Systems and ballast apparatus for operating fluorescent lamps at preselected levels of illumination

Claim 1

A BALLAST APPARATUS FOR USE IN CONJUNCTION WITH A SWITCHING MEANS FOR OPERATING A FLUORESCENT LAMP AT DIFFERENT PREDETERMINED LEVELS OF ILLUMINATION, SAID BALLAST APPARATUS COMPRISING A HOUSING, A HIGH REACTANCE TRANSFORMER CONNECTED IN SAID HOUSING AND INCLUDING A PRIMARY WINDING AND A SECONDARY WINDING INDUCTIVELY COUPLED ON A MAGNETIC CORE, AND MEANS FOR APPLYING THE OUTPUT OF SAID TRANSFORMER TO THE FLUORESCENT LAMP FOR OPERATING THE LAMP AT SAID PREDETERMINED LEVELS OF ILLUMINATION, SAID MEANS INCLUDING OUTPUT LEADS EXTENDING OUT OF SAID HOUSING FOR CONNECTION TO THE LAMP, A PLURALITY OF CAPACITANCE ELEMENTS POSITIONED IN SAID HOUSING, AND CONNECTIONS FOR PLACING SAID CAPACITANCE ELEMENTS IN SERIES CIRCUIT RELATIONSHIP WITH SAID SECONDARY WINDING ACROSS SAID OUTPUT LEADS, SAID CONNECTIONS INCLUDING AT LEAST ONE LEAD CONNECTION TO AT LEAST ONE OF SAID IMPEDANCE ELEMENTS AND EXTENDING EXTERNALLY OF SAID HOUSING FOR PLACING SAID SWITCHING MEANS IN SERIES CIRCUIT RELATIONSHIP WITH SAID AT LEAST ONE OF SAID CAPACITANCE ELEMENTS WHEREBY SAID ONE CAPACITANCE ELEMENT AND SAID SECONDARY WINDING ACROSS SAID OUTPUT LEADS MAY BE SELECTIVELY PLACED IN THE CIRCUIT WITH SAID SECONDARY WINDING ACROSS SAID OUTPUT LEADS TO VARY THE ENERGY APPLIED TO SAID LAMP AND CONTROL THE DEGREE OF ILLUMINATION THEREOF.