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Патент USA US2411370

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Nov; 19, 1946.
E. FRIES
R 2,411,370
TRANSFORMER WITH VARIABLE SECONDARY REACTANCE
Filed June 14, 1943
2 Sheets-Sheet 1
Nov. 19, 1946.
‘2,411,370
E. FRIES
TRANSFORMER WITH VARIABLE SECONDARY REACTANCE
Filed June 14, 1943
C
3
‘f- 37
// //J 1)]
2 Sheets-Sheet 2
Patented Nov. is. as ,
ES
earsnr
enrich *
W'LTTH VAREABL'E
@ECQENDAPPZ REACTANCE
Fries, @erliiron, Switzerland
_
Application dune id, 1943, Serial No. 490,78?’
in Switzerland July .6, 1942
(Claims.
((31. 171-119)
2
l.
with both the core of the transformer and the
variable reactor.
Other objects and advantages will hereinafter
The present invention relates to transformers
with variable reactance and is particularly an“
-plicable to transformers for welding or the like
in which the reactance of the secondary circuit
appear.
The preferred form of the invention provides
transformer cores of rectangular cross section
The reactance component of transformers
and rectangular coils. The transverse interspaoe
which determines the ratio of the primary and
between the primary and secondary coil is en
secondary voltage for dl?erent load currents has
larged on one side and a secondary core with an
I in the past been. made regulable by inserting iron
laminations into the leakage path of the primary 10 adjustable air gap and inductively interlinked
with the secondary coil only, is inserted into this
magnetic ?ux, that is in shunt with the main
enlarged space. This leakage or secondary core
?ux path. For heavier sections of the magnetic
consists of a. stationary part and a movable part,
circuit thin sheets were assembled in a lmown
having an air gap between them. ri‘he stationary
manner to form stacks of laminations. The mag
netic forces exerted on these stacks may be very 15 part is ?xedly connected with the main trans
former core or its support and projects axially
high, in which case they must ‘be mounted very
into the aforementioned interspace from one end
solidly in order to avoid noises and vibrations.
of the coils. The movable part which completes
This is not too di?cult for a constant reactance
the secondarycore is inserted from the other end.
which permits of stationary mounting of the
stacks. However, if a reactance which is ad 20 This latter part is arranged to be moved in and.
out of the coil by a simple mechanism in such a justable within a wide range is required, it is
manner that the air gap is approximately at the
necessary to provide a variable air gap in the
central transverse plane of the coils. In case of
shunt magnetic path. It is structurally dimcult
a two cell single phase core type transformer the
to provide for adjustment of the air gap‘ between
wide limits in a simple and inexpensive manner, 25 leakage core comprises two opposed U-shaped
parts, while for three phase transformers the
if vibrations and noises in the apparatus are to
leakage comprises two opposed E-shaped parts,
be avoided. Such vibrations are disturbing and
in which case the increased distance between the
may in time lead to the destruction of the appa=
primary and secondary coils is preferably ar~=
An object of the present invention is to provide 30 ranged on the narrow side of the rectangular
simple means for varying the air gap in the path ' coils. The stationary secondary core part has‘
at each pole at least one guide bar and the cor
of the secondary magnetic flux of transformers‘
responding movable part is pressed against this
having a high reactance which is adjustable
bar, but so that it is still possible to slide it rela
within wide limits, without producing excessive
35 tive thereto. The pressure is preferably exerted
noises or vibrations.
is variable within wide limits.
ratus.
‘
.
'
Another object is to provide in'a transformer
by spring discs.
The accompanying drawings are illustrative of
two embodiments of the invention. In the draw
core which is inductively coupled with the sec
ings,
ondary winding of said transformer only and
Fig. 1 is a vertical section of the embodiment.
so
which is provided. with a variable air gap.
of the invention in a singlephase transformer.
Another object is to provide a unitary structure
Fig. 2 is a top view and partially a cross-section
of a transformer and a reactor, the reactor being
along the lines 2-2 of Fig. 1.
inductively coupled with the secondary windings
Fig. 3 is a. side view of a modi?cation of the
of the transformer only and having an adjustable
transformer
illustrated in Fig. 1.
reluctance.
.
Fig. 4 is a front view of Fig. 3, while
Another object-is to provide a high reactance
Fig. 5 is a top view, partially in section along
transformer having primary and secondary winds
the lines 5-5 of the transformer shown in Figs.
ings, a primary core inductively interlinked with
3 and 4.
the primary and the secondary windings, and a
Referring to Figs. 1 and 2, the same illustrates
secondary core having a variable reluctance and 50
a single phase transformer having two primary
‘interlinked with the secondary winding only.
coils I, two secondary coils'2, and a closed main ,
Another object is to provide a transformer and
magnetic laminated core 3.
‘a variable reactor with a. primary winding induc
~ The coils are rectangular in‘ shape and the
tively mounted on the core of said transformer
and a secondary winding inductively interlinked 55 transverse distance between the coils l and 2 is
' with primary and secondary windings, a magnetic
2,411,370;
increased at one side thereof to provide a'space
4
planar with the core 3 and comprises a U-shaped
stationary part 5, the center section 6 of which,
of the secondary magnetic circuit and hence by
the length of the air gap I4. It is thus possible
by adjustment of the air gap to adjust the sec
ondary terminal voltage for any given current
is common with one leg of the main core 3. The
within very wide limits.
vertical legs 1 of the stationary part 5 are pro‘
vided 'at their center with ?at magnetic or non
Referring now to Figs. 3, 4, and 5, the same
illustrates a transformer having a primary closed
magnetic core 30 which is ?xedly mounted on a
support 3i by any suitable means (not shown).
for a laminated secondary core 4, which is co
' magnetic guide bars 8 and a movable U-shaped
.
_
part 9 of the secondary core is arranged to strad
dle these guide bars and to slide longitudinally 10 The two vertical limbs of the core ‘30 are each
thereon. The movable part 9 is provided with 4 provided with a primary coil 3| and a secondary
insulated bolts l0 provided with nuts II and
coil 32. In one direction the ‘inside cross-sec
interposed spring washers l2 to hold the lamina
tional dimension of the secondary coil is made
tions together and press them against the guide
considerably greater than the corresponding out
bars. The bolts II) are arranged to move in slots 15 side cross-sectional dimension of the coil 3|, to,
l3 of the guide bars, to permit movement of the
provide for a space 83 into which projects the
part 9 relative to the stationary part and thereby
vertical limbs of a secondary core 34 having a
vary air gaps l4 between adjacent limbs of the
stationary U-shaped part 35 and a movable U
respective parts.
_
shaped part 36. The part 351s ?xed to the base
' To provide for adjustment of the air gap the 20 34 and its two limbs are preferably provided at
movable part 9 has ?xed thereto a tapped boss
their center with guide bars 31 which are ar
l5 which engages a threaded shaft IS. A second
ranged and constructed similarly to the guide bar
tapped boss I‘! is attached to the core 3. The a 8 of Fig. 1. The movable U-shaped member 38
threads in the twov bosses and the coacting
is preferably arranged similar to the part 9 of
threads of the shaft are in opposite directions, 25 Fig. 1, so as to straddle the guide bars 31. The
so that upon turning of the shaft It by the hand
laminations of the member 36 are clamped to
wheel l8 attached to its upper end the movable
gether and against the guide bars 31 in the man
part 9 is moved toward or away from the station
ner shown in Fig. 2 for the part 9. A threaded
' ary part, to thereby vary the air gap I4 and thus
boss 38 is ?xed to the center limb of the member
vthe reluctance of the leakage core and the react 30 35 and a similar boss 39 to the member 33. The
ance of the secondary coils.
.
.
two bosses are threaded in opposite directions
In order to provide for a more gradual adjust
and engage cooperating screw threads of a shaft
ment of the leakageireactance the air gap may be
40 provided with a handwheel M. By turning
arranged as shown at an angle to the direction of
the handwheel in one direction or the other the
movement of the movable part. However the air 35 member 36 is moved relative to the member 35
gap may be of any other desired shape and it may
in the manner aforedescribed in connection with
partially be bridged by a magnetic shunt such as
Figs. 1 and 2 to vary an air gap 42 therebetween.
the guide bars 8 if they are made of magnetic
The entire apparatus is preferably enclosed in
material.
- a casing of which only a portion of the top is
.
The apparatus functions in the following man
ner: When the primary coils are connected to
‘an alternating current source a current ?ows
therethrough which induces a flux in the main
magnetic core 3. This ?ux in turn induces an
electromotive force in the secondary coils 2 in the
usual manner. If now the circuit of the second
40
shown at 43. The shaft 40 extends through the
casing and the handwheel 4! is arranged outside
thereof. In order to indicate the position of the
ary coils‘ is closed through a translating device, I
as for instance a welding machine, a current ?ows
member 36 an indicator 44 is provided. The same
comprises a bracket 45 which is ?xed to one of
the guide bars 37 or any other stationary part
of the apparatus and is provided with a horizontal
axle 46. Mounted on said axle is a bell crank
lever having an arm 48 which is provided with a
in the secondary winding. This current induces
roller 49 which engages the top surfaces of the
a secondary ?ux which passesthrough the core 50 member 36. The bell crank is biased in a counter
3 in a direction opposite to that of the primary
clockwise direction by a spring 59. A second arm
?ux. An additional flux is induced in the sec
5! of the bell crank carries a circular segment 62. '
ondary core 4, the two secondary ?uxes being so
The cover 63 is provided with a window 54 through
related that they jointly are proportional to the
which the circular segment 52 can be observed.
counter electromotive force induced in the sec 55 The window is provided with a pointer 55. The
ondary winding.
.
outer circumference of segment 52 is provided
The lower the reactance of the leakage core
relative to the reluctance of the main core the
with indicia which may be in terms of the re
actance of the secondary circuit vor in terms of
greater is the proportion of the total secondary
the welding current for which the reactance is
flux which passes through the secondary core.‘ 60 to be adjusted. If the member 36 is moved up
' The reluctance of the secondary core is largely
and down by operation of the handwheel 4| the
determined by the length of the air gap l4 so
bell crank is rotated in a clockwiseor counter=
that by increasing the air gap the secondary flux
is reduced and vice versa. Thus by moving the
part 9 up and down relative to the part 5 the‘
secondary counter-electromotive force is varied
to thereby vary the net or output secondary volt
age of the transformer. The secondary or leak
age ?ux varies with the current flowing in the
secondary winding so that for any given adjust
ment of the air gap l4 the secondary voltage
decreases with increasing current, as is desirable
for a welding transformer or the like. On the
other hand, the open circuit voltage of the trans
clockwise direction respectively. so that different
indicia corresponding to the position of the mem
ber appear at the window opposite the pointer 53.
In this‘manner the adjustment of the reactor is
facilitated from the outside.
' ‘ While the drawings show only a single guide
bar 8 and 31, respectively, at each'leg of the re-=
actor, it is obvious that a multiplicity of such
guide bars may be employed. This is particularly
advantageous if the structure is very large in the
direction transversely to the laminations, that is
if it comprises a large number of laminations.
former is only slightly a?ected by the reluctance 75 By providing more than one guide bar the pres
, accuse/o
e
,
single phase transformer providing for
adjustment ‘of its secondary reactance within
side on the laminations is better equalized, there=
reducing the amount of noise and vibration
incident to the magnetic e?ccts in the laminated
wide limits, comprising, a closed rectangular pri
structure.
The apparatus shown is capable of many motile
pair of secondary coils, one of said primary and
mary magnetic core, a. pair of primary and a
one oi said secondary coils being mounted on
one and the other primary and secondary coil
being mounted on the other of two opposite side
reactor, whereby the transformer is provided with
members oi'seid rectangular core, said coils be»
three limbs and three ‘sets of primary and sec
ondary coils and the two halves of the reactor 10 lng oi’ substantially rectangular transverse cross
section with each secondary coll telescoped over
each comprise an E-shaped frame, each leg of
the respective ‘primary coil and having one side
the E projecting into the space between the cor
of its inner circumferential wall spaced a sub
responding primary and secondary coils.
stantial
distance from the outer circumferential
' What I claim was new and desire to secure by
wall of the respective primary winding, s- rec
Letters Patent is:
.
tangular secondary magnetic core arranged with
l. A transformer providing for adjustment of
its opposite side members passing axially through
‘ications, forinstance, the invention may be used
with a three phase transformer and three phase
its secondary reactance with-in wide limits, com
prising, a closed primary magnetic core, e mi»
the space between said walls so as to be induc
tively interlinked with said secondary coll only,
mary winding of substantially rectangular trans:
said secondary core comprising a U-shaped part
20
verse cross-section inductively mounted on said
mounted stationary with respect to said coil and
v core in ?xed relation thereto, a secondary wind
an inverted U-shaped part which is movable
ing of substantially rectangular transverse cross
relative to said stationary part to interpose a
section telescoped over said primary winding and
variable air gap between the respective opposed
mounted in ?xed relation to said primary wind=
pole faces of said parts and said air gaps being
ing and said core, and having one side of its
located near the transverse central plane of said
inner circumferential wall spaced a substantial
secondary coils, a guide bar ?xed to each of
distance from the outer circmnferential wall of
the side, members of said stationary part, means
said primary winding, a secondary magnetic core
attached to the side members of said movable
arranged to passaxially through the space be»
part and arranged to hold the latter in resilient
tween said walls of the primary and secondary
sliding engagement with said bar, and means
windings so as to be inductively interlinked with
to reciprocate said movable part relative to said
‘said secondary winding only, said secondary core
stationary part to vary the length of said air gap.
~comprlsing a part mounted stationary with re
4. A single phase transformer providing for
spect to said windings and another part which
adjustment of its secondary reactance within
wide limits, comprlslng,'a closed rectangular pri
is movable relative to said stationary part to
interpose a variable air gap in the‘ path of the
mary magnetic core, a pair of primary and a
?ux induced in said parts bysaid secondary wind
pair of secondary coils, one Of said primary and
one each oi’ said secondary coils being mounted
lng, said air gap being located near the trans
verse central plane of said secondary winding, 40 on one and the other primary andv secondary
coil being mounted on the other of two opposite
a guide bar fixed to one of said parts, means
side members of said rectangular core, said' coils
attached to said other part and arranged to
being of substantially rectangular transverse
hold the latter in resilient sliding engagement
cross-section with each secondary coil telescopecl
with said bar, and means to reciprocate said
over the respective primary coil and having one
movable part on said guide bar for varying the
side of its inner circumferential wall spaced a
‘length of said air gap.
substantial distance fromthe outer clrcumieren- I
2. A single phase transformer providing for
tial wall of the respective primary coll, a rec
adjustment oi its secondary reacta'nce within
tangular secondary magnetic core arranged with.
wide limits, comprising, a. closed rectangular pri
its opposite side members passing axially through
mary magnetic core, a pair of primary and a
the space between said walls so as to be induc
pair of secondary coils, one of said primary and
tively interlinked with said secondary coil only,
one of said secondary coils being mounted on one
said secondary core comprising a U-shaped part
and the other primary and secondary coil being
mounted stationary with respect to said coils and
mounted on the other of two opposite sidemem
an inverted U-shaped part which is movable
bers of said rectangular core, said coils being of
relative to said stationary part to interpose vari-i
substantially rectangular transverse cross-sec
able air gaps between the respective opposed pole
tion with each secondary coil telescoped over
faces of said parts, and said air gaps being lo~
the respective primary coil and having one side
cated near the transverse central plane of said
of its inner circumferential wall spaced a sub
' stantial distance from the outer circumferen
60 secondary coils, and means to move said movable
tial wall of the respective primary coil, a rec
part relative to ‘said stationary part to vary the
' tangular secondary magnetic core arranged with
length of said air gaps, said means comprising a
screw tap attached to said stationary part and
a screw top attached; to the movable part, said
its opposite side members passing axially through
the space between said walls so as to be inductive
ly interlinked with said secondary coil only, said
secondary core comprising a U-shaped part
mounted stationary with respect to said coils and
an inverted U-shaped part which is movable
relative to said stationary part to interpose variable air gaps between the respective opposed 70
pole faces 0! said parts, and said air gaps being
and a shaft provided with threads cooperat
ing with said taps and with a handwheel whereby
rotational said handwheel in opposite directions
affords relative movement between said parts to
thereby adjust the length of said air gap.
5. A single phase transformer providing for
adjustment of its secondary reactance within wide
limits, comprising, a closed rectangular primary
magnetic core, a pair of primary and a. pair or
movable part relative to said stationary part to
75 secondary coils, one of said primary coils and one
vary the length of said air gaps.
located near the transverse central plane 01 said
‘secondary coils, and means to reciprocate said
' .'
taps having their threads in opposite directions
of said secondary coils being mounted on one and
the other primary and secondary winding being
mounted on the other of two oppositeside meme
bers of said rectangular core, said ‘coils being of
substantially rectangular transverse cross-section
with the secondary coil telescoped over the re
8
tial distance from the outer circumferential wall
of the respective primary Winding, a secondary
magnetic core having a leg for each of said sec
ondary windings, said secondary core being closed
save for a variable air'gap in each of said last
named legs, said last named legs being arranged
spective primary coil‘ and having one side of its
to pass axially through the space between the
inner circumferential wall spaced a substantial
walls of the respective primary and secondary
distance from the outer circumferential wall oi’
windings, and said air gaps being located near
the respective primary coil, a rectangular second 10 the transverse central plane of ,said secondary
ary magnetic core arranged with its opposite side
windings, and means to vary the length of said
members passing axially through the space be- '
tween said walls so as to be inductively inter
linked with said secondary coil only, said second-g
air gaps.
8.-A transformer providing for adjustment of ,
its secondary reactance within wide limits, com-"'
ary core comprising a U-shaped part mounted 15 prising, a closed primary circuit having a plu-' ,‘
stationary with respect to said coil and an in
rality of legs, a primary winding bf substantially
verted U-sh'aped part which is movable relative
rectangular transverse cross-section for each of
to said stationary part to interpose a variable air
said legs and inductively encircling the same, a
gap between the respective opposed pole faces of
secondary winding of‘ substantially rectangular
said parts, and said air gaps being located near 20 transverse cross-section for each of said legs tele-- the transverse central plane of said secondary
scoped over the respective primary winding and
coils, a guide bar ?xed to each of the side members
having one side of its inner circumferential wall
of said stationary part, means attached to .the
spaced a substantial distance from the outer cir
side members of said movable part and arranged
cumferential wall of the respective primary wind
to hold the latter in resilient sliding engagement 25 ing, a secondary magnetic core having a leg in.
with said bar, and means to move said movable
cluding a variable air gap for each of said sec
part relative to said stationary part to vary the
ondary windings and being arranged to pass
length of said air gaps, said means comprising a
through the space between the respective walls of
screw tap attached to said stationary part and a
the primary and ‘secondary windings, said air gaps
screw tap attached to the movable part, said taps 30 being located near the transverse central plane
having their threads in opposite directions, and a
of said secondary windings and extending be—
shaft provided withthreads cooperating with said
tween two planar pole faces parallel with each
taps and with a handwheel whereby rotation of
other and at an angle to said plane and means to
said handwheel in opposite directions affords rela
vary the length of said air gaps.
tive movement between said parts to thereby ad 35 9. A transformer providing for adjustment of
just the length of said air gap.
its secondary reactance within wide limits, com
6. A transformer providing for adjustment of
prising, a closed primary magnetic core having a
its secondary reactance within wide limits, com
plurality of legs, aprimary winding of substan
prising, a closed primary magnetic core having a
tially rectangular transverse cross-section for
plurality of legs, a primary winding for each of 40 each of said legs and inductively encircling the
said legs and inductively encircling the same, a
same in ?xed relation thereto, a secondary wind
secondary winding for each of said legs and en
ing of substantially rectangular transverse cross
circling the same and the respective primary
section for each of said legs and telescoped over
winding and having its inner circumferential wall
the respective primary winding and mounted in
spaced from the outer circumferential wall of the
?xed relation thereto and having one side of its
respective primary winding, a secondary magnetic
inner circumferential wall spaced a substantial
core having a leg for each of said secondary wind
distance from the outer circumferential wall of '
ings, each of said last named legs being provided
the respective primary winding, a secondary mag
with an adjustable air gap and being arranged
netic core having a leg for each of said secondary
to pass axially through the space between the 50 windings and arranged to pass axially through
walls of the respective primary and secondary
the space between the walls of the respective pri
windings, and means to vary the length of said air ‘
mary and secondary windings, said secondary core
comprising a part mounted stationary with re
'7. A transformer‘providing for adjustment of
spect to said windings‘ and another part which is
its secondary reactance within wide limits, com 55 movable relative to said stationary part to inter
prising, a closed magneticv core having a plurality
pose variable air gaps in the path of the ?ux in
of legs, a primary winding of substantially rec
duced in saidparts by said secondary windings,
tangular transverse cross-section for each of said
said air gaps being located near the transverse
legs and inductively encircling the same, a sec
central plane of the respective secondary wind
ondary winding of substantially rectangular cross 60 ings,
and means to move said movable part rela
section for each of said legs telescoped over the
tive
to
said stationary part to vary the length of
respective primary“ winding and having one side
said air gaps.
of its inner circumferential wall spaced a substan
‘gaps.
- EDUARD FRIES.
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