US3678429A - H.v. testing transformer winding arrangement - Google Patents
H.v. testing transformer winding arrangement Download PDFInfo
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- US3678429A US3678429A US104953A US3678429DA US3678429A US 3678429 A US3678429 A US 3678429A US 104953 A US104953 A US 104953A US 3678429D A US3678429D A US 3678429DA US 3678429 A US3678429 A US 3678429A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/18—Rotary transformers
Definitions
- a high-voltage transformer for producing test voltages has a low-voltage primary winding, a high-voltage secondary winding, and a cascade winding.
- the primary winding is formed by two separate low-voltage windings wound on separate limbs of a ferromagnetic core and connected in parallel so that their magnetic fluxes assist in the wound core limbs.
- the high-voltage secondary winding is wound over one only of the low-voltage windings.
- the cascade winding is formed by two separate low-voltage windings connected in parallel and in phase, one being wound over the high-voltage winding on one limb and the other being wound over the low-voltage winding on the other limb.
- each transformer except that at the highest voltage is provided with a low-voltage cascade winding which is used to supply the primary winding of the next transformer in sequence.
- the usual winding arrangement for a high-voltage testing transformer having a cascade winding involves winding the low-voltage primary winding around one limb of the transformer core. Over this, suitably insulated, is wound the highvoltage secondary winding. The end of this winding adjacent to the primary winding is connected to the transformer tank whilst the high-voltage end of the winding is taken out through a bushing. Over the high-voltage winding is wound the lowvoltage cascade winding, one end of which is brought out so that it may be connected to the primary winding of a further transformer, and the other end of which is connected to the high-voltage terminal.
- the high-voltage terminal of the first transformer is connected to the tank of the second transformer, which is insulated from the ground against the output of the first transformer.
- the low-voltage primary winding of the second transformer is connected between the end of the cascade winding and the tank of the second transformer. If a third is also to be used then the second transformer will also have a cascade winding connected in the same way. The last transformer in the sequence does not require a cascade windmg.
- Such a winding arrangement has the disadvantage that any capacitive load which may have to be supplied by two or more such transformers connected in series would be limited owing to the high impedance arising from the reactance between the low-voltage input to the first transformer and the cascade winding of the transformer. This impedance increases as the number of series-connected transformers increases.
- a transformer which includes a ferromagnetic core having at least two limbs, a separate low-voltage primary winding wound around two of said limbs, the two windings being connected in parallel with one another such that the magnetic flux produced in the wound limbs by one winding assists the flux produced in the wound limbs by the other winding, a highvoltage winding wound over the low-voltage winding on one only of the wound limbs, a first cascade winding wound over the high-voltage winding on said one limb and a second cascade winding wound over the low-voltage winding on the other wound limb, the two cascade windings being connected in parallel and in phase with one another.
- FIG. 1 is a schematic sectional view of a winding arrangement in accordance with the invention.
- FIG. 2 is an equivalent circuit diagram of the winding arrangement of FIG. 1.
- the core 10 (FIG. 1) of the transformer has two limbs 11 and 12, each of which carries a low-voltage winding 13 and 13 respectively.
- the two low-voltage windings are connected in parallel with one another such that the magnetic flux produced by one winding in the two wound limbs assists the flux produced by the other winding in the two limbs, and leads are brought out of the tank for connection to the low-voltage supply.
- the high-voltage winding 14 Over the low-voltage windings 13 on limb 11, is wound the high-voltage winding 14. The end of this winding adjacent to the low-voltage winding 13 is connected to the transformer tank, and the other end of the highvoltage winding is brought out through an insulating bushing.
- the cascade winding is wound in two parts, one of which, 15, is wound over the high-voltage winding 14 on limb ll of the core.
- the other part 15' of the cascade winding is wound over the low-voltage winding 13 on limb 12 of the core, suitably insulated from the low-voltage winding, since one end of the cascade winding is connected to the high-voltage end of the high-voltage winding 14.
- the two parts of the cascade winding are connected in parallel and in phase with one another, and the end not connected to the high-voltage winding is brought out of the tank.
- the core of the transformer may have more than two limbs if required, the other limbs not carrying windings.
- FIG. 2 shows the equivalent circuit of the transformer described above.
- Each winding is represented by an impedance given the winding reference from FIG. 1.
- the magnetizing impedance of the primary of a transformer of this type is assumed to be very high and is therefore not shown in the equivalent circuit.
- the high voltage output terminal is given the reference H and that of the cascade winding is C.
- the two primary winding impedances Z and Z are shown connected in parallel with one another, as is actually the case. Since the high-voltage winding 14 is physically wound over one primary winding 13, its impedance 2, is shown in series with the primary impedance 2, The cascade winding 15 which is wound over the high-voltage winding 14 has its impedance Z connected to the junction between Z and Z to form a star network, as is usual with three-winding transformer equivalent circuits. The other cascade winding 15' is wound over the primary winding 13', and hence its impedance Z 1 is effectively in series with the impedance Z The other ends of the two cascade winding impedances Z and Z W are shown connected together to the terminal C as is the case in practice.
- a transformer which includes a ferromagnetic core having at least two limbs, a separate low-voltage primary winding wound around two of said limbs, the two windings being connected in parallel with one another such that the magnetic flux produced in the wound limbs by one winding assists the flux produced in the wound limbs by the other winding, a highvoltage winding wound over the low-voltage winding on one only of the wound limbs, a first cascade winding wound over the high-voltage winding on said one limb and a second cascade winding wound over the low-voltage winding on the other wound limb, the two cascade windings being connected in parallel and in phase with one another.
- a high-voltage transformer for producing test voltages comprising a ferromagnetic core having at least two limbs, a
- each low voltage winding forming the primary winding is adjacent the limb, said low voltage primary windings and associated secondary and cascade windings being coaxially disposed on said limbs.
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Coils Of Transformers For General Uses (AREA)
Abstract
A high-voltage transformer for producing test voltages has a low-voltage primary winding, a high-voltage secondary winding, and a cascade winding. The primary winding is formed by two separate low-voltage windings wound on separate limbs of a ferromagnetic core and connected in parallel so that their magnetic fluxes assist in the wound core limbs. The high-voltage secondary winding is wound over one only of the low-voltage windings. The cascade winding is formed by two separate lowvoltage windings connected in parallel and in phase, one being wound over the high-voltage winding on one limb and the other being wound over the low-voltage winding on the other limb.
Description
United States Patent Collin [151 3,678,429 [45 uly 18, 1972 [72] Inventor:
gland Fen-anti, Limited, cashire, England [22] Filed: Jan. 8, 1971 [21] App1.-No.: 104,953
[73] Assignee: Hollinwood, Lan- [30] Foreign Application Priority Jan. 8, 1970 Great Britain ..901/70 [52] US. Cl ..336/170, 336/184 [51] Int. Cl. 101127/28 [58] FleldoiSearch ..336/l80,l84,170, 145,146,
Frank Anthony James Collin, Oldham, En-
1,761,732 6/1930 Kiichling, ..336/184 X 1,699,292 1/1929 ..-.336/184 X I FOREIGN PATENTS OR APPLICATIONS 1,488,336 5/1969 Germany ..336/ 184 1,488,209 4/1969 Germany ..336/184 Primary Examiner-Thomas J Kozma Attorney-Cameron, Kera n & Sutton 1' ABSTRACT A high-voltage transformer for producing test voltages has a low-voltage primary winding, a high-voltage secondary winding, and a cascade winding. The primary winding is formed by two separate low-voltage windings wound on separate limbs of a ferromagnetic core and connected in parallel so that their magnetic fluxes assist in the wound core limbs. The high-voltage secondary winding is wound over one only of the low-voltage windings. The cascade winding is formed by two separate low-voltage windings connected in parallel and in phase, one being wound over the high-voltage winding on one limb and the other being wound over the low-voltage winding on the other limb.
3Clains,2DrawingF1gures a s a a i a 5 PATENTED JUL 1 8 m2 H.V. TESTING TRANSFORMER WINDING ARRANGEMENT This invention relates to transformers, and in particular to winding arrangements for transformers used to produce high voltages for testing purposes.
For the testing of high-voltage electrical equipment it is usual to produce the necessary voltages by means of high-voltage transformers. The particular type of transformer normally used has one end of the high-voltage winding connected to the tank and the other end brought out through an insulating bushing. Frequently two or more transformers are connected in series to produce the desired output voltage, and it is then necessary to insulate the tanks of all but one of the transformers from the ground. In such a case it is no longer possible to supply all the low-voltage primary windings from a common source because of insulation problems, since the tank of the first transformer of the series will be at earth potential, the
tank of the next transformer willbe at, say, SOOKV, the tank of the next at lMV and so on. In order to overcome this problem each transformer except that at the highest voltage is provided with a low-voltage cascade winding which is used to supply the primary winding of the next transformer in sequence.
The usual winding arrangement for a high-voltage testing transformer having a cascade winding involves winding the low-voltage primary winding around one limb of the transformer core. Over this, suitably insulated, is wound the highvoltage secondary winding. The end of this winding adjacent to the primary winding is connected to the transformer tank whilst the high-voltage end of the winding is taken out through a bushing. Over the high-voltage winding is wound the lowvoltage cascade winding, one end of which is brought out so that it may be connected to the primary winding of a further transformer, and the other end of which is connected to the high-voltage terminal. The high-voltage terminal of the first transformer is connected to the tank of the second transformer, which is insulated from the ground against the output of the first transformer. The low-voltage primary winding of the second transformer is connected between the end of the cascade winding and the tank of the second transformer. If a third is also to be used then the second transformer will also have a cascade winding connected in the same way. The last transformer in the sequence does not require a cascade windmg.
Such a winding arrangement has the disadvantage that any capacitive load which may have to be supplied by two or more such transformers connected in series would be limited owing to the high impedance arising from the reactance between the low-voltage input to the first transformer and the cascade winding of the transformer. This impedance increases as the number of series-connected transformers increases.
One method of overcoming this problem is to increase the core size of the transformer, but this results in a larger and more expensive transformer. Another solution which has been employed is to split the low-voltage primary winding into two parallel-connected windings wound around separate limbs of the core. The high-voltage winding is wound around one lowvoltage winding and the cascade winding is wound around the other low-voltage winding. This effects a slight reduction in the impedance, but is still not entirely satisfactory.
It is an object of the present invention to provide a highvoltage testing transformer having a cascade winding in which the impedance between primary and cascade windings is still further reduced.
According to the present invention there is provided a transformer which includes a ferromagnetic core having at least two limbs, a separate low-voltage primary winding wound around two of said limbs, the two windings being connected in parallel with one another such that the magnetic flux produced in the wound limbs by one winding assists the flux produced in the wound limbs by the other winding, a highvoltage winding wound over the low-voltage winding on one only of the wound limbs, a first cascade winding wound over the high-voltage winding on said one limb and a second cascade winding wound over the low-voltage winding on the other wound limb, the two cascade windings being connected in parallel and in phase with one another.
The invention will now be described with reference to the accompanying drawings, in which:
FIG. 1 is a schematic sectional view of a winding arrangement in accordance with the invention, and
FIG. 2 is an equivalent circuit diagram of the winding arrangement of FIG. 1. I
The core 10 (FIG. 1) of the transformer has two limbs 11 and 12, each of which carries a low- voltage winding 13 and 13 respectively. The two low-voltage windings are connected in parallel with one another such that the magnetic flux produced by one winding in the two wound limbs assists the flux produced by the other winding in the two limbs, and leads are brought out of the tank for connection to the low-voltage supply.
Over the low-voltage windings 13 on limb 11, is wound the high-voltage winding 14. The end of this winding adjacent to the low-voltage winding 13 is connected to the transformer tank, and the other end of the highvoltage winding is brought out through an insulating bushing.
The cascade winding is wound in two parts, one of which, 15, is wound over the high-voltage winding 14 on limb ll of the core. The other part 15' of the cascade winding is wound over the low-voltage winding 13 on limb 12 of the core, suitably insulated from the low-voltage winding, since one end of the cascade winding is connected to the high-voltage end of the high-voltage winding 14. The two parts of the cascade winding are connected in parallel and in phase with one another, and the end not connected to the high-voltage winding is brought out of the tank.
The core of the transformer may have more than two limbs if required, the other limbs not carrying windings.
FIG. 2 shows the equivalent circuit of the transformer described above. Each winding is represented by an impedance given the winding reference from FIG. 1. The magnetizing impedance of the primary of a transformer of this type is assumed to be very high and is therefore not shown in the equivalent circuit. The high voltage output terminal is given the reference H and that of the cascade winding is C.
The two primary winding impedances Z and Z are shown connected in parallel with one another, as is actually the case. Since the high-voltage winding 14 is physically wound over one primary winding 13, its impedance 2, is shown in series with the primary impedance 2, The cascade winding 15 which is wound over the high-voltage winding 14 has its impedance Z connected to the junction between Z and Z to form a star network, as is usual with three-winding transformer equivalent circuits. The other cascade winding 15' is wound over the primary winding 13', and hence its impedance Z 1 is effectively in series with the impedance Z The other ends of the two cascade winding impedances Z and Z W are shown connected together to the terminal C as is the case in practice.
It is the connection of the impedance 2,, which has the effect of reducing the reactance between the primary and cascade windings of the transformer as compared with previous winding arrangements using only a single cascade winding.
What we claim is:
l. A transformer which includes a ferromagnetic core having at least two limbs, a separate low-voltage primary winding wound around two of said limbs, the two windings being connected in parallel with one another such that the magnetic flux produced in the wound limbs by one winding assists the flux produced in the wound limbs by the other winding, a highvoltage winding wound over the low-voltage winding on one only of the wound limbs, a first cascade winding wound over the high-voltage winding on said one limb and a second cascade winding wound over the low-voltage winding on the other wound limb, the two cascade windings being connected in parallel and in phase with one another.
2. A high-voltage transformer for producing test voltages comprising a ferromagnetic core having at least two limbs, a
primary winding having two separate low voltage windings each wound on a separate limb of the core, said low voltage windings being connected in parallel so that the magnetic flux produced in the two limbs by one winding assists the flux produced in the two limbs by the other winding, a high-voltage secondary winding, said high-voltage secondary winding being wound over the low voltage winding on one only of the limbs on which a low voltage winding is wound and a cascade winding including two separate low voltage windings, one of said last mentioned low-voltage windings being wound over the high-voltage secondary winding, the other of said last mentioned low voltage windings being wound over the low-voltage winding on the other limb and said two separate low-voltage windings forming the cascade winding being connected in parallel and in phase with one another.
3. A transformer as set forth in claim 1 wherein each low voltage winding forming the primary winding is adjacent the limb, said low voltage primary windings and associated secondary and cascade windings being coaxially disposed on said limbs.
Claims (3)
1. A transformer which includes a ferromagnetic core having at least two limbs, a separate low-voltage primary winding wound around two of said limbs, the two windings being connected in parallel with one another such that the magnetic flux produced in the wound limbs by one winding assists the flux produced in the wound limbs by the other winding, a high-voltage winding wound over the low-voltage winding on one only of the wound limbs, a first cascade winding wound over the high-voltage winding on said one limb and a second cascade winding wound over the low-voltage winding on the other wound limb, the two cascade windings being connected in parallel and in phase with one another.
2. A high-voltage transformer for producing test voltages comprising a ferromagnetic core having at least two limbs, a primary winding having two separate low voltage windings each wound on a separate limb of the core, said low voltage windings being connected in parallel so that the magnetic flux produced in the two limbs by one winding assists the flux produced in the two limbs by the other winding, a high-voltage secondary winding, said high-voltage secondary winding being wound over the low voltage winding on one only of the limbs on which a low voltage winding is wound and a cascade winding including two separate low voltage windings, one of said last mentioned low-voltage windings being wound over the high-voltage secondary winding, the other of said last mentioned low voltage windings being wound over the low-voltage winding on the other limb and said two separate low-voltage windings forming the cascade winding being connected in parallel and in phase with one another.
3. A transformer as set forth in claim 1 wherein each low voltage winding forming the primary winding is adjacent the limb, said low voltage primary windings and associated secondary and cascade windings being coaxially disposed on said limbs.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB901/70A GB1271635A (en) | 1970-01-08 | 1970-01-08 | Improvements relating to transformers |
Publications (1)
Publication Number | Publication Date |
---|---|
US3678429A true US3678429A (en) | 1972-07-18 |
Family
ID=9712474
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US104953A Expired - Lifetime US3678429A (en) | 1970-01-08 | 1971-01-08 | H.v. testing transformer winding arrangement |
Country Status (7)
Country | Link |
---|---|
US (1) | US3678429A (en) |
CH (1) | CH512814A (en) |
DE (1) | DE2063148A1 (en) |
FR (1) | FR2075984B1 (en) |
GB (1) | GB1271635A (en) |
NL (1) | NL7100078A (en) |
SE (1) | SE360209B (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4060783A (en) * | 1973-11-02 | 1977-11-29 | General Electric Co. | Magnetic circuit and method of making |
US4466051A (en) * | 1982-10-25 | 1984-08-14 | Rca Corporation | Regulated power supply incorporating a power transformer having a tightly coupled supplemental power transfer winding |
US5455506A (en) * | 1994-07-21 | 1995-10-03 | Copek Electro Ltee | Method and portable testing apparatus for safely testing an autotransformer for power distribution lines |
WO2010095955A1 (en) | 2009-02-23 | 2010-08-26 | Badger Explorer Asa | High voltage transformer |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1699292A (en) * | 1926-08-21 | 1929-01-15 | Firm Emil Haefely & Cie A G | High-tension transformer |
US1749388A (en) * | 1926-11-08 | 1930-03-04 | Bbc Brown Boveri & Cie | Transformer |
US1761732A (en) * | 1928-01-28 | 1930-06-03 | Gen Electric | Transformer |
DE1488209A1 (en) * | 1964-07-31 | 1969-04-03 | Licentia Gmbh | Transformer, especially a locomotive transformer |
DE1488336A1 (en) * | 1964-04-04 | 1969-05-14 | Siemens Ag | High-voltage test transformer |
-
1970
- 1970-01-08 GB GB901/70A patent/GB1271635A/en not_active Expired
- 1970-12-22 DE DE19702063148 patent/DE2063148A1/en active Pending
- 1970-12-31 FR FR7047456A patent/FR2075984B1/fr not_active Expired
-
1971
- 1971-01-05 CH CH8171A patent/CH512814A/en not_active IP Right Cessation
- 1971-01-05 NL NL7100078A patent/NL7100078A/xx unknown
- 1971-01-07 SE SE00124/71A patent/SE360209B/xx unknown
- 1971-01-08 US US104953A patent/US3678429A/en not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1699292A (en) * | 1926-08-21 | 1929-01-15 | Firm Emil Haefely & Cie A G | High-tension transformer |
US1749388A (en) * | 1926-11-08 | 1930-03-04 | Bbc Brown Boveri & Cie | Transformer |
US1761732A (en) * | 1928-01-28 | 1930-06-03 | Gen Electric | Transformer |
DE1488336A1 (en) * | 1964-04-04 | 1969-05-14 | Siemens Ag | High-voltage test transformer |
DE1488209A1 (en) * | 1964-07-31 | 1969-04-03 | Licentia Gmbh | Transformer, especially a locomotive transformer |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4060783A (en) * | 1973-11-02 | 1977-11-29 | General Electric Co. | Magnetic circuit and method of making |
US4466051A (en) * | 1982-10-25 | 1984-08-14 | Rca Corporation | Regulated power supply incorporating a power transformer having a tightly coupled supplemental power transfer winding |
US5455506A (en) * | 1994-07-21 | 1995-10-03 | Copek Electro Ltee | Method and portable testing apparatus for safely testing an autotransformer for power distribution lines |
WO2010095955A1 (en) | 2009-02-23 | 2010-08-26 | Badger Explorer Asa | High voltage transformer |
US20120007706A1 (en) * | 2009-02-23 | 2012-01-12 | Badger Explorer Asa | High Voltage Transformer |
US9490065B2 (en) * | 2009-02-23 | 2016-11-08 | Zaptec Ip As | High voltage transformer |
Also Published As
Publication number | Publication date |
---|---|
FR2075984B1 (en) | 1976-03-19 |
DE2063148A1 (en) | 1971-07-15 |
GB1271635A (en) | 1972-04-19 |
FR2075984A1 (en) | 1971-10-15 |
NL7100078A (en) | 1971-07-12 |
CH512814A (en) | 1971-09-15 |
SE360209B (en) | 1973-09-17 |
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