Resetting an electronic ballast in the event of fault

An emergency lighting system for driving a lamp, said system comprising:

• a primary ballast for driving a lamp comprising:
• a rectifier connected to a primary power source, the rectifier configured to receive electricity from the power source and to generate a DC bus voltage upon receiving electricity;
• a driver circuit configured to receive the DC bus voltage from the rectifier and to generate a lamp voltage to drive the lamp upon receiving the DC bus voltage;
• a controller configured to control the driver circuit, said controller to monitor a first value corresponding to the DC bus voltage and to monitor a second value corresponding to the lamp voltage, wherein when the controller detects a fault condition, the controller disables the driver circuit for a preset period of time and thereafter resets to control the driver circuit to drive the lamp, and wherein when a ratio of the second value to the first value falls below a threshold value, the controller resets to control the driver circuit to drive the lamp;
• and
• a current reduction circuit configured to accelerate the resetting of the controller in the event of a power toggle, wherein the current reduction circuit reduces the second value supplied to the controller in a period of time that is less than the preset period of time, such that the ratio of the reduced second value to the first value falls below the threshold value, causing the controller to reset;
• and
• a backup ballast configured to selectively drive the lamp from a backup power source when the primary power source is de-energized, said backup ballast including a relay configured to selectively connect the primary power source to the rectifier of the primary ballast when the primary power source is energized, to selectively connect the backup ballast to the lamp when the primary power source is de-energized and to selectively disconnect the lamp from the driver circuit when the primary power source is de-energized;
• wherein when the primary power source is energized, the lamp is driven by the primary ballast and the backup ballast relay selectively connects the driver circuit and the lamp;
• wherein when the primary power source is de-energized, the lamp is driven by the backup ballast and the backup ballast relay selectively disconnects the driver circuit and the lamp, so that the controller detects a fault condition due to the disconnect of the driver circuit and the lamp;
• and
• wherein when the power source is re-energized, the controller resets and the lamp is driven by the primary ballast and the backup ballast relay selectively connects the driver circuit and the lamp.