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What is fluorescent lamp?
Rose   utmel.com   2021-10-21 17:37:03

Topics covered in this article:
Ⅰ. What is fluorescent lamp?
Ⅱ. How does fluorescent lamp work?
Ⅲ. What're the characteristics of fluorescent lamp?
Ⅳ. Why fluorescent lamp do not light up
Ⅴ. How do I pick a fluorescent lamp?


Ⅰ. What is fluorescent lamp?

The low-pressure mercury lamp is a conventional fluorescent lamp that employs low-pressure mercury vapor to release ultraviolet photons after being activated, allowing the phosphor to create visible light. As a result, it's a light source with a low-pressure arc discharge.

Philips in the Netherlands was the first to produce a phosphor that could emit red, green, and blue light that was visible to the human eye in 1974. Three primary colors (also known as three primary colors) phosphors were developed and used for the first time in the development of fluorescent lights.

 

Ⅱ. How does fluorescent lamp work?

1. Working principle

The power supply applies a voltage between the two poles of the starter when the switch is closed, causing the neon gas to discharge and generate a glow. The U-shaped movable contact piece, which is attached to the static contact piece, expands and stretches due to the heat generated by the light. The ballast coil and the filament in the lamp tube both conduct electricity. The neon gas in the starter stops discharging after the circuit is connected (due to a low partial pressure in the starter, the glow discharge cannot be performed, and the starter does not work), the U-shaped plate cools and shrinks, the two contact plates separate, and the circuit is automatically disconnected. A extremely strong self-induced electromotive force will be generated when the circuit is abruptly severed due to the quick fall in ballast current. The voltage is applied in the same direction as before. To create an instantaneous high voltage, the two self-induced electromotive forces and the power supply voltage are joined together. The gas in the lamp tube begins to discharge when both ends of the lamp tube are connected, and the fluorescent lamp becomes a current path and begins to emit light. Because the alternating current travels through the coil of the ballast when the fluorescent lamp starts to emit light, self-induced electromotive force is generated in the coil, which always prevents the current from changing. The ballast functions as a step-down and current-limiting function at this time to keep the fluorescent bulb operating normally Work.

Following that, the fluorescent lamp will glow regularly. Because the alternating current runs through the coil of the ballast on a constant basis, self-induced electromotive force is generated in the coil, which prevents the current in the coil from changing. The ballast then functions as a step-down and current-limiting function to keep the current within the lamp's rated current range. Within the rated working voltage range, the voltage across the lamp tube is also stable. The starting connected in parallel at both ends no longer functions since this voltage is lower than the ionization voltage of the starter. When the power is turned on, current is generated, and the heat causes the two contact parts in the starter to pass through owing to thermal expansion and contraction. The phenomena of current self-inductance states that an immediate change in current will result in an instantaneous increase in voltage. The gas in the lamp tube is also turned on, since when it is activated, it will glow, allowing it to light up. Then there's the wait for the contact piece to warm up to the unexpected passing.

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2. Luminescence principle

Within the tube: The tube is coated with phosphor and contains mercury vapor and a small amount of inert gas (argon).

After being activated, the lamp emits light for the following reasons:

Atoms emit visible photons when electrons are energized. If you already understand how atoms work, you're aware that electrons are negatively charged particles that orbit the nucleus. The energy levels of electrons in an atom vary based on a number of factors, including their speed and distance from the nucleus. Electrons with different energy levels occupy different orbital functions and orbits. High-energy electrons are generally found further away from the nucleus. Electrons migrate between the low and high orbits as an atom gains or loses energy. The electron can be briefly driven to a higher orbit when something transfers energy to the atom, such as heat (away from the nucleus). The electron only stays in this orbit for a short time before being retracted back to the nucleus and returning to its normal orbit. The electron emits more energy in the form of photons at this point. The wavelength of light emission is determined by the amount of energy released, which is also determined by the electron's orbital location. As a result, different kinds of atoms emit different kinds of visible photons. In other words, the sort of excited atoms determines the hue of light. This is almost every light source's most basic working mechanism. The mechanism of activating the atoms is the fundamental distinction between these light sources. Atoms are excited in an incandescent light source by heating; atoms are excited in a lamp tube by chemical processes. The sealed glass tube is the heart of a fluorescent lamp. This tube includes a small amount of mercury as well as an inert gas, usually argon, which must be kept at a very low pressure. A layer of fluorescent powder is individually deposited in the glass tube, and the tube also includes fluorescent powder. Each end of the glass tube has an electrode that is connected to the current.

A gas conduction current is created when the lamp's inert gas is ionized under high pressure. During the collision with the mercury atom, the flowing gas ions continuously contribute energy to the mercury atom, allowing the extranuclear electrons of the mercury atom to always travel from the low orbit. Transition to the high orbit, and then, due to their higher energy, the extranuclear electrons of the mercury atom will spontaneously transition from the high orbit to the low orbit (or ground state), releasing energy in the form of photons. At the same time, most of the general lines are concentrated in the UV range due to the atomic properties of the mercury atom. The majority of photons emitted by mercury atoms are in the ultraviolet range, as can be observed. When these high-energy photons (ultraviolet rays) collide with the phosphor, they produce white light.

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Ⅲ. What’s the characteristics of fluorescent lamp?

Advantage: 

★It emits no ultraviolet or infrared radiation, is simple to install and can be directly replaced with regular fluorescent tubes.

Disadvantages: 

★The circuit is complicated and necessitates the use of a beginning circuit (ballast).

★Heavy metals are present (mainly mercury).

★There is a stroboscopic effect.

(It's worth noting that the most prevalent type of energy-saving lamp in our life is a fluorescent lamp.)

 

Ⅳ. Why fluorescent lamp do not light up?

1. Both ends of the fluorescent tube generate light, but the tube does not light up normally: mostly because the temperature is too low, which is usual in the winter; also, the power supply voltage is too low; the tube is severely aging, and the two ends are plainly black.

2. The light turns in the tube after it is lighted, a phenomenon known as the "rolling dragon" that occurs frequently in new tubes or due to inadequate contact.

3. The lamp is unable to produce light due to a lack of contact, damage to the starter, a broken filament, switch replacement, a broken lamp cap, or a broken ballast.

4. The lamp may be bright, but the light flickers, indicating that the lamp's quality is poor.

5. The lamp's brilliance has decreased as it has aged (the two ends of the lamp are black).

6. The lamp's two ends are black, indicating that it is old and has to be changed.

7. Dark spots emerge on both ends of the light: Mercury is condensed in the lamp, and it is typical for it to evaporate and dissipate after it is turned on.

8. There is a loud electromagnetic sound: the ballast is of poor quality, and the silicon steel sheet rattles a lot.

9. Ballast overheating or smoking: insufficient ventilation and heat dissipation, or internal coil short circuit.

10. Pull the switch, and the lamp will quickly turn off after flashing: This could be a wiring problem, and the filament will be burnt out.

 

Ⅴ. How do I pick a fluorescent lamp?

1. First, define the words used in the industry: T4, T5, T8, T10, T11, T12, T13, T14, T15, T16, "The letter T stands for "Tube," which signifies tubular, and the number after it denotes the tube's diameter. T8 denotes the presence of eight "Ts" and one "T." "is 1/8 of an inch After that, each inch equals 25/4 mm. "T" measures 25/48=3/175mm.

2. T12 tube has a diameter of (12/8)25.4=38.1mm. T10 tube has a diameter of (10/8)25.4=31.8mm. T8 tube has a diameter of (8/8)25.4=25.4mm [T8 is a one-inch diameter tube]. LED integration refers to a fluorescent lamp with an LED chip as the light source, and LED lights do not often highlight dead spots.

3. Double tube bracket light with shade: a bracket lamp with two parallel tubes and a lampshade. Shopping malls, office buildings, rooms, warehouses, and industrial workshops are all good places to employ the lamp tube. The illumination is more prevalent, and the smaller diameter is better for assembly line applications. T8 and T10 are often suited for large-area lighting, as are console lighting and specific display cabinet lighting in shopping malls. Please refer to the electrician's suggestions for power and quantity choices. Because there is no dead angle in the light, no particular circumstances, the brightness is high, and there are various applications, the LED integrated bracket is a good choice. Covered double tube bracket Shopping malls, storefronts, and small processing factories all benefit from the use of lamps.

4. Fluorescent lamp on the market now all fall into the same type. Except for branded items, all other pricing are essentially the same. The ordinary light comes with a two-year warranty, while some specific brand items come with a three-year warranty. In most cases, the lamp bracket is made of aluminum. The quality is better, iron is more prone to rust, aluminum lamp holders are less prone to corrosion, long-term use is less likely to fade, and the aesthetic is unaffected. It's worth noting that the shaded double-tube lamp is largely made of iron. Whether the ballast installed inside is up to snuff.


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