Exit sign lamp flashing system with self-checking provisions

摘要

An emergency exit sign auxiliary lamp flashing system operates from self-contained rechargeable batteries upon failure of the electrical power from the AC power mains supplying power to the exit sign, including a charging circuit for recharging the batteries, with provisions for preventing overcharging and for disconnecting the load from the batteries before the battery voltage drops to a level which would impair its service life. Included is a solid state circuit which provides for automatically exercising and self-testing the proper functioning of the system to ensure its being serviceable when called upon to function during a power failure by periodically simulating the effect of a failure of AC power and verifying that the battery, lamp and flashing circuit operate normally or signalling a visual and/or audible alarm if they fail to operate properly.