1 / 46

FOWLER CHAPTER 12 LECTURE 12 TRANSFORMERS

FOWLER CHAPTER 12 LECTURE 12 TRANSFORMERS. TRANSFORMERS CHAPTER 12 TRANSFORMERS ARE MULTIPLE WINDING INDUCTORS. WORK ON THE PRINCIPLE OF MUTUAL INDUCTANCE. TRANSFORMERS ARE 2 OR MORE COILS LINKED BY MAGNETIC FLUX . PRIMARY COIL INDUCES A VOLTAGE IN A SECONDARY COIL BY MUTUAL INDUCTANCE.

eilis
Download Presentation

FOWLER CHAPTER 12 LECTURE 12 TRANSFORMERS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. FOWLER CHAPTER 12LECTURE 12 TRANSFORMERS

  2. TRANSFORMERS CHAPTER 12 TRANSFORMERS ARE MULTIPLE WINDING INDUCTORS. WORK ON THE PRINCIPLE OF MUTUAL INDUCTANCE. TRANSFORMERS ARE 2 OR MORE COILS LINKED BY MAGNETIC FLUX. PRIMARY COIL INDUCES A VOLTAGE IN A SECONDARY COIL BY MUTUAL INDUCTANCE. THE AMOUNT OF MUTUAL OR SELF INDUCTION IS MEASURED IN HENRY’S.

  3. http://www.youtube.com/watch?v=GMePE7NZcxw Electrical Transformer Tutorial http://www.youtube.com/watch?v=Q2mShGuG4RY How electric motors work YOU TUBE: Transformer Animation http://www.youtube.com/watch?v=VucsoEhB0NA YOU TUBE: How Transformers Work http://www.youtube.com/watch?v=ZjwzpoCiF8A

  4. SYMBOLS

  5. TRANFORMER WINDINGS

  6. TRANSFORMERS TRANSFER POWER FROM PRIMARY TO SECONDARY WINDINGS. PRIMARY TAKES ELECTRICAL ENERGY AND CONVERTS IT TO MAGNETIC ENERGY SECONDARY TAKES MAGENTIC ENERGY AND CONVERTS IT TO ELECTRICAL ENERGY. THERE IS NO PHYSICAL COUPLING BETWEEN THE PRIMARY AND SECONDARY WINDINGS.

  7. STEP UP/DOWN TRANSFORMERS STEP UP STEP DOWN

  8. COEFFICIENT OF COUPLING (COC) THE PORTION OF FLUX THAT LINKS ONE COIL TO ANOTHER. COC CAN VARY FROM 0 TO 1. AT 1, ALL THE FLUX IS COUPLED. COC CAN ALSO BE EXPRESSED. AS A %. 100% = COUPLING OF 1. COUPLING IN Fe CORE TRANSFORMERS IS NEARLY 100%. SINCE THERE IS LITTLE FLUX LEAKAGE INTO THE AIR. AIR CORE TRANSFORMERS HAVE LOW COC DUE TO THE HIGH RELUCTANCE OF AIR, CAUSING A LARGE AMOUNT OF LEAKAGE. THIS IS CALLED LEAKAGE FLUX. THIS CAN BE CONTROLLED SOMEWHAT BY SPACING THE COILS CLOSER TOGETHER. IF COILS ARE PERPENDICULAR TO EACH OTHER COC IS CLOSE TO ZERO.

  9. CHANGING VOLTAGE VAULES STEP UP, STEP DOWN TRANSFORMERS. WITH 100% COULPING THE TURNS RATIO AND VOLTAGE RATIO ARE EQUAL.

  10. ADVANTAGES OF HIGH VOLTAGE TRANSMISSION LINES STEP UP TRANSFORMER AT POWER PLANT STEP DOWN DISTRIBUTION TRANSFORMER AT SUBSTATION TO LOADS AND OTHER STEP DOWN TRANSFORMERS. 20KV 500A 10 MW 400KV 25A 10 MW 20KV 500A 10 MW 400KV 25A LONG DISTANCE TRANSMISSION LINES

  11. EFFICIENCY OF TRANSFORMERS IN THE REAL WORLD CORES AND COILS OF TRANSFORMERS CONVERT SOME ELECTRICAL ENERGY INTO HEAT. EFFICIENCY OF TRANSFORMERS IS EXPRESSED IN TERMS OF POWER. EX.12-3 P309 WHAT IS THE EFFICIENCY OF A TRANSFORMER WITH A INPUT OF1880W INTO THE PRIMARY COIL AND 1730W OF OUTPUT FROM THE SECONDARY COIL. 150W LOSS, CALLED POWER LOSS.

  12. POWER LOSS IN TRANSFORMERS IS CAUSED BY: 1.HYSTERSIS LOSS: CAUSED BY RESIDUAL MAGNETISM LEFT IN THE CORE EACH TIME THE FIELD REVERSES, WHICH CAUSES HEAT LOSS.

  13. HYSTERSIS LOOP, THE NARROWER THE LOOP, THE LESS THE LOSS. HYSTERSIS LOSSES INCREASE WITH THE FREQUENCY OF PRIMARY CURRENT. Steel has a "fat" hysteresis loop. It is difficult to demagnetize, so steel is used for permanent magnets. Substances, such as soft iron, with thin hysteresis loops, are used for transformer cores. Eddy Currents, Magnetic Braking and Lenz's Law http://www.youtube.com/watch?v=otu-KV3iH_I

  14. 2. EDDY CURRENT LOSS ARE INDUCTED CURRENTS IN THE CORE FROM ITS OWN MAGNETIC FLUX. THESE EDDY CURRENTS FLOWING THRU THE CORES RESISTANCE PRODUCES HEAT. What Is Eddy Current http://www.youtube.com/watch?v=zJ23gmS3KHY

  15. HOW CAN WE REDUCE EDDY CURRENT LOSES? BY INSULATING EACH LAMINATION OF THE CORE WITH A THIN LAYER OF OXIDE. THIS INCREASES THE RESISTANCE OF THE CORE WHICH REDUCES HEAT LOSS SINCE, Eddy Current Demo. http://www.youtube.com/watch?v=Yu1uRvErM80

  16. 3. COPPER LOSS POWER LOSS IN THE WINDINGS OF THE TRANSFORMER. CAN BE FOUND FROM P= I²R, R IS THE OMIC RESISTANCE OF THE WINDING TURNS. LOSS AND EFFICIENCY TRANSFORMERS ARE MOST EFFICIENT WHEN FULLY LOADED. EFFICIENCY DECREASES AS THE LOAD DECREASES. WHY? CURRENT FLOW IN THE TRANSFORMER PRIMARY DOES NOT DECREASE IN DIRECT PORPORTION TO THE DECREASE IN LOAD. PRIMARY CURRENT CAUSES CORE AND Cu LOSS WHEN LIGHTLY LOADED.

  17. TRANSFORMER CORES. CLASSIFIED BY CORE MATERIALS. SUCH AS Fe AND AIR CORE, I AND E LAYERS ALTERNATE IN STACKING WHEN BUILDING THE CORE. MAKES AN AIR GAP WHICH HELPS KEEP THE INDUCTANCE MORE CONSTANT FOR DIFFERENCE CURRENTS. Disassembling laminated transformer core http://www.youtube.com/watch?v=B8fTLXs50lU

  18. TYPES OF TRANSFORMERS CLASSIFIED BY USE: POWER TRANSFORMERS, @ 60Hz, FROM 115 TO 1000’S VOLTS. USED FOR POWER DISTRIBUTION AND LIGHTING.

  19. CONTROL TRANSFORMERS :USED BY SMALLER RECTIFIERS AND CONTROL CIRCUITS USING RELAYS SOLENOIDS.

  20. AUDIO TRANSFORMERS. WORK AT FREQUENCIES UP TO 20KHz.

  21. RF TRANSFORMERS f (RADIO RANGES) CAN BE Fe OR AIR CORE.

  22. CONSTANT VOLTAGE TRANSFORMERS: PROVIDE STABLE SECONDARY VOLTAGE, DESPITE VARING PRIMARY VOLTAGE.

  23. ISOLATION TRANSFORMER HAVE EQUAL PRIMARY AND SECONDARY VOLTAGE, USED TO ISOLATE ELECTRICAL EQUIPMENT FROM THE POWER DISTRIBUTION SYSTEM.

  24. VARIOUS ISOLATION TRANSFORMERS

  25. MORE ISOLATION TRANSFORMERS

  26. AUTO TRANSFORMER: PRIMARY WINDING IS PART OF THE SECONDARY WINDING AND VICE-VERSA.

  27. 1,000 MVA, 1050/525kV single-phase autotransformer

  28. VARIABLE TRANSFORMER: WORK AT POWER FREQUENCIES. THESE ARE AUDIOTRANSFORMERS WITH AN ADJUSTABLE SECONDARY.

  29. IMPEDANCE MATCHING (IM) P.317 THIRD MOST COMMON USE FOR TRANSFORMERS IS IM WHY? WHEN IM OF SOURCE IS MATCHED TO IM OF THE LOAD. MAX. POWER TRANSFER OCCURS. A TRANSFORMER CAN MAKE A LOAD APPEAR TO THE SOURCE LARGER OR SMALLER THEN IT ACTUAL IS. REFLECTED IMPEDANCE (Z) FROM THE SECONDARY APPEARS TO THE PRIMARY AS BEING EQUAL.

  30. TRANSFORMER RATINGS VOLTAGE RATING ARE SPECIFIED FOR PRIMARY AND SECONDARY WINDINGS UNDER LOAD AND NO LOAD CONDITIONS. POWER RATINGS: GIVEN IN WATTS GOING TO A RESISTIVE LOAD

  31. Full Load Current Ratings of Self-CooledThree-Phase Transformers208 -7200V

  32. SERIES AND PARALLEL WINDINGS P.230 SOME TRANFORMERS CAN BE BUILT WITH MULTIPLE PRIMARY AND SECONDARY WINDINGS WHICH CAN BE CONNECTED IN SERIES OR PARALLEL.

  33. 3 PHASE TRANSFORMERS

  34. 500 KVA 3 PHASE TRANSFORMERS

  35. 3 PHASE TRANSFORMER UNDER CONSTRUNTION

  36. ULTIMATE USE FOR TRANSFORMERS: A SUPERCONDUCTING FUSION REACTOR

  37. MAGNETIC CONFINMENT CONTAINTER FOR A PLASMA FUSION REACTOR

  38. DRAWING SHOWING HOW MAGNETIC FIELDS COMPRESS 1 MILLION DEGREE PLASMA

  39. INTERIOR OF A FUSION REACTOR

More Related