Improvements in Dynamos, Motors, and Motor Generators for use with Alternating Currents.
Year: 1889

page_text: PROVISIONAT. SPECIFICATION.
Improvements in Dynamos, Motors, and Motor Generators for use
with Alternating Currents.
LLEWELYN BIRCHALL ATKINSON % W. T. Goolden & Co. Woodfield Road Harrow
Road London, W. do hereby declare the nature of this invention to be as follows:-
As at present constructed dynamo machines for alternate currents consist of an
armature, and field magnets composed of a number of seperate poles as those
constructed by Siemens, Ferranti, Lowrie Parker etc., or of two poles subdivided as in
the case of the machines known as the Mordey, in each case differing essentially from
the usual construction of continuous current dynamos.
In machines constructed according to the present invention any of the usual
constructions of dynamos for continuous currents may be adapted, by simply
modifying the pole pieces and by an altered winding of the armature. Taking as a
special case a bipolar dynamo with a gramme ring, the poles instead of having a
continuous surface, have grooves formed in them parallel to the axis of the
armature, the grooves being of equal or nearly equal width to the intervening teeth.
Between the pole points a space is left equivalent to an even number of teeth or
spaces, usually two unit spaces.
Considering any single turn of wire on the armature revolved in such a magnetic
field, passing under the N. pole it alternately passes through spaces of N. polar
induction and spaces of little or no induction, and then through two blank spaces to
the south pole, where it passes through spaces of S. polar induction alternating with
spaces of no induction, and finally through two more blank spaces to its original
position.
The armature is wouud with a number of coils equal to the total number of teeth
and spaces, and these coils are connected alternately in opposite directions the ends
coining to collecting rings.
In
The result of revolving such an armature is to set up alternating currents.
order to make the machine self exciting, the spaces between the coils described are
wound with a second set of coils connected to a gramine collector in the ordinary
way, and connected by means of brushes to the exciting coil or coils of the field
magnet. The coils being connected in series, the notching of the poles has no
effect as regards the production of a continuous current, which depends on the total
induction.
Machines constructed according to this invention may be used as synchronous
motors, provided they are run up to the required speed corresponding to the speed
of alternation.
To do this a starting apparatus is provided in the form of a small secondary battery
or primary battery.
The method of starting is as follows. The gramme winding and field winding
form a shunt motor. The cells are connected to the armature & field-winding
through a resistance or resistances. The motor starts on light load and runs up to
the proper speed when the alternating circuit is closed onto the alternator coils. The
machine now runs as a synchronous motor, and the resistance in the field circuit
being reduced, the magnetism and volts rise, and the machine acts as a shunt motor-
generator and excites its iron field and recharges the cells, and develops motive
power.
By an extension of this principle the machine acts as a motor-generator, trans-
forming alternating into direct currents, which may be used for charging cells
electro plating etc.

page_text: Although a bipolar machine has been described the same principle of construction
may be applied to the pole pieces of multipolar machines, and the winding may
be in drum form, or the coils may be laid flat on the peripheral surface.
Where very high volts are used in the alternating circuit making it desirable to
use a closed circuit, the armature may be fixed and the field magnets revolve either
outside or inside the armature.
Where it is desired that the machine used as a motor or motor generator should be
run at various speeds, in order to keep the relative speed of armature and magnets
constant to maintain synchronism, the armature and magnets are constructed to
revolve in opposite directions, in which case a second armature which may or may
not be electrically connected to the first armature, is provided. The object of this
armature which is fixed is to provide an electro-magnetic break to the revolution of
the magnet so that the magnet revolves only slowly unless the load is increased, or an
adjustment made, and the speed of revolution depends automatically on the action of
the electro magnetic break.
It is understood that in the latter arrangement the magnet may be inside or outside
the two armatures respectively, and the one armature may be fixed and one revolve,
in which case half the magnet system is fixed and half revolves. In cases where it is
inconvenient to use a secondary battery to start the machine as a motor or inotor
generator, other methods of running it up to the speed may be adopted. Thus
through a separate winding on the magnets closed on the external alternator circuit
a current may be passed, which induces a current in the armature which by a suitable
setting or lead of the brushes runs as a motor up to the proper speed, when it is
allowed to work as a generator. Or the gramme wound armature and field may be
used as a series motor driven by an alternating current, the power in these enses being
small but sufficient to start the machine on light load.
Improvements in Dynamos, Motors, and Motor Generators for use
with Alternating Currents.
I, LLEWELYN BIRCHALL. ATKINSON, care of Messrs. W. T. Goolden and Company
Woodfield Road, Harrow Road London, W. Civil Engineer, do hereby declare the
nature of this invention and the manner in which the same is to be performed to be
particularly described and ascertained in and by the following statement:-
As at present constructed dynamo machines for alternate currents consist of an
armature, and field magnets composed of a number of separate poles as those
constructed by Siemens, Ferranti, Lowrie Parker etc., or of two poles subdivided as
in the case of the machines known as the Mordey, in each case differing essentially
from the usual construction of continuous current-dynamos. In machines constructed
according to the present invention any of the usual constructions of dynamos for
continuous currents may be adapted by simply modifying the pole pieces and by an
altered winding of the arinature. Taking as a special case a bipolar dynamo with a
gramme ring, the poles instead of having a continuous surface have grooves formed
in them parallel to the axis of the armature, the grooves being of equal or nearly
equal width to the intervening teeth. Between the pole points a space is left
equivalent to an even number of teeth or spaces, usually two unit spaces.
Considering any single turn of wire on the armature revolved in such a magnetic
field passing under the N. pole it alternately passes through spaces of N. polar
induction and spaces of little or no induction, and then through two blank spaces to
the south pole, where it passes through spaces of S. polar induction alternating with
spaces of no induction and finally through two more blank spaces to its original
position,

page_text: The armature is wound with a number of coils equal to the total number of teeth
and spaces, and these coils are connected alternately in opposite directions the ends
coming to collecting rings.
The result of revolving such an armature is to set up alternating currents. In
order to make the machine self exciting, the spaces between the coils described are
wound with a second set of coils connected to a gramme collector in the ordinary
,way, and connected by means of brushes to the exciting coil or coils of the field
magnet.
The coils being connected in series, the notching of the pole has no effect as regards
the production of a continuous current, which depends on the total induction.
Machines constructed according to this invention may be used as synchronous motors
provided they are run up to the required speed corresponding to the speed of
alternation.
To do this a starting apparatus is provided in the form of a small secondary
battery or primary battery. The method of starting is as follows. The gramme
winding and field winding form a shunt motor. The cells are connected to the armature
and field winding through a resistance or resistances. The motor starts on light load
and runs up to the proper speed when the alternating circuit is closed on to the
alternator coils. The machine now runs as a synchronous motor and the resistance in
the field circuit being reduced, the magnetism and volts rise, and the machine acts as
a shunt motor generator and excites its own field and recharges the cells and develops
motive power.
By an extension of this principle the machine acts as a motor-generator trans-
forming alternating into direct currents which may be used for charging cells electro
plating etc.
Although a bipolar machine has been described the same principle of construction
may be applied to the pole pieces of multipolar machines, and the winding may be in
drum form, or the coils may be laid flat on the peripheral surface.
Where very high volts are used in the alternating circuit making it desirable to
use a closed circuit the armature may be fixed and the field magnets revolve either
outside or inside the armature.
Where it is desired that the machines used as a motor or motor generator should
be run at various speeds, in order to keep the relative speed of armature and magnets
constant to maintain synchronism, the armature and magnets are constructed to
revolve in opposite directions in which case a second armature which may or may
not be electrically connected to the first armature is provided. The object of this
armature which is fixed is to provide an electro magnetic break to the revolution of
the magnet so that the magnet revolves only slowly unless the load is increased, or an
adjustment made, and the speed of revolution depends automatically on the action of
the electro magnetic break.
It is understood that in the latter arrangement the magnet may be inside or
outside the two armatures respectively, and the one armature may be fixed and one
revolve, in which case each of the magnet systems is free to revolve. The cases
where it is inconvenient to use a secondary battery to start the machine as a motor or
motor generator, other methods of running it up to the speed may be adopted, as
follows:-
Thus, through a separate winding on the magnets closed on the external alternator
circuit a current may be passed, which induces a current in the armature the brushes
being short circuited which by a suitable setting or lead of the brushes causes the
arinature to run as a motor up to the proper speed, when it is allowed to work as a
generator; or the gramme or drum wound armature and field magnet may be used as
a series notor driven by an alternating current, the power in these cases being small
but sufficient to start the machine on light load.
Figure 1 shows two forms of field magnets & internal armatures of the kind
usually adapted for continuous current machines modified by notching the pole piece
so as to be applicable for alternating current machines in accordance with the present
invention.

page_text: Figs. 2 and 3 show in end elevation and side elevation the combined continuous
current and alternating current armature to be placed in field magnets as shown
in Fig. 1.
In Figure 2, a a are the alternating current coils wound in alternate direction and
connected in series, the end connections being brought to the insulated collecting
rings bb, Fig. 3.
c. c. are the continuous current coils wound and connected in the said manner to
the commutator d.
Figure 4 shows in diagram the method of connecting the motor or motor generator
to the source of alternating current, is the alternating dynamo the brushes fj
pressing on the commutator d are connected to the terminals of the accumulator g
and through a resistance gl to the exciting coil or coils on the field magnets. To
start the motor generator the current from the accumulators is switched to the coils h
and to the continuous current coil wound on the armature, which acting as a motor
revolves until it reaches a speed equivalent to the speed at which it will run as a
synchronous motor. A supply from the alternator e is then switched on and the
resistance may now be reduced until the field magnets are excited to such an extent
that the continuous current arinature acting as a generator recharges the accu-
mulators and also supplies a current to the field magnet coils and to a lamp or
lamps or other device as may be required.
Fig. 5 shows an arrangement where both the field magnet and armature revolve in
opposite directions.
Figs. 6 & 7 shew detached view ends respectively of the two armatures & field
magnets shown in front elevation which are combined in the one machine in Fig. 5,
Fig. 6 showing the arrangement of the revolving field magnet and double wound
armature as already described & illustrated in Figs. 2 & 3, and Fig. 7 showing the
fixed field magnet system with ordinary continuous current armature which is
mounted on the same shaft as the revolving field magnet & placed between the poles m,
forms a generator to be used as an electric brake.
The letters in Figs. 5, 6 and 7, corresponding in the following description, will
show the connection between them.
The armature is started, as previously described, by means of a secondary
battery Fig. 4 and the continuous current winding on the armature the field
magnets being supposed for the moment as stationary; when the armature reaches
k
the proper speed the supply current is switched on to the alternating coils of the
armature if now, the revolving field magnets are released, they will revolve in the
opposite direction to the armature at some speed depending on the mechanical
resistance against which they have to work. This mechanical resistance is obtained
& regulated by adding to the shaft carrying the revolving magnets an ordinary
armature n to form a generator within a magnetic field m as in Fig. 7 and variable
resistance may be obtained as desired by adjusting the electrical resistance tbrough
which the armature n is working. If from any cause the mechanical load n on the
pulley provided with a driving strap is increased, the speed of revolution of the
field magnets in the opposite direction will be increased until such time as
the electrical load on the armature n again balances the mechanical load on the
pulley p.
By these means the speed of rotation of the armature and the pulley p may be
varied without altering the relative speed of the armature and field magnets upon
which synchronism depends.
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. The construction of a self-exciting alternating dynamo with one field magnet
and one armature having two windings substantially as and for the purposes
described.
2nd, The construction of an alternating self-exciting synchronizing motor, with one

page_text: field magnet, and one armature having two windings substantially as and for the
purposes described.
3rd. The construction of a motor generator for converting alternating into
continuous current, having one field magnet and two windings substantially as and
for the purposes described.
4th. The construction of an alternating self-exciting, synchronizing motor with
one field magnet and one armature having two windings, the field magnets being
free to revolve and being controlled by an electro magnetic brake, substantially as
and for the purposes described.
1000
FELL & WILDING,
1, Queen Victoria Street, E.C., Agents for the Applicant.