Improvements in Electric Transformers.
Year: 1891

page_text: Date of Application, 30th July, 1891-Accepted, 12th Sept., 1891
COMPLETE SPECIFICATION.
Improvements in Electric Transformers.
I, WILLIAM MORRIS MORDEY, of Victoria Works, Lambeth, in the County 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 :-
This invention relates to improvements in electric transformers, sometimes called
convertors, or induction coils of the kind described in a former Specification
No. 6917 of 1887 and has for its object to construct such transformers with a
greater economy of material and so that they shall be simple and easy to build,
or to take to pieces, shall have a high degree of insulation and efficiency, and shall
possess good self regulating qualities.
In order that the nature of my present invention may be clearly understood I
will proceed to explain the same by aid of the accompanying drawings in
which,
Fig. 1 is an elevation of a bobbin with the primary and secondary coils.
Figs. 2 and 3 illustrate the form of iron stampings employed to form the
sheath.
Fig. 4 is a cross section; and
Fig. 5 a longitudinal section of the complete transformer.
Fig. 6 is an elevation partly in section, and to a larger scale, of the
terminal slab.
The primary and secondary coils P and S respectively are wound in a long link
shaped bobbin or support A (Fig. 1) of suitable material, for example wood, that
serves to insulate the said coils from the iron sheath B shown in Figs. 4 and 5.
Between the two windings P and S is placed a sufficient thickness of insulating
material C to prevent contact between them. The coils P. S, are coated exteriorly
with a layer of insulating material and are then surrounded by or encased in a
sheath B of thin iron sheets built together in the manner hereinafter described with
reference to Figs. 2 and 3. These sheets are electrically separated in pairs by thin
paper pasted on one side of each of them, or by a coating of varnish, or of an oxide,
for the purpose of preventing the generation of wasteful eddy currents.
The iron sheath which, as a whole, is marked B in Figs. 4 and 5 is built up from
stampings of thin sheet iron prepared as follows and as illustrated in Figs. 2 and 3.
A number of rectangular sheet iron stampings A* B* C* D* are prepared each of
the form shown in Fig. 2, and the length and width of which are in the proportion
of 3 to 2. From each stamping A* B* C* D*, a rectangular piece E. F. G. H. is
stamped out leaving a rectangular hole the length and width of which are in the
proportion of 2 to 1. The pieces E. F. G. H. are placed between the
stampings A* B* C* D* and across the rectangular holes therein, so as to occupy
the position E F G H¹. It will be evident however that by this arrangement
which is similar to that described in the said former Specification, spaces will be
left between the end portions of the sheets, and also between the central portions of
the several sheets E F G H. In order to fill these spaces and so utilise to the
utmost the available space, other stampings prepared according to Fig. 3 are used
according to this invention as follows:-Square sheet iron stampings A' B' C¹ D',
having sides equal in length to A. D. of Fig. 1 that is to say in the proportion
of 2 to 2, have square pieces a b c d stamped out of each and by a cut ef the
remaining outer square portion is separated into two shaped pieces H¹ A' D' G¹,
and E' B¹ C₁ F¹. The three pieces of sheet metal thus produced from each
sheet A¹ B¹ C¹ D' are inserted during the construction of the sheath in such a

page_text: manner as to fill up the spaces which would be left if the stampings of Fig. 2 were
used alone, the shaped pieces being placed in the positions E¹B* C* F¹
and H¹ A* D* G shown in Fig. 2 while the small pieces a b c d are placed
as shewn at a¹¹ c¹ d¹ in Fig. 2 so as to alternate with the longer
pieces E F G H².
By this construction I am enabled to build transformers of small size because the
whole of the space is utilised to the best advantage. At the same time I effect
economy of material, as by means of the arrangement and proportions named, I
entirely avoid waste of iron.
:-
Figs. 4 and 5 shew the relative position and arrangement of the bobbin A, the
laminated iron sheath, and the coils or windings P. S. The outer casing or
envelope II is of cast iron constructed to conveniently receive the actual trans-
former, which is thereby protected against injury and rendered waterproof. The
casing I, I is formed in two longitudinal portions which are bolted together with a
rubber band J between the joints. The lower part is provided with feet K and the
upper part with eyes L. At one end of the casing I I bolts M are inserted
(Fig. 5) for the purpose of compressing and firmly setting up the iron sheets
forming the laminated sheath B. At the other end of the casing is a door or lid N
by opening which access can be gained to a porcelain terminal slab O, seen in
sectional elevation in Fig. 5, and to a larger scale in front view in Fig. 6. This
slab O which is cemented into place, is formed with ribs or corrugations o, o, for the
purpose of ensuring efficient insulation. It is provided with the following fittings ::
Primary terminals Q Q. A double pole switch for closing and opening the
primary circuit and consisting of a movable cam shaped insulating block R, that
can be turned by an external knob or handle R', and two springs q q' which by
the turning movement of the cam shaped block R. can be pressed against the
terminals QQ. From the springs q q', when the switch is closed, the primary current
passes through high tension fuses to the primary winding, which is connected
between the terminal springs T T¹ of the fuses. One of these fuses which is of the
kind described in the Specification of another application for Letters Patent filed
by me No. 19076 of 1890 is shewn in section in Fig. 6. It consists of a glass tube S
closed at the ends by metallic caps s s¹ between which is the fusible wire or other
conductor g. Spring clips T t, T₁ t¹ make contact with and hold the tubes in
position. For the purpose of preventing the formation or continuance of an arc
between the fuse terminals, the glass tube is filled, or nearly filled, with a suitable
non-conducting substance h such as mica, asbestos, marble, or emery placed about
the fuse conductor g in a powdered or finely divided condition. By means of this
arrangement I am enabled to use very short fuses (even for very high tension)
which I can conveniently place within transformer cases or other confined places.
This form of fuse I use, suitably mounted, for the ordinary purposes for which high
tension fuses are required, and thus I avoid the necessity for using long, costly, and
wasteful fuses which have hitherto been employed on high tension circuits in order
to prevent the formation of arcs.
The secondary winding is usually arranged in two separate portions connected
respectively to the terminals U U, V Vi for convenience of connection to the
external secondary circuit. The two portions may be used in parallel, or in series,
or in the manner usual in " 3-wire " distributions. The primary conductors are
taken in to the transformer through the glands W W', while other glands X X¹ X'
are used for secondary conductors.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:-
1. In an electric transformer of the kind herein referred to, constructing the
laminated iron sheath for the primary and secondary coils or winding of sheet iron
cut and arranged substantially in the manner described and shewn so that the
spaces left between the several iron sheets A* B* C* D*, and also the spaces

page_text: between the several iron sheets E, F, G, H, are filled by other sheets of iron for the
purposes specified.
2. The combination and arrangement of parts constituting my improved electric
transformer substantially as hereinbefore described and shewn, and whether with or
without safety fuses of the kind mentioned.
Dated this 30th day of July 1891.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.