonal
connection of the commutator blocks, is through wires 5 and 6, the other through
wire 7. Arms are moved to change the connections as above explained. As
shown, there is nearly the full field strength with the full resistance in circuit.
A mode of throwing the armature gradually into circuit is shown in figures 11
to 11 in a compound motor having differential coils E in the armature shunt. In
figure 11 the armature is shunted around only a small part of the field coils and
in figure 11° one terminal of the shunt is shifted so as to shunt around all of them.
It is evident that the armature may then be placed in circuit with a very weak

page_text: current and the current then gradually increased to the maximum or to any desired
intermediate point. In 11 is shown the armature shunted around the full field,
but with the direct and differential field terminals shifted to vary the field strength.
Figure 11 shows a simple shunt wound motor with a commutator adapted to
produce the effects just described upon the armature and main field coils. An extra
arm c(a portion of which is broken away in the drawing) forming one terminal of
the armature sbunt, travels upon the contact blocks of commutator D: and the
connection from arm a¹ extends to contact block d and thence to the supplying
circuit. Otherwise, this commutator is the same as that in figure 1º.
When arm c
is on block & the armature is shunted around all the field coils; but in the position
shown it is shunted on only a part thereof.
In figures 12 to 120 is illustrated an arrangement whereby the simple shunt
motor may be made a differential one with negative field coils in series with the
armature, and the relation between the shunt and series field coil sets may be
changed to produce different magnetizing effects as has been hereinbefore explained.
In figure 12 there is a full set of direct field coils in circuit and the arma-
ture terminals are connected at opposite points of the continuous circuit. There
would thus be the same potential at both terminals of the armature shunt and
consequently no current in the armature.
In 12 both terminals are shifted to other than opposite points and a portion of
the current passes through the armature. Here it will be seen that parts of the
field circuit are in series with the armature the whole field effect being still a
direct one.
In 12 there is a zero field with no current in the armature, and in 12° the
shifting of the armature terminals by changing the resistance of the different paths
for the current makes a weak field and allows a certain current to traverse the
armature shunt.
It will be seen that the armature may thus be thrown in upon a full field or a.
zero or any intermediate field.
In figures 12 and 12 is illustrated more explicitly the changing of the simple
motor into a compound motor. By shifting the armature and supplying terminals
to the positions in figure 12d, it is evident that there are two sets of reversed coils
in series with the armature, and outside the terminals of the armature shunt, and
two sets of direct coils in shunt each to the armature and one series field coil. By
shifting armature terminals as in 12° certain direct coils are added to the differential
coils in series with the armature whereby the differential effect is weakened; and
it is evident that by shifting armaturo and supply terminals any desired relation
and magnetic effect may be produced. These features have already been fully
explained.
In Figure 12' is illustrated the means for producing these changes. By shifting
arms ff parts of which are broken away in the drawing for clearness, the
armature terminals are connected to any desired points of the closed field circuit.
Figure 13 illustrates an automatic regulating device for a motor.
An adjustable centrifugal governor m is placed upon or connected with the shaft
of the motor so as to be affected by variations in speed.
The moving portion of the governor carries the contact arins n, n¹ placed between
contact arms o o¹ o. Arms n, n¹ are insulated from each other and wires extend
from them respectively to the commutator brushes of a small electro-dynamic
motor M.
The armature shaft of this motor is connected with the contact arms a a¹ of
commutator D by any suitable gearing, such for example as belts and pulleys, so
that the speed of the motor is reduced at the commutator arms. This gearing is
not shown in the drawing as any suitable form of speed-reducing gear may be used
for the purpose.
An increase of speed raises the governor balls and closes circuit through motor M
in such direction as to move arms a a² to properly regulate the field, and a decrease
in speed moves motor M in the opposite direction. At the normal speed the circuit

page_text: is open at n o. Current is supplied to motor M from any desired source-As
shown, a shunt 10, 9, from the field circuit leads to contacts o o¹ o².
Figures 14 and 15 show automatic regulators for generators. In figure 14 the
circuit reverser on for motor Al is controlled by magnet N placed in a shunt
around the armature.
This is for a constant potential generator. A decrease of electro-motive force
causes magnet N to close circuit to motor M. so as to move the commutator arms to
strengthen the field; and an increased electro-motive force produces an opposite
effect.
Figure 15 shows a constant current generator, magnet N being directly in the
line and acting oppositely upon the field to that in figure 14.
In some cases these last described automatic regulators are applicable also to
motors.
Figures 16 and 16" show the short circuiting of part of the field coils to change
the resistance of the field. In figure 16, the full field is in circuit and in 16°
portions of it are short circuited. It is evident that all the regulating operations
may be readily performed upon the partially short-circuited field.
A commutator for accomplishing this short-circuiting is shown in figure 17. In
addition to the contact blocks to which the field connections are brought as shown,
and on which the arms a a¹ travel, there are two arcs x and x² to which the blocks
may be connected by the insertion of plugs y. Thus any two blocks may be
connected with the arcs with the effect of short circuiting the sections between
those with which they are connected.
The construction of the commutator which my said foreign correspondent prefers
to use in connection with the arrangement shown in figures 9-10 is illustrated in
figures 18 and 19.
S and S are arcs of insulating material upon the opposing faces of which are
ranges of contacts 8 s.
These are split contacts which are entered by wedges tt
carried by arms T, T. These arms are carried by the same shaft U and to each
extends one of the circuit wires. Each contact s is connected at a different point
to the field coils and thus by moving arms T the circuit connections are shifted to
such different points.
Thus far in all the diagrams the sections have been shown as wound side. by
side on the cores, although as stated this is only for illustration the sections being
wound longitudinally in practice. The longitudinal winding is, however, illustrated
in figures 20 and 21.
Figure 20 is a motor with a single magnet C. Each section is wound the whole
length of the core; the ends of successive sections being joined by wires 3, 3, and
the series on opposite limbs of the magnet being joined together by wires 4, 4 to
make a continuous series.
Connections are brought from between the sections to the commutator D and the
latter is manipulated in the manner already explained.
The motor in figure 21 has a double field magnet and the connections are made
as just explained, all the coils of the double magnet being in the continuous series.
The manner in which it is preferred to wind the field magnet is to take several
wires, four being shown in figure 22, and wind them all in a layer covering the
whole core G; other layers are similarly wound upon this inner one. Each wire
wound from end to end of the core forms a section of the field, and the sections
are all connected as shown in the preceding figures.
In a compound motor it is preferred to wind the differential coils also along the
whole length of the core together with the main coils.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
1st An electric motor or generator having sections of field magnet coils,
each wound from end to end of the core or a definite portion of the core, and all

page_text: the said sections being connected together to form a continuous closed circuit, in
combination with the terminals of the supplying circuit adapted to be connected
to different sections of the series, substantially as hereinbefore described.
2nd A shunt-wound electro-dynamic motor having field magnet coils wound
and connected so as to form a continuous closed circuit, in combination with the
supplying terminals adapted to be connected to different points of the said closed
field circuit, substantially as herein before described.
3rd An electro-dynamic motor having main field magnet coils in shunt relation
to the armature whose magnetizing effect is variable in any known manner and
differential field magnet coils in series with the armature whether the magnetizing
effect of the said differential coils is or is not variable.
4th An electro-dynamic motor having main field magnet coils in shunt relation
to the armature and differential field magnet coils in series with the armature such
differential coils being provided with means for varying their magnetizing effect.
5th In an electro-dynamic motor, the main field coils in shunt relation to the
armature, and the differential field coils in series with the armature each wound
and connected so as to form a continuous closed circuit, in combination with
supplying terminals for each circuit adapted to be connected to different points
thereof, substantially as herein before described.
6th In a differentially wound electro-dynamic motor, the employment of a switch
for placing the differential or series coil either inside or outside the terminals of the
armature and main field shunts, substantially as herein before described.
7th Constructing an electro-dynamic motor so that the resistance of the field
magnet coils may be gradually introduced without varying their magnetizing effect
and then in order to regulate the motor that the magnetizing effect may be varied
without changing the resistance, substantially as herein before described.
Sth In an electro-dynamic motor the field inagnet coils joined together in a
continuous closed circuit in combination with one or both of the armature terminals
adapted to be connected to different points of the said closed circuit, substantially
as liereinbefore described.
9th In an electro-dynamic motor, the combination of the armature, main field
coils in shunt relation to the armature, differential field coils in series with the
armature and either inside or outside the terminals of the armature and main field
shunts, and means for varying the relation between the effective ampère turns of
the two sets of field coils, and for changing the total number in the two sets without
changing such relation.
10th The use in an electro-dynamic motor, of the arrangement shown in figures 12
to 12 of the drawings and particularly described with reference to those figures.
THS J. HANDFORD,
50, Bedford Row
(Late of 42, Southampton Buildings),
London, W.C.