Improvements in Armatures for Dynamo Electric Machines.
Year: 1890

page_text: Date of Application, 27th Mar., 1890
Complete Specification Left, 24th Jan., 1891-Accepted, 21st Mar., 1891
PROVISIONAL SPECIFICATION.
Improvements in Armatures for Dynamo Electric Machines.
1, JOHN NEBEL, of Charlton, in the County of Kent, Electrical Engineer, do
hereby declare the nature of this invention to be as follows:-
In winding drum armatures for dynamo electric machines it is usual to arrange
the convolutions in two parallel circuits from brush to brush, round the armature
so that each has to conduct half of the total current produced by the machine.
When this current is considerable, the sectional area of the conductors has to be
proportionally large, and as the depth of each conductor in radial direction cannot
practically be much increased, the large area required in the section of the con
ductor must be obtained by increasing its width. The circumferential space thus
occupied by each conductor is therefore large and the number of conductors and of
commutator segments is necessarily small.
The result is that considerable eddy currents occur in the conductors, causing
heating of the armature and that owing to the small number of commutator
segments heavy sparking may take place at the commutator brushes.
This invention relates to means of avoiding these evils by winding the armature
with two three or more sets of convolutions side by side, each set connected to its
own set of commutator segments, thus reducing the sectional area required for each
conductor to one half, one third or other fraction of the area required for each
conductor as it is usually wound, the number of commutator segments being
proportionally increased.
When this method of winding is adopted, brushes are necessarily arranged to
touch simultaneously as many of the commutator segments as there are parallel
windings.
And
Fig. 1 of the accompanying drawing is a diagram showing the unrolled or
developed surface of a drum armature having from brush to brush six conductors
wound round the armature and commutator and brushes arranged in the following
manner. The commutator C has 48 segments which may be considered to be
numbered 1, 2, 3 &c. successively. A wire starting from segment is wound once
round the armature and connected to segment 4 again round and connected to
segment 7 and so on until after 8 windings it connects to the segment opposite to 1,
and after other 8 windings it returns to the segment 1 from which it started. A
second wire, starting from segment 2, is similarly wound 16 times being connected
at the successive windings to segments 5, 8 &c. until it returns to segment 2.
similarly a third wire starts from segment 3 and connecting to 6, 9 &c. returns to 3.
Each of the brushes B being made to cover 3 segments of the commutator, there
are thus from the one brush to the other 3 pairs or 6 parallel conducting lives each
passing 8 times round the armature. The spaces marked NS, indicate the magnetic
fields crossed by the parallel lines, which represents those parts of the conductors
that extend along the cylindrical surface of the drum. The oblique lines crossing
each other represent the courses of the conductors across the ends of the drum.
Instead of winding 3 separate wires as above described, a single continuous wire
might be wound as indicated in Fig. 2.
Here the commutator has 52 segments.
Assuming the wire to start from segment 1 and at each winding to be connected
to 4, 7 &c. it would after 17 windings return to the last segment 52. From 52 its
winding is continued, connecting it to the segments 3, 6, 9 &c. returning to 51.
Thence its winding is continued 17 times, connecting it to 2, 5 &c. up to 50, and
finally after the 18th winding it is connected to the segment 1 whence it started.

page_text: In this case, as in the former, each brush covering 3 segments of the commutator,
there are three pairs or 6 parallel conducting lines from brush to brush.
Although the diagrams indicate the arrangement of conductors in sets of three,
it is obvious that sets each of 2 may be used or sets each of 4 or of a greater
number may be arranged as described, the brushes being arranged to cover as
many segments of the commutator as there are parallel conductors in each set.
Also, although the diagrams indicate that each conductor is wound 16 and
17 times round the armature, it is obvious that it might be wound a greater or less
number of times.
Dated this 27th day of March 1890
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Armatures for Dynamo Electric Machines.
I, JOHN NEBEL, of Charlton, in the County of Kent, Electrical 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 winding drum armatures for dynamo electric machines it is usual to arrange
the convolutions in two parallel circuits from brush to brush round the armature so
that each has to conduct half of the total current produced by the machine. When
this current is considerable, the sectional area of the conductors has to be propor-
tionally large, and, as the depth of each conductor in radial direction cannot
practically be much increased, the large area required in the section of the
conductor must be obtained by increasing its width. The .circumferential space
thus occupied by each conductor is therefore large and the number of conductors
and of commutator segments is necessarily small. The result is that considerable
eddy currents occur in the conductors causing heating of the armature, and that,
owing to the small number of commutator segments; heavy sparking may take place
at the commutator brushes.
This invention relates to means of avoiding these coils by winding the armature
with two, three or more sets of convolutions side by side, cach set connected to its
own set of commutator segments, thus reducing the sectional area required for each
conductor to one half, one third or other fraction of the area required for each
conductor as it is usually wound, the number of commutator segments being
proportionally increased.
When this method of winding is adopted, brushes are necessarily arranged to
touch simultaneously as many of the commutator segments as there are parallel
windings.
Figure 1 of the drawings accompanying my Provisional Specification is a
diagram shewing the unrolled or developed surface of a drum armature having from
brush to brush six conductors wound round the armature and commutator and
brushes arranged in the following manner.
The commutator C has 48 segments which may be considered to be
numbered 1, 2, 3 &c. successively. A wire starting from segment 1 is wound
once round the armature and connected to segment 4, again round and connected
to segment 7, and so on until after 8 windings it connects to the segment
opposite to 1 and after other 8 windings it returns to the segment 1 from which
it started.
A second wire starting from segment 2 is similarly wound 16 times being con-
nected at the successive windings to segments 5, 8 &c. until it returns to segment 2.
And similarly a third wire starts from segment 3 and connecting to 6, 9 returns
Each of the brushes B being made to cover 3 segments of the commutator,
there are thus from the one brush to the other 3 pairs or 6 parallel conducting lines
to 3.

page_text: each passing 8 times round the armature. The spaces marked N S indicate the
magnetic fields crossed by the parallel lines which represents those parts of the
conductors that extend along the cylindrical surface of the drum. The oblique
lines crossing each other represent the courses of the conductors across the ends of
the drum.
Instead of winding 3 separate wires as above described, a single continuous wire
might be wound as indicated in Figure 2. Here the accumulator has 52 segments.
Assuming the wire to start from segment 1 and at each winding to be connected
to 4, 7 &c. it would after 17 windings return to the last segment 52. From 52 its
windings is continued, connecting it to the segments 3, 6, 9 &c. returning to 51.
Thence its winding is continued 17 times, connecting it to 2, 5 &c. up to 50, and
finally after the 18th winding it is connected to the segment 1 whence it started.
In this case as in the former, each brush covering 3 segments of the commutator,
there are 3 pairs or 6 parallel conducting lines from brush to brush.
Although the diagrams indicate the arrangement of conductors in sets of three,
it is obvious that sets each of 2 may be used or sets each of 4 or of a greater
number may be arranged as described, the brushes being arranged to cover as many
segments of the commutator as there are parallel conductors in each set. Also,
although the diagrams indicate that each conductor is wound 16 and 17 times
round the armature, it is obvious that it might be wound a greater or less number
of times.
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 :-
A drum armature for a dynamo electric machine having two or more separate
conductors, or two or more lengths of a continuous conductor wound a number of
times round the armature, each convolution being connected to a separate segment
of a commutator, of which each brush simultaneously covers as many segments as
there are conductors, substantially as and for the purpose set forth.
Dated this 24th day of January 1891.
ABEL & IMRAY,
Agents for the Applicant.