page_title: Electrical ballast
section_title: Current limiting
hierarchical_section_title: Electrical ballast / Current limiting
caption_attribution_description: English: S12 starter used with choke style ballasts in many tanning beds. Русский: Стартер S12, используемый в соляриях
context_page_description: An electrical ballast is a device placed in series with a load to limit the amount of current in an electrical circuit.
  A familiar and widely used example is the inductive ballast used in fluorescent lamps to limit the current through the tube, which would otherwise rise to a destructive level due to the negative differential resistance of the tube's voltage-current characteristic.
  Ballasts vary greatly in complexity. They may be as simple as a resistor, inductor, or capacitor wired in series with the lamp; or as complex as the electronic ballasts used in compact fluorescent lamps and high-intensity discharge lamps.
context_section_description: An electrical ballast is a device that limits the current through an electrical load. These are most often used when a load (such as an arc discharge) has its terminal voltage decline when current through the load increases.  If such a device were connected to a constant-voltage power supply, it would draw an increasing amount of current until it is destroyed or causes the power supply to fail. To prevent this, a ballast provides a positive resistance or reactance that limits the current. The ballast provides for the proper operation of the negative-resistance device by limiting current.
  Ballasts can also be used simply to limit the current in an ordinary, positive-resistance circuit. Prior to the advent of solid-state ignition, automobile ignition systems commonly included a ballast resistor to regulate the voltage applied to the ignition system.
  Series resistors are used as ballasts to control the current through LEDs.
caption: A lamp starter, required with some inductor type ballasts.  It connects the two ends of the lamp to preheat them for one second before lighting.
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