Electric lamp and discharge devices: systems – Condenser in the supply circuit – Inductance in the condenser circuit
Patent
1984-01-16
1986-08-26
Chatmon, Saxfield
Electric lamp and discharge devices: systems
Condenser in the supply circuit
Inductance in the condenser circuit
315242, 315243, 315DIG7, H05B 3700, H05B 3900, H05B 4114
Patent
active
046085238
ABSTRACT:
In a series-resonant ballast, the voltage from an AC power source is applied directly across a ballast circuit consisting of a series-combination of an inductor and a capacitor--with a gas discharge lamp connected in parallel with the capacitor. Before the lamp ignites, the series-combination is substantially resonant at the frequency of the AC source; and, by way of resonant Q-multiplication, the voltage developed across the capacitor is of much higher magnitude than that of the voltage provided directly from the power source. This Q-multiplied voltage is effective in causing lamp ignition. Once the lamp has ignited, however, the circuit is no longer resonant. Rather, due to the loading provided by the ionized lamp, the circuit has now become inductive at the frequency of the AC source; which implies that the power provided to the lamp from the source is not provided at an optimum power factor. To compensate for the de-tuning caused by lamp loading, subject invention provides for phase-correction means that automatically takes effect upon lamp ignition, and which is effective in keeping the ballast circuit operating at or near reasonance even after lamp ignition. In the preferred embodiment, this phase-correction means consists of an auxiliary inductor connected in series with the lamp. Before lamp ignition, this auxiliary inductor has negligible effect on the circuit; but after ignition, it acts to cancel the otherwise net inductive reactance of the circuit, thereby keeping it substantially in resonance.
REFERENCES:
patent: 2333499 (1943-11-01), Warren
patent: 2417742 (1947-03-01), Dosio
patent: 2695375 (1954-11-01), Mendenhall et al.
patent: 3555352 (1971-01-01), Michalski
patent: 3586817 (1971-06-01), Manz
patent: 4358712 (1982-11-01), Filgas, Jr. et al.
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