TYPES OF LAMPS

Suhail TP MES Collage of Engineering

Light sources

• Incandescent lamp• Discharge lamp– Florescent lamp– Sodium lamp– High pressure mercury vapour lamp

OLD TYPES OF KEROSEN LAMPS

INCANDESCENT LAMP

• HOT WIRE – FILAMENT SEALED IN A GLASS JAR (BULB)

• ELECTRIC CURRENT PASS THROUGH THE WIRE HEATS IT TO INCADESCENCE, AND THE WIRE EMITS LIGHT. USE STANDARD VOLTAGE CIRCUIT.

• Inside gas is argon with nitrogen.

• At the center of the lamp is a tungsten filament.

• Electricity heats this filament up to about 2,500 degrees Celsius.

• Light output is 15 lumens/watt• Operating life 1000 hour• Efficency increased by using– Coiled filament– Coiled coil filament

Parts

1. GLASS BULB

2. VACUUM OR GAS FILLED

3. WIRE/FILAMENT

4. 5. LEAD-IN WIRES

6. SUPPORT WIRES

7. NECK

8. 11. ELECTRIC FUSE

9. BASE

Pros and Cons

ADVANTAGES:

1. LESS EXPENSIVE

2. EASIER TO DIM WITH RHEOSTATS

3. WARMER COLOR THAN FLUORESCENT AND THUNGSTEN-HALOGEN LAMPS

4. LIGHT OUTPUT IS RELATIVELY HIGH

5. CAN BE DIMMED

DISADVANTAGES:

1. ENERGY INEFFICIENT

2. SHORT LAMP LIFE TIME

3. WARM SOURCE

Discharge lamps

• Light is produced by passage of an electric current through a vapor or gas, rather than through a tungsten wire as in incandescent lamp.

FLUORESCENT LAMP

FLUORESCENT LAMP

• Inside bulb is coated with florescent powder• Oxide coated tungsten filament is used as

electrodes• Light output is 70 lumen/watt• Average life is 7500 hours

• ADVANTAGES:

•Heat is relatively low

•Energy efficient

•Range from low grade to high grade

•Long lamp life

•Usually Cool source

• DISADVANTAGE:

•Color temperature

•Require ballast: preheat, instant-start, rapid-start

•Requires controlling elements for glare control

Sodium Lamp

• gas-discharge lamp that uses sodium in an excited state to produce light

• Efficency is 75 lumens/watt• Average life 60000 hours

Cont..

• Discharge will not start at low voltage

• Leak transformer produce starting voltage of about 400V

• First neon gas will discharge after sodium vaporises and discharge continues

• Pf is too low(0.3) to correct capacitor is used

High pressure mercury vapour lamp

• Inner gas used is Argon and mercury

• Efficiency 40 lumen/watt• Inner tube have two main

electrodes and an auxiliary electrode

Artificial Light Sources• Incandescent Lamps• Fluorescent Lamps• High – Intensity Discharge Lamps• Mercury Lamps• Metal Halide Lamps• High Pressure Sodium Lamps• Low Pressure Sodium Lamps• Electrodeless Lamps• Compact arc xenon &Mercury Lamps• Electroluminescent Lamps• Light Emitting Diodes (LED)• Carbon arc Lamps• Gaslights

Lamp efficiency & efficacy

• Efficacy for a light source is how well it turns input power into the desired output, which is lumens

• Efficiency is the actual percentage of power in which comes out as photons.