US1776078A - Electrical transformer - Google Patents

Description

p 1930- A. E. MIGNOT 1,77 ,078

ELECTRICAL TRANSFORMER Filed Feb. 8, 1928 V INVENTOR ArtkurEM I dim ATTORNEY Patented Sept. 16, 1930 UNITED STATES PATENT OFFICE ARTHUR E. MIGNOT, 0F NEWARK, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO GENERAL CABLE CORPORATION, JERSEY OF NEW YORK, N. Y., A CORPORATION OF NEW ELECTRICAL TRANSFORMER Application filed February 8, 1928. Serial No. 252,699.

The present invention relates, generally to electric transformers, and the invention relates, more particularly, to transformers having a comparatively high ratio of step up from primary to secondary. The invention relates further to transformers adapted for use for energizing high voltage gaseous discharge lamps and the like, and the invention is useful in the electrical arts generally.

Heretofore, in electrical systems for energizing lamps of the neon type difficulty has been experienced through the burning out of the secondary windings due to the high voltage impressed thereon and particularly from the grounding of the. secondary by fail ure of the insulation and consequent connection to the transformer core and thence to ground or to another part of the secondary which has been grounded. These d-ifficulties are present particularly when the secondary is operated on open circuit, as for ex-' ample, when a condenser is interposed in series in the secondary circuit, or when a secondary lead becomes broken, or the work circuit becomes open. More particularly, on neon sign circuits the neon lamps are frequently broken in which case the insulation of the glass is lost at the broken point so that a discharge occurs which disrupts the insulation at a secondary lead or between a point on the secondary coil and a grounded part of the apparatus such as the core.

Commonly one side of the secondary, usually the inside end, is grounded and the core is grounded in an attempt to prevent shorting of other points on the secondary but still spark occurs between some points of the secondary and the core, and often disruption of the insulation occurs due to the high voltage necessary for some uses.

An object of the present invention is to provide a connection between the transformer core and that point on the secondary which has the least potential difference with respect to each of the terminals of the secondary, for the purpose of minimizing the potential drop between the secondary and the core.

Other objects and advantages of the invention will be apparent from the following description of an illustrative example of the invention and from the drawing showing the same and from the appended claims. And the invention consists in the novel construction and circuit hereinafter set forth, and in electrical distributions comprising transformers of the invention.

Similar characters of reference are employed in all the views of the drawing to indicate corresponding parts.

Referring now to said drawing, 1 indicates a closed core of iron or other magnetic material. On the leg 2 of said core 1 are mounted the two coils 3 and 4. The coil 3 has an end 5 free for terminal connection and an end 6 connected to said core leg 2, and the coil 4 has an end 7 free for a terminal connection and an end 8 connected to said core leg 2. Said coils 3 and 4 are disposed on said core leg 2 so that when theyare energized they will produce lines of magnetic force in the same direction. As indicated in the drawing with the coils 3 and 4 assembled on the core leg 2, the terminals 6 and 8 extend from their respective coils in opposite directions from the center of said core leg 2, and the direction of the turns of the two windings is the same. The two windings, however, can be wound in op osite directions provided the coils are assemb ed upon the core and the connections are made so that the two coils cooperate in their generation of magnetic lines of force. In such case with the coils assembled on the coil leg, the terminals connected to the core leg extend from their respective coils in the same direction. in successive overlying layers. The transformer primary winding'9 is mounted on the core leg 10.

In Figure 2 of the drawing there is shown diagrammatically a system of electrical distribution in which said primary winding 9 has its terminals connected to a source of al The turns are arranged core can be grounded without affecting the possibility ternating current 11 and in which said secondary terminals 5 and 7 are connected by the conductors 12 and 13 to the neon gas lamp 14, the secondary terminals 6 and 8 being points of intermediate potential with respect to said terminals 5 and 7 and being connected to said core 1. The lead 15, shown in dotted line, is ,used to. indicate that the transformer core 1 can be connected to the ground 16 without affecting its use and operation.

In Figure 3 is shown, diagrammatically, on a closed core 1, a primary 9 and" a pair of secondary sections 17 17 which are wound both in the same direction with the layers laidlongitudinally with respect to said core 1. Leads '19, 19' are brought out one from the top layer of each of said sections 17 17 and are adapted for connection to a work circuit. Leads 18, 18 are brought out one from each of said sections 17, 17 and from a bottom or inside layer thereof, and are connected together. Said leads 18, 18 are connected to said core 10 and the core 10 can be grounded. Also a ground connection can be made from one of said leads 19, 19, but in this case the leads 18, 18 and core 10 cannot be grounded. With core 10 grounded there is a relatively low potential difference between the core 10 and adjacent .portions of sections17, 1-7.

' .In the preferred form of the invention the secondary sections are made substantially alike in size of wire, number of turns, and number of layers per turn so that the elec- ,trical conditions and relations of one balance those of the other. Also in the preferred form of'the invention the secondaries are wound in the same direction and in overlying layers and are connected so that the inside layer in each secondary is at substantially mid-potential with respect to the terminal ends 5 and 7, so that a minimum amount of insulation is required between said coils 3 and'4 and said core 1. Also in the preferred form, the ends 6 and 8 are brought out in opposite directions from their respective coils 3 and 4 so as toaid in reducing the potential difi'erence between any part of said coils and said core.

In the transformer of the invention the operation of the transformer; and, in cases .whereone side of the secondary is grounded the possibility of shorting through the insulation of the secondary to ground is greatly reduced because the difference in potential between the core and any adjacent part of the secondary is greatly reduced. Further the of the occurrence of a short between any part of'the'secondary and the core is further reduced because the points of high otential difference are at greater distance rom the core. It is apparent that with core 1 grounded, should one of the high tension leads 5 or 7 become accidentally grounded the corresponding section 3 or 4 of the secondar winding will be short circuited and thoug the short circuit current may be several times normal, effecting the opening of suitable relays and shutting off the current supply, yet since the potential difference between the core 1 and adjacent portions of the winding 3, 4 is low at all times, there is no tendency to puncture the insulation of the turns of this winding adjacent the core. On the other hand with core 1 grounded, were the sections 3 and 4 not connected together through the core 1 and one of the leads 5 or 7 should become grounded, then a high potential drop may be developed between the core 1 and the adjacent layers of sections 3 and 4 efi'ecting a disruptive discharge which may result in the destruction of the insulation of the inner turns of sections 3 and 4. This will become apparent from an analysis of any particular case, for example, assume that the neon lamp 14 has 15,000 volts impressed across its terminals. With, the novel. arrangement of this invention should one of these terminals become grounded, the corresponding section 3 or 4 will be short circuited since it is grounded at one-end by the grounded terminal and at the other end by the core 1. Hence no damaging voltages are created in the shorted section. On the other hand were the sections not grounded on the core and thecore grounded, then with sections 3 and 4 of like properties there would be a potential drop of substantially 7500 volts between the core and the adjoining turns of the sections 3 and 4 which would tend to disrupt the insulation and destroy the transformer.

Variations in the construction and arrangements of parts other than those above'noted can be made by one acquainted in the art without departing from the spirit of the invention or from the scope thereof as set forth in the accompanying claims.

I claim:

1. A high tension transformer having a closed core, and a low tension winding and a high tension winding on said core, said high tenison winding comprising two parts, each of said two parts being wound in successive overlying layers, the inside end of' each of said high tension parts being connected to said core and the outside end of each being adapted to. serve as a high tension terminal, and said high tension parts being wound in a direction with respect to their terminal connect-ions so as to be adapted to cooperate with each other in the production of magnetic lines of force.

2. In a high tension transformer, a core, and a secondary coil thereon, said secondary having two separate parts both wound in outermost layer adapted for connection to a work circuit.

3. A h gh tension transformer having a closed core, a primary coil on said core, and a secondary coil on said core, said secondary coil having two separate parts on the core, each of said separate parts having an end connected to said core and an end adapted for connection to a work circuit, said separate parts being wound and having their connections with respect to each other so as to adapt them to generate magnetic lines of force in the same direction.

4. A high tension transformer having a closed core, a primary coil on said core, and a secondary coil on said core, said secondary coil having two separate parts on the core, each of said separate parts being Wound in successive overlying layers and having an inner end connected to said core and an outer end adapted for connection to a work circuit, said core serving as an electrical connection between said parts, said separate parts being wound and having their connections with respect to each other to adapt them to generate magnetic lines of force in the same direction.

5. A transformer having a core, a low tension coil on said core and a high tension coil arranged in two sections on said core, said sections being wound in successive overlying layers with respect to said core and each sect-ion being adapted to cooperate with the other in the production of potential gradient, and each of said sections having one of its ends connected to said core, said core serving as a current path for conducting current from one section to the other.

6. A transformer having a core, a low tension coil on said core and a high tension coil arranged in two sections on said core, said sections being substantially uniform one with the other in numbers of turns and in their disposition on the core, said sections being wound in successive overlying layers with respect to said core and each section being adapted to cooperate with the other in the roduction of potential gradient, and each 0 said sections having one of its ends connected to said core.

7. A transformer having a core, a low tension coil on said core and a high tension coil arranged in two sections on said core, said sections being adapted to cooperate with each other in the production of potential gradient, and one of said sections having an innermost turn connected to the low potential side of the other and to said core.

8. Atransformer having a core, a low tens1on e011 on said core, and a high tension coil arranged in two sections on said core, each sectlon being in successive overlying layers with respect to said core and adapted to cooperate with the other section in the production of potential gradient, and each of said sections having one of its inner turns brought out in opposite direction to an inner turn of the other section and connected to the said inner turn of the other through said core.

9. In a system of electrical distribution, a transformer having a core, a low tension coil on said core, and a high tension coil arranged in two sections on said core, said sections being'wound in successive layers with respect to said core, and each section being adapted to cooperate with the other in the production of potential gradient, and each of said sections having one of its inner turns connected to said core; said low tension coil being adapted to be connected to a source of current of varying potential; a work circuit connected to the high potential side of each of said secondary sections; and a ground connection on said core.

10. A high-tension, transformer. having a closed core, a primary winding on said core, and a secondary winding on said core, said secondary winding having a plurality of separate unitary parts on the core, each of said unitary parts having one of its ends connected to said core, its other end being adapted for connection to a work circuit, said unitary parts being wound and having their connections with respect to each other so as 9 to generate magnetic lines of force in the same direction.

11. A high-tension transformer, comprising, in combination, a core, a high-tension winding on said core, said high-tension winding including a plurality of sections each wound in overlying layers, and an electrical connection between an inner turn of each section and the core.

In testimony that I claim the invention set forth above I have hereunto set my hand this 6th day of February, 1928.

ARTHUR E. MIGNOT.

CERTIFICATE or CORRECTION.

Patent No. 1,776,078. Granted September 16, 1930, m

ARTHUR 1:. MIGNOT.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3;, lines 57 and 58, claim 7, for the'vrords "the low potential side" read an innermost turn; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of October, A. D. 1930.

I M. J. Moore, (Seal) Acting Commissioner ,of Patents.

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