Harmo Symposium By Tahir Saleem

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Harmo Symposium by Tahir Saleem

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Harmo Symposium By Tahir Saleem

  1. 1. symposium 2008 23rd Multi-Topic International Symposium March 28 & 29 2008 <ul><ul><li>Harmonics and Its Impact On Industrial Consumers </li></ul></ul>
  2. 2. Power Quality <ul><li>Perfect power supply should be one that is always available ways within voltage and frequency tolerances and has a pure noise free sinusiodal wave shape </li></ul>symposium 2008
  3. 3. <ul><li>It is the consumers responsibility to take steps to ensure that the quality of power delivered to his process is good enough </li></ul>symposium 2008 Power Quality
  4. 4. <ul><li>Care full design using high resilience techniques can minimize the effect created by power quality defects </li></ul>symposium 2008 Power Quality
  5. 5. Power Quality Defects <ul><li>Harmonics Distortion </li></ul><ul><li>Blackouts </li></ul><ul><li>Under or over voltage </li></ul><ul><li>Dips and surges </li></ul><ul><li>Transients </li></ul>symposium 2008
  6. 6. Harmonic distortion <ul><li>Harmonics has always existed in electrical power system. It harmless as long as its level is not substantial. However with the recent rapid advancement of power electronics technology, so called non linear loads, such as variable speed drives, induction furnaces, Ups, computers etc.These equipments are finding their way to industrial consumers. </li></ul><ul><li>Harmonics induced by non linear loads are potential risk if they are not predicted and controlled. </li></ul>symposium 2008
  7. 7. Non Linear Load <ul><li>Draws current only part of cycle and acts as an open circuit for the balance cycle. </li></ul><ul><li>Change the impedance during the cycle have the resultant wave form is distortion and no longer confirm to a pure sine wave </li></ul>symposium 2008
  8. 8. <ul><li>This yields RMS value of distortion as a percentage of the fundamental frequency </li></ul><ul><li>This condition is called a non-linear load or non sinusoidal load </li></ul><ul><li>The total amount of harmonics will determined the THD Of non-linear load </li></ul><ul><li>The more sources impedance the more voltage distortion </li></ul>symposium 2008
  9. 9. <ul><li>Harmonics are represented by a frequency multiple of the fundamental frequency. </li></ul><ul><li>Harmonics are designated by their harmonic numbers or multiple of frequency </li></ul><ul><li>Total harmonic distortion is calculated as the sequences of all harmonics divided by normal frequency </li></ul>symposium 2008
  10. 10. <ul><li>Linear Loads Resistance Induction motors </li></ul><ul><li>Non Linear Load Induction Furnace Variable Drives </li></ul><ul><li>Speed Drives </li></ul><ul><li>Solid State Soft starters </li></ul><ul><li>Instrument </li></ul>Classification of Load symposium 2008
  11. 11. Poor Power Quality symposium 2008
  12. 12. Ideal Power Quality symposium 2008
  13. 13. Power quality self assessment <ul><li>Computer lock ups </li></ul><ul><li>Flickers </li></ul><ul><li>Equipment damage </li></ul><ul><li>Failure of data processing equipment </li></ul><ul><li>Problems with switching of high loads </li></ul><ul><li>Over heat neutrals </li></ul><ul><li>Nuisance tripping </li></ul><ul><li>Utility metering problems </li></ul>symposium 2008
  14. 14. Power quality cost <ul><li>Power quality cost industry about 15 billion dollars per annum </li></ul>symposium 2008
  15. 15. Harmonics Distortion <ul><li>Results high current and voltages </li></ul><ul><li>High energy consumption </li></ul><ul><li>Shorter equipment life </li></ul><ul><li>Increased maintenance cost </li></ul><ul><li>Design failure in explosion proof equipment </li></ul>symposium 2008
  16. 16. Effects of Harmonic <ul><li>Generators </li></ul><ul><ul><li>Thermal Losses </li></ul></ul><ul><ul><li>Effect of Sequence Components </li></ul></ul><ul><ul><li>Voltage Distortion </li></ul></ul><ul><ul><li>Line Notching </li></ul></ul>symposium 2008
  17. 17. Transformers <ul><li>Thermal Losses </li></ul><ul><li>Unbalance, Distribution, Transformers and Neutral Currents. </li></ul><ul><li>Transformer Derating </li></ul>symposium 2008
  18. 18. Induction Motor <ul><li>Thermal Losses </li></ul><ul><li>Effect of Harmonic Sequence Component </li></ul><ul><li>Explosion proof motors and voltage distortion </li></ul>symposium 2008
  19. 19. Motors <ul><li>Effect Of Harmonics On Explosion Proof Motors </li></ul><ul><li>They are designed on pure sine waves, the rotor may over heat due to harmonics resulting hot rotor and damage of seals. Temperature exceed the T class . </li></ul><ul><li>EExd,EExe,EExp,EExN according toEN60034- </li></ul><ul><li>1-2%voltage distortion is permitted . 3% voltage distortion is permitted forEExN asperEN60034-2o </li></ul>symposium 2008
  20. 20. Induction Motor Impact <ul><li>1- Voltage harmonics causes extra losses in direct line connected motors </li></ul><ul><li>2- The 5th harmonics creates a counter rotating field, where as the 7th harmonic creates a rotating field beyond the motors synchronous speed. The pulsating torque causes wear and tear on couplings and bearing </li></ul>symposium 2008
  21. 21. Variable Speed Drives <ul><li>Lighting </li></ul><ul><li>Flicker </li></ul><ul><li>Effects of Line Notching on lighting </li></ul><ul><li>Potential for Resonance </li></ul>symposium 2008
  22. 22. Effect s of Harmonics <ul><li>Capacitors </li></ul><ul><li>Capacitive reactance decreases as the frequency increases. A relatively small percentage harmonic voltage can cause a significant current to flow in capacitor circuit </li></ul><ul><li>Presence of harmonic current causes distortion in wave form </li></ul><ul><li>If the natural frequency of capacitor bank/power system reactance is closed to a harmonic than partial resonance occur with amplified values of voltage and and current, the elevated current will cause over heating . </li></ul>symposium 2008
  23. 23. Uninterruptible Power Supplies (UPS) Computer & Computer Based Equipment Creates Third Harmonic symposium 2008
  24. 24. Cables <ul><ul><li>Thermal Losses </li></ul></ul><ul><ul><li>Skin & Proximity Effects </li></ul></ul><ul><ul><li>Neutral System in four-wire system. </li></ul></ul><ul><ul><li>Additional Effect Associated with Harmonic </li></ul></ul>symposium 2008
  25. 25. Cables <ul><li>Effect of harmonics on cable </li></ul><ul><li>Thermal losses </li></ul><ul><li>Example </li></ul><ul><li>load current=600 </li></ul><ul><li>harmonic current=42% </li></ul><ul><li>Rms current=600x square </li></ul><ul><li>=651A </li></ul><ul><li>Increase in losses=(651/600)squrex100 </li></ul><ul><li>=17.73% </li></ul>symposium 2008
  26. 26. Miscellaneous Effects <ul><li>EFFECTS AND NEGATIVE CONSEQUENCE </li></ul><ul><li>Conductor over heating/skin effect depending on frequency </li></ul><ul><li>Capacitor failure </li></ul><ul><li>Faulty operation of fuse and circuit breaker </li></ul><ul><li>Increased stray losses in transformer resulting increase in iron, copper or eddy </li></ul><ul><li>Increased losses in generator/multiple zero crossing affect the timing of the voltage regulator, causing interference and operation instability </li></ul><ul><li>Incorrect recording by utility meters </li></ul><ul><li>Miss operation of drives </li></ul><ul><li>Interferences in computer/telephone </li></ul>symposium 2008
  27. 27. Measurement <ul><li>Harmonics Problem In Measurement </li></ul><ul><li>Peak factor=peak value/rms value </li></ul><ul><li>Form factor=rms/mean </li></ul><ul><li>Measurement is based on average reading,rms calibrated, </li></ul><ul><li>Which is measuring average(0.636xpeak) and multiplying the result by form factor 1.11 </li></ul><ul><li>This is valid only for pure sine wave </li></ul><ul><li>Pure sine wave crest factor=peak/rms or 1.414(1/0.707) </li></ul><ul><li>The higher the crest factor more accurate it will be </li></ul>symposium 2008
  28. 28. Measuring Equipment Telephones Circuit Breakers Fuses Relays Radio, Television, Audio & Video Equipment Capacitors symposium 2008
  29. 29. Inter Harmonics <ul><li>IEC 1000-2-1 </li></ul><ul><li>Frequencies which are not integer of the multiple frequencies </li></ul><ul><li>SUB HARMONICS </li></ul><ul><li>Whose frequency is less than fundamental </li></ul>symposium 2008
  30. 30. <ul><li>Allowable Limit of Current and Voltage Harmonics </li></ul><ul><li>Voltage Harmonic 5% </li></ul><ul><li>Current Harmonic 10% </li></ul>symposium 2008
  31. 31. Harmonic Calculation <ul><li>1-Calculate the source S.C capacity and reactance </li></ul><ul><li>2-Harmonic current/order = I*Ih% </li></ul><ul><li>Voltage/harmonic order </li></ul><ul><li>= 1.732*h*S*Ih </li></ul>symposium 2008
  32. 32. Harmonic Calculation <ul><li>3- Harmonics voltage as percentage= Vh/Vr X 100 </li></ul><ul><li>4- Transformer S.C Current = transformer full load current/transformer impedance </li></ul><ul><li>5- Generator s.c = generator full load current/generator reactance </li></ul><ul><li>6- Source impedance = V2/s.c mva </li></ul>symposium 2008
  33. 33. Example <ul><li>Direct Calculation Of Harmonic Voltage Distortion </li></ul><ul><li>1-Transformer full load current of 2000KVA current=2886 Amps </li></ul><ul><li>2-S.C current=2886/0.06=48.1KA </li></ul><ul><li>3-S.C MVA=1.732x400x48100=33.32 MVA </li></ul><ul><li>4- Supply reactance=400x400/33.32MVA=0-00480 ohm </li></ul><ul><li>HARMONIC CURRENT PER ORDER </li></ul><ul><li>Motor full load current=962A </li></ul><ul><li>5th harmonic current=32.27% </li></ul><ul><li>=962x0.3227=310.44A </li></ul><ul><li>Voltage=1-732x5x0-00480x310.44=12.9 V </li></ul><ul><li>Harmonic as% of rms=18.6x100/400=3.225 %. </li></ul><ul><li>THD=/v5 squre+V7 squre+----- </li></ul>symposium 2008
  34. 34. <ul><li>The profusion of non linear loads makes harmonics distortion of power a phenomenon of increasing amplititudes. The effects of which cannot be ignored since almost all the power network components are in practice affected. </li></ul><ul><li>The issue of power harmonics are more apparent then ever. controlling and monitoring industrial system and their effects are a potential problem for industrial consumers. </li></ul>symposium 2008
  35. 35. <ul><li>Thanks </li></ul>symposium 2008

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