Improvements in and connected with Electric Transformers.
Year: 1889

page_text: PROVISIONAL SPECIFICATION.
Improvements in and connected with Electric Transformers.
I, JAMES SWINBURNE, of 49 Queen's Road, Wimbledon, Surrey, Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
Trans-
In cases where transformers are used in houses there is enormous loss because the
transformer must be large enough to do the maximum work, and is generally doing
very little, while the waste of power in the iron is going on all the time.
formers designed with little enough iron to be ethic.ent under these circumstances are
very expensive, as they need a great deal of copper.
or more are used for each house and are put into or out of circuit by automatic gear
According to my invention two
as required. Thus n 100 lamp house may have a 90 & a 10 lamp transformer. The
10 lamp transformer is ordinarily in circuit, but when the current rises to that of
eleven lamps an electromagnet or other suitable mechanism cuts the primary &
secondary of the 90 light transformer into circuit. When no lamp is used the
mechanisin may be arranged to cut out even the 10 lighter, and leave in a minute
transformer just big enough to work the mechanism.
For regulating transformers for house, substation or other work I arrange either
the primary or secondary circuit, or both circuits with a few or several turns led to
contacts, with a switch, so that more or less may be cut in or out. The switch has a
double contact arrangement, with resistance or a choking coil between the contacts to
avoid short circuiting or opening the circuit.
an open iron circuit transformer may be used. Instead of making the ends of the
When it is necessary to have little iron
core as now usual in such cases, I let the wire protrude a little, and separate the ends
so as to form a sort of bush or brush at each end. The magnetic induction is then
not so great in the air at the ends, so that less inagnetizing force is needed.
Where transformers are used in the houses the present practice is to make them
with a great deal of iron. I have discovered that such transformers should have very
little iron, and that the proportions should be widely different from those now in
general use. According to my invention the copper coils form one link and there are
two links of iron interlinked with it. The section of the copper link is nearly square,
and the section of the iron links where together is also nearly square. This gives the
maximum efficiency. In cases where the transformers are only lighting the full lond
of lamps for short periods very little iron is used according to my invention.
ron may be in the form of wire or of lengths of flat strip.
Dated this 23rd day of May 1980
The
COMPLETE SPECIFICATION.
JAS. SWINBURNE.
Improvements in and connected with Electric Transformers.
I, JAMES SWINBURNE, of 49 Queen's Road, Wimbledon, in the County of Surrey,
Electrical Engineer, do hereby declare the nature of this invention and in what
manner the saine is to be performed, to be particularly described and ascertained in
and by the following statement :—
In transformers as at present designed the volume of the iron is large in proportion
to that of the copper coils, & the loss of power in reversing the magnetisation is very
considerable.
When the transformers are used in the houses this waste of power is very
serious, as the transformer has to be made large enough to supply the maximum
number of lamps ever needed in the house, and it generally supplies only a portion of
[Price 8d.]

page_text: his number during the evening, & lies idle, or nearly cuuning
serious waste of power in the iron is, however, going on all the time."
To overcome this evil I proportion the iron and copper so that the total loss of energy
n a given time, such as for instance a day, is as small as possible.
I have found that for most outputs commonly needed a new form of open iron
circuit transformer is most efficient.
This form is shown diagrammatically in Fig. 1. def g are four divisions of the
primary coil wound on an insulating former or reel h. The secondary k is wound on
the core which is made of soft iron wire. The core & secondary are passed into
the primary, & the ends of the wires of the core are spread out into a sort of bush or
hedgehog.
5
1
In winding the primary coil, beginning with, say d, the end of the wire is passed
The coil d is then wound. The foriner is
through the partition into the space for c.
then turned end for end in the winding lathe & the end of e is joined to the end of a that
was passed through the partition. The coil is then wound. The coils f & g are 1
wound similarly. The pairs of coils are then coupled in series. By this arrangement
the inside wire has not to cross all the others, making insulation difficult. The
secondary coils are entirely separate from the primary. Instead of wire, strips of thin
sheet iron may be used. They are arranged as shown in section in fig. 4, & are bent
over as shown in figures 2 & 3.
To find the best proportions the dimensions of an imaginary transformer may be
varied one at a time till the form giving the least loss of energy per day under the
required conditions is found.
The object of spreading out the ends of the core is to prevent the magnetic induction
being high at any region in the air, so that the core is not difficult to magnetise. It
the core were cut off at the ends of the coils there would have to be a large number of
current turns in the primary. Even in the transformer as shown, the exciting
current is comparatively large, but it is practically a quarter of a period behind the
electromotive force in phase, so there is little loss of power. The primary wire is
made a little larger to allow for the exciting current.
When closed iron circuit transformers or even hedgehog transformers are used for
such purposes as lighting houses the loss of energy between midnight & the following
even is very serious. To reduce this waste I provide an automatic switch controlled
by the output of the transformer. The simplest forın is a drop cat-out which cuts off
the primary circuit whenever the load is reduced to a certain value. For instance, in
a house wired for 50 lamps the transformer may be automatically cut off when the
load falls to 3 lamps, which will probably be about midnight. When the lights are
again wanted, say at 5 p.in. the cut out switch is moved back to the working position
by hand, a fourth lamp having been first put in circuit.
In some cases, for instance, where one or two lamps are always needed, for cellars
or dark passages, these lamps are put on a special circuit fed by a small transformer.
The main transformer is then provided with the automatic switch as described.
In large houses I arrange a large & a small transformer in parallel, with an automatic
switch. The switch has three positions A, B, & C. In position A both transformers
In position B the small one is
are in use in parallel, or the large one is alone in use.
alone in use, the primary & secondary of the large one being open. In position C
neither is in use. A spring presses the switch into position C, but it is held by catches
in positions A or B. For instance, if the large transformer can supply 100 lamps, &
the small one 10, in the evening the switch is in position A. Towards midnight the
lamps decrease to 10. As soon as only, say, 9 are in use the switch is released &
Towards the following
moves to position B, cutting off the large transformer.
evening more than 10 lamps are needed, so the servant moves the switch hack
position A. Should he or she forget & turn on say 12 lamps, the switch moves t
position C& turns out all the lamps.
The switch may be worked by a time piece, which may also work the meter; bu
as a switch which makes good contacts needs some appreciable energy to work it,
that the energy should be supplied by hand.

page_text: Fig. 5 of the drawings is a diagram of the first kind of switch. l, m, are the
primary leads connected to the transformer n one, being taken through the double
contact switch. The secondary circuit leaving at o, passes round the electromagnet q
& away to the house along r. If the current falls below a certain limit, say that of
three lamps, the armature t is pulled off by the weight of the ball on the end of its
lever. The primary circuit comes from / to the contact piece u.
し
The bar vis led
through the circular insulating body of the switch to the other contact piece u. When
the armature falls the lever catches the pin 10 & opens the switch, & turns off the
transformer by breaking the primary circuit. At night when the lamps are wanted
again, a fourth is switched on, & the armature t is raised by the handle. The lever
catches on the pin & closes the switch; the armature then clings.
Fig 6 shows the arrangement of a large & small transformer, n & a are the trans-
formers. When the current is well within the output of the smaller transformer, the
armature t falls & releases the catch 6. A spring which for clearness is omitted, is
constantly pressing the switch in the direction shown by the airow.
The switch is
shown in position A. When the catch B is released the switch rotates till the tooth Y
takes in the catch 8. The switch is then in position B. The primary of the
larger transformer is opened at y & the secondary at Z. The switch arm from Z
now makes contact with & makes the secondary circuit of the small transformer.
At night, when more lights are wanted, the switch is turned by the handle till
held by the catch B. Should this be neglected, as soon as the load is too great
for the small transformer, the electromagnet releases the catch &, & the contact
at is broken, the switch being rotated by the spring till the bar catches the
stop 7.
This turns the lamps out & reminds the servant of his duty. The contacts
are adjusted so that the primary of the large transformer is broken first, & the
secondary is broken just before the secondary of the small transformer is made.
This is advisable in open circuit transformers, for a sudden break of the circuits
at an instant when the iron is magnetised, is trying to the insulation. In the
arrangement shown, the primary of the small transformner is always on. Any
lamps for dark passages or cellars that are wanted all day are connected between r
& so as not to be controlled by the switch If no lainps are wanted in this
manner, another contact in the primary of n corresponding with is provided.
It is to be understood that these are mere diagrams; in practise the switch
gear is arranged compactly & covered in, with only the handles accessible.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what mauner the same is to be performed, I declare that what I
claim is:
1. An open iron circuit transformer with the core designed to need little excita-
tion substantially as described and for the purposes set forth.
2. An open iron circuit transformer with the ends of the core spread out into
a bush or brush substantially as described & for the purposes set forth.
3. A transforiner made as described so as to have little waste of power in the
iron.
4. An automatic switch substantially as & for the purposes set forth.
5. An automatic switch for cutting transformers out or in controlled by the
output, substantially as and for the purposes set forth.
Thi 1-4 JL. 1000