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ELECTRCIAL ENGG. DEPT.


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"DESIGNING AND TESTINGOF ALTERNATOR"


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Prepared By:RANA NISHANT H. (106540309042)

PATEL RAJAT M. (106540309016)

SAIYAD SAJIDSHAH K. .(106540309025)

PANCHAL VIJAY S. .(106540309051)

RATHOD SIDDHARAJ D. .(106540309032)

Guided By: Industrial Guided:

MR. KARTIK K. PATEL MR. M.C.PATEL

(LECT.-EE DEPT.) (OWNER-MAHAKALI MOTORS)


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Aim

Objective

Introduction

Principle Types Of Alternator

Theory Design Of Alternator

Design Steps Of Rotor, Stator, Main Damnation, Efficiency

Testing Of Alternator (Only Introduction) Out Comes Of 5th Sem Project

Bibliography


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To Get Brief Knowledge Of Alternator &Study Its Design, Testing Before Operation


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To Get Brief Knowledge About An Alternator.

Theory Design Steps Of Alternator. (5TH SEM)

To Know About All Factors affecting on Design.

Testing Of Alternator.


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What is alternator?

An alternator is an electromechanical device thatconverts mechanical energy to electrical energy in the

form ofalternating current Most alternators use a rotating magnetic field with a

stationary armature but occasionally, a rotatingarmature is used with a stationary magnetic field; or

a linear alternator is used. The early machines were developed by pioneers such

as Michael Faradayand Hippolyte Pixii.
http://en.wikipedia.org/wiki/Generator_(device)http://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Armature_(electrical_engineering)http://en.wikipedia.org/wiki/Linear_alternatorhttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Hippolyte_Pixiihttp://en.wikipedia.org/wiki/Hippolyte_Pixiihttp://en.wikipedia.org/wiki/Hippolyte_Pixiihttp://en.wikipedia.org/wiki/Hippolyte_Pixiihttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Linear_alternatorhttp://en.wikipedia.org/wiki/Linear_alternatorhttp://en.wikipedia.org/wiki/Linear_alternatorhttp://en.wikipedia.org/wiki/Armature_(electrical_engineering)http://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Generator_(device)http://en.wikipedia.org/wiki/Generator_(device)http://en.wikipedia.org/wiki/Generator_(device)


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Faradays Law:-The induced emf in a wire loop is proportional to

the rate of change of magnetic flux through

the loop.


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There are following types of Alternator:1. Hydro alternator (rating up to 750 MW)2. Turbo alternator (rating up to 1000 MW)3. Engine driven alternator (rating up to 20 MW)

There are following types of Prime Movers:1. steam turbines2. Hydraulic turbines3. Diesel engines4. Gas5. Nuclear6. Wind


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Here we are present the theory steps of alternator andalso factor affecting on alternator.

Basic Introduction about testing of alternator.


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Synchronous machines are designed to obtain thefollowing information.

(i) Main dimensions of the stator frame.

(ii) Complete details of the stator windings.(iii) Design details of the rotor and rotor winding.

(iv) Performance details of the machine.


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(i) Specifications of the synchronous machine.

(ii) Information regarding the choice of designparameters.

(iii) Knowledge on the availability of the materials.

(iv) Limiting values of performance parameters.

(v) Details of Design equations.


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Stator Stator winding

Rotor

Rotor winging

Poles

Damper winding

Bearings

Brakes and jacks Slip rings

Outer body


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1. Cost

2. Durability

3. Compliance


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Then we cant calculate is all parts dimension

Then we cant assemble its all parts.

Then alternator not work properly

Then we cant calculate all electrical parameters likes

voltage, current, frequency etc.

Then we cant calculate efficiency.


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Step 1 Rating of alternator1. Full load kVA Q

2. Full load power, kW P

3. Line voltage Vlv4. Phase voltage Vph

5. Power factor cos

6. Frequency f

7. Speed ns

8. Number of Poles p


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KVA output Q =(1.11 B avac Kw *10-3)Va2L/nsWhere,

Q = output KVA

Bav

= air gap flux density

Ac = amp conductor per meter

Kw = winding Factor

Va = peripheral Speed (Va=pi*D*Ns)

L = lengthNs = sync. Speed


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1. Specific magnetic loading

2. Specific electrical loading

3. Stator bore

4. Gross core length5. Radial ducts : No width

6. Gross iron length

7. Net iron length

8. Pole pitch

9. Current per phase


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There are following points to affect in stator:1. Type of Pole2. Pole section3. Radial length of pole

4. Turns per pole5. Conductor : size, area6. Full load current7. Current density8. Length of mean turn9. Voltage drop10. Field copper loss11. Peripheral speed

Stator


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Types of Poles:

1. Round Pole

2. Rectangular Pole

Length of air gap:The increase in length of air gap, a larger value of field

mmf is req. so increase the cost of machine.


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No of armature slots:

Following factors should be considered for theselection of armature slots.

1. Balanced winding2. Cost

3. Temperatures

4. Leakage reactance

5. Tooth ripples

6. Flux density


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Armature winding, coils & insulator:Types of coils

1. Single turn bar

2. Multi turn

Methods of Elimination of harmonics in voltages:

1. Distribution

2. Chording

3. Skewing4. Fractional slot windings

5. Large length of air gap


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single layer winding:

-One coil-side occupies the total slot area

-Used only in small ac machines


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Double layer winding:

-Slot contains even number (may be 2,4,6 etc.) of coil-sides in two layers

- Double-layer winding is more common above about5kW machines


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Easier to manufacture and lower cost of the coils

Fractional-slot winding can be used

Chorded-winding is possible

Lower-leakage reactance and therefore , betterperformance of the machine

Better emf waveform in case of generators


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Turns per phase:Tph=Eph/4.44f Kw

Conductor section:

As

=Iz

/a

Length of mean turn:

Lml=2L+2.5+0.06kV+0.2

Stator core:

De=*2Li*Bc


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Armature permanents:

1. Armature resistance

2. Armature leakages reactance


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1. Winding2. Number of Parallel Paths3. Number of Slots4. Slots per Pole per Phase

5. Conductors per slot6. Conductor : sizearea

9. Current density10. Slot size : width

depth11. Resistance per phase12. Total copper loss


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Types of rotor:1. Salient-ple type

2. Smooth-cylindrical type

Height of Pole:

Hp=Hf+0.02

Where,

Hf=total winding area/Df Hight of pole:

Hs=2Dg


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There are flowing mmf are affecting:

1. Mmf for air gap

2. Mmf for armature teeth

3. Mmf for core4. Mmf for poles

5. Mmf for yoke


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Design of field winding:- Voltage across each field coil

- Winding height- Field wingding depth

- Voltage across each field coil- Field current

- Field turens- Resistance of winding- Cooling co efficent- Temp. rise

Pole pitch Winding depth

0.1 25

0.2 350.4 45


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Losses in alternator

1. Iron loss due to main field

2. Iron loess due to parasitic fields

3. Copper loss4. Eddy current loss

5. Stray loss

6. Friction and winding loss

7. Excitation loss


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A single-phase alternator hasall the armature conductorsconnected in series

The stator is two pole. The

winding is wound in twodistinct pole groups, bothpoles being wound in thesame direction around thestator frame.

The rotor also consists of twopole groups, adjacent polesbeing of opposite polarity.


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The two poles of the statorwinding are connected to eachother so that the AC voltages arein phase, so they add.

As the rotor (field) turns, itspoles will induce AC voltages in

the stator (armature) windings.Since one rotor pole is in thesame position relative to astator pole as any other rotorpole, both the stator poles arecut by equal amounts ofmagnetic lines of force at any

time. As a result, the voltagesinduced in the two poles of thestator winding have the sameamplitude or value at any giveninstant.


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Poles RPM for 50 Hz RPM for 60 Hz RPM for 400 Hz2 3,000 3,600 24,0004 1,500 1,800 12,0006 1,000 1,200 8,0008 750 900 6,000

10 600 720 4,80012 500 600 4,00014 428.6 514.3 3,42916 375 450 3,00018 333.3 400 2,66720 300 360 2,40040 150 180 1,200


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Visual inspection (marking, completeness) Loss tangent test on installed stator winding

Insulation resistances of windings, temperature sensors, space heaters, bearings

DC resistances of windings, temperature sensors, space heaters

Adjustment of magnetic centre of generators with sleeve bearings

Measurement of rotor impedance

Phase-sequence test Vibration severity measurement

Check of voltage balance

No-load characteristic, generator mode

Short-circuit characteristic, generator mode

Shaft voltage measurement (where design permits)

Shock pulse measurement, if SPM nipple is provided High-voltage test

Functional check of accessories

Functional check of excitation system.


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Polarization Index Testing

Dielectric Absorption Testing

Pole Balance Tests

Winding Resistance Testing

Impedance testing

Power factor testing (doble)

Wedge & end blocking Inspections

(a) Insulation test

(b) Control function test*

(c) Dummy load test*

(d) Earthing protection test (e) Battery charger output test*

(f) Step-load acceptance test*

(g) Noise level measurement


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Overspeed test with generator on balancing machine No-load characteristic

Determination of iron and friction loss

Noise measurement at no-load

Measurement of THF factor

Moment of inertia in deceleration test

Sudden short-circuit test

Temperature rise test at rated data or equivalent load test

Temperature rise time constants

Load characteristics h = f(Pel)

Regulation characteristics for different cos j

Determination of nominal excitation current Determinations of synchronous machine characteristics (reactances, time

constants)

Measurement of coolant flow rate


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This test is conducted to measure-winding resistanceof a synchronous generator

when it is at rest and the field winding is open. Theresistance is measured between

two lines at a time and the average of the threeresistance readings is taken to be

the measured value of the resistance, RL from line to

line. If the generator is Y-connected, the per-phaseresistance is

Ra= RL0.5


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he open-circuit test, or the no-load test, is performedby

1) Generator is rotated at the rated speed.

2) No load is connected at the terminals.

3) Field current is increased from 0 to maximum.

4) Record values of the terminal voltage and fieldcurrent value.


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The OCC follows a straight-line relation as long as the magnetic circuit of the

synchronous generator does not saturate. Since, in the linear region, most of theapplied mmf is consumed by the air-gap, the straight line is appropriately calledthe air-gap line.


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The short-circuit test provides information about thecurrent capabilities of a synchronous generator. It isperformed by

1) Generator is rotated at rated speed.

2) Adjust field current to 0.

3) Short circuit the terminals.

4) Measure armature current or line current as the

field current is increased.


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Ratio of the field current required for the rated voltage at open circuit to the fieldcurrent required for rated armature current at short circuit.CR=f,c/If,sc


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The scope of the Operating and Maintenance Manual is agreedwith the customer on the basis of the General Terms of Delivery for Products of the Electrical Industry. The standard version of the manual comprises: Data sheet

Test report Dimension drawing of generator Dimension drawing of cable connection Connection diagrams Erection instructions Subsupplier documentation Spare parts list Manufacturers declaration (CE)


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Failure of prime movers Failure of excitation:

Failure of insulation in the stator or interconnectingcable can be further divided into:

- Interphase short circuits

- Single phase to earth fault

- inter turn faults

- Earth fault on the rotor


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