Improvements in Dynamo Electric Machines.
Year: 1896

page_text: Date of Application, 27th Jan., 1896
PROVISIONAL SPECIFICATION.
Improvements in Dynamo Electric Machines.
SEBASTIAN ZIANI DE FERRANTI, Engineer and Electrician, 27, Charterhouse
Square, London E.C. do hereby declare the nature of this invention to be as
follows:-
This invention has for its object improvements in the armatures of dynamo electric
machines where iron is used in the armatures. My invention also has for its object the
building of armatures in such a way that the conductors are mechanically driven and
enclosed so as to be protected from injury and yet so arranged as not to suffer from
the principal disadvantages of sunk winding.
According to my invention I build the standing or revolving armatures of dynamo
electric machines of laminated iron. These plates I pierce with holes round about
their edges nearest to the magnetic field, but these holes or slots instead of having
their greatest dimension radially have their greatest dimension in the direction of
rotation. The object of this is to get the equivalent of a smooth.cored armature, then
a space for the conductors and then a further ring of iron round about the conductors
through which the magnetism passes, and which is exposed to the pole faces round
about the conductors. The object of making the stampings of the armature
preferably with holes punched in as described is so that the very thin pieces of iron
between the holes which support the outer ring may act as drivers for the coils of the
armature.
Where the machine so constructed is a single phase alternator I wind the coils
through a portion only of the holes so formed leaving the other holes, empty. The
effect of this is to get a machine similar in its characteristics to a plain face wound
one as opposed to one in which the magnetism is largely varied by the shape of the
armature stampings or by the demagnetising effect of the coil when the iron of the
armature is in a position to facilitate this effect.
In some cases I make the holes which do not receive the winding rather larger or
deeper radially through the armature than those in which the conductors are wound!
This is so as to increase the resistance of the magnetic circuit when the poles are
not passing the conductors forming. the coils and so as to avoid to a certain
extent some of the demagnetising effect of the current in the armature on the.
field.
In some cases where I punch the discs or sections from laminated iron to form the
armature, I insert by means of a press a number of small brass or other non-magnetic
metal tie-pieces between the outer ring and the main body of the plates. After these
have been inserted and fixed due to the pressure with which they are forced into
position at the same time as the iron the place of which they are taking has been
removed I cut away the iron in between these tie-pieces and leave holos in which the
winding of the armature can be placed. The armature then consists of the central
core or main body of the segment and an outer magnetic ring which conducts the
magnetism close down on to the winding and also protects the winding as already
explained.
In some cases where I wish to diminish the de-magnetising effect of the armature
I may make the armature with slightly raised pole pieces, instead however of
winding the coils in the depressions between each of these pole faces I fix the coils

page_text: of the armature on to the faces of these armature poles this gives a greater magnetic
conductivity when. the poles of the field are opposite the coils than when they are
passing from one to another.
In some cases I may wind armatures with iron conductors passing through the
holes. The end connections.or the completion of the coils is made up by means of
copper pieces on account of their higher conductivity.
In some cases the iron conductors may be wound on to a flat drum made up of
laminated plates of sheet iron. In other cases they may be wound through or into
holes or slots in the armature.
In some cases I may make the iron conductors of different radial depths and
provide notches in the armature iron so that some of the conductors may register into
these notches and thus give a positive drive to themselves and the remainder of
the conductors.
1
Improvements in Dynamo Electric Machines..
I, SEBASTIAN ZIANI DE FERRANTI Engineer and Electrician, 27, Charterhouse
Square London, E.C. 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 :-
My invention has for its object improvements in the armatures of dynamo
electric machines, where iron is used' in the armaturės.
My invention also has for its object the building of armatures in such a way that
the conductors are mechanically driven and enclosed so as to be protected from injury.
and yet so arranged as not to suffer from the principal disadvantages of sunk
winding.
In order that my invention may be better understood, I will now proceed to
describe same in relation to the drawings hereunto annexed; reference being bad
to the letters marked thereon, like letters referring to like parts in the several
drawings.
Fig., 1 is a side elevation of a portion of an armature constructed according to
my invention, the magnet pole pieces being shown in elevation, the armature being in
section.
Fig. 2 is a sectional plan of the armature.
Fig., 3.is a cross section of a portion of the armature and
Fig., 4 is an enlarged section of a sinall portion of the armature showing the method
of winding the coils.
According to my invention, I build the standing or revolving armatures of dynamo
electric machines of laminated iron. These plates A, Figs., 1 to 4, I pierce with
holes B, round about their edges nearest to the magnetic field, but these holes or
slots instead of having their greatest dimension radially, have their greatest dimension
in the direction of rotation. "The object of this is to get the equivalent of a smooth
cored armature, then a space for the conductors G, Fig., 4, then a further ring of
iron D, Figs., 1, 3, & 4, round about the conductors through which the magnetism
passes, and which is exposed to the pole-faces E.
The object of making the stampings with holes punched in and described is so that
very thin pieces of iron F, between the holes B, which pieces F, support the outer
ring D, may act as drivers or supporters, of the coils of the armature. Where the
machine so constructed is a single phase alternator, such as is shown in part in the
Figs., 1 to 4, I wind the coils through a portion only of the holes, so as to leave

page_text: the other holes empty. I have shown this in Fig., 2 by the thick lines which represent.
the wires threaded through the holes. The effect of this is to get a machine similar
in its characteristics to a plain face wound one, as opposed to one in which the
magnetism is largely varied by the shape of the armature stampings or by the
de-magnetising effect of the armature coils, when the relative positions of these coils
to the magnets is such as to facilitate this effect.
In some cases where I punch the discs or sections from laminated iron to form the
armature, insert, by means of pressing, a number of small brass or other
non-magnetio metal tie-pieces between the outer ring and the main body of the plates..
In Fig., 5 I have shown a plate made in this manner where, H, is the main plate,
I are the small pieces of non-magnetic metal dovetailed into the plate H, and the.
outer ring K. After these pieces, I, have been inserted and fixed due to the pressure
with which they are forced into position after the iron, the place of which they are
taking, has been removed, I cut away the iron in between these tie-pieces, leaving the
holes L, in which the winding of the armature can be placed; the armature then
consists of a central core or main body of the segment H, and an outer ring K,.
which conducts the magnetism close down to the winding and also protects the
winding as already explained.
Although I have particularly described this invention with reference to the
drawings showing a portion of the machine in which the armature is stationary with
the field magnets revolving inside this armature ring, I would have it understood
that I may construct armatures in a similar manner in which the armature is made-
to revolve while the field magnets remain stationary, and I may make the armature-
oylindrical in form revolving inside two or more fixed magnetic poles.
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. In a dynamo electric machine the construction of an armature of laminated'
iron plates having holes punched near the surface adjacent to the field magnets,
which holes are separated by narrow strips of iron of sufficient width only to give the
necessary mechanical support to the coils.
2. In a dynamo electric machino the construction of an armature of laminated
plates having holes punched in these plates substantially as described and shown
in the accompanying drawings Figs., 1 to 4.
3. In dynamo electric machines the construction of an armature of laminated
plates having a ring of magnetic metal attached to the main body of the plate by
means of strips of non-magnetic metal substantially as described and shown
in Fig., 5.
4. My improvements in dynamo electric machinery substantially as described and.
illustrated.
Dated this 26th day of October One thousand eight hundred andininate air