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Study on Tube Light Connection and TwoStudy on Tube Light Connection and Two--wayway

EE 2200 EXP 06

w cw c

Md. HabibullahAssistant Professor

Department of EEE

KUET, Khulna

28 November 2012 1Electrical & Electronic Shop PracticeElectrical & Electronic Shop Practice


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Fluorescent LampsFluorescent Lamps

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What is fluorescence?What is fluorescence?

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Fluorescence is the property of emitting electromagnetic radiation in the

form of light as the result of (and only during) the absorption of light

from another source.

Im ortant characteristics o luorescence:

1. It is the result of the absorption of light.

2. It occurs during absorption only.

3. It involves the emission of light.4. An outside source of energy is required.



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Connection of Tube LightConnection of Tube Light

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AC Supply



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Connection of Tube LightConnection of Tube Light

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HOW IS LIGHT PRODUCEDHOW IS LIGHT PRODUCED

The fluorescent lamp produces light by the passage of an electric

current flowing through a vapor of mercury.

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1.Electron emitted from electrode collides with mercury atom.

2.Impact produces ultraviolet rays

3.Phosphor converts ultraviolet to visible light.

This process is known as fluorescence, hence the name fluorescent

lamp.



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THE ELEMENTS OF A FLUORESCENT LAMPTHE ELEMENTS OF A FLUORESCENT LAMP

A fluorescent lamp contains the following basic elements:

Bulb Electrodes Gases

Base Phosphors Mercury

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THE BULB

Most fluorescent lamps are

made in straight tubular

bulbs in various diameters.

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Circline lamps are in theform of a circle.

U-Bent lamps are

essentially straight lampsbent to form a U shape.



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THE BASE

The base provides the means of holding the lamp firmly in the lamp

holders or sockets and providing the electrical connections for the

lamp/ballast circuit. The basic types are:

Bipin Used on preheat and rapid start lamps.

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PHYSICAL DIMENSIONS

The significant dimensions of fluorescent lamps are:

Bulb diameter

Nominal overall length

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Bulb Diameter Expressed in eighths of an inch.

Diameter = 12 8 = 1 inches



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Nominal Length Unique to fluorescent lamps.

Straight Lamps Measured from the back of one socket or lampholder to

the back of the other socket. Pin to Pin.

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U-Bent Lamps Measured from the back of the socket to top of the lamp.

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Circline Lamps Measured from the outside diameter of the lamp.



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THE ELECTRODES

Coiled tungsten wires coated with an emission

material

When heated, emit electrons

Electrons bombard mercury atoms producing

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.

THE PHOSHPORS

Phosphors are the coated powders on the inside of the bulb that convert the

ultraviolet rays to visible light. There are two basic types:

Halophosphates

Trichromatics or Triband Phosphors



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THE GASES

In the manufacturing process, all the air in a fluorescent is removed, and the

lamp filled with a small amount of gas. The gas affects the lamps startingand operating characteristics.

Argon is most commonly used in the US

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energy saving fluorescent lamps

A blend of Xenon, Krypton and Argon is used in European energy saving

lamps.



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BALLASTSBALLASTS

All fluorescent lamps require a ballast for starting and operation. The ballast

has two basic functions:

Limit the lamps operating current

Provide the required voltage to start the lamp

LIMITING THE CURRENT

When a fluorescent lamp is started, its resistance to the current flow

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decreases dramatically.If not controlled, the current would increase rapidly and destroy the lamp

virtually instantaneously.

The ballast limits the current.



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BALLASTSBALLASTS

STARTING VOLTAGE

Each lamp type has a specific voltage required to start it.

If the supply voltage is not sufficient to start the lamp, the ballast alsocontains a device to provide the required starting voltage.

BALLAST ARE OF TWO BASIC TYPES:

Electromagnetic

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Electronic



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BALLASTSBALLASTS

Electromagnetic Ballasts

The current lighting device is a reactor.

Supply voltage sufficient to start the lamp

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The starting voltage device is an auto transformer.

Supply voltage insufficient to start the lamp

Operate the lamps at 50/60 Hertz



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BALLASTSBALLASTS

Electronic Ballasts

Both starting and current limiting functions are provided by electronic

components.

Operate the lamp at 20kHz or greater.

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Merits of high frequency electronic ballastsMerits of high frequency electronic ballastsover conventional magnetic ballastsover conventional magnetic ballasts

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Energy savings about 30 to 50 %.

Lights instantly. Improved power factor (more than 0.90 power factor).

Less heat dissipation, which reduces the air conditioning load.

.

No stroboscopic effect.

Operates in low voltage.

Less in weight.

Increases the life of lamp.



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StarterStarter

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StepStep--ByBy--Step Starter ActionStep Starter Action

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LAMP TYPES AND THEIRLAMP TYPES AND THEIROPERATING CIRCUITSOPERATING CIRCUITS

PREHEAT LAMPS

Have bi-pin bases

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Utilize a starter circuit that preheats the electrodes before lamp starting Starts within 2 3 seconds



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The Preheating Cycle

Switch Open:

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No current flows through the lamp Supply voltage insufficient to strike the arc



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Switch Closed:

Current flows through each electrode

Ends of lamp glow



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Switch Open:

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Arc strikes Current flows through the lamp

The switch in the starting circuit can be:

A manual switch An automatic starter



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Manual switch

Held down for preheating Released to start the lamp

Used in desk lamps, under-counter fixtures

and other applications

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Automatic starter

Contains a glow switch

Closes and opens automatically



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MAINTENANCE HINTSMAINTENANCE HINTS

The following will service as a guide in recognizing common operating

conditions or problems.

End Discoloration

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MAINTENANCE HINTSMAINTENANCE HINTS

Electromagnetic Interference (EMI)

Electronic ballasts operate at high frequency and generate EMI.

The interference may feed back into the power system and affect operation ofdata processing and communication equipment.

Electronic ballasts must meet standards set by the Federal Communications

Commission (FCC).

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Connection of TwoConnection of Two--way Switchway Switch

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EE 2200 EXP 06

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Electrical & Electronic Shop PracticeElectrical & Electronic Shop Practice

tube light & 2-way switch connez1=3+4j;ction [compatibility mode] - copy - copy - copy

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