If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. There are 2 coil sides per slot. The coil-span chosen is less than the full-pitch because of the inherent advantages of chording. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. 85 lagging. Number of slots: 3 Number of poles: 2 Number of phases: 3 Number of layers: 1 Coil span : 1 Number of slots per pole per phase: 1/2. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. ; Coil Span: It is the angular distance between the two sides of the coil. It may be the full pitched or short pitch. An alternator having 10-poles, 3-phase, and 60 Hz has 8 conductors per slot in single layer arrangement with 4 slots/pole/phase. frame. It is lesser than the value in the first case. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. The phase winding factor for short-pitched coils is given by: K_p = cos(π * s / 2) where s is the coil span in terms of pole pitches. No matter how many poles, each pole always spans exactly 180 electrical degrees, and it is called pole pitch. Condition for designing a Mush winding:- 21. Full pitched coils have the advantage of giving maximum emf induced in the coil. This chapter covers the calculation of winding factors and armature MMFs, harmonic analysis of armature MMFs. Thus, the total. Here, e = E 1 = E 2 = E. 951, 0. 31. In a 10 pole, lap wound de armature, the number of active armature conductor per pole is 50. Coil Span: It is the angular distance between the two sides of the coil. Display and compare winding harmonicsElectrical Engineering. Pole – pitch. Similarly, if the emf induced in coil sides 2 and 11 are E 2 & E 11, then the total emf in coil 2-11 is given as arithmetic sum of E 2 and E 11. 3, Fig. 50Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. Calculation: Given that, Number of coils = 16Q2: For a 3-phase winding with 3 slots per pole per phase and coil span of 8 slots, compute the distribution and pitch factor for fundamental and 3rd harmonics. Determine the equation for the emf induced in one turn, and its RMS value. If each coil is short pitched by an angle of 36 ∘ electrical. Kr ==sink 2 · Kp =pitch factor in dcci111al p" =span of the coil in electrical degrees. Problem 1 : Develop the layout of a lap winding for a 3 phase ac machine having 4 pole and 24 slots. . The stator of a synchronous machine is such that:3-phase; 4 poles; 36 slots; winding double-layered; 2 slots short pitched and 2-turn for each single coil. 9 and pf = 0. The highest winding factor can be obtained with 4-solt span coil (the coil span is closest to pole pitch 3. poles, 18 slots alternator, the pole pitch is n = 18/2 = 9 slots. The flux per pole has a fundamental component of 0. 5. Pole pitch is always equal to 180o electrical. fs. 9: Rated speed (rpm) 170: Rated current (Arms) 3. Coil Span or Coil pitch. . Here, e = E 1 = E 2 = E. Assuming double turn coil, Calculate the back pitch for progressive and retrogressive winding. ( c) 96 stator slots, six-poles, coil spans 1 to 13. m. It may be the full pitched or short pitch. Publisher: PEARSON. [Answer: 0. – Comparator. Let the coil have a pitch short by angle q electrical space degrees from full pitch and induced emf in each coil side be E. β = 180o/ = 20o. It is in fact the periphery of the armature spanned by the two sides of the coil. 1. Expert Solution. Not ( I want a solution within 20 minutes because it is very urgent ) Q3//The armature of a 6600 volt, three-phase, 20-pole, 300 rpm star-connected alternator has 180 slots. If coil span is equal to pole pitch then it is called full pitch coil. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. – Comparator. Use a diagram like that shown in fig. , Y = 2/3 τ p. to the induced emf in the same coil when it is full pitched is called a coil span factor or pitch factor or chorded factor and it is generally denoted be K p. 955, whilst the second option gives (k_{sk1}) equal to 0. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. The coil-span is 144° (electrical). Assume = 0. It mainly focuses on two PM machines with different slot/pole number combinations (N s /2p), that is, the 24-slot/10-pole and 24-slot/14-pole machines (2p = N s /2 ± 2). Place the arrows according to the slot pitch. Its flux per pole is 0. An alternator has 18 slots per pole and the first coil lies in slots 1 and 16. Pitch factor or coil-span factor In general, if the coil span falls short of full-pitch by an angle (electrical)*, then kc = cosα/2. If the coil sides are placed in slots 1 and 6, then it is short-pitched or fractional-pitched because coil span is equal to 5/6 of a pole-pitch. #Alternator #Protectionofalternator#elect. The length of the mean turn depends on the following factors (i) Gross length of the stator core: Each turn consists of two times the gross length of stator core. 6A. For example if S/P = 10. Slots/pole/ph = m = 72/ (8×3) = 3. Calculate the pitch for the given windings: (i) 36 stator slots, 4 poles, coil span 1 to 8 (ii) 72 stator slots, 6 poles, coil span 1 to 10 (iii) 96 stator slots, 6 poles, coil span 1 to 12;. Author: Robert L. Front connections 8+7=15; 30+7-30=7 8. c. 4. the distance between the two sides of coil is called the coil-pitch. A. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. The arithmetic sum of induced emfs is 2E. If the maximum flux per pole, with a sinusoidal distribution, is 0. Armature Currents and MMF of 5-Phase Machine The armature currents of 5-phase machine can be expressed with formula (1). We must note that the coil-pitch and flux barriers of the NC2 are adjusted as shown in. pdf from CSE 302 at World University of Bangladesh. The winding distribution factor of the alternator is. For a short pitch coil KC. The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degrees. In a 4 pole, 3 phase alternator, armature has 36 slots. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. Number of slots: 3 Number of poles: 2 Number of phases: 3 Number of layers: 1 Coil span : 1 Number of slots per pole per phase: 1/2. m. 1NP2. 25 O 5. A winding constituting a basic unit under a pole-pair (N and S) is repeated for any number of pole pairs when q is integral. Here’s the best way to solve it. e. 3 mWb and the total number of armature conductors is 1000. p. • Coil span is nothing but the spacing between the two coil sides of a coil. 16. The pitch of the coils is 2 slots less than the pole pitch. Calculation: Given that,For making coil span equal to a pole pitch in the armature winding of a d. A coil when placed in a slot, the distance between two coil sides of a coil is equal to the distance between the center of one pole to the center of an adjacent pole ( i. The winding pitch of a generator is the number of slots spanned by each coil in the stator winding divided by the number of slots per pole. In SWAT-EM we can set the coil span explicite. We will start Red at slot 1. it is defined as the peripheral distance between the center of two adjacent poles in a DC machine. First, a double-layer winding is investigated with the number of slots Q, pole pairs p and a constant coil pitch . m. ( b) 42 stator slots, four-poles, coil. in. 1 the coil span should be approximately equal to a pole pitch. Introductory Circuit Analysis (13th Edition) 13th Edition. If the coil span is equal to the Pole pitch then it is called a full pitch coil. If the coil span is less then one pole pitch than it is called short pitch coil. number of slots and a coil span of two slots require at least 18 slots. the coils cannot be full - pitched; they may be short - pitched with 15 slots, or long - pitched with 16 slots. Pitch: Pole and Winding • Pole pitch is the mechanical angle between adjacent poles, e. g. The displacement between the sides of the coil is called the coil span. the coil span is (180-ε), therefore the emf induced in these coil sides will also be separated by this angle. Design a suitable double-layer lap winding for a 6-pole armature with 18 slots and two coil-sides per slot. Compared to the overlapping winding above we need only 3 slots for the two poles. b. For making coil span equal to a pole pitch in the armature winding of a dc generator, the back pitch of the winding must equal the number of – Commutator bars per pole. 6. 00 O…influence of slot/pole number (S/P) combinations on the rotor bar copper loss, a winding harmonic index is described in Section 2. M. The reduction fraction is the pitch factor. The coil span is 150 electrical degrees. There. Looking at the diagram in the question. When the. 1 the coil span should be approximately equal to a pole pitch. The pole pitch is 35cm, the core length is 32cm & sta- 4th tor coil span is of pole pitch. Publisher: McGraw-Hill Education. It. The resultant coil voltage $𝐸_{𝐶}$ is equal to the phasor sum of $𝐸_{𝐶1}$ and $𝐸_{𝐶2}$. pole pitch5. Use: (Y) =) 2. e. First. For a 3-phase winding with 5 slots per pole per phase and with a coil span of 12 slot pitch, the value of pitch factor is. 0. If the coil. The winding is double-layer. If the coil span is equal to the Pole pitch then it is called a full pitch coil. I need answer within 20 minutes please please with my best wishes. 71 O 120. 2. In this. What is a coil span? The coil span is the distance between one conductor of a certain phase and the corresponding return conductor. The slots per pole per phase are 8 and the coil span is 20 slots. Winding Question 9. 10 slots d. If we used short pitched winding for armature winding than pitched factor is included in EMF equation in Alternator. When the coil span is equal to pole pitch (180 deg electrical), the winding is called full pitched winding. 0. If the coil span is equal to the Pole pitch then it is called a full pitch coil. g. The analyses of different six-pole winding configurations, obtained by changing the coil pitch number, winding layer, and stator slot number for the families of , are presented in Section 3. The value of α will usually be given in the question, if not, then assume kc = 1. Pole pitch is always equal to 180o. (Assume lap. The coil span is 150 electrical degrees. It is sometimes convenient to speak of an armature coil span as having a fractional pitch expressed as a fraction e. An alternator has 18 slots per pole and the first coil lies in slots 1 and 16. Number of Commutator Segments - Number of Commutator Segments is the count of cylindrical assembly of insulated segments that are mounted on the shaft. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. Calculate the sinusoidally distributed flux per pole required to give a line voltage of 11 kV on open circuit, and the full load current per conductor. advertisement. If coil span is 6 and if top coil side of a coil lies in slot 1 then the. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Hence pole pitch is equal to the total numbers of armature slots divided by the total numbers of poles, we alternatively refer to it as armature slots per pole. The pole pitch is 10 slots, and the coil pitch is 9 slots. In this study, the electromagnetic performances of dual 3-phase permanent magnet (PM) machines with coil span of two slot-pitches are comparatively investigated. The coil-span chosen is of course less than the full-pitch. The number of segments lying between the ends of the coil is known as the commutator pitch. The back pitch and front pitch adopted could be respectively. If the coil pitch is less than one pole pitch, the coil is called the short-pitch coil or fractional-pitch coil. Y-connected alternator has 9 slots per pole and a full-pitch. If the coil span is equal to the Pole pitch then it is called a full pitch coil. the flux per. 10. ISBN: 9780073373843. Calculate the RMS value of the induced emf per phase of a 10-pole, 3-phase, 60_Hz alternator with 3 slots per pole per phase and 4 conductors per slot in two layers. It is one pole pitch. Zoom In Zoom Out Reset image size. must be exactly equal to pole pitch C. Front pitch (Y f):. Full Pitch and. generator, the back pitch of the winding must equal the number of (a) commutator bars per pole (b) winding elements (c) armature conductors per path (d) armature parallel paths. It is always equal to 180° electrical. Hence, during rotation when one side of the coil comes under north pole, the other side of the coil comes under south pole. 15. If the coil sides are placed in slots 1 and 6, then it is short-pitched or fractional-pitched because coil span is equal to 5/6 of a pole-pitch. The coil span equal to 180 electrical degrees: The coil span is less than 180 electrical degrees. ); and k y is the short pitch factor. The alternator has 18 slots per pole and the first coil lies in slots 1 and 16. Assume the coil span as 150° electrical. Calculate the pitch factor for (a) fundamental (b) 3rd harmonic (c) 5th harmonic (d) 7th harmonic. Download these Free Coil Span or Coil Pitch MCQ Quiz Pdf and prepare for your upcoming exams Like Banking, SSC, Railway, UPSC, State PSC. Compared to the overlapping winding above we need only 3 slots for the two poles. [8+8] 2. 0 D. fs. If the coil span is less then one pole pitch than it is called short pitch coil. Then, the pitch factor will be equal. are e. 0. A 144-slot stator has a whole coiled 12-pole three-phase winding. Determine both the winding factor and the effective turns per phase. 3K views. 5, then the coil-span can be either 11 or 10 slots. 7 slots c. You can investigate three-phase integer-slot, fractional-slot and concentrated windings, both with single and double winding layers where appropriate. In all cases, the coil span should not differ too much from the pole pitch to ensure that when one coil side is under a north pole, the other coil side is under a south pole . arrow_forward A. It may be the full pitched or short pitch. d5. p. The arc diagram contains all the necessary information for connecting the pole-groups correctly. 15, 13; 19, 17; 21, 19; 23, 21;150° is (frac{5}{6}) parts of 180° i. m. Transcribed Image Text: (d) obtain a full-pitch winding. m. (a) Describe armature reaction and explain its effect on terminal voltage (b) Calculate the speed and open circuit line and phase voltages of a 4-pole, 3-3 pitch factor or coil span factor in alternator tutorialspoint web oct 1 2021 1 2 if the coil span of a single coil is less than the pole pitch of 180A two pole three-phase 50 hz wye-connected AC generator has 9 slots per pole and 6 conductors per slot . When the coil span of the winding is equal to pole pitch, the coils are called the full pitched coils. 0. Pole Pitch, Coil Span, Back Pitch, Front Pitch, Commutator Pitch in Armature Winding of DC Machines are explained in this video. A 3-phase, 50 Hz, 2-pole, star connected turbo alternator has 54 slots with 4 conductor per slot. If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. A coil has a pitch of 10 slots instead of 12 slots in the figure above, so its spread is no longer equal to pole pitch. A 4-pole, 50 Hz alternator has double layer winding with 10 turns per coil and number of slots are 60. 60º / 90º = 2/3. 5. 1. SEE MORE TEXTBOOKS. P. Pole and slot numbers. Calculate its coil span factor. What is the short pitch in electrical degrees. Result- ant flux in the air-gap is 5 ´ 10– 2 webers per pole sinusoidally distributed. Commutator pitch of a progressive lap winding is yc = +1. Emf induced per coil side is E. In a short pitch coil, the coil span will be (180 – α)° electrical ( α = angle by which coils are short-pitched and always less than pole pitch ). c. 6 turns. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. Pole pitch = 180 electrical degrees = S/P = 2C/P. generator, the back pitch of the winding must equal the number of (a) commutator bars per pole (b) winding elements (c) armature conductors per path (d) armature parallel paths. 23. Calculate the distribu factor for a 36-slot. (8) A SIMPLE explanation of Full Pitch and Short Pitch Winding. , pole-pitch ) is known as 'Full Pitch'. With a full-pitch coil, the emfs induced in the two coil sides are in phase with each other and the resultant emf is the arithmetic sum of individual emfs. m. 2. The coils are place in 60 uniformly distributed slots around the inner perimeter of the stator. Assume the coil span as 150° electrical. The first coil lies in slots 1 and 16. e. 14. Back Pitch Question 2: A 36-slot, 4-pole, dc machine has a simplex lap winding with two conductors per slot. 966 Distribution factor = 0. On the other hand, if its span is less than a pole-pitch. EXAMPLE: Calculate the pitch factor for a alternator winding with 36 slots, 4. This lecture will discuss;1. It is always 180° electrical. For alternator having fractional pitch winding of 8/14 the coil span is 102. Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. of poles, P= 4 No, of slots = 24; No. The short equidistant winding of 48 grooves, 4 pole three phase asynchronous motor individual layers of the present invention is totally 12 groups of coils, and every group of coil is comprised of two coils; The pitch of all coils, shape and size are all identical, and coil span is 9; And adopt overlapping method rule and Salient pole. 3. The coil span is five-sixth of a pole pitch. Answer: 0. The coil span is 150°. When the parallel path is twice the number of poles then it is known as Duplex Lap Winding. It is possible to suppress the higher harmonics by using double-layer windings using shortened span coils. If the coil span is less than the pole pitch (as in coil B where coil pitch is 3/4th of the pole pitch), then the Fig. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. ; It means one side of the coil in a particular slot, after how many conjugative slots, the other side of the same coil is placed. 0 C. Coil–span or coil-pitch. We will start Red at slot 1. 6. What is meant by a full pitch winding a fractional pitch winding? If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. A pole pitch is always 180 electrical degrees, regardless of the number of poles on the machine. Register to editPitch factor problem. The pitch factor, in rotating electrical machinery, is. If the pole span or coil pitch is equal to the pole pitch (as in the case of coil A where pole-pitch of 4 has been. ∴ e = E 1 + E 2 = 2E. e. C machines short pitch winding is generally used to reduce harmonic and. After updating the table, the drop-down list below lets you select whether to display the number of slots per pole per phase, the maximum possible fundamental winding factor, the number of winding symmetries,. The correct answer is option 2): 5 slots Concept: Coil span (also known as coil pitch) is defined as the peripheral distance between two sides of a coil, measured in terms of the number of armature slots between them. Better emf waveform in case of generators 6. Solution for Calculate the pitch factor for the following windings: a) 72 stator slots, 6 pole, coil span 1 to 10. 86. Calculate the emf generated in each phase when the machine runs at 375 rpm Hey Aspirants. Calculate the average voltage generated in a six-turn full pitch coil of a 25 cycle alternator if the. 10 are one pole pitch or n slots or 180° electrical apart, the coil is called full pitch coil. TYPES OF AC MACHINES WINDINGS. (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. A 6-pole, 3-phase, 60 cycle alternator has 12 slots per pole and four conductors per slot. of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a. A pole pitch is always 180° electrical regardless of the number of poles on the machine. it is said to the a fractional-pitch coil. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. . 966The pole pitch, mQ ′ ∕ p, is also fractional, so that the coil-span cannot be of full-pitch. 5 c) 18 d) 6 View Answer. A 4-pole, 50-Hz, star-connected alternator has 15 slots per pole and each slot has 10 conductors. 50 Q 1. To understand, it simply means that one parallel path is in N-Pole and another parallel path in S-pole. 7. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . fs. MARASIGAN, REE, RME Figure 11 If the coil span is less than the pole pitch (as in coil B where the coil pitch is ¾ of the pole pitch) then the winding is fractional pitched. 86 O 119. It means that coil span is 180 electrical degrees. of slots per pole = 15 but coil span is… question_answer Q: A synchronous generator is generating 320 V at 55 Hz at a field current of 3. o5Wb. ∴ e = E 1 + E 2 = 2E. The pole arc should be about 70% of pole pitch and length of core about 1. The coil span is 150°. In such coils, the two coil sides are not under the poles. View full document. The pitch factor. Lap winding • Suppose we want to make a lap winding for a P = 4 pole D. Calculate the RMS value of the induced emf per phase of a 10-pole, 3-phase, 60_Hz alternator with 3 slots per pole per phase and 4 conductors per slot in two layers. of a 10-pole three-phase 50Hz alternator with 2 slots per pole per phase and 4 conductors. Pitch Factor or Coil Span Factor is defined as the ratio of EMF generated in the short-pitch coil to the EMF generated in the Whefull-pitch coil. the coil-span needs to be increased, so as to link a higher flux. 1kv. Determine the equation for the emf induced in one turn, and its RMS value. the core length 32 cm, and the stator coil span four fifth of the pole pitch. Generators 897. fs. The pole pitch is always 180 degrees electrical regardless of the number of poles in a machine. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. . Calculate the pitch factor for an alternator winding with 36 slots, 4 poles, and coil span of 1 to 8. Back Pitch. 125 Wb and a 25% third component. m. I need answer within 20 minutes please please with my best wishes. What is the pitch factor if a six-pole, three-phase alternator has 72 slots and a coil span of 1 to 10? Solution: 72 slots 6 poles = 12 slots pole k P = sin θ P 2 = sin (10-1) 12 × 180 ° 2 = 0. y=Coil span τ=Z/2P is the Pole pitch or full span II. arrow_forward. The flux per pole is 80 m Wb and the coil span is 160° electrical. coils having span which is equal to one pole-pitch i. The arc diagram contains all the necessary information for connecting the pole-groups correctly. Pole pitch is always equal to 180o. Calculate the emf generated in each phase when the machine runs at 375 rpm Hence, pitch factor or coil span factor K p = Cos(/2). a. 10. Note. Coil span Coil span (also known as coil pitch) is the angular distance between two sides of a coil, measured in terms of armature slots. Answer: a. The pitch factor for third harmonic in an alternator having 18 slots per pole and coil span 5/6 of pole pitch is _.