Ballast system to trigger high voltage for Xenon lights
Xenon light sources (HID) require high voltage to be triggered. HID headlamp bulbs cannot operate on a low-voltage direct current, so they require a ballast system with an ignitor. The ignitor may be either internal or external to the lamp.The ignitor is integrated into the bulb in D1 and D3 systems, and is a separate unit or part of the ballastin D2 and D4 systems. The ballast controls the ignition voltage and current to the bulb.
Depending on the Xenon generation, fitting rules may differ slightly, but the principle remains that basic measures must be taken prior to manipulating and servicing the Xenon system. Twenty thousand volts (20kV) are emitted by the ballast and the ignitor during the Xenon lamp startup, so it is essential to secure the system power-off for a lighting maintenance procedure.
Some vehicles equipped with comfort functions may switch the lighting system according to key-entry or door-opening events, but the variety of vehicles on the market leads to the conclusion that only a disconnected battery can totally secure operators from a 20kV discharge.
Xenon lamps are high-voltage and high-current controlled, with a 200Hz frequency in steady state mode. These signals are potential sources for car electronic disturbances. To comply with automotive Electro Magnetic Compatibility (EMC), the whole system is shielded from the ballast unit to the lamp connector.