Bulb ignition

During the ignition procedure, the ballast produces an AC voltage, running voltage, from ballast pin 4 to ignition pin 2 and ballast pin 5 to ignition pin 1. The task of the ignition impulse is to start discharge in the bulb (an ignition impulse is usually needed). Running voltage then takes over.

The ballast measures the current in the running voltage circuit. If it rises after the ignition impulse, the ballast knows that the bulb has been lit and switches off the charge voltage. If current does not rise after an ignition impulse, the ignition attempt is repeated until the bulb lights. The number of ignition attempts is limited to 15 for a period of 0.2 s. If the bulb does not light during these attempts, the ballast stops the ignition attempts and the bulb remains off.