News Archives

3/2009
End-of-Lamp-Life Compatibility Update

Many Philips Bodine fluorescent emergency ballasts are compatible with end-of-lamp-life (EOL) circuitry in AC ballasts. “ELC” indicates that a Philips Bodine ballast is end-of-lamp-life compatible and is a significant product advantage.

The EOL circuit in an AC ballast detects lamps that are near failure, or near their end-of-lamp-life. EOL circuits typically sense this condition by measuring the DC offset of the lamp voltage wave form that occurs as the lamp electrode decays. When the circuit determines that the lamp is nearing its end, the AC ballast will shut down rather than powering 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.

When AC ballasts with EOL circuitry are paired with non-ELC fluorescent emergency ballasts, unnecessary AC ballast shutdown can occur. This happens because the EOL circuitry can mistakenly interpret a transition from emergency operation to normal operation as an end-of-lamp-life condition. The EOL circuit then instructs the AC ballast to shut down. Normal lighting is not restored until the AC ballast is reset.

The Philips Bodine ELC circuit was developed to eliminate this problem. Our ELC circuit delays AC ballast operation for approximately three seconds upon restoration of AC power. The delay prevents false tripping of AC ballast end-of-lamp-life shutdown circuits. Because AC ballast operation is delayed for a few seconds, the EOL circuit cannot “see” the transition. Therefore, it cannot misinterpret the transition.

Emergency ballasts marked STD, in contrast to ELC, are Philips Bodine standard units. Standard units are not equipped with the ELC circuit. If you have any questions about ELC or STD products, please let us know.

 

 

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