Improvements in the Construction and Working of Electrical Transformers.
Year: 1895

page_text: Date of Application, 11th Mar., 1895
Complete Specification Left, 11th Dec., 1895-Accepted, 29th Feb., 1896
PROVISIONAL SPECIFICATION.
Improvements in the Construction and Working of Electrical
Transformers.
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 an improved construction of electrical trans-
formers whereby the iron cores can be easily removed and annealed after working,
so as to restore them to their best magnetic condition. It also relates to the
method of connecting and fixing transformers below the street level for greater
ease in manipulation, and to the working of said transformers so as to maintain
them at as high a state of efficiency as possible.
According to my invention I prefer to build transformers upon the underside of
a plate or frame and carry the insulated coils forming the primary and secondary
of the converter in frames bolted or held on to the underside of the before-
mentioned plate. These frames, which are preferably of metal, are fitted with
insulating material upon the face next to the coil. The coils are also carefully
insulated and made up into as solid a block as possible by being wound on frames
and baked together.
Contrary to the ordinary practice I do not fix the coils on to the core, they
being entirely supported by the before-mentioned frames. The cores and yokes
are made of laminated iron and are bolted together on to the plate and framing
to hold them in position. The iron core is preferably round in section being made
with pieces of heavier metal on each side rivetted through so that the whole may
maintain its shape. The yokes are also made of laminated metal of square section,
held together by plates and rivets as in the case of the core. This form is adopted
by preference so that when it is desired to anneal the yokes and cores they may
be easily removed, placed in an annealing furnace and then replaced in the
converter again. This operation may be repeated as often as it is found desirable,
from time to time.
My method of working converters is to put them into use in the ordinary way,
after they have been in use for a sufficient length of time for the iron to have
deteriorated from a magnetic point of view sufficiently to affect the economy of
the converter I remove the cores and yokes belonging thereto and anneal same.
Afterwards they are put back and the converter is then of its original efficiency.
This treatment is repeated from time to time and as often as is necessary in between
the ordinary working of the converter and while it is maintaining its efficiency for
as long a period as may be desired.
In building transformers I prefer to so construct the box, which is placed by
preference directly in the ground in the street, in such a way that the lower part
of the box is of sufficient size to contain the converter proper and so that the
framing which holds the cores and the coils may register in the bottom of the box
for the sake of rigidity. The upper part of the box is widened out beyond the
dimension required for the transformer proper and upon the edges of the box thus
formed the plate under which the transformer is built, rests. This widening of the
box enables me to bring the leads in to fix to the terminals in the box without their
having to be removed when it is necessary to remove the transformer, as they are
wider than the maximum width of the plate upon which the converter is built.

page_text: Boxes of this kind may be permanently installed in the streets and any change of
the transformer or its gear may be effected without removing the leads or other
connections.
Dated this Eleventh day of March 1905.
Improvements in the Construction and Working of Electrical
Transformers.
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 an improved construction of electrical trans-
formers whereby the iron cores can be easily removed and annealed after working,
so as to restore them to their best magnetic condition. It also relates to the
method of connecting and fixing transformers below the street level for greater
ease in manipulation, and to the working of said transformers so as to maintain
them at as high a state of efficiency as possible.
Figure 1. outside elevation of transformer case set in the ground.
Figure 2. section through transformer case and road box showing the transformer
proper in position.
Figure 3. plan of road box and transformer case with the covers, plugs and
transformer proper removed.
Figure 4. plan of plate carrying the coils, cores and yokes removed from the
case,
Figure 5. elevation of coils showing frame without cores and yokes.
Figure 6. sectional plan through line A. B. of Figure 5.
According to my invention I prefer to build transformers upon the underside of
a flat metal plate (b) and carry the insulated coils (c) forming the primary and
secondary of the converter in frames huilt or held on the underside of the
before mentioned plate. These frames, which are preferably of metal, are fitted
with insulating material upon the face next to the coil. The coils (c) are also
carefully insulated and made up into as solid a block as possible, by being mounted
on frames and baked together.
Contrary to the ordinary practice I do not fix the coils (c) on to the core (a),
they being entirely supported by the before mentioned plate & frame. The cores (a)
and yokes (d) are made of laminated iron and are bolted together on to the plate
and framing to hold them in position. The iron core is preferably round in section
being made with pieces of heavier metal. The yokes (d) are also made of laminated
metal, of square section, held together by plates and rivets as in the case of the
core. This form is adopted by preference so that when it is desired to anneal the
yokes and cores they may be easily removed, placed in an annealing furnace and
then replaced in the converter again. This operation may be repeated as often as
it is found desirable.
In building transformers I prefer to so construct the box (e), which is placed by
preference directly in the ground in the street, in such a way that the lower parts
of the box is of sufficient size to contain the converter proper and so that the
framing which holds the cores and the coils may register in the bottom of the box
for the sake of rigidity. The upper part (f) of the box is widened out beyond
the dimensions required for the transformer proper, and upon the edges of the box
thus formed, the plate (b), under which the transformer is built, rests. This.
widening of the box enables me to bring the leads in to fix to the terminals in the

page_text: box without their having to be removed when it is necessary to remove the trans-
former, as they are wider than the maximum width of the plate (6) upon which the
couverter is built.
Boxes of this kind may be permanently installed in the streets and any change
of the transformer or its gear may be effected without removing the leads or other
connections.
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.) Supporting the coils of the transformer in a frame independent from the
iron core.
(2.) Carrying the copper coils of a transformer in a frame attached to the
underside of a plate, which plate also carries the iron forming the magnetic circuit
on the underside and the terminals and connections on its upper side.
(3.) In converter boxes for placing in the ground which contain the converter in
their lower part and the terminals and connections in the upper part forming the
upper part of the larger size so that the transformer may be removed without
fouling the wires and connections substantially as described.
(4.) Electrical transformers substantially as described and illustrated.
(5.) My improvements in the construction and working of electric transformers
substantially as described.
Dated this 11th day of December 1895