UTILIZATION OF ELECTRICAL ENERGY & TRACTION

DIPLOMA IN ELECTRICAL ENGINEERING

3^rd SEMESTER

​

​

​

​

​

​

​

ABINASH PANI

ASST. PROFESSOR

GANDHI INSTITUTE FOR EDUCATION AND TECHNOLOGY, BANIATANGI, BHUBANESWAR

ELECTRICAL ENERGY

• It is flexible
• Easily available
• Can be converted to other forms of energy.
• Can be easily transported to required location
• Economical
• Mature technology
• Saves manual labor in industry and domestic applications

UTILISATION

Electrical energy is used in variousapplications:

1. Electric Drives; DC and ACmotors
2. Electric heating and welding
3. Illumination
4. Electric Traction
5. Electric Vehicles

ELECTRIC HEATING AND

WELDING

OUTLINE

• Introduction.
• Definition.
• Electric Resistance Heating.
• Types of Electric Resistance Heaters.
• Mathematical analysis
• Fanheaters.
• Conclusion.

INTRODUCTION

The energy is converted from shape to other shape

Such as:

• Electrical energy
• Thermal energy

DEFINITION

Electric heating is any process in which electrical energy is converted to heat. Common applications include heating of buildings, cooking, and industrialprocesses.

An electric heater is an electrical appliance that converts electrical energy into heat . The heating element inside every electric heater is simply an electrical resistor, and works on the principle of joule heating: an electric current flowing through a resistor converts electrical energy into heatenergy.

A heat pump uses an electric motor to drive a refrigeration cycle, drawing heat from a source such as ground water or outside air and directing it into the space to be warmed. Such systems can deliver two or three units of heating energy for every unit of purchased energy.

ELECTRIC RESISTANCE HEATING

Electric resistance heating converts nearly 100% of the energy in the electricity to heat. However, most electricity is produced from oil, gas, or coal generators that convert only about 30% of the fuel's energy into electricity. Because of electricity generation and transmission losses, electric heat is often more expensive than heat produced in the home or business using combustion appliances, such as natural gas, propane, and oilfurnaces.

TYPES OF ELECTRIC RESISTANCE HEATERS

• Electric Furnaces
• Electric Baseboard Heaters
• Electric Wall Heaters
• Electric Thermal Storage
• Control Systems

MATHEMATICAL ANALYSIS

According to Joule's Law,the heat power produced by a resistor is:

P=IV

where

Pis the power in watts

I is the current in amperes,and

Vis the potential difference involts,

and according to Ohm's Law I and V are relatedas follows:

V= IR

where

Ris the resistance of the heating element, in ohms.

FANHEATERS

A fan heater is a variety of convection heater that includes an electric fan to speed up the airflow.

This reduces the thermal resistance between the heating element and the surroundings, allowing heat to betransferred more quickly.

CONCLUSION

Although they all use the same physical principle to generate heat, electric heaters differ in the way they deliver that heat to the environment.

SOLID-STATEWELDING PROCESSES

COLDWELDING

• Pressure is applied to the workpieces through diesor rolls

​

• Preferably both workpieces

should be ductile

​

• The work pieces should cleaned thoroughly

Fig: The roll bonding or

cladding process

• Cannot join dissimilarmetals

ULTRASONICWELDING

• Surfaces of the two components are subjected to a static forces andoscillating shearing force

​

• Produces astrong, solid-state bond

• Versatile and reliable

for joiningmetals

Fig: a) Components of an ultrasonic weldingmachine for lap welds.The lateral vibration of the tool tip cause plastic deformation and bonding at the interface of the work piece b)Ultrasonic some welding using a roller c)An ultrasonically welded part

FRICTION WELDING

• Developed in the 1940’s

​

• Parts are circular in shape

​

• Can be used to joina wide variety of materials

Fig: Sequence of operation in the friction welding process 1)Left-hand component is rotated at high speed. 2) Right-hand component is brought into contact under an axial force 3)Axial force is increased;the flash begins to form 4) Left-hand component stops rotating;weld is completed.The flash can subsequently be removed by machining or grinding

FRICTION WELDING

• Process can be fully automated

​

• Can weld solid steel bars up to 250mm in outsidediameter

Fig:Shape of friction zone in friction welding,as a function of the force applied and

the rotational speed

INERTIA FRICTION

• Modification of^WFri^Ectio^LDnW^INel^Gding
• Energy is supplied by a fly wheel
• The parts are pressed together by a normal force
• Asfriction at the interface increases, the fly wheel slows down
• The weld is completed when the flywheel stops

Fig : The principle of the friction stir welding process. Aluminum- alloy plates up to 75mm (3in) thick have been welded by this process

LINEARFRICTION WELDING

• Parts are joined by a linear reciprocatingmotion

​

• Parts do not have to be circular or tubular

​

• In this application, one part is moved across the face ofthe

other part using a balanced reciprocatingmechanism

FRICTION STIRWELDING (FSW)

• New Process for welding aerospacemetals

​

• Research is being directed towards using this process for polymers

​

• FSWuses a 3^rd nonconsumable tool inserted between the two bodies to heat the material to be joined

RESISTANCEWELDING

• Developed in the early1900’s

​

• Aprocess in which the heat required for welding is produced by means of electrical resistance across the two components

​

• RWdoes not requiring thefollowing:
• Consumableelectrodes
• Shieldgases
• Flux

RESISTANCESPOTWELDING

• RSWuses the tips of two opposing solid cylindrical electrodes

​

• Pressure is applied to the lap joint until the current is turned off in order to obtain a strongweld

Fig: (a) Sequence in the resistance

spot welding

RESISTANCESPOTWELDING

• Surfaces should be clean
• Accurate control of and timing of electric current and of pressure are

essential in resistance welding

Fig: b)Cross-section of a spot weld,showing the weld nugget and the indentation of the electrode on the sheet surfaces.This is one of the most commonly used process in sheet-metal fabrication and in automotive- body assembly

RESISTANCESEAMWELDING

• RSEMis modification of spot welding wherein the electrodes are replaced by

rotating wheels or rollers

• The electrically conducting rollers produce a spotweld
• RSEMcan produce a continuous seam & joint that is liquid andgas tight

Fig : (a) Seam-Welding Process in which rotating rolls act as electrode (b) Overlapping spots in a seam weld. (c) Roll spot weld (d) Resistance- welded gasoline tank

RESISTANCEPROJECTIONWELDING

• RPWis developed by introducing high electrical resistance at a joint by embossing one or more projections on the surface to bewelded

​

• Weld nuggets are similar to spotwelding

Fig: a) Resistance projection Welding b)Awelded bracket c) & d) Projection welding of nuts r

RESISTANCEPROJECTIONWELDING

• The electrodes exert pressure to compressthe projections

​

• Nuts and bolts can be welded to sheet andplate by this process

​

• Metal baskets, oven grills, and shopping carts can be made by RPW

FLASHWELDING

• Heat is generated from the arc as the ends as the two memberscontacts
• An axial force is applied at a controlledrate
• Weld is formed in plasticdeformation

Fig : (a)Flash-welding process for end-to –end welding of solid rods or tubular parts

(b) & (c) Typical parts made by flash welding (d)Design Guidelines

STUDWELDING

• Smal part or a threaded rod or hanger serves as aelectrode
• Also cal ed as Stud arc welding
• Prevent oxidation to concentrate theheat generation
• Portable stud-welding is also available

Fig:The sequence of operation in stud welding,which is used for welding bars

threaded rods

an

d

UNIT - II

ELECTRIC HEATING AND WELDING

CONTENT

• Types oflow intensity discharge lamps
• Colour rendering of low intensity discharge lamps
• Operating principles of low intensity discharge lights
• Control equipment associated with low intensity discharge lights
• Efficacy of low intensity discharge lights
• Common faults in fluorescentlights

TYPES

• Fluorescent
• Low Pressure Sodium Vapour
• Induction Lamps

FLUORESCENT

History

• Worked on by Edison & Teslain the1890s
• Daniel Moore worked on Edison’s ideas and developed it further up to a

working system until in 1904 a number were installed inshops and offices

• General Electric bought the patents in 1912
• 1938 saw GEcommercial production of 4 different sizes of lamp

PRINCIPLE OF OPERATION

Aglass cylinder is filled with

Avacuum is created inside the tube

• MercuryVapour
• Argon
• Xenon
• Neon
• Krypton

0.3% of the outside Atmosphere

PRINCIPLE OF OPERATION

An arc is established between the two ends of the tube through the gas

The current is carried by free electrons and +ions

PRINCIPLE OF OPERATION

An arc is established between the two ends of the tube through the gas

The current is carried by free electrons and +ions

FLUORESCENT

Principle Of Operation

When a free electron hits anatom

One ofthe outer electrons in the

atom is forced to a higher level

It is unstable and falls back to its

originalposition

The energy released is in the form ofa

light photon

FLUORESCENT

Principle Of Operation

The wave length can be either

Ultra VioletSpectrum

Invisible to theeye

65%•

10 – 20%•

253.7nm

or

185nm

FLUORESCENT

Principle Of Operation

On the wall of the tube is a mixture of fluorescent

& phosphorescentmaterials

​

​

The UV photons strikes this layer

This shifts the electrons in the coating atomsand

a photon is again generated

Visible light

The wave length is dependant on the coating materialsused

WHAT’STHE DIFFERENCE BETWEEN

Fluorescent & Phosphorescent Materials

​

Fluorescent

Only glows when struck by UVlight

​

Phosphorescent

Glows when struck by UVlight. Aswell as

Glows for a period after the removal of UVlight

HOW DO WE START A FLUORESCENT TUBE

• Gas is heated by elements at each end of the tube

HOW DO WE START A FLUORESCENT TUBE

• Gas is heated by elements at each end of the tube
• High voltage is placed across the tube

HOW DO WE START A FLUORESCENT TUBE

• Gas is heated by elements at each end of the tube
• High voltage is placed across the tube
• Arc is established and current is controled

HEATING ELEMENTS

• Made of Tunsten
• Electrons are emited from this element
• The electrons collide with and ionize the gas atoms in the bulb surrounding the filament to form a plasma
• As a result of avalanche ionization, the conductivity of the ionized gas rapidly rises, allowing higher currents to flow through the lamp

HEATING ELEMENTS

• To aid the emission of electrons the elements are coated

with

• This reduces the thermionic emission temperature

• Barium
• Strontium
• CalciumOxides

How Do We CreateA High Voltage

Mostly comes from a back emf generated by a coil when switched off

HOW DO WECONTROL THE CURRENT?

• Tube exibits a Negative Differential Resistance

​

• If connected directly to the mains would rapidly self distruct

​

• Constant current source to regulate the current flow through the tube usually in the form of an inductor (Ballast)

FLUORESCENT CONTROL CIRCUIT

Glow/Switch Starter

A

N

FLUORESCENT STARTERS

FLUORESCENT STARTERS

How The Work

Glass Envelope filled with Neon Gas

• Power applied to light fitting
• Current passesthrough heating elements
• Current jumps across gas in starter
• Heat of arc bends bimetalstrip

□ Contacts close

FLUORESCENT

• Power applied to light fitting
• Current passesthrough heating elements
• Current jumps across gas in starter
• Heat of arc bends bimetalstrip
• Contacts close
• Bimetal stripcools
• Contacts snap open
• open circuiting supply tofitting

How T^Sh^Te^AWo^Rrk^TERS

Glass Envelope filled with

NeonGas

ELECTRONIC STARTERS

BALLAST

• Provides the high voltage kick in a switch start system
• Limits current when tube running
• Consumes (Wastes) 12% and 15% of input
• Being replaced with electronic ballasts
• With the addition of a filament transformer can be dimmed

ELECTRONIC BALLASTS

• More efficient 5% and 8%
• Operates the lamp at higher frequencies (20-40kHz)
• Less lamp flicker
• Faster start as a HV spike happens more often
• Can have the option to dim the lamp as low as 10%

OTHER FLUORESCENT TUBES

□ Previous example is of a hot Cathode tube

□ Thermionic emission Lamps

□ Preheat Starting System

OTHER FLUORESCENT TUBES

Cold Cathode

Electrons are liberated only by the level ofpotential difference provided

i.e. operate at a very high voltage

​

• Cathodes are operated below their thermionic emission

temperature

• Have no thermionic emission coating to wear out,
• Have much longer lives than is commonly available with thermionic emissiontubes.
• General y less efficient than thermionic emission lamps
• Canbe instantly switchedon/off.

OTHER FLUORESCENT TUBES

Rapid Start

Special Bal ast Required

​

• Bal ast provides filament power windings within theballast
• Rapidly and continuously warm the filaments/cathodes using low-voltage AC
• No inductive voltage spike is produced for starting
• Lamps must be mounted near a grounded (earthed) reflector to allow the glow discharge to propagate through the tube and initiate the arc discharge
• May have "starting aid" strip of grounded metal is attached to the outside

of the lampglass.

COLOUR SPECTRUM OF A TYPICAL FLUORESCENT

TUBE

Combination of light directly emittedby:

• Mercury vapor
• Phosphorescent coating

Colour Spectrum Of A TypicalFluorescent Tube

COLOUR RENDERING OF FLUORESCENTS

The ability of the applied light to make the object appear as if it was viewed in normal sunlight

COLOUR RENDERING OF FLUORESCENTS

Daylight and, an incandescent lamp CRI = 100%

• Fluorescent lamps CRIRange from 50% to 99%.
• Low CRIhave phosphors which lack red light
• Skin appears less pink, and hence "unhealthy" comparedwith incandescent lighting.
• For example, a tube with a CRI= 50%, 6800 Kwill makereds

appear brown.

• 1990s, higher quality fluorescent lamps use a triphosphor

mixture, based on europium and terbium ions

• Have higher CRIsof typicaly 82 to 100%
• more natural color reproduction to the human eye

LUMINOUS EFFICACY

• Fluorescent lamps convert more of the input power to visible light

than incandescent lamps.

• 100 W incandescent lamp may convert only 2% of its power input to

visible white light

• fluorescent lamps convert about 22% of the power input to visible

white light

• 50 to 67 lm/W
• Electronic ballast gives about 10% efficacy improvement over an

inductive ballast

• Fluorescent lamp efficacy is dependent on lamp temperature
• The ideal temperature for a T8 lamp is 25 °C
• T5 lamp = 35 °C

LOW PRESSURE SODIUM VAPOUR

• Low pressure sodium (LPS)
• Sodium Oxide (SOX)

LOW PRESSURE SODIUM VAPOUR

Cathode Same as A fluorescent (made from coatedtungsten

Outer envelope coated with an infrared

reflecting layer of indium tinoxide

LOW PRESSURE SODIUM VAPOUR

Sodium only vaporises when pressure and temperaturebuilds

​

​

Discharge Tube

LOW PRESSURE SODIUM VAPOUR

DischargeTube

Standard LampGlass (SodaLime)

Borate Glass Inner sleeve

(0.02mm)

LOW PRESSURE SODIUM VAPOUR

Standard LampGlass (SodaLime)

​

​

Borate Glass Inner sleeve

(0.02mm)

• At operating temperature the Sodium reacts with ordinary glass tuning it brown
• Stained and unstained areas have different operating temperatures
• The differences in temperatures will cause ordinary glass to crack

Borateglass

• Does not react as much and has with the sodium
• Hasa very low rate of thermalexpansion
• “Short Glass” short working temperaturerange
• Used to line standard glass (then easer to work with)

LOW PRESSURE SODIUM VAPOUR

Sodium only vaporiseswhen pressure and temperature builds

​

Discharge Tube

LOW PRESSURE SODIUM VAPOUR

(monochromatic).

Monochromatic

LOW PRESSURE SODIUM VAPOUR

(monochromatic).

LOW PRESSURE SODIUM VAPOUR

• Strike voltages as high as 23kV are required to restart ahot

lamp

• Once an arc has been struck the ionised gas becomesa conductor with a resistance often lower than 100 Ω.
• The voltage across the lamp must be reduced to around 100V
• Up to 80% efficient in turning light intoelectricity
• Physical y big bulbs

LOW PRESSURE SODIUM VAPOUR

• Striking voltage is not sensitive to temperature
• Lamp will restrike as soon as thepower is restored and no cooling down time is required
• The burning position is general y confined to thehorizontal position ±20°
• No colour rendering is possible every colour to eitheryellow

or muddybrown

LOW PRESSURE SODIUM VAPOUR

Ra

Incandescent Lamp 100

Florescent Lamps

Colour 33 65

Colour 54 72

Colour 83 86

Colour 93 93

-44

Low Pressure Sodium

High Pressure Sodium 26

High Pressure Mercury 45

Metal Halide 70

LOW PRESSURE SODIUM VAPOUR

• Rated life is shorter than other types of discharge lamps
• SOX18 – 14,000 hours
• Other Discharge lamps – 18,000 hours
• 100 to 200lm/W
• Wires or conductive coatings around the arc tube canassist with starting

LOW PRESSURE SODIUM VAPOUR

N

Control Equipment

Limit current whenoperating

​

A

I

gnitor

Provides high voltageto

start lamp

UNIT-IV ELECTRIC TRACTION-I

INTRODUCTION:

• The locomotion in which the driving force is obtained from electric motor is called the electric traction system.
• There are various system of electric traction existing such as electric train, trolley buses, diesel-electric vehicles and gas turbine electric vehicles

ELECTRIC TRACTION SYSTEM

MAJOR CLASSIFICATIONS OF TRACTION

• Non-electric traction:

examples

steam engine drive ic engine drive

• Electric traction:

examples

diesel electricdrive

gas turbine electricdrive

REQUIREMENTS OF AN IDEAL

TRACTION SYSTEM

• The starting tractive effort should be high so as to haverapid acceleration.
• The wear on the track should be minimum.
• The equipments should be capable of withstanding large

temporary loads.

• Speed control should beeasy.
• Pollutionfree.
• Low initial and maintenancecost.
• The locomotive should be self contain and able to run onany route.

MERITS OF ELECTRIC TRACTION

• High starting torque.
• Lessmaintenance cost
• Cheapest method of traction
• Rapid acceleration and braking
• Lessvibration
• Free from smoke and flue gases henceused for underground and tubular railway.

DEMERITS OF ELECTRIC TRACTION

• High capital cost.
• Problem of supply failure.
• The electrically operated vehicles haveto move on guided track only.
• Additional equipment is required for achieving electric braking and control.

DIFFERENT SYSTEMS OF TRACTION:

• Direct steam engine drive
• Direct ICengine drive
• Steam electric drive
• ICengine electric drive
• Petrol electric traction
• Battery electric drive
• Electric drive

IC ENGINE ELECTRIC DRIVES

SUPPLY SYSTEMS FORELECTRIC TRACTION:

• D.Csystem
• A.Csystem
• Single phase
• Three phase
• Composite system
• Single phase ACto DC
• Single phase to three phase

SPEED TIME CURVE FORTRAIN MOVEMENT

• Acceleration
• Constant acceleration
• Speed curve running
• Free run or constant speedperiod
• Coasting period
• Retardation or braking period

TYPICAL SPEEDTIME CURVES FOR

DIFFERENT SERVICES

• Urban or city services
• Sub urban services
• Main line services

​

TYPESOFSPEEDIN TRACTION

• crest speed
• Average speed
• Schedule speed

FACTORS AFFECTING ENERGY CONSUMPTION

• Distance between the stops.
• Train resistance
• Acceleration and retardation.
• Gradient
• train equipment.

TRACTION MOTORS

• DCseries motor
• Ac series motor
• Three phase induction motor

TRACTION MOTOR ELECTRICAL FEATURES

• High startingtorque
• Simple speedcontrol
• Regenerativebraking
• Bettercommutation
• Capability of withstanding voltagefluctuations.

MECHANICAL FEATURES

• Light in weight.
• Smal spacerequirement.
• Robust and should be able to withstandvibration.

UNIT-V ELECTRIC TRACTION-II

MICRO PROCESSOR CONTROL

TRACTION MOTOR CONTROL

• Rheostat control
• Series parallel control
• Field control
• Buck and boost method
• Metadyne control
• Thyristor control
• Phasecontrol
• Chopper control

BRAKING

ELECTRICBRAKING

• Plugging or reverse currentbraking
• Rheostaticbraking
• Regenerativebraking
• DC shuntmotor
• DC seriesmotor
• Inductionmotor

​

MECHANICALBRAKING

• Compressed air brakes
• Vacuumbrakes

RECENT TRENDS IN ELECTRICTRACTION

• Tapchanger control
• Thyristor control
• Chopper control
• Micro processorcontrol