LAMP BALLAST DEVICE

• US 3,772,565 A
• Filed: 07/28/1972
• Issued: 11/13/1973
• Est. Priority Date: 07/28/1972
• Status: Expired due to Term

• Current Assignee: James E. Lenz, Wayne R. Neal
• Original Assignee: James E. Lenz, Wayne R. Neal
• Inventors: Neal, Wayne R., Lenz, James E.
• Primary Examiner(s): Brody, Alfred L.
• Application Number:
  US05/275,947
• Time in Patent Office: 473 Days
• Field of Search: 315/100,138,276,278,280,282 336/165
• US Class Current: 315/276
• CPC Class Codes: H01F 38/10 Ballasts, e.g. for discharge lamps
• CPC Class Codes: H05B 41/391 using saturable magnetic devices

Abstract

Electrical ballast provides regulation of the operating wattage for gaseous discharge lamps such as high pressure sodium lamps over the entire life of the lamp. Ballast comprises a high leakage reactance transformer having primary and secondary windings on different core portions with a magnetic shunt between the windings, slots in the core under the secondary winding, and a capacitor connected in series with the secondary winding. The transformer is constructed so that its leakage reactance is from two to four times the capacitive reactance provided by the series capacitor. The control of the leakage reactance is obtained by provision of a predetermined cross-sectional area of the magnetic shunt in combination with a non-magnetic gap.

Claims

1. Ballast apparatus for operating a gaseous discharge device from an alternating current source comprising, in combination, a transformer having a core of magnetic material providing a closed magnetic circuit, primary winding means on a first portion of said core and secondary winding means on a second portion of said core adapted to be connected in series with the gaseous discharge device, means for providing a predetermined secondary magnetizing reactance, a capacitor connected in series with said secondary winding means and having sufficient capacitive reactance for limiting current to the gaseous discharge device, and means for providing leakage reactance in the ballast apparatus which is between two and four times the capacitive reactance of said capacitor.

2. Ballast apparatus as defined in claim 1, said leakage reactance means comprising magnetic shunt means between said primary and said secondary winding means in combination with non-magnetic gap means between said core and said magnetic shunt means.

3. Ballast apparatus as defined in claim 2, including a restricted cross-sectional area in the secondary portion of said core to provide localized saturation thereof for reducing the secondary magnetizing reactance.

4. Ballast apparatus as defined in claim 1, and means connecting said secondary winding means to said primary winding means for providing a predetermined voltage additive to said secondary winding means for improving the line power factor.

5. Ballast apparatus as defined in claim 2, and means connecting said secondary winding means to said primary winding means for providing a predetermined voltage additive to said secondary winding means for providing a line power factor of at least 90 percent.

6. Ballast apparatus as defined in claim 5, and a high pressure gaseous discharge sodium lamp connected in series with said capacitor.

7. Ballast apparatus as defined in claim 2, said magnetic shunt means having a predetermined cross-sectional area and said gap means having a predetermined length for providing controlled saturation of said magnetic shunt means for producing a characteristic volt-watt curve for said gaseous discharge device which has a relatively steep front and a relatively flat tail.

8. Ballast apparatus as defined in claim 1, said leakage reactance means comprising an induction coil connected in series with said secondary winding means.

9. Ballast apparatus as defined in claim 1, said secondary magnetizing reactance means comprising an induction coil connected in parallel with said secondary winding means.

10. Ballast apparatus as defined in claim 1, said leakage reactance means comprising a first induction coil connected in series with said secondary winding means, said secondary magnetizing reactance means comprising a second induction coil connected in parallel with said series connected secondary winding means and first induction coil.