US2449367A - Tapped transformer system - Google Patents

Tapped transformer system Download PDF

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Publication number
US2449367A
US2449367A US634571A US63457145A US2449367A US 2449367 A US2449367 A US 2449367A US 634571 A US634571 A US 634571A US 63457145 A US63457145 A US 63457145A US 2449367 A US2449367 A US 2449367A
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US
United States
Prior art keywords
tap
voltage
contactor
load
taps
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US634571A
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English (en)
Inventor
Boyajian Aram
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE483427D priority Critical patent/BE483427A/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US634571A priority patent/US2449367A/en
Priority to GB36460/46A priority patent/GB619439A/en
Application granted granted Critical
Publication of US2449367A publication Critical patent/US2449367A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F29/00—Variable transformers or inductances not covered by group H01F21/00
    • H01F29/02—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings
    • H01F29/04—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings having provision for tap-changing without interrupting the load current

Definitions

  • This invention relates to electric circuits and more particularly to alternating-voltage control systems based on tap-changing under load and involving an alternating-current transformer and auxiliary equipment including contactors adapted to control the output voltage of the transformer. while under load, by changing taps on the transformer without interruption of theload.
  • a particular object of the invention is toreduce the recovery-voltage duty on the contactors so as to avoid their failure under short-circuit conditions and damage to other parts of the system.
  • a further object of the invention is to reduce fluctuations of load voltage due to the impedance drops of tap-changing equipment.
  • a still further object of the invention is to reduce circulating currents in loops formed by tapchanging equipment.
  • Fig. l is the simplified diagram of a conventional tap-changing system, which is helpful in explaining the problems which the present invention solves
  • Figs. 2 and 3 show various operative positions of Fig. 1
  • Fig. 4 illustrates diagrammatically an embodiment of the present invention
  • Figs. 5-8 inclusive illustrate various steps in a cycle of tapchanging by the equipment of Fig. 4.
  • I is a two-winding trans-'- former with primary winding 2, fed from an alternating-current source 3, while 4 is a secondary winding of the transformer, with taps.
  • a pair of movable fingers are represented by i and 8; 9 and in are contactors in series with 1 and 8, respectively; and H is a mid-tapped impeder-usuall a reactor-autotransformer-with its two terminals connected to the circuits of I and 8, respectively, while the mid-point of II and a terminal I! of the secondary, are connected respectively to the two terminals of a load l3.
  • Fig. 1 shows both movable fingers 1 and 8 as engaging tap 5, so that the load is furnished by the voltage corresponding to this'trap. If it is desired to change to the adjoining tap 8, the circuit is made to pass through two successive representative positions illustrated by Figs. 2.and 3.
  • Figs. 4-9 inclusive Successive steps of a complete cycle of changing taps from 5 to 6, according to the present inventlon, are illustrated in Figs. 4-9 inclusive.
  • contactor H must first be closed, if it was open before.
  • Contactor II is then opened, and finger 8 is disengaged from tap l, as shown in Fig. 5.
  • This corresponds to the socalled quarter-cycle position of Fig. 2, but now the reactance of H is relatively low because a portion of it is short-cireuited.
  • Finger I is now made to engage tap B, and contactor I is closed, making ll bridge across the two taps I and 6. as seen in Fig. 6.
  • a desirable value for the reactance of ii in Fig. '7,'that is, with I4 open, is such as to render the circulating current less than half of the full load current.
  • the double-valued reactor-autotransformer makes two different circulating-current values possible, a low circulating current for continuous mid-tap operation, and a higher circulating current in preparation for the breaking of this mid-tap connection, with a low reactive drop for the load and a low recovery voltage for the interrupting contactor.
  • the higher circulating current is only momentary, its heating effect is negligible.
  • the invention not only assures the following benefits, namely, the contactor recovery voltages are lowered, any tap-totap short circuits during tap-changing operations avoided, the circulating currents in continuous operation in bridgin positions are reduced, and the fluctuations of load voltage due to reactive drops during tap changing are reduced, but also all these benefits are accomplished by a single compact and economical reactor-autotransformer unit to provide two diflerent and independent impedance values with the aid of a contactor.
  • a transformer winding having a plurality of taps, mean for selectively connecting said taps into a circuit under load, said means including impedance means, and means. for causing said impedance means to offer two different and independent substantial impedance values, namely, a high impedance value to circulating currents when in continuous operation in shunt connection across a pair of said taps, and a low impedance value preparatory to interrupting said shunt connection.
  • the method of changing taps under load with switching mean and impedance means being characterized by the mid-tap operation of the system continuously with a high value of said impedance connected in shunt across a pair of said taps, and changing to a lower finite value of said impedance before changing said shunt connection.
  • a transformer winding having a plurality of taps, a terminal for said winding, means including a pair of contactors for selectively connecting said terminal to various ones of said taps including the connection of said terminal simultaneously to electrically adjacent taps.
  • an impedance connected to limit the circulating current through said mean when said terminal is connected to electrically adjacent taps. and means for reducing the effective value of said impedance to a relatively low but finite value prior to the opening of either of said contactor so as to reduce its recovery voltage during short circuit conditions of said winding.
  • a transformer winding having a plurality of taps, a terminal for said winding, means including a pair of contactors for selectively connecting said terminal to various ones of said taps including the connection of said terminal simultaneously to electrically adjacent taps, an impedance connected to limit the circulating current through said means when said terminal is connected to electrically adjacent taps, and means for reducing the effective value of said impedance to a relatively low but finite value substantially simultaneously with the opening of either of said contaotors so as to reduce its recovery voltage during short circuit conditions of said winding.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Electrical Variables (AREA)
  • Housings And Mounting Of Transformers (AREA)
US634571A 1945-12-12 1945-12-12 Tapped transformer system Expired - Lifetime US2449367A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE483427D BE483427A (en)) 1945-12-12
US634571A US2449367A (en) 1945-12-12 1945-12-12 Tapped transformer system
GB36460/46A GB619439A (en) 1945-12-12 1946-12-10 Improvements relating to on-load tap changing systems for electric transformers

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US634571A US2449367A (en) 1945-12-12 1945-12-12 Tapped transformer system

Publications (1)

Publication Number Publication Date
US2449367A true US2449367A (en) 1948-09-14

Family

ID=24544341

Family Applications (1)

Application Number Title Priority Date Filing Date
US634571A Expired - Lifetime US2449367A (en) 1945-12-12 1945-12-12 Tapped transformer system

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US (1) US2449367A (en))
BE (1) BE483427A (en))
GB (1) GB619439A (en))

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2617978A (en) * 1950-05-29 1952-11-11 Detroit Edison Co Electrical regulating apparatus
US2674716A (en) * 1951-03-29 1954-04-06 R T & E Company Line voltage regulator
US2979658A (en) * 1957-12-26 1961-04-11 Honeywell Regulator Co Switching circuit
DE1538018B1 (de) * 1965-07-28 1969-11-13 Reinhausen Maschf Scheubeck Stufenschalteinrichtung fuer Regeltransformatoren
US4384247A (en) * 1981-05-08 1983-05-17 Trw Inc. Under-load switching device particularly adapted for voltage regulation and balance

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2617978A (en) * 1950-05-29 1952-11-11 Detroit Edison Co Electrical regulating apparatus
US2674716A (en) * 1951-03-29 1954-04-06 R T & E Company Line voltage regulator
US2979658A (en) * 1957-12-26 1961-04-11 Honeywell Regulator Co Switching circuit
DE1538018B1 (de) * 1965-07-28 1969-11-13 Reinhausen Maschf Scheubeck Stufenschalteinrichtung fuer Regeltransformatoren
US4384247A (en) * 1981-05-08 1983-05-17 Trw Inc. Under-load switching device particularly adapted for voltage regulation and balance

Also Published As

Publication number Publication date
GB619439A (en) 1949-03-09
BE483427A (en))

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