Improvements in Dynamo Electric Machines.
Year: 1894

page_text: Date of Application, 31st Mar., 1894
Complete Specification Left, 31st Jan., 1895-Accepted, 30th Apr., 1895
Improvements in Dynamo Electric Machines.
SEBASTIAN ZIANI DE FERRANTI, 27, Charterhouse Square in the County of
London, Electrician and Engineer, do hereby declare the nature of this invention
to be as follows:-
This invention has for its object improvements in the mechanical construction
and electrical insulation of dynamo electric machines, electro motors and continuous
current transformers.
According to my invention I make dynamo electric machines with iron armatures
pierced with holes close to their surface nearest the field magnets and wind these
with the electric conductor in which the currents generated by the magnetic field
are produced.
In order to satisfactorily insulate these conductors I insert insulating tubes in the
holes in the iron. These tubes may be made of porcelain, glass, ebonite, vulcanised
fibre, paper, or a compound of mica and paper or any other suitable insulating
material of sufficient mechanical strength.
Where it is only desired to have a few turns of conductor through each hole
I may completely insulate the conductors by means of covering with ebonite or
other suitable material before putting them in to the holes in the iron.
The insulation whether in the form of tubes or covering put direct on to the
conductors, stands out on either side of the iron, the ends of the tubes are received
into boxes on each side of the iron, in which they make a tight joint. The
conductors therefore pass through the tubes in the iron and round through the
boxes on each side of the iron. It is thus possible to fill up these boxes with an
insulating compound of either oil, wax or some other suitable material so that the
conductors and ends of the tubes are entirely covered and therefore surface leakage
is entirely avoided, the only thing necessary to provide for being the piercing effect
of the current on the insulation used.
Where the insulating composition in the boxes is of a sufficiently liquid nature
An armature
to require it these boxes are covered with lids screwed or fastened on.
constructed in this way may be made of segments corresponding to one or two
bobbins, and be built up complete with its boxes and windings in blocks of a
segmental shape.
The boxes are tied together by means of bolts from one to another through
spare holes in the iron. These bolts also act as keys for the iron and may be run
up with sulphur or other insulating material so as to make the whole mass solid.
A number of these segments are bolted or held together in a suitable frame and
so make up a complete circular armature. Preferably this armature is allowed to
stand, and rotating magnets pointing out radially towards it are employed.
These magnets I prefer to wind with circular coils made of flat copper strip
wound edgeways and insulated with washers of paper or vulcanised fibre between
each layer.
Where my improved method of building dynamo electric machines is applied to
machines for producing continuous currents, in which any of the well-known forms
of continuous current armatures are used but with holes near the surface of the
iron, I prefer to make one insulating box or chamber at each end of the armature,
in which the ends of the insulating tubes and electrical conductors may be sealed
off and protected as above described.

page_text: Where the conductors require to come through to the commutator they may pass
through insulating glands and be protected by means of corrugated insulation so as
to give the greatest surface and avoid surface leakage. The commutator may be
built in the ordinary way or may be air insulated between the segments, and the
segments carried upon the rods which come through the insulating glands from the
armature. This form is suitable where special high tension is worked.
According to another method I construct drum and ring armatures in the ordinary
way or else with the conductors wound in slots and finish the ends of the armature
with a non-magnetic casing coming close up to the windings and finished off with
insulating rings. I then insulate the surface of the armature preferably with mica
and instead of binding it in by means of bands of ordinary wire I wind it from end
to end with a wire of locked section in which a packing may be used, or I may
wind it with a square section wire with a rib on one side and a hollow in the other
in which also it is desirable to use packing. In any case it is better to wind
with several locking wires so that in case one should break the other wires would
prevent the binding coming loose or setting the broken wire free.
When the armature is so constructed 1 fill up internally the whole of the
remaining space with oil or other suitable insulating compound, so that there
may be no surface leakage from the armature and so that it may be entirely
protected from external injury & the entry of moisture. This construction is
also suitable for machines for producing alternating currents where the armature
is of iron and has the coils bound on to its exterior surface. In some cases
I make the binding of soft iron wire so as to reduce the air gap.
In some cases build continuous current machines of a construction herein
explained with standing armatures and revolving fields so as to facilitate the
insulating of the armatures on the above methods. In this case the commutator
is of very large diameter and the surface speed upon it would be too great for
the use of ordinary brushes, I therefore prefer to collect the current by means
of running copper ropes or bands pressing against the surface of the commutator
in the desired positions.
Or in case the armature is standing and the brushes have to rotate I prefer to
collect the current by means of a flexible copper strip or ring mounted upon a
springy substance on a wheel such as india rubber or some such suitable material.
By this means I am enabled to run very much higher surface speeds on the
commutators, and so make them larger, enabling air insulation to be used and
a fair clearance between a large number of segments.
In all cases where either running bands or spring bands upon wheels are used
for collecting the current these bands are connected to collectors running at a
lower surface speed from which the current is collected in the ordinary way.
In some cases where continuous current machines are built with a very large
number of sections for high tension current I prefer to bring out a number of
the connections separately insulated but through one large insulating gland which
can be sufficiently protected against surface leakage so as to minimise the number
of bands which have to be insulated for the high tension work in air.
Where I build continuous current transformers for use with high tension
currents and embodying the above principles of construction I prefer to wind a
corresponding amount of the primary and secondary windings in the same slot or
hole in the iron and the armature. This enables me to work with a much smaller
expenditure of magnetising force without an objectionable amount of sparking due
to distortion of the fields. In this case the primary winding may be in one tube
and the secondary winding in another insulating tube in the same slot and termi-
nating in the same or a separate box for the purpose of insulating the ends.
In some cases I replace the boxes on the ends of the tubes by means of blocks of
insulating material of sufficient length to give surface insulation. Or these blocks
may be corrugated so as to increase their surface insulation. In all cases it is
desirable that they should be stuck on to the ends of the tubes to prevent a leakage
to earth through dust or dirt getting into the crevices between the two.

page_text: Where boxes are used the connections from one segment or coil to another are
made preferably through glands in the boxes.
In some cases I may build the continuous current machines for use on vertical
shafts such as those from turbines. In this case it is desirable where the tension is
very high to allow the conductors to the air space commutator to stand out through
a bath of oil or other suitable insulating compound so as to give a good surface
insulation. This oil may be separate from the oil insulating the armature and may
be changed or cleaned as it becomes dirty with use.
Dated this Thirtieth day of March 1894.
Improvements in Dynamo Electric Machines.
SEBASTIAN ZIANI DE FERRANTI, 27, Charterhouse Square, in the County of
London, Electrician and 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:-
This invention has for its object improvements in the mechanical construction
and electrical insulation of dynamo-electric machines, electro-motors and continuous
current transformers, as shown in the drawings hereto annexed.
Fig. 1 shows cross section through armature.
Fig. 2 shows half section on line C. D. Fig. 1.
Fig. 3 shows section on line A. B. of Fig. 1.
Fig. 4 shows magnet.
Fig. 5 shows arrangement of magnet connections.
Fig. 6 shows section through fly wheel.
Fig. 7 shows half plan of top and bottom of Fig. 5.
Fig. 8 shows half elevation and elevation with box cover removed.
Fig. 9 shows section on line C. D. of Fig. 8.
Fig. 10 shows half plan and half sectional plan on A. B. of Fig. 8.
Fig. 11 shows section through rotating armature.
Fig. 12 shows section through armature of direct current machine.
Fig. 13 shows plan of Figure 11.
Fig. 14 end view of Fig. 12.
Fig. 15 shows section of armature through insulating block.
Figs. 16, 17, 18, 19, and 20 sections of locking wires.
According to my invention 1 make dynamo electric machines with iron armatures,
pierced with holes, a, Figures 1, 2, 3, 8, and 10, close to their surface nearest the
field magnets b, Figures 4, 5, 6, and and wind these with the electric conductor c,
Figures 1, 2, 3, 9, and 10, in which the currents generated by the magnetic field are
produced.
In order to satisfactorily insulate these conductors I insert insulating tubes d,
Figures 1, 2, 3, 8, and 10, in the holes a, in the iron. These tubes may be
made of porcelain, glass, ebonite, vulcanised fibre, paper, or a compound of mica
and paper, or any other suitable insulating material of sufficient mechanical
strength.
Where it is desired to have a few turns of conductor through each hole, I com-
pletely insulate the conductors e by a solid cover e, Figure 12, by means of
covering with ebonite or other suitable material before putting them into the
holes in the laminated iron z, Figures 1, 2, 3, 9, 10, 11, 12.
The insulation whether in the form of tubes or other covering pat direct on
to the conductors, stands out on either side of the iron, z as shown at f, Figures 3

page_text: and 10, the ends of the tubes d, are received into boxes g, Figures 1, 3, 8, 9,
10 and 12, in which they make a tight joint and are supported by insulating
block, Fig. 113. The conductors c, therefore pass through the tubes in the
iron and round through the boxes on a each side of the iron. It is thus possible
to fill up these boxes with an insulating compound of either oil, wax, or other
suitable material so that the conductors c and the ends of the tubes d, are entirely
covered and surface leakage is thereby avoided. The only thing necessary to
provide for, being the piercing effect of the current on the insulation used. In some
cases where the pressure used is not great I may line the boxes throughout with
several layers of mica and in this case it would not be necessary to fill up the boxes
with insulating compound.
Where the insulating composition in the boxes g, is of a sufficiently liquid
nature to require it, these boxes are covered with lids screwed or fastened on.
The armature constructed in this way may be made of segments 1, Figures 2, 3,
and 8 and may be built up complete with its boxes and windings in blocks of a
segmental shape.
The boxes are tied together by means of insulated bolts i, Figures 2, 3, and 10,
passing from one box to the other through holes made for this purpose in the iro
stampings projecting into boxes g, through insulation tubes y, Figures 3, and 10.
These bolts also act as keys for the iron and may be run up with sulphur or other
insulating material so as to make the whole mass solid. The heads of these bolts
are covered by means of an insulating-block r, so as to prevent any chance of
leakage from the conductors to them.
A number of these segments h, are held together in a suitable frame j, Figures 1,
2, 8, and 9, and so make up a complete circular armature. Preferably this
armature is stationary, as shown in Figures 1, 2, 3, 8, 9, and 10, and the rotating
magnets Figures 4, and 8 point out radially towards it.
These magnets I prefer to wind with circular coils made of flat copper strip k,
Figures 5 and 7 wound edge ways and insulated with washers of paper, vulcanised
fibre, or other suitable insulating material between each layer.
Where my improved method of building dynamo electric machines is applied to
machines for producing continuous currents in which any of the well known forms of
winding of continuous current armatures are used, but with holes near the surfa
of the iron, I prefer to make an insulating box or chamber g, Figure 12, at each
end of the armature in which the ends of the insulating tubes e, and the electric
conductors c, may be sealed off and protected as above described.
Where the conductors require to come through to the commutator they pass
through an insulating gland 1, Figure 12, and are protected by means of corrugated
insulation m, so as to give the greatest surface and avoid surface leakage. The
commutator n, Figure 12, may be built in the ordinary way or may be air insulated
between the segments o, Figure 14, and the segments carried upon the rods which
come through insulating glands 1, from the armature. This form is most suitable
where specially high tension is worked.
According to another method, Figures 11 to 13 I construct drum and ring
armatures in the ordinary way or else with conductors wound in slots and finish the
ends of the armature with a non-magnetic casing p, coming close up to the
windings g, and finish off with the insulating rings r, 1 then insulate the surface
of the armature preferably with mica and instead of binding it in by means of
bands of wire in the ordinary manner I wind it from end to end with a wire
of locked section, Figures 16, 17, 18, 19, and 20 in which an insulating packing o,
may be used.
This lock wire is preferably made of a high resistance metal of
great tensile strength. In any case it is better to wind with several locked wires
so that in case one should break the others would prevent the binding coming loose
and setting the broken wire free.
When the armature is so constructed I fill up internally the whole of the
remaining space with oil or other suitable insulating compound so that there may
be no surface leakage from the armature and so that it may be entirely protected

page_text: from external injury and the entrance of moisture. This construction is very
suitable for machines for producing alternating currents where the armature is of
laminated iron and has the coils bound on its exterior surface. In some cases I make
the binding wire of soft iron wire so as to reduce the magnetic resistance of the
air gap.
In some cases I replace the boxes on the ends of the tubes by means of blocks of
insulating material A¹ Figure 15 of sufficient length to give surface insulation these
blocks being preferably corrugated, as shown, so as to increase their surface
insulation. In all cases it is desirable they should be stuck on to the ends of the
tubes d, to prevent a leakage to earth through dust or dirt getting into crevices
between the two.
Where boxes are used the connections v, Figures 2, 3, 8, and 10, from one
segment or coil to another are preferably made through insulated glands u,
Figures 2, 3, 8, and 10, in the boxes g.
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. The use of insulated tubes placed in holes in a laminated iron armature
through which the armature conductors are wound.
2. The use of solid conductors covered with insulation so that complete rods can
be put through the laminated iron of the armature.
3. In dynamo machines in which insulation is in the form of tubes or covering
put direct on to the conductors the projection of same from the ends of the
armature into insulated boxes on either side of the iron in which the tubes make a
tight joint, substantially as described.
4. In dynamo machines in which the insulation is in the form of tubes or covering
put direct on to the conductors the projection of same from the iron ends of the
armature into insulated boxes on either side of the iron in which the tubes make a
tight joint. Also the filling up of these boxes with insulating compound so as to
cover the conductors and ends of the tubes. Substantially as set forth and
described herein.
5. The building up of armatures by segments corresponding to one or two
bobbins, which may be built up complete with boxes and windings in blocks of
segmental shape, the whole being keyed together by means of insulated bolts,
substantially as described.
6. Coils for electro magnets wound of flat copper strip on edge, insulated
with washers of paper or fibre between each layer, substantially as described.
7. The use of insulated end chambers attached to the ends of continuous or
alternating current armatures using buried conductors.
8. The use of insulated end chambers attached to the ends of continuous or
alternating current armatures using buried conductors, and filling up these end
chambers with suitable insulating material.
9. The use of insulated glands for protecting conductors coming from armatures
of continuous current machines to a commutator, and corrugating these glands,
substantially as set forth and described herein.
10. The protection of armature for both direct and alternating currents by
winding on wire of locked section, substantially as described and set forth.
11. The use of locked wires for protecting armatures from dust, dirt &c.,
substantially as described and set forth.
12. The use of soft iron locked wires, substantially as set forth and described.
13. The filling in of internal spaces of armatures with insulating material,
substantially as described and set forth.
14. The winding of coils for alternators through insulated tunnels, the insulating
tubes lining same being supported in insulating boxes, constructed to give large
surface insulation, substantially as described and set forth herein.
15. Where the armature coils are protected by being wound in boxes, the

page_text: connection of one coil to another through insulated glands in the said boxes,
substantially as described and set forth herein.
16. The construction of dynamo machines, substantially as herein before described
and illustrated in the drawings annexed.
S. Z. DE FERRANTI.