Year: 1885

page_text: I SEBASTIAN ZIANI DE FERRANTI of St. Benet Chambers Fenchurch Street in
the City of London Electrician do hereby declare the nature of this invention to be
as follows:
In order to obtain an electric current of one potential from an electric current of
another potential I construct an electrical converter of a number of strips of iron
placed one over the other or it might be of a number of wires with primary and
secondary insulated coils wound around the bundle of strips at the centre of its
length. The ends of the strips or wires projecting beyond one end of the coils
I double back over the exterior of the coils-one half of the strips or wires in one
direction and the other half in the opposite direction. Similarly I double back the
ends of the strips or wires projecting beyond the opposite end of the coils and
make them to lie alternately between the ends of the strips or wires turned back
from the first mentioned end.
By making the converter in this way it can be formed as a flat plate with the
insulated coils in very close proximity both to the interior iron core and to the iron
on the exterior which completes the magnetic circuit and so I obtain an electrical
converter in which the magnetic. field is very intense on account of its close
proximity to the whole of the conducting coils and the diffusion of heat is very
perfect owing to the large surface which is exposed in comparison to the mass.
In addition to obtaining these advantages the whole of the winding of the
insulated coils may be performed in an ordinary lathe-this I effect by clamping
the iron plates together at their two ends and mounting the clamps between the
lathe centres.
The plates might be pressed into a trough form and two sets of troughs placed
back to back have the coils wound around the abutting backs afterwards the sides
of the trough may be doubled inwards over the exterior of the coils.
A flat convertor with the coils in close proximity to iron both on the inside and
outside may also be made in the form of a Gramme ring-the coils being wound
around a core of iron of a ring form and a ring of iron placed inside and another
outside of the wound core.
With this construction I prefer to wind the core with a single layer of primary
and a single layer of secondary or if more layers are used to make the depth of
each layer very shallow so that the magnetic field may be very intense. Electrical
convertors of a shallow or flattened form with. closed magnetic circuit might also be
formed in other ways than those I have described above. In such convertors
I also according to my invention in some cases form the insulated conductor of
which one or both of the insulated coils are formed of square or oblong section
either with or without rounded corners.

page_text: I also in some cases form an electrical convertor of concentric cylindrical con-
ductors of iron or copper or both-the insulation between the conductors may be
obtained by an air space left between them. The conductors may be formed of
two tubes or a tube and rod and be simply supported on suitable insulated supports
at their ends in this way high insulation and good ventilation are obtained.
A number of such concentric conductors may be erected side by side and the
exciting current be led say up the inner conductor of the first then down the inner
conductor of the second and so on so as to connect them all in series whilst the
outer conductors may be coupled in parallel or in series as well as parallel and a
current led off from two three or more of them.
Each element of such an electrical converter may be composed of two concentric
copper tubes forming the two conductors with or without an iron rod or tube
inside the inner one and with another iron tube outside the outer one.
Or it may
be composed of one copper rod or tube and one iron rod or tube, or of two iron
tubes or a rod and tube as primary and secondary.
Where an iron tube covers a copper rod or tube, the iron tube may be drawn
down over the rod or tube either direct on to the metal or with insulation between
and vice versa or flat washers of iron placed one against the other might be used
instead of iron tubes.
The primary or the secondary may be divided longitudinally into segmental
strips the segments being insulated and connected up in series. The insulation
may be made by insulating studs or strips inserted between them and between
them and the inner or outer tube as the case may be or other means for effecting
the insulation of the strips might be adopted.
L
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110OK
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Electrical Converters.
I, SEBASTIAN ZIANI DE FERRANTI of St. Benet Chambers Fenchurch Street in 3
the City of London 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:—
In order to obtain an electric current of one potential from an electric current of
another potential I construct an electrical converter of a number of strips of iron 3
placed one over the other or it might be of a number of wires with primary and
secondary insulated coils wound around the bundle of strips at the centre of its
length. The ends of the strips or wires projecting beyond one end of the coils
I double back over the exterior of the coils-one half of the strips or wires in one

page_text: direction and the other half in the opposite direction. Similarly I double back the
ends of the strips or wires projecting beyond the opposite end of the coils and make
them to lie alternately between the ends of the strips or wires turned back from the
first mentioned end.
By making the converter in this way the insulated coils are brought into very
close proximity both to the interior iron core and to the iron on the exterior which
completes the magnetic circuit. I so obtain an electrical converter in which the
magnetic field is very intense on account of its close proximity to the whole of the
conducting coils and the diffusion of heat is very perfect owing to the large surface
which is exposed in comparison to the mass.
. In addition to obtaining these advantages the whole of the winding of the
insulated coils may be performed in an ordinary lathe or may be put on after
winding which for converters of large size is more convenient.
A converter with the coils in close proximity to iron both on the inside and
outside may also be made in the form of a Gramine ring. The coils are wound
around a core of iron of a ring form and a ring of iron is placed inside and another
outside of the wound core.
I also in some cases form an electrical converter of concentric cylindrical con-
ductors, the insulation between the conductors may be obtained by an air space
left between them. The conductors may be formed of two tubes or a tube and rod
and be simply supported on suitable insulated supports at their ends-in this way
high insulation and good ventilation are obtained.
A number of such concentric conductors may be erected side by side and the
exciting current be led say up the inner conductor of the first then down the inner
conductor of the second and so on so as to connect them all in series whilst the
outer conductors may be coupled in parallel or in series as well as parallel and a
current led off from two three or more of them.
Each element of such an electrical converter may be composed of two concentric
copper tubes forming the two conductors with or without an iron rod or tube inside
the inner one and with another iron tube outside the outer one.
The primary or the secondary may be divided longitudinally into segmental.
strips the segments being insulated and connected up in series.
In order that my said invention may be fully understood and readily carried into
effect I will proceed to describe the drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 shows a side elevation, one half in section, of a converter constructed in
accordance with my invention.
Figure 2 is an end elevation, one half in section.
Figure 3 is a horizontal section of the same; a portion is broken out or omitted
from the centre of the apparatus to reduce the dimensions of the figure.
The converter here shown full size is suitable say for working on a circuit in
which say 70 incandescent lamps are included and to maintain a tension between
the leads of the lamp circuit of 100 volts; the tension of the alternating current in
the primary or dynamo circuit being 2400 volts.
A, A, is a cast iron frame or casing made in two main parts which are held
together by bolts B, B. By way of precaution the parts of the frame are more or
less insulated from each other. C, C, C, represent ribbons of soft Swedish iron
about of an inch in thickness formed into bundles; the different ribbons in each
bundle are not in metallic contact being separated by paper. The paper is cemented
to the ribbons. Each ribbon in thus covered on one side for one half of the length
and for the other half it is covered upon the other side. The ribbons after receiving
the windings upon them are bent round and made to overlap at their ends, and
where they so overlap the two ends of each ribbon are in metallic contact; but
every ribbon is separated by the paper from the other adjacent ribbons. Thus
each ribbon forms' a ring in which there is a complete magnetic circuit.

page_text: In the converter shown by the drawings, four such bundles of ribbons C, C, are
indicated but the number and dimensions will vary according to the size and
capacity of the converter. Around the central part of each bundle a taping is
applied to keep it together; and then before the ends of the ribbons are brought
together the coil or spiral of copper rod D is passed around the bundle so that the
coil D surrounds the central parts of the four bundles. To separate the coil D
from the bundles short insulators or chairs E E of vulcanised fibre or vulcanite are
inserted. Over the coils D I apply rings FF previously prepared and wound upon
a former. Each ring consists of an inner layer F' of insulated material (paper
saturated with shellac varnish is that which I employ) over this is a winding of
copper wire insulated in the usual way with cotton and over this again is another
layer F of the same insulated material. The insulating material F F is applied
only at the upper and under surfaces of the ring; at the ends of the ring where
the wire is at a distance from other metal it has no other covering but the cotton
wound around it.
The wire which I employ in the converter shewn by the drawings has a sectional
area about that of the rod D and the number of convolutions is 24 for each turn
which the spiral D makes around the core of iron ribbons C.
As shown in the drawing each ring is made to overlap two convolutions of the
coil D and it contains 48 turns of wire. The rings F F should be applied around
the bundle C whilst the shellac insulation is still in a more or less plastic condition.
The wires of the rings F F are then connected electrically from ring to ring so as to
form a continuous circuit through all the rings from end to end of the apparatus
the terminal wires of the series of rings are then brought out and are electrically
connected with the metal blocks. G. G. which are secured in their places by the
screw pieces H H.
•
These pieces have flanges upon them and insulated washers are embraced
between the flanges and the blocks G. These insulating washers are inserted
into apertures provided in the frame A to receive them. In each piece N there is
a conical recess adapted to receive a ferrule I, to these ferrules the electric leads
from the dynamo are attached in such manner as to insure a good connection. K is
a cover plate with apertures in it through which these leads pass; the holes in the
cover plate are bushed with insulating washers to insure due isolation of the leads.
The coupling of the leads with the rings F F is thus effected simply by screwing
up the bolt K¹ which secures the cover and thereby forcibly thrusting the
ferrules I into the conical recesses in the screw pieces H H.
The copper coil or spiral D intended to form part of the lamp circuit is similarly
brought to terminals on the other side of the machine; the connections are made
in the manner already described except that the dimensions of the leads are
different, and that this being the low tension circuit, the thickness of the
insulating material is diminished; a lesser separation of the metallic parts will
here suffice.
It will be observed in this machine free spaces for ventilation are left between
the several bundles C and between these and the coil D, and again between the
coils and the rings of coiled wire F. This is an important feature in condensors of
which the dimensions are at all considerable as it allows currents of air to pass
freely through and to carry off the heat which is generated in working.
Figure 4 is a plan partly in section of a converter in the form of a gramme ring.
The figure shows two forms the one to the left and the other to the right of the
figure.
Figure 5 is a transverse vertical section.
I will describe first the arrangement shown on the left side of Figure 4.
M is the central bundle of soft iron ribbons; over this there is applied an
insulation N consisting of a lapping of paper and shellac, upon this the copper
spiral is wound. Outside the copper there is another insulating covering P.
Q. Q, are rings formed of insulated wire and corresponding to the rings F in
Figures 1, 2 and 3; they are coupled together to form the primary or dynamo

page_text: circuit as already explained. R is an outer covering of insulated material
separating the rings Q from an outside jacket S formed of thin sheets of soft iron
either made into rings or simply wound upon the outside of the converter so as to
form a inagnetic circuit outside the rings Q continuous from end to end of the
winding. T is a similar hoop or hoops of soft iron within the rings Q and there
also forming a closed or partially closed magnetic circuit.
The description already given applies to the arrangement on the left side of the
figure, on the right side the primary and secondary wires are wound upon the
ring as an ordinary gramme ring is wound. The former arrangement however is
preferable because the construction is easier and also because ventilation spaces are
left, which is a matter of much importance. The ends of the core ribbons M are
brought together after the coils or rings are upon them and the two ends of each
ribbon are placed in metallic contact whilst, by an insulation of paper, each ring is
separated from its neighbour. The part of the ring in which this overlapping
takes place is left unwound.
Figure 6 is an elevation partly in section of a portion of a converter constructed
in accordance with my invention with concentric conductors. Figure 7 is a
transverse section. T, T, T, T, are a series of say copper rods connected with one
another and forming part say of a circuit receiving the alternating currents of the
dynamo. U. U. are copper tubes surrounding the conductors T, and coupled in
several parallel series with another circuit in which say electric lights are exhibited.
Between the rods T and the tubes U an air space is left as is seen in section at
Figure 8. Insulation is applied around the tubes U and outside this are a series
of rings or washers of iron V separated the one from the other by discs of paper
between. These rings form closed magnetic circuits around the exterior conductor.
In place of using solid rods T, it is better as is shown in Figure 8 to use tubes T¹.
I then prefer to arrange iron rods W, W, passing through the tubes T¹. These rods
render the inductive action more efficient. I may also if desired build the tubo U
of a series of strips arranged side by side and insulated the one from the other, as
is shown in Figure 9.
When the arrangement shewn by Figure 9 is resorted to the segments into
which the lube U is divided are so coupled as to form one continuous circuit
through the machine always in the same direction, and thus a primary circuit of
a length many times that of the tubes U is obtained, the inner tubes T which are
undivided carry the low tension or lamp current.
When the apparatus is arranged as shown in Figure 6 the dynamo current is
continuous through the converter, whilst the other conductors which are to be
maintained at the lower potential are separated into several different series. Thus
if the object be to reduce the potential from 2,400 volts to 100 volts, 24 different
series would be formed and these would be connected in parallel arc with the leads
of the light circuit.
The converters which I have described in this specification may be used not
only for reducing from a high tension to a low, but also for increasing from a low
tension to a high or simply for transferring energy from one circuit to another.
Thus for example, in electric lighting it may sometimes be convenient to use
dynamo electric machines which maintain a potential of 100 volts only and to
increase this potential in the main conductor by means of a converter say to
2,400 volts; in such a case a converter such as is shown by the Figures 1, 2 and 3
would be suitable, the dynamo being then connected with the copper coil D and
the high tension main to the rings F F. I make these converters of all sizes,
from a few ounces in weight for telephonic use and for other purposes where the
amount of electrical energy to be converted is small, up to a ton or more in
weight where the electrical energy to be converted is large. Beyond the latter
dimensions it may perhaps be more convenient to employ several converters to
supply the same main circuit.
In small converters I provide but one bundle C and in such ventilation spaces
are not usually required."

page_text: 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.
1. An electrical converter consisting of strips ribbons or wires or iron placed one
over the other and carrying a primary and secondary winding, and having their
ends doubled back on either side over the exterior of the winding substantially as
described.
2. An electrical converter consisting of an iron core of ring form with windings
upon it and outside the windings also iron forming closed magnetic circuits
transverse to the winding substantially as described.
3. An electrical converter in which the windings are upon an iron ring core
and are located. between this and other rings of iron forming completed magnetic
circuits transverse to the windings substantially as described.
4. An electrical converter consisting of an iron core composed of strips, ribbons
or wires forming closed metallic circuits and with primary and secondary winding
on the said core and having air spaces amongst and around the said windings
substantially as described.
5. An electrical converter consisting of concentric conductors separated by air
spaces substantially as described.
6. An electrical conductor consisting of concentric tubes separated by air spaces
substantially as described.
7. An electrical converter consisting of concentric conductors and with iron
disposed around the exterior conductor and forming closed magnetic circuits around
it substantially as described.
8. An electric converter consisting of straight parallel conductors arranged in
two circuits a high tension and a low tension circuit; the low tension current
flowing in central conductors and the high tension in numerous conductors
arranged around the low tension conductors substantially as described in respect
to Figure 9.
9. Electric converters substantially as described and represented by the annexed
drawings.
1000