Improvements in Dynamos.
Year: 1896

page_text: Date of Application, 2nd Apr., 1896
Complete Specification Left, 2nd Jan., 1897-Accepted, 6th Mar., 1897
PROVISIONAL SPECIFICATION.
Improvements in Dynamos.
SEBASTIAN ZIANI DE FERRANTI, of 27 Charterhouse Square, in the County
of London, Engineer and Electrician do hereby declare the nature of this invention
to be as follows:-
This invention relates to improvements in dynamo electric generators and motors
and has for its object the increase of the efficiency, the reduction in size and weight
and the reduction in cost of such machinery. It is known that in dynamo electric
generators and motors the current in the coils on the armature distorts the magnetic
field of the field magnets, thereby causing a liability to sparking at the commutator
of continuous current machines and generally a loss in efficiency in the machines.
To obviate this distortion it has been proposed to wind conductors, carrying the
armature current, on the face of the field magnet poles, or in grooves in these poles
and so connect them that the current traverses the conductors in an opposite
direction to the current in the adjacent conductors on the armature, great difficulty
has however been found in keeping these conductors in place and therefore the
method has not hitherto met with success.
My invention relates to means of overcoming these difficulties, and consists in
the means of supporting the conductors in grooves formed in the faces of the pole
pieces in which 1 wind conductors of suitable size either in the form of wire or
strip, the several conductors in each groove, when there are more than one being
insulated from one another.
I firmly lock these conductors in position either by making the groove wider at
the inside than at the surface of the pole piece and inserting therein conductors of
corresponding section, or I may form notches on either side of the groove near
the surface of the pole into which I place suitable locking strips which close up
the groove, and I form strips of either an electric insulator when I desire to more
thoroughly insulate the conductors in the groove, or I may form them of metal,
and in some cases when I use metal I insulate the strips and use them as conductors
for carrying the current.
In some cases it is not convenient to use the methods of fixing the conductors.
already described and in that case I use conductors of sufficient rigidity to prevent
them bending and I support these only at the ends. This I effect in some cases
by enclosing the conductors where they pass from one pole to the next in suitable
annular boxes fixed on to the pole pieces, supporting them in these boxes by strong
insulating materials such as mica or I cast them round with solid insulating material
so as to fill up the space between the conductors and the annular box. If it is not
desirable to prevent ready access to the conductors, I form the conductors in the
grooves on the poles of strips of metal of sufficient strength and rigidity, and at
the ends of these I form suitable notches, or I form a bevelled surface on the ends
of the conductors and I support them by means of rings of metal carried by the
poles, which project into the notches or bevelled edges in the conductor but are
insulated from each conductor.
In some cases I prefer to form the poles on the inner surface of a ring or hollow
cylinder of iron or steel and 1 form additional poles between the main poles, round
which I wind suitable conductors carrying a current, to form a suitable magnetic

page_text: field for reversing the current in the armature conductors at the moment when
commutation is taking place.
I sometimes find it convenient to form the polar rings out of stampings of thin
plate in the same way as armature cores are built up, and they may be made out
of the same plates as the armature cores. In this case I form the grooves in the
pole surfaces by stamping notches in the plates.
Dated this 2nd day of April
Improvements in Dynamos.
SEBASTIAN ZIANI DE FERRANTI, of Hollinwood, in the County of Lancaster,
late of 27 Charterhouse Square in the County of London Engineer and Electrician
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 improvements in dynamo electric generators and motors,
and has for its object the increase in efficiency, the reduction in size and weight,
and the reduction of cost of such machinery. It is known that in dynamo electric
generators and motors the current in the coils on the armature distorts the magnetic
field of the field magnets thereby causing liability to sparking at the commutator
of continuous current machines, and generally a loss in efficiency in the machines.
To obviate this distortion, it has been proposed to wind conductors carrying the
armature current on the face of the field magnet poles or in grooves in these poles,
and to so connect them that the current traverses the conductors in an opposite
direction to the current in the adjacent conductors on the armature. Great
difficulty has however been found in keeping these conductors in place and
therefore the method has not hitherto met with success.
My invention relates to means of overcoming these difficulties, and consists in
the means of supporting the conductors in grooves formed in the faces of the pole
pieces in which I wind conductors of suitable size either in the form of wire or
strip, the several conductors in each groove, when there are more than one, being
insulated from one another.
In order that my invention may be better understood I will now proceed to
describe the same, having reference to the several figures in the accompanying
drawings, reference being had to the letters and figures marked thereon.
Fig. 1 is a cross section through a portion of one of the pole pieces showing two
grooves carrying conductors.
Fig. 2 is a similar section showing two grooves with their conductors.
Fig. 3 is a similar section showing a different method of supporting the
conductors.
Fig. 4 is a similar section showing another method of supporting the conductors.
Fig. 5 is a longitudinal section through a portion of a complete pole ring showing
a section through one of the grooves.
Fig. 6 is a part plan of same.
Fig. 7 is an end view of a portion of the ring.
Fig. 8 is a longitudinal section through a portion of one of the grooves showing
another method of supporting the conductors.
Fig. 9 is an end view of a portion of the same.
In Fig. I show the method whereby I firmly lock the conductors "c" in the
grooves "a" formed in the pole "b" by making the groove "a" wider at the

page_text: bottom than near the surface, so that when the conductors are slid in from the end
during the process of winding they become firmly wedged in position.
In Fig. 2 I show the same construction where there are two or more conductors.
in each notch.
In Fig. 3 I show another method of carrying out my invention where the
grooves "a" are made parallel, but have notches "d" formed on either side near
the reface and having placed the conductors "e" in position I insert locking strips.
which in some cases as shown in the drawing may be formed of metal insulated
from the pole as shown by the thick black line, and may then be used to form one-
of the conductors.
I sometimes prefer to form these locking strips as shown on "d" in Fig. 4 in.
which they are made either of non-magnetic metal insulated from the conductors.
or of an insulating material.
In some cases where it is not convenient to use the methods already described
I form the conductors "e" in Figs. 5, 6 & 7, of sufficient rigidity to prevent them-
bending, and I support these only at the end of the poles where they pass from
one notch "a" to the corresponding notch on the next pole "a'," and this I effect
by enclosing them in annular boxes "" attached to each end of the pole piece","
supporting them in these boxes by means of a strong insulating material, such as
mica, or I cast them round, with a solid insulating material "q" so as to fill up the
spaces between the conductors "c" and the annular boxes "f"
If it is not desirable to prevent ready access to the conductore "" in Fig. 8,.
I form the conductors of strips of metal of sufficient strength and rigidity to
prevent their bending, and at the end of each conductor 1 form a bevelled
surface "," and 1 support the conductors by means of metal rings "j" carried by
the pole piece "b" which have a correspondingly bevelled surface projecting into.
the bevelled surface "h" on the conductors and being insulated from the conductors.
by a suitable ring of insulating material "."
I sometimes prefer to connect the conductors "c" which are in the slots in the
pole piece to one another by means of the conductors "e" in Fig. 9, which are
attached to the main conductors "e" by rivetting, brazing or other suitable-
method.
In some cases I prefer to form the poles on the inner surface of a ring or hollow
cylinder, as shown in Figs. 5, 6 & 7, the several poles "L" and "being
connected together by thinner pieces of iron or steel "m" so as to form on the
outer surface a complete cylindrical surface, and in this case between the main.
poles "" and ""I form subsidiary poles "o" round which I also wind
conductors "p" as shown in Fig. 6. These conductors "p" also carry the main.
armature current in such a direction as to produce a suitable magnetic field beneath
the pole "o" for reversing the current in the armature conductors at the moment
when commutation is taking place. I sometimes find it convenient to form these
complete pole rings out of stampings of thin plate in the same way as armature
cores are built up, and they may be made out of the same plates as the armature
cores, the round plate required for the armature core having been stamped out of
the centre of the plates forming the pole ring; and in this case I form the
grooves "a" in the pole "b" by means of stamping notches in the plate.
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. In dynamo electric generators or motors the forming of grooves in the pole
pieces parallel with the axis of the armature, the said grooves being wider at the
bottom than at the surface, for carrying conductors of a similar section substantially,.
as shown and described in connection with Figs. 1 and 2.
2nd. In dynamo electric generators or motors, the forming of grooves in the pole
pieces parallel with the axis of the armature, having notches on either side near-
the surface of the pole-face, into which are placed strips of material of suitable.

page_text: section for holding the conductors in the grooves in position substantially as shown
and described in Figs. 3 and 4.
3rd. In dynamo electric generators and motors, the supporting of conductors
wound into grooves formed in the pole pieces parallel with the axis of the armature,
by means of an insulating material, supported by annular boxes of non-magnetic
material carried from the ends of the pole pieces substantially as shown and
described in Figs. 5 and 6.
4th. In dynamo electric generators and motors the supporting of conductors
wound into grooves formed in the pole pieces parallel with the axis of the armature
by means of metal rings having bevelled edges fitting into similar grooves in the
end of the conductors and supported from the end of the pole pieces substantially
as shown and described in Figs. 8 and 9.
5th. In dynamo electric generators and motors, the forming of the poles on the
inner surface of a complete cylinder of iron or steel, the said poles having grooves
in the surface for carrying conductors, and being provided with subsidiary poles
between the main poles, substantially as described and illustrated in Figs. 5, 6
and 7.
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