Working Principle Of Old-fashioned Fluorescent Lamps

- Jul 08, 2018-

The filament is quickly heated by electric current, emitting large quantities of electrons. At this time, because the two poles of the starter are closed, the voltage between two poles is zero, the glow discharge disappears, the temperature inside the tube decreases, the bimetallic strip is reset automatically, and the two poles are disconnected. At the moment of the two poles break, the circuit current is cut off suddenly. The ballast produces a great sense of self EMF, the high voltage pulse, the self inductance voltage produced at the starting moment is over 1kV, and the lamp tube is about 130V after starting. In addition to start-up instant, the output voltage of the inductance ballast will not exceed the supply voltage. The power supply voltage is superimposed on the two ends of the tube.

When the filament is heated, a large number of electrons emit at high voltage at both ends of the lamp will move from low potential to high potential at a great speed. During accelerated motion, the argon molecules in the collision tube ionize rapidly. Argon ionize heat, heat causes mercury to generate steam, and mercury vapor is also ionized and emits strong ultraviolet light. Under the excitation of ultraviolet light, the phosphor in the tube wall gives near white visible light.

After the lamp is lit, the conductor is equivalent to a conductor, so that the voltage at both ends of the starter is not enough to glow. The lamp is connected to the ballast in series and connected to the circuit. The ballast continues to play the role of limiting current and the circuit works normally.