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July 22, 1947.
Filed Jan. 9, 1945
2 Sheets-Sheet l
“ 1111A ; “
July 22, 1947.
Filed Jan. -9, 1945
2 Sheets-‘Sheet 2
Patented July 22, 1947
James A. Anderson, Memphis, Tenn.
Application January 9, 1945, Serial No. 571,974
4 Claims.
(Cl. 171—242)
This invention relates to adjustable reactance
transformers of the type used for welding and
other purposes in which the electrical ‘output of
way of example; it will be obvious to those skilled
in the art that changes and variations may be
introduced which will produce further embodi
the secondary coil is controlled by ‘means of a
control of the magnetic ?ux.
Transformers of this type are usually ‘either
ing from the essence or spirit of the invention.
provided with a movable coil or with a magnetic
shunt, but both methods as hitherto applied have
ments of this invention without, however, depart
In the accompanying drawings:
Figure 1 is an elevational view of the trans
former according to the invention.
inconveniences and drawbacks. To obtain. a
Figure 2 is a sectional view at right angles to
large variation of current in the case of a mov 10 that shown in Figure 1, the cross section being
able coil, a long track of the coil is necessary 1 taken along line 2--2 of Figure 1.
to obtain a small variation while in the case of
Figure 3 is a view of a horizontal section
a magnetic shunt, the control of output with most
through the middle or center leg of the trans
constructions presents the di?iculty that exces
former, the section being taken along line 3—3
sively large and non-linear variations of the re
of Figure 1.
actance result from certain displacements of the
Figure 4 is a perspective view of the movable
movable piece. Other constructions which have
bridge piece.
been proposed have the drawback already men
The adjustable transformer comprises a lami
tioned of requiring an excessive length of travel
nated core 5 carrying the two coils 6, ‘I, one of
of the movable member for a required adjust 20 which forms the primary winding while the other
forms the secondary winding of the transformer.
It is the object of this invention to provide
Between the two legs 8, 9 carrying the coils 6, ‘I
means for controlling the output of an adjustable
a middle or central leg I0 is arranged which is
reactance transformer which avoid these di?i
provided with a fixed air gap II. This leg is
25 covered by shields l2 of non-magnetic material
According to the invention, the transformer
arranged on both sides of the leg l0 and ?xed
core is provided with a leg having a ?xed air gap
to it in any appropriate manner. These shields
which is bridged by a movable ?ux-carrying
prevent the formation of stray magnetic ?elds
bridge member of variable cross section. The
through the parts and members mounted on the
magnetic flux through the air gap and thereby
leg Ill. In the modi?cation shown the shields
through the core carrying the coils is thus regu
are fastened to each other by means of screws
lated by the adjustment of the cross section of
13 arranged above and below the transformer
the bridge piece which is adjusted according to
core 5.
the requirements.
The shields are provided with a stepped portion
M for a purpose to be described.
Said magnetic flux, as well known, is propor—
tional to the number of magnetic lines of forces
passing through the leg and through the cross
section regulating the passage through its gap so
that a ?nely adjustable control within practical
limits is possible.
Adjacent to the leg l0 and the air gap H is a
movable leg member, generally indicated by the
reference numeral l5 which consists of a body I6
of laminated magnetic material held by two
This regulating arrangement 40 clamping members I1. These clamping members
permits to obtain a relatively wide range of re
actance variations for a transformer of a given
I‘! are held by means of screw bolts l8 passing
through them and through the movable leg mem
ber I6 and they are provided at their rear ends
A modi?cation of the invention is illustrated
with inwardly projecting guiding ?anges or ledges
in the accompanying drawings and is described 45 [9 which are sliding along the stepped portion [4
in the following speci?cation.
It is, however, to
be understood that the fact that merely one em
bodiment of the invention is described in speci?c
terms is not to be considered as limitative. The
modi?cation shown illustrates the basic idea by ‘
of the shields l2.
The movable leg member [6 is provided with a
rear or guiding face 20 applied against the face
of the leg HI and against the front ends of the
shields 12 which are lying ?ush with the said
face; the guiding portions [4 are holding the
movable leg member [5 and provide a guideway
to any desired relationship between these two
the rack together with the clampingmembers l‘!
and the movable leg member I 6.
with variable or adjustable reactance are useful
adjustment factors.
The adjustable reactance transformer as de
for the same, along which it may slide.
scribed has a number of advantages over other
Said movable leg member is provided with a
constructions. As already stated, it provides
wedge-like end portion 2| formed by an inclined
means which can perform an adjustment entail
surface as shown in Figures 2 and 4. This wedge
ing large variations of current without displace
like portion furnishes varying cross sections
ment of parts over a long track. On the other
through which the magnetic lines of force are
hand, it avoids non-linear and excessive current
passing on their way around the air gap H.
One of the clamping members I‘! is provided 10 variations. A special advantage resides in the
fact that the primary coil need not any longer be
with a rack 22 at its front end which meshes with
tapped or provided with a contactor arrangement
a pinion 23, carried by a shaft 24. The shaft runs
to change the ratio of translation between the
transversely towards the panel board which is
windings of the primary and those of the sec
not shown and is provided at its end with a handle
or crank or some other means for rotating it. It 15 ondary coil. The adjustment of the transformer
therefore simpli?es the transformer construction.
will thus be clear that rotation of the shaft 24
It may ?nally be mentioned that transformers
will rotate the pinion 23 and will lower or raise
in several ?elds, the most important ?eld being
that of the welding machine, supplying current
The function and operation of the parts will 20
of high amperage to the welding arcs. The pres
be clear from the following description. When
ent invention is, therefore, most useful in this
the movable leg member is fully retracted on its
?eld although the invention itself is not related
uppermost position (as shown in the ?gures) the
leg ID will have a substantial air gap offering a
and not limited to any speci?c use as it is mainly
resistance which practically concentrates the 25 concerned with the means for adjusting the re
actance of the transformer itself, and not with
magnetic flux on the legs 3 and 9, only a very
the speci?c application of such an adjustable
small part of the magnetic flux produced by the
primary coil being able to pass through the gap
What I claim is:
in leg [0.
1. An adjustable reactance transformer of the
When the movable leg member [5 bridges the 30
character described comprising a core carrying
air gap the magnetic lines of force may pass be
windings, a transformer leg forming a magnetic
tween the sections of leg I!) separated by air gap
shunt to the winding carrying core consisting of
l I to a varying extent. The extent to which such
two sections, separated by a ?xed air gap, a fur
passage takes place depends on the smallest cross
section of the shunt around the gap. On account 35 ther movable ?ux carrying leg member of mag
netic material provided with a tapering section,
of the wedge-like portion of the movable leg mem
movable alongside both leg sections and bridging
ber, the cross section may be adjusted according
the gap between the same during such movement,
to requirements by raising or lowering the mov
and means for adjusting the position of the ta
able leg member l5, whereby a smaller 01' larger
section of the wedge 2! will act as a flux con 40 pering section for varying the cross section of the
permeable ?ux carrying material for the passage
ductor in accordance with the position of the
of the magnetic flux.
wedge member and with the wedge section ap
2. An adjustable reactance transformer of the
plied against leg 20 corresponding to this position.
character described comprising a core carrying
The magnetic ?ux passing through leg [0 will,
therefore, vary in accordance with the position 45 windings, a transformer leg forming a magnetic
shunt to the winding carrying core and consisting
of leg member l5 and thereby a larger or smaller
of two leg sections separated by a fixed air gap,
portion of the magnetic flux produced by the pri
2, further ?ux carrying leg member with a wedge
mary coil will be diverted through leg l0 and will
shaped section, bridging said gap and adapted
fail to help in providing a current in the sec
to be moved alongside said divided transformer
leg in contact with both leg sections, for adjust
Transformers of the type above described, pro
ing the cross section of the magnetically per
vided with a ?xed gap, bridged by a movable flux
meable ?ux carrying material across the gap and
carrying bridge piece or leg member permit to
further adapted to be moved along one leg sec
adjust the smallest cross section of the permeable
tion out of contact with the other section in order
material through which the magnetic flux of the
to provide an adjustable gap Within the ?xed gap.
transformer leg, forming the magnetic shunt to
the main legs, has to pass. The shifting of the
bridge piece thus produces a ?ne adjustment of
the magnetic reluctance in this leg. In addition,
a further adjustment is possible by moving the
bridge piece to such an extent that the thin edge
portion of the wedge is no longer in contact with
3. An adjustable reactance transformer of the
character described comprising a core carrying
windings, a transformer leg forming a magnetic
shunt to said core and consisting of two leg sec
tions, separated by a ?xed transverse air gap, a
further ?ux carrying leg member with a wedge
shaped end section bridging said gap and adapted
to be moved alongside said separate leg sections,
means for moving said leg member in substantial
mit to introduce an adjustable gap. It will thus
parallelism with leg sections across said gap and
be seen that a very wide range of adjustment is
through said gap, said means comprising clamp
obtainable, the most important range section of
ing plates of non-magnetic material arranged
which may show full linear proportionality be
along one leg section, for gripping, holding and
tween the adjustment made and the variation of
the magnetic ?ux entailed by it, if desired.
70 guiding said ?ux carrying leg member, and means
including hand-operated members, and a rack
It is also seen that the interdependence be
and pinion transmission for moving said leg mem
tween the magnitude of the variation obtained
her along the aforesaid leg section between the
and the adjustment to be made depends on the
clamping plates.
angle of inclination of the wedge-like face, which
4. An adjustable reactance transformer of the
may be straight or curved, so as to conform itself 75
one of the le‘7 sections bordering the gap.
movement of the wedge-like bridge piece will per
character described comprising a core carrying
transformer windings and forming a magnetic
circuit, a magnetic shunt circuit including two
separate members of magnetic material, project
ing from the said circuit forming core, a movable
and adjustable leg member provided with a vary
ing cross section, movable alongside of and in
magnetic contact with ?ux carrying surfaces of
the said projecting members and presenting por
magnetic flux through the magnetic shunt circuit
and means for adjusting the movable leg member.
The following references are of record in the
?le of this patent:
tions of variable cross section to at least one of w
the said ?ux carrying surfaces of the projecting
members of the shunt circuit for adjusting the
Thordarson _______ __ May 17, 1921
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