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Nov. 5,1946.
c. P-. Bo'ucHER
Original Filed April 10, 1940
I l I
I l
Patented Nov. 5, 1946
umreo srA-ras PATENT ornca
Charles Philippe‘Boucher, Paterson, N. J., as
‘ slgnor, by mesne assignments, to National!!!
ventions Corporation, a corporation of New
Original application April 10, 1940, Serial No.
328,970. Divided and this application February
'7, 1941, Serial No. 377,922
(Cl. 171-119),
My application for patent is a division of my
co-pending application Serial No. 328,970, filed
April 10, 1940. and entitled Transformer appa
ratus, now U. S. Letters Patent 2.312.867 of March
2, 1943, and the invention relates to electrical
transformer apparatus, and more particularly to
electrical transformer apparatus for supplying
two or more negative loads, as, for example, in
the operation of a luminescent tube system.
In the accompanying drawing:
The ?gure is a diagrammatic representation of
a transformer according to my invention.
As conducive to a clearer understanding of cer- .
tain features of my invention, it may be noted at
‘this point that in the operation of a luminescent
sign or display employing one or more luminese
centegas ?lled tubes of desired size and configura
tion, high potential electrical energy is required.
One of the objects of my invention is ‘to provide 10 Ordinarily the desired high potential electrical
energy is supplied by alternating-current trans
simple, practical and thoroughly reliable trans;
former apparatus connected to a standard single
former apparatus for supplying a plurality of
phase ‘sixty cycle source at either one hundred
separate negative loads and for ensuring auto
and ten volts or two hundred and twenty volts.
matically that substantialiy no voltage difference
exists between the secondary circuits throughout 15' In order to supply the highest possible potential
across the terminals of a tube without exceeding
the entire cycle of operation, and also that the
the maximum potential to ground permitted by
currents in the ‘various circuits are substantially
the fire underwriters, it has been the practice to
the same.
energize each tube from two coils having their
Another object is to provide compact, inexpen
sive and highly ef?cient transformer apparatus 20 one ends grounded placing the coils in series and
their other ends connected to the tubc By this
for supplying a plurality of negative loads and
for energizing in a dependable manner the re
mainder of said'loads after one or more of them
has struck.
arrangement, each coil section may have induced
in it a potential of about seven thousand five ,
hundred volts to ground, which is approximately
Another object of my invention is to provide a 25 the maximum value permitted by the under
transformer system in which negative loads of
either equal or unequal resistances may be op
erated from the same transformer.
writers, and yet the voltage across the tube ter
minals will be about fifteen thousand volts.
In the operation of a single sign or luminous
display, it is frequently necessary to use‘a plu
‘A further object of my invention is the provi
of luminescent tubes. In order that the‘
sion of a transformer apparatus of the character 30 rality
energizing potential may not reach values in
described which lends itself to rapid, efficient and
excess of those specified by the underwriters, and
economical production employing a minimum of
since luminescent tubes have negative load char
different parts and requiring a minimum of skill
acteristics and vary among themselves as to strik
in construction, installation and repair.
and operating potentials, each tube must have
Another object is the provision of transformer as
its own separate secondary winding. To use a
7' apparatus of the character indicated whichyis
separate transformer for each tube would result
peculiarly adapted to withstand the varying-con
in an exceedingly high cost of equipment. Fur
ditions encountered in actual use, including short
thermore, the cost of the labor for installing
circuiting and grounding, of the whole or parts
of the apparatus, without damage to the appa 40 equipment using a transformer for each tube
would be obiectionably high because a separate
ratus and the consequent necessity for shut-down
and replacement or repairs.
Another object is the provision of high voltage
charge is made for each connection to the source
of supply.
In transformers I have heretofore designed for
transformer apparatus of the character indicated
a luminescent sign or display, these
which supplies a plurality of separate loads in
objections are removed by placing two or more
such a way as to require a minimum amountof
secondary windings in series upon a transformer
core. Each winding comprises two coils and en
Other objects will be obvious inpart and in
ergizes one negative load. Each coil has associ
part pointed out hereinafter.
f The invention accordingly consists in the com 50 ated with it a magnetic by-pass of high reluc
tance which limits the flow of current through
bination of elements, features‘ of construction,
the coil to a safe value. The major portion of
, and arrangement of parts, and in the several op
the main magnetic flux passes through the by
erational steps, all as described herein, the scope
pass when the current ?owing through the coil
of the application of which is indicated in the
55 reaches such a value that it generates a counter
appended claim.
magnetomotive force which is su?lcient to buck
0| and 92 interposed between the ends of the
most of the main mix. As' a consequence of the
coils being mounted in series on the core, when
the counter-magnetomotive force of one coil
causes the main flux to be by-passed through a
longitudinal bars. The bar 93 has a central ex
tension 830. which abuts the bar 04. Bar 93 also
has integral shunt arms 93b and 930 whichex
tend closely toward but do not abut bar Bl, form
ing therewith air-gaps GI and G2. The member
coils is no greater than it was before the ?rst
9| interposed between the end part 93d of bar
93 and longitudinal bar 9| forms a magnetic path
coil became loaded. In fact, due to the increased
reluctance of its path, the ?ux coursing through
of low reluctance, the core parts being held in
the core will be somewhat diminished in amount. 10 firm contact by the band I03, preferably of ‘mag
Consequently, the remaining coils will not have
netic material. Likewise, the member 92 inter
as high voltages induced in them 'as if they had
posed between the end part 930 of bar SI and the
bar 90 forms another magnetic path of low re
become loaded ?rst. Moreover, the instant at
which the load of the remaining coils becomes
luctance, the core parts being held together by
operative lags substantially behind the time ‘of
the band I04 which also ‘preferably is of mag
shunt, the flux then interlinking the remaining
striking of the ?rst load.
netic material.
One of the objects of my present invention
The primary coil P is mounted on the central
extension 93a of bar 93 and is energized from
above and assure a substantially simultaneous
the source of alternating current electrical en
striking of luminescent tubes although of slight
ergy 96 through leads 9‘! and 98.
inequalities in voltage‘ ratings.
Secondary coil Si is mounted on the end part
It may be noted further that in the operation
93d of bar 93 at the point where a space is formed
of a luminescent tube sign or display, conditions
between part 9311 and bar 94 and between shunt
may be encountered which cause a short-circuit
arm 53b and member 9|. One terminal of coil
ing of part or all of the apparatus. This may be
Si is grounded to the core at 99 and its other
caused by fog, rain, ice or other moist weather
terminal is connected by lead I00 to one terminal
conditions in an atmosphere containing dust,
of a negative load. Coil S2 is mounted on the
mild sulphur-bearing agents in industrial areas,
end part 930 of bar 93 at the point where a
or salty particles near the seashore. The appa
space is formed between part 93c and bar 94 and
ratus may also be subjected to a certain amount 30 between shunt arm 93c and member 92. One
of shock and vibration. ‘Furthermore, it is not
terminal is connected to load by conductor NH.
uncommon for insects to pack themselves around
The other terminal of coil S2 is grounded to the
the tube electrodes and in between them and the
core at I02. Coils SI and S2 may be connected
supporting metallic structure, thus providing a
either in series-aiding or in series~opposition re
conductive path around the tube. Under these
lationship, the transformer being more particu
conditions of operation, the tubes frequently be
larly designed for the operation of a load com
come short-circuited from terminal to terminal
prising a series of tubes, TI and T2, grounded at
or from terminal to ground.
their approximate mid-point, as at I08. The
load must be grounded at its approximate mid
Under the conditions of short-circuit, certain
heretofore known and/or used transformer ap 40 point, or connected from the mid~point to the
paratus, unless specially designed to accommo
mid-point of the coils, as by the lead I01, if the
coils are connected in series-opposition in order
date an excess current, is inclined to excessive
heating which results in the ultimate charring
that two complete circuits will be formed, one
and burning of the insulation and the destruction
for each half of the load and its corresponding
of the transformer apparatus, necessitating shut 45 secondary coil. Where the coils are connected in
series-aiding relationship. the load may be
down and replacement or repair. This situation
is especially prevalent in certain heretofore
grounded at its mid-point to form a complete cir
known and/or used transformer apparatus hav-‘
cuit for each half of the load with its secondary
ing the secondary winding grounded at its mid
coil but this is inclined to cause an unbalanced
point. When a luminescent tube energized by 50 operating condition for the transformer and for
such transformer apparatus becomes grounded
this reason ordinarily is omitted.
at one terminal, as indicated above, excessive
The coils SI and S2 have induced in them
current is inclined to ?ow in one half of the
voltages high enough to energize their respective
secondary winding while no current ?ows in the
portions of the load at substantially the same
other half of the winding. The ?ow of excessive 55 instant, where a bucking connection is used and
current damages the winding unless it is designed
the load mid-point is connected to the common
to carry this heavy current. Such a design, of
connection of the two coils as by grounding
course, requires larger, heavier, and more ex
them. There is substantial equality between the
pensive coils.
Accordingly, another object of my invention is 60 output voltages of the secondary coils. No danger
exists of excessive current ?owing through either
to provide a transformer apparatus which is in
coil because of the peculiarmagnetic shunt con
expensive in construction, employing windings of
struction provided. Perfectly safe and economi
minimum necessary current-carrying capacity
cal operation is assured for all conditions of
and of minimum cost, and yet. which is of such
short-circuiting, grounding, or open-circuiting of
construction as to reliably withstand the many
. therefore is to overcome the difficulties noted
varying conditions encountered in actual. practi
cal use.
all or any part of the load of one or both coils.
In the event of a short circuit occurring across
Referring now more particularly to the prac
the whole secondary winding, the coursing of the
tice of my invention, attention is invited to the
magnetic flux through the core of the transform
?gure of the drawing in which there is shown a 70 er apparatus is substantially the same as it is
transformer embodying certain features of my
during the conductive periods of its load. The
invention. The transformer comprises the longi
amount of current ?owing in the winding in this
tudinal core bars 93 and 94, upon which are
condition of operation is about the same as that
mounted primary and secondary windings as
encountered under normal operating conditions.
noted below, and also the short core members 75 In neither condition of operation does this cur
rent rise to such excessive values as to cause ob
jectionable heating and damage to the coils.
In the event that only one coil section of the
secondary winding becomes grounded, the ?ow
of an excessively high current in this coil sec
tion is effectively prevented by the major por
tion of the magnetic flux coursing along a path
of intermediate reluctance provided by a, shunt
mum of different shaped core members and re—
quiring a minimumv of expensive dies, tools and
equipment in its construction. It will be seen,
further, that luminescent tubes of the maximum
length energizable by any existing equipment
approved by the ?re underwriters are energized
by my transformer without there being present
any of the tube puncturing dielectric discharges
arm and its associated air-gap. This path ex
frequently encountered in the use of’ present
tends around and excludes the short-'circuited 10 equipment. Moreover, my transformer meets the
section. The portion of the total magnetic flux
‘requirements of ?re underwriters in that the
that interlinks the primary winding with the
potential from no point to ground substantially
short-circuited coil section, that is the minor
exceeds 7500 volts. In the operation of my trans
portion of the flux, is substantially the same as
former there is no'posvsibility of overloading and
that interlinking these two under normal oper 15 consequent damage to the secondary winding in
ating conditions or under short-circuited oper
the event of accidental grounding of either .one
ating conditions of the entire secondary winding.
or both coil sections of these windings.
In all instances, the electromotive forces induced
While I have illustrated transformers having
in the secondary winding are not so great as to
only one or two secondary windings and two or
cause the flow of an, excessively high current in 20 four coils, it is to be understood that three or_
the coil sections of this winding.
more windings may be employed with associated
The transformer of the ?gure has internal
core portions and shunts, the additional second
shuntpaths which will not be appreciably af
ary windings and core members being mounted
fected by the casing. The casing, being oppo
out from the plane of the construction shown in
site only a small portion of the air-gap, will‘have 25 the drawing for example. With the number of
little bridging effect. Thus good air-gap control
windings illustrated, however, the transformer
is possible. Moreover, the transformer is made
apparatus is exceptionally compact and yet, be
of simpler parts, which can be readily manufac
cause of the peculiar core construction and the
tured and assembled.
relation of this core to the secondary winding,
My transformer has the advantages of com
it is fully protected from damage under the vari
pactness of construction, symmetry of ?ux and
ous conditions encountered in use. The com
current distribution, and safe operation’under
pactness and coil protection feature assures an
conditions of short and'open circuits. Further
inexpensive, ef?cient and thoroughly reliable
more, for a single tube load, or a load compris
piece of apparatus.
ing two .or more tubes not grounded at their mid 35
As many possible embodiments may be made
' point, where the secondary coils are connected
of my invention and as many changes’ may be
series-aiding, a high'output potential is obtained
made in the embodiments hereinbefore set forth,
with nevertheless no more than a safe maximum
it will be understood that all matter described
potential to ground. Where the load comprises
herein, or shown in the accompanying drawing,
two or more tubes which are grounded at their 40 is to. be interpreted as illustrative, and not in a
mid-point and the secondary coils are connected
limiting sense.
in series opposition, a condition of balanced volt
ages and currents across the two halves of the
In electrical transformer apparatus of the
load will obtain. There will be dependable oper
character described, in combination, two sub
ation of each half of the load and a minimum
stantially parallel linear core members, one of
time lag will exist between the striking of the, 45 said linear members having intermediate its ends
two halves. Dielectric discharge between the
a central extension joining said other linear
two halves of the load is eliminated. Moreover,
member and two shunt arms one on either side
the transformer is made of a minimum number
of said central extension, extending toward but
of relatively simple parts which are readily as
not abutting said other linear member and form
sembled. Finally, the advantage of an internal 50 ing therewith magnetic shunt paths including
shunt construction, that is, ‘a minimum oi,’ fring
air-gaps of high reluctance; two end core mem
ing tdthe casing, is obtained.
bers connecting said linear core members ex
Thus it will be seen that there has been pro
teriorly of said shunt arms, the connected mem
vided in this invention transformer apparatus in
bers forming two closed magnetic circuits with
which the various objects hereinbefore noted, to
said central extension; a primary winding '
gether with many practical advantages thereof,
mounted on said central extension; and two sec-'_
are successfully achieved. It will be seen that
ondary coils mounted on said linear core mem
my transformerv apparatus is exceedingly com
ber having a central extension, each secondary
pact and rugged in construction and that it lends
coil lying between one of said shunt arms-and
.itself to inexpensive and efficient commercial
one of said end core members.
production and installation, employing a mini
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