Improvements in Secondary Generators, Transformers, or Converters of Electricity.
Year: 1887

page_text: Date of Application, 1st Oct., 1887
Complete Left, 21st June, 1888
Complete Accepted, 27th July, 1888
PROVISIONAL SPECIFICATION.
Improvements in Secondary Generators, Transformers, or Converters
of Electricity.
WO JOHN DIXON GIBBS Esquire and EMIL FESQUET Engineer both of 18 Warwick
Street, Regent Street in the County of Middlesex do hereby declare the nature of this
Invention to be as follows
11.
This Invention relates to improvements in the electrical induction apparatus known
as Secondary Generators transformers or converters.
The object of the invention is to utilise in the best possible manner the mutual
induction of the primary and secondary circuits as well as the induction produced on
the Secondary circuit by the successive magnetizations and demagnetizations of the
iron core, and to render at the same time the construction of the apparatus more simple
and economical than are those made as hitherto.
The secondary circuit is formed of a continuous insulated copper wire or flat ribbon
rolled on a mandrel in a lathe or otherwise. The length of this wire or ribbon is pro-
portionate to the tension required by the lamps or other translating devices and its
section should be such that it will support without undue heating the desired quantity
of current for the maximum number of lamps or other translating devices which the
apparatus has to supply.
The primary circuit consists of two coils united in series each formed of a continuous
insulated wire which may be rolled on a mandrel in a lathe or otherwise. The length
of this primary circuit depends upon the ratio of transformation. For instance if the
primary circuit employed be of 2000 volts and the lamps or translating devices on the
secondary circuit be of 100 volts, the primary circuit will be 20 times longer than
the secondary circuit. It was demonstrated by the Specification of the Patent No. 2858
of 1884 granted to Messrs. Gaulard and Gibbs, that to obtain a maximum return for a
given weight of copper the metallic masses of the two circuits should be equal so the
section of the primary wire must if the example given in the above be just th of that
of the secondary wire.
The coils, after having been rolled are placed one inside the other, the secondary
coil being inside, and insulated from both sides of the primary which may be effected
by an air space as air is a good insulator and such space insures great facilities for

page_text: ventilation. The primary coils both outside and inside as well as at the points where
the iron core are fixed, are covered with insulating material to prevent any contact
between the coils and the iron core.
The iron core is next placed on the coils and this is very rapidly effected as the said
core consists of very thin plates of soft iron of shape the metallic surface on one
side being bare and the other side having secured to it by gumlac or otherwise a thick-
ness of paper or equivalent material. The said plates are placed one, on one side of
the coils, and the other, on the other side, so that two consecutive plates touch each
other with their bare metallic surfaces, forming a closed magnetic field, surrounding
the two circuits. The two following plates form another closed magnetic field, but
they are magnetically insulated from the field on either side by the thicknesses of paper
or equivalent material. When the requisite number desired of plates is in place the
apparatus is placed in a cast iron box of two pieces and the whole may be securely
fastened by a bolt, through the centre. These cast iron boxes have projections or
mouldings on an inclined plane which projections or mouldings fit into the interval
left open by the iron sheets and when the central bolt is tightened these projections
or mouldings press the iron plates together and thus prevent noise which might
otherwise be caused by vibrations, insuring at the same time a perfect contact between
the plates. When the apparatus is required for use in the open air the aforesaid box
should be hermetically closed.
To make them capable of being conveniently moved the cast iron frames may be fitted
with an iron ring at the top.
It is understood that, interposed between the apparatus and the line (primary as well
as secondary) thé usual or any suitable safety devices will be provided.
The fuses where they are used may be fitted on to a piece of insulating substance
attached to the frame, or they may be place in a separate box by the side of the apparatus
according to circumstances.
The Invention may be applied to a secondary generator transformer or converter
either for transforming a current of electricity of high tension to one of low tension or
for transforming a current from low tension to high tension by employing the secondary
circuit, as the primary circuit.

page_text: Improvements in Secondary Generators, Transformers, or Converters
of Electricity.
We JOHN DIXON GIBBS Esquire and EMILE FESQUET Engineer both of 18 Warwick
Street Regent Street in the County of Middlesex 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 the electrical induction apparatus known
as secondary generators transformers or converters.
The object of the Invention is to utilise in the best possible manner the mutual
induction of the primary and secondary circuits as well as the induction produced on
the secondary circuit by the successive magnetizations and demagnetizations of iron
and to render at the same time the construction of the apparatus more simple and
economical than are those made as hitherto has been usual.
The secondary circuit is formed of a continuous insulated copper wire or flat ribbon
rolled on a mandrel in a lathe or otherwise. The length of this wire or ribbon is
proportionate to the tension of the current required by the lamps or other apparatus
of consumption and its section should be such that it will support without undue
heating the desired quantity of current for the-maximum number of lamps or other
translating devices which the apparatus has to supply.
The primary circuit consists of a coil or coils united in series each formed of a
continuous insulated wire which may be rolled on a mandrel in a lathe or otherwise.
The length of this primary circuit depends upon the ratio of transformation. For
instance if the primary current employed be of 2000 volts and the lamps or apparatus
of consumption on the secondary circuit be of 100 volts the primary circuit will be 20
times longer than the secondary circuit. It is demonstrated in the Specification of
the Patent No. 2858 of 1884 granted to Messrs. Gaulard and Gibbs that to obtain a
maximum return for a given weight of copper the metallic masses of the two circuits
should be equal therefore the section of the primary wire must in the case of the
example hereinbefore given be just goth of that of the secondary wire.
The coils after having been rolled are placed side by side or one inside the other the
secondary coil being inside and insulated from both sides of the primary which may
be effected by suitable insulating material or by an air space as air is a good
insulator and such space insures great facilities for ventilation. The coils both out-
side and inside as well as at the points where the iron is fixed are covered with
insulating material to prevent any contact between the coils and the iron.
The iron is next placed on the coils and this is very rapidly effected as the said iron
is in the form of very thin plates of soft iron of C or equivalent shape the metallic
surface on one side being bare and the other side having a thickness of paper or
equivalent insulating material secured to it by gum lac or otherwise. The said plates
are placed one on one side of the coils and the other on the other side so that two
consecutive plates touch each other with their bare metallic surfaces forming a closed

page_text: magnetic field surrounding the two circuits. The two following plates form another
closed magnetic field but they are magnetically insulated from the field on either side
by the thicknesses of paper or equivalent material. The plates may be L shaped and
in contact at their ends which are angled. When they are shaped the connecting
limb is preferably double the width of the side pieces so as to give an equal
distribution of metal throughout as when the E pieces are placed together the metal
is double at the sides but single at the connecting piece so that by making the latter
of double width the mass of metal is in each pair equal all round. The plates described
are placed around each of the sides of the coil so as to leave a space between in the
centre of the coil instead of the said plates each embracing both the sides of the coils.
When the requisite number of plates is in place the apparatus may be placed in a cast
iron box of two pieces and the whole may be securely fastened by clamping plates and
bolts at the sides or by a bolt through the centre. The cast iron box may have
projections or mouldings on an inclined plane which projections or mouldings fit into
the interval left open by the iron sheets and when the central bolt is tightened these
projections or mouldings press the iron plates together and thus prevent noise which
might otherwise be caused by vibrations insuring at the same time the proper
compacting of the plates. When the apparatus is required for use in the open air tho
aforesaid box should be hermetically closed.
To make the apparatus capable of being conveniently moved it may be provided
with an iron ring at the top.
It is understood that interposed between the apparatus and the line (primary as well
as secondary) the usual or any suitable safety devices may be provided. The fuses
where they are used may be fitted onto a piece of insulating substance attached to the
frame or they may be placed in a separate box by the side of the apparatus as may
be most convenient.
The Invention may be applied to a secondary generator transformer or converter
either for transforming a current of electricity of high tension to one of low tension
or for transforming a current from low tension to high tension by employing the
secondary circuit as the primary circuit.
The accompanying Drawings shew arrangements according to this Invention.
Figure 1 is a side view and Figure 2 a transverse section-Figure 3 is a modification
of the arrangement of the coils. Figure 4 shews one of the plates separately.
The apparatus consists of the secondary circuit s and the primary circuit p and of a
body or case of iron c. The secondary circuit is formed of an insulated copper wire
or cable with several strands or a flat insulated ribbon of suitable length, wound on
the lathe on a flat shaped mandrel with its ends rounded spherical or oval. On the
secondary circuit is placed a sufficient thickness of insulating material i and the primary
wire of a length and thickness necessary for required transformation is wound beside
the secondary coil as in Figure 3 or on it as in Figure 2 and is also covered with
insulating material i. The primary wire can be wound on first and the secondary
wire after.
In all cases the primary and secondary coils are separated from each other and from
the surrounding iron plates by insulating material.
When the two coils have been formed as described the body of iron c is placed in
position. This body of iron c is formed of thin soft iron plates which are of the shape-
shewn in Figure 4 and can be cut by machinery and insulated from each other by a
thin sheet of paper coated on one side with gum lac or any other suitable adhesive
material.
Two plates as in Figure placed opposite each other form a rectangle which
surrounds the two circuits on all sides. The plates are in two series one embracing
each of the sides of the coil. Two other plates are placed above them so that the solid
parts cover the cuts of the first plates and that the bare parts of each pair of frames
formed by the pieces touchi thus forming a magnetically closed field of very short
length around the two circuits. When the required number of plates has been set in a
position on each side of the coils the whole is kept in place by two cast iron frames ƒ
bolted together as shewn in Figure 1.
•

page_text: The plates of soft iron forming the body can also be of the shape shewn in Figure 5.
The base or connecting piece a opposite the opening being preferably twice as broad
as each of the two sides y so that when two of these plates are put one above the other
to form a closed magnetic field there is at every point of the magnetic field the same
mass of iron. Figure 6 shows these pieces put in place around one secondary coi!
with two primary coils. Figure 7 shews the plates arranged in groups around
circular coils.. We may make the plates of iron of a rectangular shape and
cut on one of the sides or in a corner, the cut parts being bont over to allow of the
plate being slid into position over each side of the coil.
Plates as above described can be put in such a position that the plates on one side
overlap those on the other side so as to allow between each plate a free space for the
passage of air as shewn in Figure 8. The primary and secondary bobbins being wound
in flat shape and the distance between the two parallel sides being equal to the width
of the sides of the plates. We place the necessary plates on one side of the circuits
to form a closed magnetic field, the same is done on the other side of the circuits so
that there is a double thickness between the two parallel parts of the circuit, the plates
thus placed alternately forming a compact mass in the middle and leaving a free space
between each plate outside. It is to be understood that the coils are not necessarily of
the shape shewn in the drawings.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :-
:-
1. In secondary generators or transformers or converters of electricity iron plates
so shaped and disposed that they form magnetic circuits round each of the sides of a
coil with a space between in the centre of the coil substantially as hereinbefore described
and illustrated.
2. In secondary generators or transformers or converters of electricity iron plates
of the shape shewn in Figure 5 reversely placed so as to form by each pair of plates
an insulated and closed magnetic circuit the said plates being in two series one on each
side of the coil substantially as hereinbefore described and illustrated.
3. In or for secondary generators or transformers or converters of electricity plates
shaped as shewn in Figure 4 for being arranged on the coils as shewn in Figures 2
and 3.
4. The several constructions or combinations of parts to form a secondary generator
or transformer or converter of electricity substantially as severally described with
reference to Figures 1 to 4, Figures 5, 6 and 7 and Figure 8 of the accompanying
drawings.