Discharge device ballast component which provides both voltage

Abstract

Composite structure for use as an HID device ballast component and which performs the dual functions of voltage transformation and provision of ballasting reactance which can be cntrollably shifted in value. A multi-leg magnetic structure has a primary winding carried on a first leg thereof and an output winding carried on a second leg thereof. A control winding is carried on a third leg and a gap of predetermined dimensions is provided in the magnetic path which includes the third leg. The magnetic core member and the windings carried thereon display leakage flux paths of predetermined total permeance. A bilateral switch connects to the control winding and is operable to be closed once each half cycle of normal lamp operation. With the control winding closed, the counter mmf generated in the third leg decreases the inductive reactance of the structure by a predetermined amount, with the inductive reactance of the structure essentially established by the permeance of the leakage paths. With the control winding open, the inductive reactance of the structure is established both by the reactance of the wound third leg and the permeance of the leakage paths. Thus, the effective ballasting inductive reactance can be controllable varied between two predetermined values in order to control the performance of the ballasted device and the composite structure also provides voltage transformation.