FORMSWRTHYPHASCISPELPRGHDOC h PICP6LINP6Z BOXP6Z dOVLP6Z dSWCL@BlackWhiteRedGreenBlueCyanYellowMagentafSalmonwPeachUBrownellowLight GreenwwwGrey DarkOrangeݙVanillalowGrey LightIDXHIDXDSoftSansdTitleepz,IDXDSoftSansdBlank LinefIDXDSoftSansdLetter HeadergIDXDSoftSans dIndex EntryhTOCH TOCDSoftSansdTitlenz%TOCDSoftSans dBlank LineoTOCDSoftSansdZLevel 1pTOCDSoftSans dZLevel 2qTOCDSoftSerif dLevel 3rTOCDSoftSerif dhLevel 4sTOCDSoftSerif dvLevel 5tTOCDSoftSerif d*Level 6uTOCDSoftSerif dLevel 7vTOCDSoftSerif d8Level 8wIDXPSEC1 PTPAG3pA PRN3KBYUtils:APPLICATIONS/FinalWriter/FWFonts/SWOLFonts/Serif/WŬWW~W#W  ELX.LectureTitleW PASDSoftSans_BoldvWWFW Utils:APPLICATIONS/FinalWriter/FWFonts/SWOLFonts/W WWŬWW~W#W d ELX.TopicTitle{W PASDSoftSans{WŬWΆWvtW-PWg `` ?<>g< a` 0|g<`?fg>ffc!`??fg>fg?Apx ?s{ ffg>fg A 0 ~ffg>fg 0c0? |~ ?gg 0< gq < ?s?>?g0 l 8 ?>>> 0>`0 ``?χ?3k3 0030x|x|x0xxx?3?33S3??33?3c33? 0030?0 `0?33s33??3?3>03c330 03000x|`03?3s33??3??03c30`0 |`0`s3Ç?0<xx|| x8x >> >     w  ' 8C={ ÇpǼs""{up!" p   @ ww A wt=Ì788w AS->N...). These alternating flux are linked to the secondary coil via the magnetic core. In the ATTR dCHRS open coreATTR dCHRS, all flux has to pass from air, and this results a lot of flux leakage (loss), since from the flux leaving the primary coil, very few manage to return in the core from the secondary coil. On the other hand, in the ATTR dCHRS closed coreATTR dCHRS, most of the flux will pass from the iron core, and there is a very few loss of flux. This makes the latter type of transformer a better one. For an ideal transformer, the leakage should be very near to none.RULE  ATTR dCHRSRULE  ATTR dCHRSWhen the primary coil produces the alternating magnetic flux, this will cut the secondary coil and as a result it induces an Electro Motive Force (EMF), i.e. a Voltage in the secondary. If the secondary coil has a load, such as a resistor, or lamp, current will flow through it and the primary current increase to make the demand of the load, and keep the secondary current flowing from the load. If the load is removed, the primary current falls practically to 0A, and hence one can say that a transformer is a Watt-Less component.RULE  ATTR hdCHRSRULE  +ATTR+ hdCHRS+In fact, transformers (and capacitors) are energy less (Watt-less) components since they do not consume electrical energy as they give the energy gained all back. On the contrary, resistors (for example), convert electricity into heat and so the electric energy given is changed into heat and lost.RULE  ATTR hdCHRSRULE  ATTR hdCHRSRULE  ATTR dCHRS LaminationsRULE ~,ATTR} hdCHRS}The transformer has a soft iron magnetic core made of laminations whose shape can be of two types; the T&U or E&I design:ATTR dCHRS RULE ATTR hdCHRST&U = ATTR XdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRSE&I = RULE ATTR hdCHRSRULE ATTR hdCHRSthese laminations are interleaved (placed one over the other) and packed tight, otherwise they vibrate and create energy loses due to friction, heat and sound thus less efficiency.RULE ATTR hdCHRSRULE ATTR hdCHRSRULE ATTR hdCHRSRULE  #ATTR#hdCHRS#How to wind a coil of a TransformerRULE YATTRY dCHRSYWinding wire is sold depending the diameter of Cu wire in mm. Before the metric system was introduced, winding coil wire was sold depending its SWG (Standard Wire Gauge) number code. There was a conversion table which gives the diameter inn mm for a certain SWG number. As a rule the smaller the SWG number, the thicker the diameter of the wire.RULE ATTR dCHRSRULE ATTR dCHRSAn instrument which can be used to measure exactly the diameter of a piece of Cu wire, is the micrometer. The winding wire is covered with an insulating varnish to prevent adjacent turns from shorting. RULE ATTR dCHRSRULE ATTR dCHRSSo for a certain voltage, there is a number of turns around the winding bobile( or former). Now it is estimated that for getting 1 Volt, 8 turns every inch square of bobile cross-sectional area should be coiled.RULE ATTR dCHRSRULE  KATTRK dCHRSKIf 240 V are required, then, in 1 inch, 240 x 8 = 1920 turns are required. RULE  $ATTR$ dCHRS$12 Volts require 12 x 8 = 96 turns. RULE  PBATTR# dCHRS#A former of a c.s. area of 0.5 inchATTR dCHRS2ATTR, dCHRS,, 12V would require 12 x 8 x 2 = 192 turns. RULE  eBATTR8 dCHRS8Similarly, by simple proportion, if the bobile is 2 inchATTR dCHRS2ATTR, dCHRS,, 12V are obtained by 12 x 8 2 = 48 turns.RULE ATTR dCHRSRULE 3ATTR3 dCHRS3Hence the following equation could be applied: RULE 8ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR hdCHRS ATTR3 dCHRS3Where: V=Voltage required in transformer in VoltsRULE DATTR dCHRS V = n ATTR dCHRSxATTRdCHRS A ATTRdCHRS ATTRhdCHRS ATTRhdCHRS ATTR! dCHRS!n = number of turns around formerRULE [nATTR#dCHRS# 8 ATTRdCHRS ATTRhdCHRS ATTRhdCHRS ATTR3 dCHRS3A = cross sectional area of former in Square InchesRULE ATTR dCHRSRULE ATTR dCHRSRULE XATTRX dCHRSXExample 1: The area of the former is 0.25 sq.inch. Find the turns per Volt required.RULE ;ATTR; dCHRS;V = n.A ; n = 8 x V = 8 x 1 = 32 turnsRULE 3ATTR3 dCHRS3 8 A 0.25RULE  ATTR hdCHRSRULE  .ATTR. hdCHRS.Example 2: A transformer requires a coil to be wound around a former of length and breath of 508 and 381 mm respectively. The transformer is required for an input of 240V 50Hz a.c. and give an output of 12 V. Calculate the turns required for making the primary and secondary coil. (1 Inch = 254 mm).RULE  ATTR hdCHRSRULE  [ATTR[ hdCHRS[Converting metric to inches: 508mm = 2 inches (508/254) and 381mm = 1.5 inches (381/254)RULE HBATTRF hdCHRSFTherefore cross sectional area of former is 2 x 1.5 = 3 inches ATTR hdCHRS2ATTR dCHRS RULE ATTR dCHRSRULE WBATTRN dCHRSNV = n A For input, 240 V = n . 3 n = 240 x 8 n = ATTR dCHRS640ATTR dCHRS turnsRULE QATTRQ dCHRSQ 8 8 3RULE  [BATTRS hdCHRSS For output, 12 V = n . 3 n = 12 x 8 n = ATTR hdCHRS32ATTR hdCHRS turnsRULE  SATTRS hdCHRSS 8 3RULE  ATTR hdCHRS Remember that:RULE  [,ATTR hdCHRS Transformer ratio = ATTRA hdCHRSA n 1 = V1 ( = I2 640 = 240 = 20 :1RULE  [ATTR[ hdCHRS[ n 2 V2 I1 ) 32 12RULE  ATTR hdCHRSRULE  .ATTR. hdCHRS.Note that the winding cannot be done by calculating the length required (no. of turns x perimeter of bobile) but should be counted using a tool called the winding counter. Also one should use the same thickness of coil wire as the one which was used originally in the transformer before burning out. RMSTRULEATTR dCHRSLMSTRULEATTR dCHRS