US1868483A - Transformer - Google Patents

Description

Patented July 26, 19:'2

UNITED STATES PATENT oil-FICE ARTHUR O. AUSTIN, F NEAR BARBERTON, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE OHIO BRASS COMPANY, OF MANSFIELD, OHIO, A CORPORATION OF NEW JERSEY TRANSFORMER Application med June 7, 1930. Serial No. 456,703.

This' invention relates to apparatus for diverting energy from high potential transmission lines for voltage and current indica,

tion and for other purposes, and has for one of its objectsthe provision of an economical and eiiicient connection for high potential transmission lines.

Another object of the invention is to provide an improved transformer connection by which the voltage of a high potential transmission line may be stepped down in a plurality of steps.

A further object is to provide apparatus of the class described which shall be of improved construction and operation.

Other objects and advantages will appear from the following description.

The invention is exemplified in the combination and arrangement of parts shown in the accompanying drawing and descrlbed 1n the following specification, and it is more particularly pointed out in the appended claims.

In the drawing:

Fig. 1 is a somewhat diagrammatic, vertical, sectional View of transformer apparatus embodying one form of the invention.

Figs. 2 and 3 are views similar to Fig. l

showing modifications.`

In potential transformers used on high voltage lines, considerable difficulty is encountered in providing a transformer which will have the desirable electrical properties and, at the same time, which will withstand a high voltageon the line as well as high Voltage transients to which the transformer may be subjected.

In winding a potential transformer for high voltages, it is necessary to use a large number of turns or a large iron core. This results in insulation diiliculties and considerable cost for a transformer which may be re uired to deliver a small amount of energy 0n Y- "5 The concatenated or chain system of transformers, as used at present, has the advantage that the voltage may be stepped up or down in several units. If the several units are placed in a single metal tank or container o or in separate containers which are insulated from each other, it is very -diiicult to obtain a proper electrostatic distribution of stress between the several transformers for a transient surge on the line, and for high voltages a very large tank and bushings are required. The tank and bushings, together with the oil for filling them, involve a very large cost compared to the transformer units themselves. Where transformers with individual cases are used, there is considerable difficulty owing to the poor electrostatic distribution of stress for transients, and the additional difficulty of insulating the several transformer units from each other.

In the present invention the transformers may be enclosed in a housing which makes it possible to place the units near together and, at the same time, obviates partially, if not entirely, the necessity for entrance bushings and tanks or containers. With the present invention the gradient produced by leakage over the housing, as well as the electrostatic field, will tend to distribute the potential between the several transformers. This may be further supplemented as will be explained later.

In the form of the invention shown in Fig. 1 the transformers 10, 11 and 12 are enclosed in a porcelain or other dielectric housing 13,

and are connected in chain or cascade formation, as explained in an article appearin in the Electrical World and Engineer of ovember 26, 1904, Vol. XLIV, No. 22, on page 898 and entitled Transformers in series for high tensions. The high voltage conductor f1 is shown at 14, and 15 is an absorbing resistance which may be connected in series between the conductor and transformers. The incoming lead 16 may be connected directly to the end of the transformer winding 10 and to a metal cover 17. With this arrangement, the electrostatic capacity of the cover 17 to ground, or objects of lower potential, has a. material function in permitting the volta e lof a transient disturbance on the line to partially absorbed in the resistance or impedance 15. This shield also tends to distribute the electrostatic stress through the various transformers 10,11 and 12. It would not be possible to cause this electrostatic distribution of stress if a metal case were used, unless the clearances were quite large or speclal arrangement was made inside the case distributing the electrostatic stress.

This abnormal potential on the transformen is likely to cause a breakdown of the winding unless the transformer has very high insulation or some means for overcoming this tendency is provided..

Since the charging current between the shield 17 and ground increases directly with the equivalent frequency or wave front on the transient, it is seen that where the frequency is high the charging current to the shield 17 may be greatly increased for a given f' voltage. The drop in potential over the resistance or impedance 15 will tend to increase directly as the current. Since, therefore, the current flowing to the shield 17 will increase directly as the frequency and as the potential, it will be seen that where the equivalent frequency is many times that of the normal frequency, the charging current due to an impulse may be quite large, so that the voltage drop across the resistance 15 will be appreciable. Since the amount of current normally iowing to the transformer at the high voltage is very small, the resistance 15 may be very high without creating excessive losses. Even where an appreciable amount of power is taken from the transformer, this resistance may be several hundred or even several thousand ohms. For potential transformer work, this resistance may easily exceed 50,000 or 100,000 ohms without seriously affecting the results. It will be seen that where the resistance is large, it is possible to absorb a very appreciable portion of the potential of a transient owing to the flow of current into the condenser formed by the. shield 17. If desired, the capacitance to ground may be further im proved by condenser elements either within or without the case or by a separate condenser stack. In Fig. 1 such a condenser is provided by condenser plates 18, 19, 20, 21 and 22. Where there is suicient capacitance between the plate 18 and the cover or shield 17, it is not necessary to connect this condenser plate to the incoming line. If,`however, the caf pacity is not sufficient or the incoming plate 17 is an insulating member, the condenser .element 18 may be connected to the incoming lead by a jumper or other Asuitable means. With the condenser so formed by the elements 18, 19, 20, 21 and 22, it is possible to provide practically any electrostatic distribution of stress. The electrostatic field set up by these elements will tend to provide. a proper distribution Vof potential for the transformer elements due to the electrostatic capacity'between the condenser members and the various transformers. If it is desired, a more definite grading may be effected by connecting condenser elements to the transformer windings or cores by leads 24, 25 and 26. Where proper electrostatic distribution of stress can be maintained by the condenser stack at normal frequency, it is possible to eliminate the connection between the winding and the core, as the condenser element will'determine the potential gradient under the transient when insulation is most needed.

In the form of the invention shown in Fig.

2,the insulating housing 30 has plates or , metallized surfaces 31, 32, 33, 34 and 35 which Jform a condenser in parallel with the incoming lead. These members are placed alternately inside and outside the main insulating shell so that the shell is used for a -double purpose. These condenser elements may. be provided with weather sheds 36 which will not only improve electrostatic distribution of stress but will tend to maintain the insulation of the shell. The insulating housing is provided with means for holding the various transformers in proper position. These transformers may be supported from the housing or from each -other by providing proper insulating supports. The transformer core rests on lugs or projections 37. In place of lugs, recesses may be used, or any other suitable means for supporting ing through a bushing 38. If desired, the cover 39 may be an integral part of the housing, thereby providing further insulation. v

In the form of the invention shown in Fig. 3, current transformers 40, 41, and 42 are included in the housing withl the potential transformers 43, 44 and 45. The potential transformer chain and the arrangement of series of current transformers are separate electrically, althou h a'portion of the core may be combined or mechanical reasons as shown in the drawing. Condenser elements or shields 46 may be used to provide an electrostatic distribution of stress, and an end shield like that in Fig. l may be provided if desired. The relatively lower impedances of the current transformers, together with the vpossibility of higherinsulation, makes it possible to 4use the current transformers for distributing the electrostatic stress for transients. At normal frequency, however, the potential transformer chain will determine the distribution of from .the insulating housing. In the particular arrangement, the lead enters the houspotential between the several transformers.

The combination of potential and current transformers in the insulated housing makes it possible to provide an economical unit for metering, relaying, or other purposes. The current transformer may be provided with a limiting gap 47 and a shunt resistance or reactance 48. These serve the purpose of not only limiting the voltage across the current transformer during a transient but may be furthenused to correct phase angle and power factor, as explained in my previous application, Serial Number 438,921, filed March 7, 1930. Any convenient ratio may be provided in the transformers, and the ratio and power factor may be corrected on either the high voltage side or the low voltage side of the current transformers or in both, as explained in my previous application. By using proper electrostatic elements in the condenser or in the shield, it is possible to correct the phase angle of a potential transformer where-close adjustment is necessary. This correction may be effected by providing suitable taps from the winding of potential transformers or by a separate winding. One method is to connect the two ends of compensating windings 49 to adja cent plates of the condenser. A material compensation may be effected by allowing the charging current flowing through the potential transformer winding to flow i'n a direction so that it will effect a compensation for the reactance or charging current of the potential transformer. It is evident that where the center of the transformer winding is connected to the core as shown in the drawing, the charging current may be largely neutralized. By shifting this center and regulating the amount of charging current which will flow to ground through the transformer windings, it is possible to correct for the phase angle displacement. The cores for the potential transformer and current transformers may be connected to the condenser elements if desired, or the connection may be entirely through electrostatic capacity. By using an insulated houslng, it is possible greatly to decrease the dimensions for the coupling transformer, which'not only results in a lower cost but a material improvement in the electrostatic distribution of stress, particularly for conditions which will tend to damage the transformer. The insulated housing permits of small size' as the cores and windings of the transformer may be in contact with the housing if desired. This reduces the size of the casing or housing to a minimum and the quantity of oil or insulating medium used for improving insulation of the transformers. In some cases it may be possible or desirable to use air insulated transformers or transformers under pressure. Insulatedhousings made of porcelain, glass, molded, or other materials may be made so that they will withstand pressures very readily. With the arrangement as shown, it is possible to develop the potential inside the case of the tnansformer elements so that the potential drop of the housing member approximates the same as that on the housing on the outside. This greatly economizes space and results in improved electrical conditions.

I claim:

l. A plurality of transformers connected in series, an insulating support for said transformers, and capacitance members for controlling' the voltage gradient of said series of transformers.

2. A plurality of transformers connected in series, a high potential line connected at one end of said series, and capacitance members disposed adjacent said transformers for distributing the voltagedrop over said trans-4 formers produced by a surge from said transmission line imposed on said transformers.

3. In combination a dielectric housing member, a plurality of transformers encased in said housing member, and capacitance members distributed .relative to said transformers for grading the relative potentials of said transformers. i

4. In' a high tension transformer system, a plurality of transformers whose high tension windings are connected in series, means for c.

exciting each succeeding transformer of the series from its preceding transformer, and means for controlling the electrostatic field about said transformers for grading the potential drop of said series.

5. In a high tension transformer system, a plurality of transformers whose high tension windings are connected in series, means for exciting each succeeding transformer of the series from its preceding transformer, a dielectric housing enclosing said transformers, and capacitance members for controlling the electrostatic field about said transformers to distribute the potential drop over said series.

6. In combination a dielectric housing, a plurality of transformers disposed within said housing and having their high potential windings connected in series, a conductor line connected with the high potential end of said series, an electrical translating device connected with the low potential winding of the transformer at the otherend of said series, and separated capacitance members distributed along said series for controlling the voltage gradient of the transformer cores.

7. In combination a plurality of trans-` formers, insulating means for supporting said transformers, said transformers having their high potential windings connected in series, capacitance members insulated from one another and distributed relative `to said transformers and forming a condenser for controlling the electrostatic field about said of said transformers, the windings of said transformers being grounded on their respective cores and connected with spaced ones of said capacitance members to insure grading of the voltage drop over said transformers.

9. In combination a high potential transmission line, a housing of dielectric material, a plurality of transformers disposed withinsaid housing and spaced therein relaw tive to one another, the high potential winding of said transformers being connected in series and having one end of said series connected to said transmission line, the low potential winding at the other end of said series being connected to ground, capacitance members disposed adiacent said transformers and spaced' in said housing relative to one another in the same direction as the spacing of said transformers, the cores of said transformers being grounded on the respective high potential windingsand connected with spaced ones of said capacitance members.

10. The combination with a high potential transmission line, of a dielectric housin having a cover plate thereon provided with an extending flange of conducting material, a pluralityA of capacitance membersdisposed within said housing and distributed therein and forming acondenser between said transmission line and ground, and' a plurality of transformers disposed within Said housing and having their cores connected with different elements of said ycondenser respectively to control the voltage gradient of said transformers.

11.. The combination with a high potential transmission line, ouf a plurality of transformers having their hi h potential windings connected in' series an having one end o said series connected with said transmission line and the other end of said series grounded, 'and a condenser electrically connected between said transmission line and ground and controlling the voltage gradient over said transformers.

l 12. The combination with a high potential transmission line, of a plurality of transformers having their high potential windings connected in series, said transmission linev ben connected with one end of said series whi e the other end of said series is grounded, an electrical translatingA device connected with the low potential winding of the transformer at the ounded end of said series, a condenser having a plurality of condenser .allel with said transformers.

y14. The combination with a high potential transmission line, of a plurality of transformers having their high potential windings connected in series with said transmission line, a condenser having a plurality of capacitance members in series, said condenser being connected with said transmission line and parallel with said transformer, an impedance electrically connected between said condenser and said transmission line.

15. The combination with a high potential transmission line, of a plurality of trans formers having their high potential windings` connected in series with said transmission line, a dielectric housing encasing said transformers, a condenser connected in parallel with said transformers, and an impedance interposed between said condenser'and said transmission line for reducing the abnormal voltage impressed on the transformers by a surge on the conductor'.

16. The combination with a lurality of transformers having their big potential windings connected in series, a correction winding for said transformers, capacitance members spaced from one another and disposed in inductive relation to said respective transformers and means connecting said correction winding with spaced capacitance members for supplying voltage to said correction windin to alter the character of the electrical manifestation in said transformers.

17. The combination with a lurality of transformers havin their li li potential windings connected 1n series, o ca acitance f members for controlling the distri ution of electrostatic iux about said transformers, and a corrective winding for said transformers connected with said capacitance members.

18. The combination with a transmission line, of la plurality of current transformers connected m series and energized by said line. and means other than the windings of said current transformers for controlling the voltl age gradient between said line and ground of the cores of said current transformers.

19. The combination with a high potential conductor, ofl a series of current transformers energized b said conductor, and a circuit connected etween said conductor and ground, the cores of said current transformers being connected respectively at different.

points in said circuit to control the voltage gradient of said current transformers.

20. The combination with a high potential conductor, of a series of current transformers energized by said conductor, a series of potential transformers also energized by said conductor, and means connectlng the respective cores of said current transformers to different points in the hi h potential circuit of said potential transformers for controlling the voltage gradient of said current transformers. L

2l. The combination with a high potential conductor, of two series of transformers connected with said conductor, and means for controlling the voltage gradient between said line and ground of one of said series from the windings of the other of said series.

22. The combination with a high potential conductor, of a series of current transformers connected with said conductor, a series of potential transformers connected with said conductor, and means for connecting the cores of one series of said transformers with the windings of the other series of said transformers for controlling the voltage gradient of said cores.

23. The combination with a high potential conductor, of a series ,ofeurrent transformers energized by said conductor, a series of p0- tential transformers energized by said conductor, the cores of corresponding transformers in said series being connected together and connected to the windings of one of said transformers for controlling the voltage gradient of said cores.

24;. The combination with a high potential conductor, of a series of current transformers energized by said conductor, a series of potential transformers energized by said conductor, a common housing of dielectric material for both series of transformers, corresponding transformers in the two series having their cores connected together, and means connecting said cores with the windings of said potential transformer for controlling the voltage gradientof said cores.

y 25. The combination withl a high potential transmission line, of a transformer electrically connected with said line and energized thereby, a condenser electrically connected with said line in parallel with said transformer for diverting abnormal surges from said transformer and resistance in series with 55 said condenser, said resistance being of sufficient amount to dissipate a material portion of the energy of surges flowing through said condenser.

26. The combination with a high potential 60 transmission line, of a transformer having its high potential winding electrically conneeted with said line and energized thereby,

a condenser in parallel with said high potential -winding for diverting abnormal surges from said winding, and aresistance of at least several hundred ohms in series with said condenser and high potential winding.

27. The combination with a high potential transmission line, of a plurality of transformers having their high potential windings connected in series and connected to said line and energized thereby, a plurality of condensers in series with one another and in parallel with said high potential windings for diverting abnormal surges from said high potential windings and for controlling the potential drop over said high ypotential windings produced by such surges, and'I 'a resistance of at least several hundred ohms in series with said condensers for dissipating the energy of such surges. p

28. The combination with a high potential transmission line, of a transformer electrically connected with said line and energized thereby, a condenser electrically connected with said line in parallel with said transformer for diverting abnormal surges from said transformer, and an impedance in series with said condenser and said transformer to reduce the voltage impressed on said transformer by said line.

29. The combination with a high potential transmission line, of a transformer electrically connected with said line and energized thereby, a condenser electrically connected with said line in parallelwith said transformer for diverting abnormal surges from said transformer, and an impedance in series with said transformer, said impedance being of sufficient amount4 to materially reduce the voltage impressed on said transformer by said line.

In testimony whereof I have signed my name to this specification this 5th day of June A. D. 1930.

.ARTHUR O. AUSTIN.

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