Abstract: A supplemental arc maintenance electrical supply for a high density discharge (HID) lamp (L) for applying a high frequency supplemental arc voltage to maintain the arc during a period of unstable or intermittent AC supply in addition to or in lieu of the voltage or current being supplied to the lamp by the HID ballast (12). AC supply instability is identified in less time than the unstable or intermittent power will cause the lamp to arc to extingish and energize a supplemental arc maintenance electrical supply to maintain the arc of the lamp during the period of instability or interruption, so long as its internal, rechargeable battery is operational. The monitoring system (18) also recognizes the re-establishment of a stable (as by being a persistently repeating cycle but not necessarily a sinusoidal AC supply) repeating electrical power supply which is also of sufficient energy level to maintain operation of the HID lamp.

Abstract: A standby ballast for a fluorescent lamp in a lighting circuit powered normally by a main AC power supply, and in the event of main power supply failure, powered by an auxiliary standby generator, the standby ballast operable to provide AC power to the lamp for the interim between failure of main AC power supply and the supply of stabilized auxiliary AC power from the standby generator as it has started and reached normal operating condition.

Abstract: A method and circuit for operating two fluorescent lamps having a starter with power supplied by a battery by generating an alternating current from energy supplied by the battery, supplying the alternating current as a starting current to the lamps for a selected period of time, and at the end of the selected period of time, generating a direct current from the alternating current and supplying the direct current to the lamps in place of the alternating current.