Patent ID: 8664878

Claim:
An arc detection circuit to detect an occurrence of arcing between a ballast and a lamp, the arc detection circuit comprising: a transformer having a primary side and a secondary side, wherein the primary side is configured for connecting between the ballast and the lamp to receive lamp current and conduct the lamp current from the ballast to the lamp during normal operation, wherein the secondary side of the transformer produces a transformer voltage as a function of the lamp current received by the primary side, and wherein the produced transformer voltage is less than a threshold value during normal operation and is greater than the threshold value during an occurrence of arcing between the ballast and the lamp; a first Zener diode and a second Zener diode connected together in series to the secondary side of the transformer, each of the first Zener diode and the second Zener diode having an anode and a cathode, the anode of the first Zener diode connected to the cathode of the second Zener diode, the cathode of the first Zener diode connected to the secondary side of the transformer to receive the produced transformer voltage, the anode of the second Zener diode connected to ground potential, wherein the first Zener diode has a first reverse breakdown voltage that corresponds to the threshold value so that the produced transformer voltage is provided to the second Zener diode during an occurrence of arcing and the produced transformer voltage is blocked from the second Zener diode during normal operation, wherein the second Zener diode has a second reverse breakdown voltage to reduce the produced transformer voltage provided thereto; and an output terminal connected to the second Zener diode to provide the reduced produced transformer voltage to the ballast to indicate that an occurrence of arcing is detected.