Improvements relating to Electric Current Transformers.
Year: 1896

page_text: [Communicated from abroad by THE ELEKTRIZITATS-AKTIENGESELLSCHAFT vormals
SCHUCKERT & Co., of Nuremberg, Bavaria, in the Empire of Germany,
Manufacturers.]
Improvements relating to Electric Current Transformers.
I, WILLIAM ROBERT LANE, of the firm of Haseltine, Lake & Co., Patent Agents,
45 Southampton Buildings, in the County of Middlesex, do hereby declare the
nature of this invention to be as follows:
Up to the present transformers for polyphase currents with common magnetic
circuits have been built in which several electromagnets are arranged side by
side between the base plate and an iron cover.
It is obvious that this arrangement can only be used with transformers of the
core type; it is however well-known that up to a certain size for single phase
currents, transformers of the ironclad type are to be preferred. For polyphase
currents the latter type has not yet been used.
The object of the present invention is to produce ironclad transformers for
polyphase systems.
In the accompanying drawing
Figure 1 is a plan of a transformer of the new type, destined for two phase
currents;
Figure 2 is an elevation of the same.
Figure 3 shows a similar apparatus for three phases;
Figures 4 and 5 illustrate the connections and
Figuro 6 illustrates the magnetic conditions of the different circuits for a special
case.
The invention cousists in arranging the electromagnets one above the other
instead of placing them side by side as heretofore, thus giving the electromagnets
a common vertical axis. The iron is laminated as usual. The single sheets may
consist of two E-shaped flat iron picces, and a third piece interposed which by
preference is of rectangular form as shown in Figure 1. The arrangement of
the iron pieces and of the windings will easily be understood from the figures.
The connections for a three phase system may be according to the A or
principle as required by the special conditions of the case. Any other connection
however may be used instead, as for instance the Steinmetz' connection shown in
Figure 4, which requires only two bobbins for three currents of different phase.
A special advantage is obtained with the three phases system ou the A or Y
principle by joining the second bobbins in the opposite sense see Figure 4.
The magnetic conditions for this special arrangement are shown in the
Figures 5 and 6. The direction of the windings is opposite in the second one,
as above mentioned, that is to say the effect will be the same as if the three
bobbins were connected in the same manner and traversed by alternating currents
רו ה'מ

page_text: differing in phase by sixty degrees. This will be easily understood from well
known theories.
Referring to the diagrams, Figure 6, it will be noted that their upper part is
only the representation of a three phase sinus system, riz. the lines denoted
by xyz correspond to three sinus differing in phase by 120°.
Each clock diagram shows the condition of the sinus system at a time which
differs from that of the system illustrated by the preceding or subsequent diagram
by ono twelfth of a complete revolution or period.
In the parts marked b, the rectangles xyz represent the bobbins; the arrows on
the right side of each diagram show the direction or winding of the wires, which
of course remain unaltered. The arrows marked on the rectangles show the
directions of the lines of force for each bobbin, and the surrounding dotted lines
indicate the composed lines of force. In Figure 6 I for instance, the direction
of current would correspond to the upper part a. Hencer is positive, y and z
negative. But as y corresponds to a coil joined in the opposite direction, as
explained above in the part b, y acts in the opposite direction riz. the currents r
and y run in the same direction i.e. in a direction opposite to that of the hands
of a clock. With regard to generally known theories it is not necessary to explain
the phases 1 to 12 in detail. If the two fluxes in a common iron are equal and
opposite, of course the resultant is zero.
Now if the winding of the middle bobbin were not joined in the opposite sense,
there would be a different effect. Assuming the maximum flux in a bobbin as
unity, the magnetic flux in I would be 1, 5, and in 2 riz. a twelfth of a period
later 1. sin. 60.2= 173, the latter expression being the maximum resultant flux.
In the condition, however, which the new arraugement embodies, the maximum
will be less. It will be observed from the diagrams, for instance at 1, that the
maximum is obtained when two components as y and z are equal and act in the
same sense that is 2 sin. 301. In other words whereas the maximum of the
resultant in the first case has been 173, in the present case the maximum will
never exceed 1.
From this fact results a saving in the section of the iron, consequently the
transformers can be built smaller in size and less in weight for the same capacity
of induction. Besides this the losses in the iron are proportionately reduced.
Dated this 29th day of August 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements relating to Electric Current Transformers.
I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
45 Southampton Buildings, 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:-
Up to the present transformers for polyphase currents with common magnetic
circuits have been built in which several electromagnets are arranged side by
side between the base plate and an iron cover.
It is obvious that this arrangement can only be used with transformers of the
core type; it is however well-known that up to a certain size for single phase
currents, transformers of the ironclad type are to be preferred. For polyphase
currents the latter type has not yet been used.
The object of the present invention is to produce ironclad transformers for
polyphase systems.

page_text: 3
Figure 18 an elevation of the same.
Figure 3 shows a similar apparatus for three phases;
Figures 4 and 5 illustrate the connections and
Figure 6 illustrates the ma netic conditions of the different circuits for a
special case and
In the additional drawi
former.
Figs. 7 and 8 show the construction of the trans-
The invention consists in arranging the electromagnets one above the other
instead of placing them side by side as heretofore, thus giving the electromagnets
a common vertical axis. The iron is laminated as usual. The single sheets
may consist of two E-shaped flat iron pieces, and a third piece interposed which
by preference is of rectangular form as shown in Figure 1. The arrangement
of the iron pieces and of the windings will easily he understood from the figures.
The connections for a three phase system may be according to the A or Y
principle as required by the special conditions of the case. Any other connection
however may be used instead, as for instance the Steinmetz' connection shown in
Figure 4, which requires only two bobbins for three currents of different phase.
A special advantage is obtained with the three phases system on the A or Y
principle by joining the second hobbins in the opposite sense see Figure 5.
The magnetic conditions for this special arrangement are shown in the
Figures 6 and 6. The direction of the windings is opposite in the second one,
as above mentioned, that is to say the effect will be the same as if the three
bobbins were connected in the same manner and traversed by alternating currenis
differing in phase by sixty degrees. This will be easily understood from well
known theories.
Referring to the diagrams, Figure 6, it will be noted that their upper part
is only the representation of a three phase sinus system, riz. the lines denoted
by yz correspond to three sinus different in phase by 1200.
Each clock diagram shows the condition of the sinus system at a time which
differs from that of the system illustrated by the preceding or subsequent diagram
by one twelfth of a complete revolution or period.
In the parts marked b, the rectangles y represent the bobbins; the arrows
on the right side of each diagram show the direction of winding of the wires,
which of course remain unaltered. The arrows marked on the rectangles show
the direction of the lines of force for each bobbin, and tne surrounding dotted
lines indicate the composed lines of force. In Figure 6 I for instance the
direction of current would correspond to the upper part a. Hence is positive,
y and z negative. But as y corresponds to a coil joined in the opposite direction,
as explained above in the part b, y acts in the opposite direction viz. the currents.r
and y run in the same direction i.e. in a direction opposite to that of the hands
of a clock. With regard to generally known theories it is not necessary to explain
the phases 1 to 12 in detail. If the two fluxes in a common iron are equal and
opposite, of course the resultant is zero.
.
period
Now if the winding of the middle bobbin were not joined in the opposite sense,
there would be a different effect. Assuming the maximum flux in a bobbin as
unity, the magnetic flux in 1 would be 1, 5, and in 2 riz. a twelfth of
later 1. sin. 60.2-1.73, the latter expression being the maximum resultant flux.
In the condition, however, which the new arrangement embodies, the maximum
will be less. It will be observed from the diagrams, for instance at 1, that tho
maximum is obtained when two components as y and z are equal and act in the
same sense that is 2 sin. 30= 1. In other words whereas the maximum of the
resultant in the first case has been 173, in the present case the maximum will
never exceed 1.
From this fact results a saving in the section of the iron, consequently the

page_text: transformers can be built smaller in size and less in weight for the same capacity
of induction. Besides this the losses in the iron are proportionately reduced.
Referring to Figures 7 and 8 the sheet iron 4, i are supported by the frame a,
and pressed together by means of bolts d acting on the corner or angle-pieces b.
The construction is secured to the frame by the bolts d and plates g. Two other
plates f, f, are pressed on the middle iron sheets by the bolts e, e the whole
arrangement thus forming a solid construction. Before fastening the bolts the
coils (not shewn in Figs. 7 and 8) may be laid in the corresponding holes.
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed, as communicated to me
by my foreign correspondents, I declare that what I claim is:-
1. An ironclad transformer for polyphase alternating currents built by placing
the single coils one ou the top of the other, so that they have a common axis,
and arranging the iron sheets so, that a section parallel to the lamination shows
iron all round the inducing coils, substantially as set forth.
2. A threephase transformer of the type specified in the first claim, having
its middle coil windings joined in an opposite sense as set forth.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.