US3489975A - Secondary winding combination for potential type instrument transformers - Google Patents

Secondary winding combination for potential type instrument transformers Download PDF

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Publication number
US3489975A
US3489975A US664792A US3489975DA US3489975A US 3489975 A US3489975 A US 3489975A US 664792 A US664792 A US 664792A US 3489975D A US3489975D A US 3489975DA US 3489975 A US3489975 A US 3489975A
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United States
Prior art keywords
transformer
turns
resistance
secondary winding
ratio
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Expired - Lifetime
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US664792A
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English (en)
Inventor
Franklin R D Entremont
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General Electric Co
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General Electric Co
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Publication date
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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
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase ac
    • H01F38/24—Voltage transformers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/42—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils
    • H01F27/422—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers
    • H01F27/425—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers for voltage transformers

Definitions

  • the true ratio of transformation does not equal the turn ratio.
  • These ratio errors can be reduced for some conditions by using a turn ratio slightly different from the marked ratio. For example, in the case of potential transformers, the number of secondary winding turns may be slightly increased.
  • the transformer is then said to be compensated for the particular condition.
  • the particular compensation for a given transformer depends largely on the characteristics, such as frequency, power factor, burden impedance and primary voltage or current.
  • the ratio errors of a potential transformer are caused by the voltage drops which are due to the cur rents which flow through the impedances of the transformer windings.
  • an error is produced by the voltage drop due t the exciting current which flows through the primary winding.
  • an addi tional error is caused by the voltage drop produced by the burden current flowing through the impedance of both the primary and secondary windings.
  • the transformer should be designed to provide the highest possible voltage at no load, within the limits set by the A.S.A. Standard. With this high no load voltage, as the burden increases the secondary voltage will not drop below the standards at rated load or burden.
  • a further object of this invention is to provide a potential transformer having parallel secondary windings of predetermined resistance to obtain a desired ratio correction factor.
  • a still further object of this invention is to provide a potential transformer in which parallel secondary windings are provided with each such secondary winding having a resistance which depends on the desired overall secondary resistance and the ratio correction factor.
  • a potential transformer having a primary winding and a pair of secondary windings connected in parallel circuit relation.
  • the primary and secondary windings are electromagnetically linked with an electromagnetic core.
  • the ratio correction factor and the secondary resistance of the transformer are preselected according to the accuracy requirements and the load characteristics of the transformer.
  • the secondary windings are each provided with a different preselected number of turns and the size of the wire of each secondary winding is selected to pr vide a required resistance of each such winding according to the predetermined ratio correction factor and overall secondary resistance.
  • a potential transformer such as illustrated in the drawing, may be constructed to obtain the most desirable turn ratio or ratio correction factor.
  • the turn ratio or the ratio correction factor is based on the exciting current required for the transformer and the impedence of the primary winding.
  • the most desirable ratio correction factor for potential transformer will be in the range of .9965 to .9969.
  • a preferred construction according to this invention is shown schematically as a potential transformer 10 which includes a primary winding 12, the primary winding 12 is shown as being connected between a high voltage line 14 and ground 16.
  • the winding 12 is electromagnetically linked with a core 18 as will be understood by those skilled in the art.
  • a secondary winding is provided in the form of a pair of secondary coils 20 and 22 which are also designated as S and 8;, respectively.
  • Secondary coils 20 and 22 are connected electrically in parallel and are also electromagnetically linked to the core 18 in the usual manner.
  • Leads 24 and 26 from the parallel connected secondary winding are connected to a secondary burden or load 28 which may be, for example, a voltage meter.
  • the most desirable ratio correction factor can be obtained by selecting the wire size of the wires used to wind the secondary coils 20 and 22 to obtain a constant ratio of resistance K.
  • the constant K is determined by the desired ratio correction factor, the basic turns of the transformer and the number of turns on the secondary coil, that is different from the basic turns.
  • the wire size for secondary winding S would be selected such that 161 turns would provide a resistance of approximately 0.569 ohm while the wire size for secondary winding S would be selected so that 159 turns would provide a resistance of approximately 1.938 ohms.
  • a potential transformer having a predetermined ratio correction factor and including a core member, a

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Coils Of Transformers For General Uses (AREA)
  • Coils Or Transformers For Communication (AREA)
US664792A 1967-08-31 1967-08-31 Secondary winding combination for potential type instrument transformers Expired - Lifetime US3489975A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US66479267A 1967-08-31 1967-08-31

Publications (1)

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US3489975A true US3489975A (en) 1970-01-13

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US664792A Expired - Lifetime US3489975A (en) 1967-08-31 1967-08-31 Secondary winding combination for potential type instrument transformers

Country Status (6)

Country Link
US (1) US3489975A (de)
BE (1) BE719815A (de)
CH (1) CH499861A (de)
DE (1) DE1763824C3 (de)
FR (1) FR1582255A (de)
GB (1) GB1226174A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5847518A (en) * 1996-07-08 1998-12-08 Hitachi Ferrite Electronics, Ltd. High voltage transformer with secondary coil windings on opposing bobbins
WO2021023472A1 (de) * 2019-08-08 2021-02-11 Siemens Energy Global GmbH & Co. KG Schutz eines wechselstromgeräts

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1865430A (en) * 1929-06-25 1932-07-05 Borkent Roelof Herman Current transformer
US1896993A (en) * 1929-05-14 1933-02-07 Frederick L Arland Resonant circuit
US2089860A (en) * 1935-03-01 1937-08-10 Albert B Rypinski Slow transformer
US2283711A (en) * 1940-04-26 1942-05-19 Gen Electric Electrical winding
US3360754A (en) * 1965-06-29 1967-12-26 Wagner Electric Corp Transformer having reduced differential impedances between secondary portions

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1896993A (en) * 1929-05-14 1933-02-07 Frederick L Arland Resonant circuit
US1865430A (en) * 1929-06-25 1932-07-05 Borkent Roelof Herman Current transformer
US2089860A (en) * 1935-03-01 1937-08-10 Albert B Rypinski Slow transformer
US2283711A (en) * 1940-04-26 1942-05-19 Gen Electric Electrical winding
US3360754A (en) * 1965-06-29 1967-12-26 Wagner Electric Corp Transformer having reduced differential impedances between secondary portions

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5847518A (en) * 1996-07-08 1998-12-08 Hitachi Ferrite Electronics, Ltd. High voltage transformer with secondary coil windings on opposing bobbins
WO2021023472A1 (de) * 2019-08-08 2021-02-11 Siemens Energy Global GmbH & Co. KG Schutz eines wechselstromgeräts
US20220317157A1 (en) * 2019-08-08 2022-10-06 Siemens Energy Global GmbH & Co. KG Protection of an ac device

Also Published As

Publication number Publication date
DE1763824C3 (de) 1975-10-09
CH499861A (de) 1970-11-30
GB1226174A (de) 1971-03-24
FR1582255A (de) 1969-09-26
DE1763824A1 (de) 1972-01-05
BE719815A (de) 1969-02-03
DE1763824B2 (de) 1973-02-08

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