We use tube light in house hold application and offices. The
tube shape fluorescent lamp is term as tube light. It works on the principle of
low pressure mercury vapor discharge phenomenon and converts UV-rays into
visible rays using phosphorous.
Normally we use 35 to 50 watts tube lights in our day to day
life. We can categories choke in the tube light based on the mechanism
·
Classic
Electromagnetic choke
·
Modern
Electronic choke
Let we see how the tube light operates on Electromagnetic
choke and what are the inner parts help to glow the tube light.
WHAT IS INSIDE THE TUBE LIGHT??
·
The glass discharge tube filled with noble gases
(Argon & krypton), little drop mercury and it contains filament on either
side. Both filaments have electrode (anode & cathode) shield.
MECHANISM OF TUBE LIGHT:
· At first mercury inside tube is vaporized by the
filaments, and then the mercury vapor ionized the gases in the tube.
- Electron flows into the ionization path between two electrodes, which produce UV-rays.·
- UV- rays converts into visible rays through phosphorous coating inside the tube(color of tube light depends upon the color of phosphorous coating).
OPERATION OF TUBELIGHT:
Tube light is connected with starter, choke and 230V
AC is supplied. We will see the operation of tube light circuit in step by
step
There are some advantages to use electronic ballast instead of electromagnetic ballast.
I Hope this article is help you to understand about working of tube light .Is there any doubt . ur comments are welcomed
- Flow of electron through choke[Choke is a real inductor],filament F1 and goes to the Bimetallic strip inside the starter.
- Bimetallic strip get heated, expanded and create closed path in the circuit.
- Filament vaporized the mercury and then ionizes the gas into the discharge tube.
- Initially inductor produces the voltage drop, so the bimetallic strip opened.
- Inductor produces the kick back voltage. But the voltage not enough to glow the light(Because the tube light initially required high voltage to glow)·
- Once again bimetallic strip closed with the help
of capacitor and the inductor charged. Then starter inactive, inductor release the peak
Kick back voltage. After that normal voltage is enough to glow the tube light
continuously.
Working of electronic ballast
Electronic ballast convert normal frequency to a very high frequency to initialize the gas ionization process in discharge tube by controlling voltage across the lamp and current through lamp.
- Electronic ballest energizes at 50 to 60Hz. It first filter the electromagnetic interference in AC supply.After that AC voltage is convert into DC voltage using rectifier
- Power facter is corrected as per required. Now the DC voltage is fed to the high frequency oscillation stage where oscillation is typically square wave and frequency range are from 20 kHz to 80 kHz
- Hence output current is with very high frequency.Generally more than 400v is required to strike the gas discharge process in tube light.
- When the switch is ON, the initial voltage across the becomes 1000V around due to high valued,hence gas discharge takes place inatantaneously.
- Once the discharge process is started, voltage across the lamp is decreased below 230V up to 125V and then electronic ballast allows limited current to flow through this lamp.
- EMI filter : Filter the electromagnetic Interference
- PFC : Power factor correction of DC voltage
- Half-Bridge Resonant Output: Converts Dc to square waved voltage with high frequency 20 to 80 kHz .
- Control unit : Control the voltage and current through the lamp.
- It operates in low supply voltage.It produces high frequency output voltage for gas discharge process.
- It does not require any starter that is used in electromagnetic ballast.
- it never creates flickering and minimal weight.
- Increase the life span of lamp.
- It does not create any RF interference.
No comments:
Post a Comment