US3350605A - Transformer with two-part core for fluorescent lamp circuits - Google Patents

Transformer with two-part core for fluorescent lamp circuits Download PDF

Info

Publication number
US3350605A
US3350605A US462638A US46263865A US3350605A US 3350605 A US3350605 A US 3350605A US 462638 A US462638 A US 462638A US 46263865 A US46263865 A US 46263865A US 3350605 A US3350605 A US 3350605A
Authority
US
United States
Prior art keywords
coils
limbs
lamp
circuit
primary
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
US462638A
Inventor
Chapman Donald Frederick
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.)
Thorn Electrical Industries Ltd
Original Assignee
Thorn Electrical Industries Ltd
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
Application filed by Thorn Electrical Industries Ltd filed Critical Thorn Electrical Industries Ltd
Priority to US462638A priority Critical patent/US3350605A/en
Application granted granted Critical
Publication of US3350605A publication Critical patent/US3350605A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/16—Circuit arrangements in which the lamp is fed by dc or by low-frequency ac, e.g. by 50 cycles/sec ac, or with network frequencies
    • H05B41/20—Circuit arrangements in which the lamp is fed by dc or by low-frequency ac, e.g. by 50 cycles/sec ac, or with network frequencies having no starting switch
    • H05B41/23—Circuit arrangements in which the lamp is fed by dc or by low-frequency ac, e.g. by 50 cycles/sec ac, or with network frequencies having no starting switch for lamps not having an auxiliary starting electrode
    • H05B41/232—Circuit arrangements in which the lamp is fed by dc or by low-frequency ac, e.g. by 50 cycles/sec ac, or with network frequencies having no starting switch for lamps not having an auxiliary starting electrode for low-pressure lamps
    • H05B41/2325—Circuit arrangements in which the lamp is fed by dc or by low-frequency ac, e.g. by 50 cycles/sec ac, or with network frequencies having no starting switch for lamps not having an auxiliary starting electrode for low-pressure lamps provided with pre-heating electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S315/00—Electric lamp and discharge devices: systems
    • Y10S315/02—High frequency starting operation for fluorescent lamp

Definitions

  • a circuit arrangement of the semi-resonant start type for electric discharge lamps has primary and secondary windings which each include two coils connected in series and each of the four coils of the windings is wound around a dilferent one of the limbs of the two U-shaped core parts which are arranged to form a magnetic circuit with air gaps between the ends of the limbs.
  • the two primary coils may be wound around the limbs of one of the U- shaped core parts and the two secondary coils around the limbs of the other or the primary and secondary coils may be arranged in alternation around the magnetic circuit.
  • the leakage reactances can easily be adjusted by altering the air gaps between the U-shaped core parts.
  • the present invention relates to circuit arrangements of the semi-resonant start type for electric discharge lamps such as fluorescent tubes.
  • This type of circuit arrangement has a primary winding in the supply circuit of the lamp and a secondary winding and a capacitor in series forming a starting circuit which, with the lamp in position, is connected to the supply circuit through the electrodes of the lamp, the primary and secondary windings being connected in opposition and magnetically coupled.
  • FIGURE 1 of the accompanying drawings shows such a circuit and FIGURES 2 and 3 show the equivalent circuits under starting and running conditions, respectively.
  • FIGURE 1 the AC. mains supply is applied across supply terminals and 11.
  • the circuit includes primary and secondary windings each of which is divided into two coils for reasons to be explained below.
  • the coils P1 and P2 of the primary winding are connected in series in the supply circuit between the supply terminal 10 and one side of an electrode filament 12 at one end of a fluorescent lamp 13.
  • the coils S1 and S2 of the secondary windings are connected in series with a capacitor C between the other side of the electrode filament 12 and one side of an electrode filament 14 at the other end of the lamp 13, the other side of the electrode filament 14 being connected to the supply terminal 11.
  • the primary and secondary windings. are coupled by a magnetic core on which they are wound and, as indicated by the arrows in FIGURE 1, are connected in opposition.
  • the opposing reactances of the primary and secondary windings are represented by XP and XS and the leakage reactances by Xp and Xs.
  • starting current at first flows only in the circuit from terminal 10 through Xp and XP, through electrode filament 12, through XS, Xs and C, and through electrode filament 14 to the terminal 11.
  • the opposed reactances XP and Xs cancel and with appropriate values for the other elements a starting voltage is developed across Xs and C which is greater than the voltage applied to the terminals 10 and 11.
  • the current flowing in this circuit heats the electrode filaments to the electron-emissive temperature and the lamp starts under the influence of the applied starting voltage.
  • the currents through XP and XS are now no longer equal but these reactances can be replaced by a mutual reactance XM through which the lamp current flows, as shown in FIGURE 3.
  • the leakage reactances Xp and Xs now serve, under running conditions, to limit harmonic frequencies generated by the lamp being fed back into the supply. To achieve the best results it is desirable to be able to adjust these leakage reactances when assembling the ballast unit formed by the two windings and the magnetic core.
  • the invention provides a novel construction which enables this to be achieved in a simple manner.
  • a circuit arrangement of the semi-resonant start type for electric discharge lamps has primary and secondary windings which each include two coils connected in series and each of the four coils of the windings is wound around a dilferent one of the limbs of the two U-shaped core parts which are arranged to form a magnetic circuit with air gaps between the ends of the limbs.
  • the two primary coils may be wound around the limbs of one of the U-shaped core parts and the two secondary coils around the limbs of the other or the primary and secondary coils may be arranged in alternation around the magnetic circuit.
  • the leakage reactances can easily be adjusted by altering the air gaps between the 'U-shaped core parts.
  • ballast unit in one example of a circuit arrangement in accordance with the invention will now be described with reference to FIGURE 4 of the accompanying drawings, which shows the ballast unit diagrammatically.
  • the coils P1 and P2 of the primary winding are wound around the limbs of a laminated U-shaped core part 15 of rectangular cross-section.
  • the coils S1 and S2 of the secondary winding are wound around the limbs of a similar U-shaped core part 16.
  • the four coils are identical coils wound from enamelled copper wire interleaved with paper.
  • the coils P1 and S1 are wound on a common former fitting closely over the limbs of the two core parts 15 and 16 and the coils P2 and S2 are wound on a second former.
  • the core parts with the coils are fitted m a sheet steel case of known type with the air gaps between the ends of limbs of the core parts set to give the desired reactances and are embedded in a potting resin in known manner.
  • the total reactance of the primary winding was 320 ohms and that of the secondary winding the same.
  • the leakage reactance of the primary and secondary windings opposition was ohms. This was used with a capacitor having a capacitance of 6.0 mfd.
  • the total harmonic content detected in the supply current waveform was less than 3%.
  • the coils P2 and S2 may be interchanged, the coils P1 and P2 remaining connected in series and in opposition to the coils S1 and S2.
  • a circuit arrangement of the semi-resonant start type for an electric discharge lamp comprising primary windings in series with the lamp and secondary windings in shunt with the lamp each including two coils connected in series and further comprising two U- shaped core parts having limbs around which said coils are wound, said core parts being arranged to form a magnetic circuit with air gaps between the ends of the said limbs, and each of the four coils of said windings being 10 wound around a different one of the said limbs.

Landscapes

  • Circuit Arrangements For Discharge Lamps (AREA)

Description

Oct. 31, 1967 D. F. CHAPMAN 3,350,605 TRANSFORMER WITH TWO-PART CORE FOR FLUORESCENT LAMP CIRCUITS Filed June 9, 1965 FIG.4
l P; s!
1N VENTOR. DONALD FREDERICK CHAPMAN ATTORNEY United States Patent 3,350,605 TRANSFORMER WITH TWO-PART CORE FOR FLUORESCENT LAMP CIRCUITS Donald Frederick Chapman, London, England, assignor to Thorn Electrical Industries Limited, London, England Filed June 9, 1965, Ser. No. 462,638 2 Claims. (Cl. 315-278) ABSTRACT OF THE DISCLOSURE A circuit arrangement of the semi-resonant start type for electric discharge lamps has primary and secondary windings which each include two coils connected in series and each of the four coils of the windings is wound around a dilferent one of the limbs of the two U-shaped core parts which are arranged to form a magnetic circuit with air gaps between the ends of the limbs. The two primary coils may be wound around the limbs of one of the U- shaped core parts and the two secondary coils around the limbs of the other or the primary and secondary coils may be arranged in alternation around the magnetic circuit. The leakage reactances can easily be adjusted by altering the air gaps between the U-shaped core parts.
The present invention relates to circuit arrangements of the semi-resonant start type for electric discharge lamps such as fluorescent tubes.
This type of circuit arrangement has a primary winding in the supply circuit of the lamp and a secondary winding and a capacitor in series forming a starting circuit which, with the lamp in position, is connected to the supply circuit through the electrodes of the lamp, the primary and secondary windings being connected in opposition and magnetically coupled.
FIGURE 1 of the accompanying drawings shows such a circuit and FIGURES 2 and 3 show the equivalent circuits under starting and running conditions, respectively.
In FIGURE 1 the AC. mains supply is applied across supply terminals and 11. The circuit includes primary and secondary windings each of which is divided into two coils for reasons to be explained below. The coils P1 and P2 of the primary winding are connected in series in the supply circuit between the supply terminal 10 and one side of an electrode filament 12 at one end of a fluorescent lamp 13. The coils S1 and S2 of the secondary windings are connected in series with a capacitor C between the other side of the electrode filament 12 and one side of an electrode filament 14 at the other end of the lamp 13, the other side of the electrode filament 14 being connected to the supply terminal 11. The primary and secondary windings. are coupled by a magnetic core on which they are wound and, as indicated by the arrows in FIGURE 1, are connected in opposition.
, In FIGURE 2 the opposing reactances of the primary and secondary windings are represented by XP and XS and the leakage reactances by Xp and Xs. During starting current at first flows only in the circuit from terminal 10 through Xp and XP, through electrode filament 12, through XS, Xs and C, and through electrode filament 14 to the terminal 11. The opposed reactances XP and Xs cancel and with appropriate values for the other elements a starting voltage is developed across Xs and C which is greater than the voltage applied to the terminals 10 and 11. The current flowing in this circuit heats the electrode filaments to the electron-emissive temperature and the lamp starts under the influence of the applied starting voltage.
The currents through XP and XS are now no longer equal but these reactances can be replaced by a mutual reactance XM through which the lamp current flows, as shown in FIGURE 3. The leakage reactances Xp and Xs now serve, under running conditions, to limit harmonic frequencies generated by the lamp being fed back into the supply. To achieve the best results it is desirable to be able to adjust these leakage reactances when assembling the ballast unit formed by the two windings and the magnetic core. The invention provides a novel construction which enables this to be achieved in a simple manner.
In accordance with the invention a circuit arrangement of the semi-resonant start type for electric discharge lamps has primary and secondary windings which each include two coils connected in series and each of the four coils of the windings is wound around a dilferent one of the limbs of the two U-shaped core parts which are arranged to form a magnetic circuit with air gaps between the ends of the limbs.
The two primary coils may be wound around the limbs of one of the U-shaped core parts and the two secondary coils around the limbs of the other or the primary and secondary coils may be arranged in alternation around the magnetic circuit.
The leakage reactances can easily be adjusted by altering the air gaps between the 'U-shaped core parts.
The construction of the ballast unit in one example of a circuit arrangement in accordance with the invention will now be described with reference to FIGURE 4 of the accompanying drawings, which shows the ballast unit diagrammatically.
The coils P1 and P2 of the primary winding are wound around the limbs of a laminated U-shaped core part 15 of rectangular cross-section. The coils S1 and S2 of the secondary winding are wound around the limbs of a similar U-shaped core part 16. The four coils are identical coils wound from enamelled copper wire interleaved with paper. To simplify winding the coils P1 and S1 are wound on a common former fitting closely over the limbs of the two core parts 15 and 16 and the coils P2 and S2 are wound on a second former. The core parts with the coils are fitted m a sheet steel case of known type with the air gaps between the ends of limbs of the core parts set to give the desired reactances and are embedded in a potting resin in known manner.
For a -watt lamp operating on a 240 volt 5O c./s. supply the total reactance of the primary winding was 320 ohms and that of the secondary winding the same. The leakage reactance of the primary and secondary windings opposition was ohms. This was used with a capacitor having a capacitance of 6.0 mfd. The total harmonic content detected in the supply current waveform was less than 3%.
When smaller leakage reactances are required the coils P2 and S2 may be interchanged, the coils P1 and P2 remaining connected in series and in opposition to the coils S1 and S2.
I claim:
1. A circuit arrangement of the semi-resonant start type for an electric discharge lamp, said circuit comprising primary windings in series with the lamp and secondary windings in shunt with the lamp each including two coils connected in series and further comprising two U- shaped core parts having limbs around which said coils are wound, said core parts being arranged to form a magnetic circuit with air gaps between the ends of the said limbs, and each of the four coils of said windings being 10 wound around a different one of the said limbs.
2. A circuit arrangement as claimed in claim 1 in which the primary coils are Wound around the limbs of one core part and the secondary coils around the limbs of the other core part.
References Cited UNITED STATES PATENTS 2,170,446 8/ 1939 Edwards 315-278 3,200,290 8/ 1965 Moerkens 315-278 FOREIGN PATENTS 786,067 11/ 1957 Great Britain.
565,576 1/1957 Italy.
DAVID J. GALVIN, Primary Examiner.

Claims (1)

1. A CIRCUIT ARRANGEMENT OF THE SEMI-RESONANT START TYPE FOR AN ELECTRIC DISCHARGE LAMP, SAID CIRCUIT COMPRISING PRIMARY WINDINGS IN SERIES WITH THE LAMP AND SECONDARY WINDINGS IN SHUNT WITH THE LAMP EACH INCLUDING TWO COILS CONNECTED IN SERIES AND FURTHER COMPRISING TWO USHAPED CORE PARTS HAVING LIMBS AROUND WHICH SAID COILS ARE WOUND, SAID CORE PARTS BEING ARRANGED TO FOR, A MAGNETIC CIRCUIT WITH AIR GAPS BETWEEN THE ENDS OF THE SAID LIMBS, AND EACH OF THE FOUR COILS OF SAID WINDINGS BEING WOUND AROUND A DIFFERENT ONE OF THE SAID LIMBS.
US462638A 1965-06-09 1965-06-09 Transformer with two-part core for fluorescent lamp circuits Expired - Lifetime US3350605A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US462638A US3350605A (en) 1965-06-09 1965-06-09 Transformer with two-part core for fluorescent lamp circuits

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US462638A US3350605A (en) 1965-06-09 1965-06-09 Transformer with two-part core for fluorescent lamp circuits

Publications (1)

Publication Number Publication Date
US3350605A true US3350605A (en) 1967-10-31

Family

ID=23837186

Family Applications (1)

Application Number Title Priority Date Filing Date
US462638A Expired - Lifetime US3350605A (en) 1965-06-09 1965-06-09 Transformer with two-part core for fluorescent lamp circuits

Country Status (1)

Country Link
US (1) US3350605A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3753076A (en) * 1972-04-27 1973-08-14 Lighting Systems Inc Inverter circuit and switching means

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2170446A (en) * 1938-03-22 1939-08-22 Gen Electric Electric discharge apparatus
GB786067A (en) * 1954-08-20 1957-11-13 Gen Electric Co Ltd Improvements in or relating to electric circuit arrangements for operating gas or vapour filled electric discharge lamps
US3200290A (en) * 1960-05-25 1965-08-10 Philips Corp Ballast device and circuit for gas discharge lamps

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2170446A (en) * 1938-03-22 1939-08-22 Gen Electric Electric discharge apparatus
GB786067A (en) * 1954-08-20 1957-11-13 Gen Electric Co Ltd Improvements in or relating to electric circuit arrangements for operating gas or vapour filled electric discharge lamps
US3200290A (en) * 1960-05-25 1965-08-10 Philips Corp Ballast device and circuit for gas discharge lamps

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3753076A (en) * 1972-04-27 1973-08-14 Lighting Systems Inc Inverter circuit and switching means

Similar Documents

Publication Publication Date Title
US2382638A (en) Fluorescent lighting
US3141112A (en) Ballast apparatus for starting and operating electric discharge lamps
US3919595A (en) Lamp ballast device
US2358810A (en) Apparatus for starting and controlling discharge devices
US3089980A (en) Ballast apparatus for starting and operating electric discharge lamps
US3225255A (en) Ballast apparatus
US3350605A (en) Transformer with two-part core for fluorescent lamp circuits
US3385999A (en) Discharge lamp transformer coil form having winding on insulated flange thereof
US2869037A (en) Fluorescent lamp ballast
US2363868A (en) Apparatus for starting and controlling discharge devices
US2824263A (en) Ballast transformer
US3080503A (en) Ballast apparatus for starting and operating gaseous discharge lamps
US3305697A (en) Ballast apparatus with air-core inductor
US2515676A (en) Fluorescent ballast
US2334567A (en) Apparatus for starting and controlling discharge devices
US2796554A (en) Electrical transformer ballast
US3080505A (en) Ballast apparatus
US2334587A (en) Starting and ballasting apparatus for electric discharge devices
US2523021A (en) Starting arrangement for electric discharge devices
US2940008A (en) Transformer for electrical discharge lamps
US3089979A (en) Ballast apparatus for starting and operating gaseous discharge lamps
US3611026A (en) Ballast circuit for low wattage gaseous discharge device
US3684921A (en) Illuminating apparatus and ballast circuit
US2885597A (en) Ballasts for gaseous discharge lamps
US2553596A (en) Induction apparatus