Lamp arrangement employing a resonant circuit formed from an autotransformer and a capacitor where the capacitor is switched out of the resonant circuit and into a power factor correcting circuit when the ignition of the lamp is sensed

An improved energy efficient ballast circuit for a commercial fluorescent lighting system using a standard commercial high voltage feed of between 220 and 347 volts for operating a high wattage, high lumen per watt fluorescent lamp, said circuit comprising:

• starter means for preheating said lamp and for providing low energy high voltage ionization pulses, said starter means including a positive temperature coefficient resistor;
• resonant circuit means including an inductance means and a capacitance means for generating an open circuit voltage significantly higher than said high voltage feed wherein said open circuit voltage is sufficient to start-up and stabilize said lamp;
• relay means, responsive to a full current draw by said lamp, to clamp off said starter means and to transfer said capacitance means from said resonant circuit whereby said transferred capacitor means acts as a power factor corrector capacitance during normal lamp operation.