What is the role of the ballast?

Ballast is a gas discharge lamp is essential to supporting the work of the annex, its function:
1, produce high-pressure, from the lamp
2, starting after the ballast from the ballast (current limiting) role, so that the lamp to normal and stable work.
The gas discharge lamp has a high starting voltage and a low discharge sustaining voltage. When the lamp through the high-voltage start, the voltage drop, the current increases, such as without restrictions, the lamp current will continue to increase until the lamp burned, so the discharge lamp lighting circuit in series with a lamp type, The ballast provides a high starting voltage for starting the lamp and limits the lamp current to stabilize within the specified range.
The process of the workpiece is: after the lamp is turned on, the ballast, the lamp tube and the light starters (connected in series in the lamp filament circuit) are connected in series, the neon bulb in the starter is lighted, Bending, neon bulb is short-circuit; power - ballast - filament circuit composed of the current reaches the maximum. While the neon bulb is short-circuit, the bimetal cooling reset off, so that current interruption. As the back EMF generated in the inductor and power superimposed on the lamp at both ends, the high voltage to light the gas breakdown light, lit the lamp current at both ends of the surge, the voltage drop. At this time by series inductance in the circuit to limit the current, so named "ballast."