What is ELC?

EOL circuits detect lamps that are near failure, or near end-of-lamp-life. They typically sense this condition by measuring the DC offset of the lamp voltage wave form that occurs as the lamp electrode decays. When an EOL circuit determines the lamp is nearing its end, the circuit will instruct the ballast to shut down rather than power the lamp. This action is designed to prevent the lamp from overheating. Most EOL detection circuits also trip when a lamp is removed or missing.

The pairing of a fluorescent emergency ballast with an AC ballast that utilizes EOL technology can be problematic. In this case, the EOL circuit may not function as intended. Instead, the EOL circuit in the AC ballast may interpret the transition from emergency operation to normal operation as an end-of-lamp-life condition.

Bodine’s patented ELC circuit prevents unnecessary shutdown. The ELC circuit delays AC ballast operation for approximately three seconds. Because AC ballast operation is delayed for a few seconds, the EOL circuit in the AC ballast cannot “see” the transition and, therefore, cannot misinterpret it.