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Electrical ballast
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Electrical ballast
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 (or a combination of these) wired in series with the lamp; or as complex as the electronic ballasts used in compact fluorescent lamps (CFLs).
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 available to that device.
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.
For simple, low-powered loads such as a neon lamp, a fixed resistor is commonly used. Because the resistance of the ballast resistor is large it determines the current in the circuit, even in the face of negative resistance introduced by the neon lamp.
Ballast was also a component used in early model automobile engines that lowered the supply voltage to the ignition system after the engine had been started. Starting the engine requires a significant amount of electrical current from the battery, resulting in an equally significant voltage drop. To allow the engine to start, the ignition system was designed to operate on this lower voltage. But once the vehicle was started and the starter disengaged, the battery's normal operating voltage was too high for the ignition system. To avoid this problem, a ballast resistor was inserted in series with the ignition system, resulting in two different operating voltages for the starting and ignition systems.
Occasionally, this ballast resistor would fail and the classic symptom of this failure was that the engine ran while being cranked (while the resistor was bypassed) but stalled immediately when cranking ceased (and the resistor was reconnected in the circuit via the ignition switch). Modern electronic ignition systems (those used since the 1980s or late 1970s) do not require a ballast resistor as they are flexible enough to operate on the lower cranking voltage or the normal operating voltage.
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Electrical ballast AI simulator
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Electrical ballast
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 (or a combination of these) wired in series with the lamp; or as complex as the electronic ballasts used in compact fluorescent lamps (CFLs).
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 available to that device.
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.
For simple, low-powered loads such as a neon lamp, a fixed resistor is commonly used. Because the resistance of the ballast resistor is large it determines the current in the circuit, even in the face of negative resistance introduced by the neon lamp.
Ballast was also a component used in early model automobile engines that lowered the supply voltage to the ignition system after the engine had been started. Starting the engine requires a significant amount of electrical current from the battery, resulting in an equally significant voltage drop. To allow the engine to start, the ignition system was designed to operate on this lower voltage. But once the vehicle was started and the starter disengaged, the battery's normal operating voltage was too high for the ignition system. To avoid this problem, a ballast resistor was inserted in series with the ignition system, resulting in two different operating voltages for the starting and ignition systems.
Occasionally, this ballast resistor would fail and the classic symptom of this failure was that the engine ran while being cranked (while the resistor was bypassed) but stalled immediately when cranking ceased (and the resistor was reconnected in the circuit via the ignition switch). Modern electronic ignition systems (those used since the 1980s or late 1970s) do not require a ballast resistor as they are flexible enough to operate on the lower cranking voltage or the normal operating voltage.
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