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History
Electrical ballast
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An electrical ballast is a device placed in series with a load to limit the amount of current in an electrical circuit.
An American electronic instant start ballast for powering a variety of American T8 fluorescent lamps.
An American electronic instant start ballast for powering a variety of American T8 fluorescent lamps.
Variety of ballasts for fluorescent and other discharge lamps
Variety of ballasts for fluorescent and other discharge lamps
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.
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.
A fluorescent lamp, a device with negative differential resistance. In operation, an increase in current through the fluorescent tube causes a drop in
A fluorescent lamp, a device with negative differential resistance. In operation, an increase in current through the fluorescent tube causes a drop in voltage across it. If the tube were connected directly to the power line, the falling tube voltage would cause more and more current to flow, until it destroyed itself. To prevent this, fluorescent tubes are connected to the power line through a ballast. The ballast adds positive impedance (AC resistance) to the circuit to counteract the negative resistance of the tube, limiting the current.
Fluorescent lamp
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A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow. A fluorescent lamp converts electrical energy into useful light much more efficiently than an incandescent lamp. The typical luminous efficacy of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output. For comparison, the luminous efficiency of an incandescent bulb may only be 16 lumens per watt.
Linear fluorescent lamps illuminating a pedestrian tunnel
Linear fluorescent lamps illuminating a pedestrian tunnel
Top: two non-integrated compact fluorescent lamps. Bottom: two fluorescent tube lamps. Both types require a ballast in the light fixture. A matchstick
Top: two non-integrated compact fluorescent lamps. Bottom: two fluorescent tube lamps. Both types require a ballast in the light fixture. A matchstick, left, is shown for scale.
Typical F71T12 100 W G13 bi-pin lamp used in tanning beds. The (Hg) symbol indicates that this lamp contains mercury. In the US, this symbol is now re
Typical F71T12 100 W G13 bi-pin lamp used in tanning beds. The (Hg) symbol indicates that this lamp contains mercury. In the US, this symbol is now required on all mercury-containing fluorescent lamps.
A "tombstone" style lamp-holder for T12 and T8 G13 bi-pin fluorescent lamps
A "tombstone" style lamp-holder for T12 and T8 G13 bi-pin fluorescent lamps