Improvements in Alternate Current Motors.
Year: 1897

page_text: Date of Application, 19th June, 1897
Complete Specification Left, 18th Mar., 1898--Accepted, 14th May,
1898
Improvements in Alternate Current Motors.
I, ALFRED SOAMES, of 16, Red Lion Street, Clerkenwell, in the City of London,
Engineer, do hereby declare the nature of this invention to be as follows:-
In order to facilitate the starting of alternate current motors, I apply two wind-
ings to the field magnet, one winding being adapted to produce a larger number of
poles than the other winding. The winding which produces the larger number of
poles is employed when starting the motor. After starting it is switched out and
the other winding is brought into circuit. In this way I obtain the advantage of
the large starting torque which results from the numerous poles and afterwards
make use of the higher speed which the smaller number of poles affords.
The armature winding is adapted to the running winding of the field magnet and
has a higher resistance than would be suitable for continuous running with the
starting polarity of the field magnet for starting, this is advantageous.
Or I may employ an armature specially wound, one winding being operative in
starting and the other in continuous running. In this case the resistances of the
armature windings may be independently adjusted to what is considered most
suitable.
Dated this 18th day of Inno 1897
I, ALFRED SOAMES, of 16, Red Lion Street, Clerkenwell, in the City of London,
Engineer, 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:-
In order to facilitate the starting of alternate current motors, I apply two wind-
ings to the field magnet, one winding being adapted to produce a larger number of
poles than the other winding. The winding which produces the larger number of
poles is employed when starting the motor. After starting it is switched out and
the other winding is brought into circuit. In this way I obtain the advantage of
the large starting torque which results from the numerous poles and afterwards
make use of the higher speed which the smaller number of poles affords.
The armature winding is adapted to the running winding of the field magnet and
LD017

page_text: has a higher resistance than would be suitable for continuous running with the
starting polarity of the field magnet for starting, this is advantageous.
Or 1 may employ an armature wound, with two windings one winding being
operative in starting and the other in continuous running. In this case the
resistance of the armature windings may be independently adjusted to what is
considered most suitable.
L
Figure 1 shows the field magnets of an alternate current motor wound in the
above manner.
In the construction shown A are numerous thin discs of sheet iron held together
side by side and slotted as shown to receive tlie windings.
The two sets of windings are shown to be adapted the one for producing. 4 poles,
the other 8 poles.
Figure 2 is a diagram view of switch connections which may be used for bringing
the several windings into action at the times' required.
B1 B2 B3 B4 are the running coils of the 4 pole winding, and C1 02 0³ C³ their
accompanying starting coils.
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D1 to 18 are the running coils of the 8 pole winding, and E to E8 their accom-
panying starting coils.
The revolving armature is not shown in these figures preferably I use a ring
wound armature but other suitable armature might be used.
In Figure 2 F G are two switches, one for the 8 pole winding, the other for the
4 pole winding.
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When the contact arms H of these switches are both in their central position 'as
indicated in the drawing no current passes to any of the coils from the con-
ductors I J of the supply main.
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When the contact arm H of switch Fis turned into the position indicated by
the dotted line ab current passes both to the starting and running coils of the 8 pole
winding. When the motor has run up to speed approximately synchronized with
the alternations in the current divided by the number of pairs of poles in the 8 pole
winding the contact arm H of switch F is turned into the position indicated by the
dotted lines c'd and the engine continues running at this speed. If a higher' speed
is required the contact arm H of switch F is turned back to its central position
and the contact arm H of switch G turned into the position indicated by the dotted
line e f current then passes both to the running and starting coils. of the 4 pole
winding and the speed increases until the motor is running at a speed approximately
synchronous with the alternations of current divided by the number of pairs of poles
in the 4 pole winding the contact arm H of switch G can then be turned into the
position indicated by the dotted line g h current then passes only through the
running coils B¹ 132 133 134 of the 4 pole winding and the armature is kept running
at twice the speed at which it was running when the current passed through the
running coils of the 8 pole winding.
In the construction of motor shown in the drawings a resistance is shewn to be
added to each running coil at the time when it is being used with its starting coil-
and when the motor has run up to sychronizing speed this resistance is cut out
from the circuit of the running coil at the same time that. the starting coil is cut
out of circuit as described in the Specification of my Patent No. 7772-but other
arrangements for obtaining the necessary difference of phase between the running
and starting coils might be used in place of this arrangement.
If the armature used has a single winding I make its resistance suitable for
continuous running with the four pole or running winding. This resistance is
higher than would be suitable for continuous running with the 8 pole or starting
winding but gives with it large starting torque or as before stated I may use an
armature having two windings one of which is operative when the four pole field
winding is in use and the other when the 8 pole field winding is in use. A
diagrammatic view of an armature so wound is shewn in Figure 3. Figure. 4
shows separately the 4. pole winding and Figure 5 shows separately the 8 pole
winding.
1

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I claim
is :-
1. An alternate current motor having two sets of field windings one adapted for
producing a larger number of poles than the other substantially as described.
2. An alternate current motor having two sets of field windings one adapted for
producing a larger number of poles than the other and with the armature winding
having a resistance adapted for continuous running with the winding which
produces the lesser number of poles.
3. An alternate current motor having two sets of field windings one adapted for
producing a larger number of poles than the other and with the armature wound
with 2 windings one operative when the field winding producing the lesser number
of poles is in use the other operative when the winding producing the greater
number of poles is in use.
4. Alternate current motors constructed substantially as hereinbefore described
and illustrated in the drawings annexed.