A New or Improved Construction of Electrical Transformer.
Year: 1886

page_text: Date of Application, 27th Sept., 1886.
Complete Left, 27th June, 1887.
Complete Accepted, 29th July, 1887.
A New or Improved Construction of Electrical Transformer.
I WILLIAM HENRY SNELL of Lamorna Oxford Road, Putney in the county of
Surrey, Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention has for its object to construct a transformer which shall maintain
approximately constant electro-motive force in the secondary coil notwithstanding
that the resistance in this circuit may be varied within limits, while the alternating
current in the primary is maintained at a constant mean value.
Under this last condition in order to obtain a perfect regulation it would be neces-.
sary that the co-efficient of self induction in the secondary circuit should be equal to
zero. But in the present state of knowledge of the art it has not been found
practicable to do away entirely with self induction without at the same time reducing
to a minimum the co-efficient of mutual induction.
The object of the new or improved construction to be described is however to reduce
the self induction of the secondary coil to the lowest practical limit at the same time
keeping the mutual induction of the two coils as large as possible.
The principle of the construction of ordinary transformers consists in taking a core
of iron wire in one bundle and winding thereon the two coils separately insulated.
According to my invention the core is constructed in several bundles of iron wire,
and the secondary coil consists of a like number of separate parts each of which is
separately wound upon one of the said bundles or divisions of the iron core and the
wires of each are then electrically connected together usually all in parallel, but they
may be connected in several separate groups if required. The primary coil may be
wound in one coil over the whole of the bundles forming the iron core, or may be
wound in the same manner as described for the secondary, in which case the coils are
connected in series from core to core. In one particular case of this latter arrange-
ment a cable is employed consisting of several separately insullated wires and an
equal length of this cable is wound upon each sub-division of the iron core:
wire or wires in the middle of the cable form the secondary coil and are connected
either all in parallel or they may be connected if desired from core to core in several
The

page_text: separate groups as before described. The outer wires in the cable form. the primary
and are connected in parallel with each other but are connected with each other from
core to core.
The greater the number of sub divisions of the secondary coil and of the iron core,
the more perfect will be the regulation.
Owing to the phenomenon of magnetic hysteresis the question of the degree to
which a closed magnetic circuit is an advantage in a transformer depends in part upon
the form and dimensions of the secondary circuit upon which it is employed. In
order to provide for this I furnish each transformer with a movable armature by means
of which the resistance of the magnetic circuit of the iron cores may be adjusted once
for all when the apparatus is set up in position for use. By this means increased
efficiency is gained.
Dated this Theanty coventh day of Sentember 1886
J. C. CHAPMAN,
70, Chancery Lane, W.C.,
Agent for Applicant.

page_text: COMPLETE SPECIFICATION.
A New or Improved Construction of Electrical Transformer.
I WILLIAM HENRY SNELL of "Lamorna" Oxford Road, Putney, in the county of
Surrey, Electrical Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
This invention has for its object to construct a transformer which shall maintain
constant or approximately constant electromotive force in the secondary coil while
the alternating current in the primary is maintained at a constant mean value.
According to my invention the iron core is constructed in several electrically and
magnetically insulated bundles or divisions or sections of divided iron forming separate
magnetic circuits upon each of which separate sections a coil of insulated wire is
wound such coils forming the secondaries and the wires of cach may then be electri-
cally connected together either all in parallel or in several separate groups or they
may be independent electrical circuits."
The primary coil may be wound in one coil over the whole of the sections of the
iron core or may be wound in the same manner as described for the secondary, in
which case these coils are connected in series from core to core. In one particular
case of this latter arrangement a cable may be employed consisting of several separately
insulated wires and an equal length of this cable is wound upon each division of the
iron core.
Certain of the wires of the cable are taken to form the secondary coils and
may be connected as before described; the remaining wire or wires in the cable form
the primary and are connected on each core in parallel but are connected in series with
each other from core to core.
One method of performing my invention is illustrated in the accompanying diagrams
though it will be obvious that many modified forms and arrangements may easily be
substituted. Figure 1 represents a side elevation of a transformer constructed
according to my invention. Figure 2 is a plan and Figure 3 is a vertical section on
line a. b.
A A A are separate division sections or bundles of divided iron, they are illustrated
as rings of the same size and shape each built up of iron wire which is preferably
insulated, but they may be of any convenient size shape and form and may be of
varying diameters and volumes of iron each according to its required duty so that
either one lamp or a group of lamps may be run from one ring if required. The
separate divisions are suitably spaced apart by distance pieces a, a and each forms a
separate magnetic circuit. B is the primary coil preferably wound over and through
the separate divisions or magnetic circuits A A A, although it may be wound upon
each division in separate coils connected with each other electrically in series. C, C, C,
are coils of wire separately wound upon each division A A A and form the secondary
coils, they are adapted either to form independent circuits, or to be connected together
in parallel.

page_text: L L is
The wire of all the coils is suitably insulated from itself and from the cores;
the main lead in which a constant mean alternating current is maintained and the
primary coil B is connected thereto as shown.
The secondary coils C, C; C are each connected to the lamp' or lamps or other
electrical resistances in the usual manner, or they may be connected in parallel with
each other in which case they are connected with a common external circuit.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed I declare that what I claim is :-
The hereinbefore described construction of electrical transformer consisting of the
division of the iron core into a number of separate sections upon each one of which
sections a separate secondary coil is wound while the primary coil is wound over all
the sections substantially as and for the purposes set forth.
1000
J. C. CHAPMAN,
70, Chancery Lane, W.C.,
Agent for Applicant.