This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Now labeling the starting end of each coil is easy, assuming an RYB phase sequence taking red as the reference. ∴ Coil span factor, Where β is the angle through which the coil is short pitched. The pitch factor corresponds to the mean span of the coils of the winding with respect to the pole pitch while the distribution factor quantifies the flux reduction due do the. In a 4-pole, 35 slot d. The pitch factor [3], [6], [7], [8] is the ratio of coil voltages for a fractional-pitch winding to those for a full-pitch one. 0. Q: For alternator having fractional pitch winding of 8/14 the coil span is 102. In other words, the distance between the two coil sides of a coil will be equal to the distance. The fundamental flux per pole is 0. 2:. Winding table. Electrical Engineering. Hence emf induced in one side of. The flux per pole has a fundamental component of 0. 339 IC function as. e. K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. 924 359. A pole pitch is always 180 electrical degrees, regardless of the number of poles on the machine. TERMS Coil Throw: The location in an armature core of the sides of a coil starting in slot number one (1). Coil–span or coil. of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a full-pitch winding. 6A. pole pitch5. #Alternator #Protectionofalternator#elect. Transcribed Image Text: (d) obtain a full-pitch winding. 05: B) 0. If we used short pitched winding for armature winding than pitched factor is included in EMF equation in Alternator. Assume the coil span as 150° electrical. Q2: 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 3 rd harmonics. B = 10 sin theta + 2 sin 3 theta kilo-gauss, when theta is measured from the neutral axis. The coil is also short-pitched (eg spam of two sides of. Q: Explain the following Armature Winding Terminologies (i) Coil Span (ii) Resultant Pitch A: In the following section, coil span and resultant pitch related to armature winding technology has… Q: Assume that a four-pole de machine has an armature with a radius of 15 cm and an effective length of…In the second example, with a pole pitch of 15. What is a coil span? The coil span is the distance between one conductor of a certain phase and the corresponding return conductor. BUY Delmar's Standard Textbook Of ElectricityThe slots per pole per phase are 8 and the coil span is 20 slots. 10 slots d. m. I need answer within 20 minutes please please with my best wishes. It is always equal to 180° electrical. Study with Quizlet and memorize flashcards containing terms like A lap winding, Twice, Full-pitch and more. m. g. In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch, back pitch, pole pitch, coil pitch, etc. 125 Wb and a. When the winding is full pitched, coil span is equal to the pole pitch. Two-and four-pole rotors have normally nonsalient poles, while rotors with more than four poles have salient poles. 1822 V C. Author: Frank D. This winding has 12 slots per pole per phase. m. Here, e = E 1 = E 2 = E. C. M. The pitch factor, in rotating electrical machinery, is. 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. The. F induced in the other side of the coil. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Calculate the rms value of the induced emf/phase of a 10 pole, 3 , 50 Hz alternator with and in 2 layers. . The arithmetic sum of induced emfs is 2E. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . = pitch factor or coil span factor ? = ratio of coil span and pole pitch ? = angle of short pitch ? = slots per pole ? = slots? = poles? = short pitch 𝑐 = coil span Distribution Factor, Breadth Factor, Winding Factor, Spread Factor (Kd) Similar to full pitch coils, concentrated winding is also rare in practice. It. 3 percent. 1kv. Degree of Reentrancy c. fs. 6 Pole pitch Coil span y=Z/2P + 1, y=Z/2P - 1 7 Conditions of P/C ϵ N, meaning P cannot be 1 and for three phase C/m N symmetry Single layer fractional slot winding with Z=30, and 2P=4 q 2 1 or q 5 D. , coil span is 180º electrical) is called a full-pitch coil. The meaning of FULL-PITCH WINDING is the winding of an armature in which the two sides of the armature coil span a distance equal to the pole pitch. In a short pitch coil, the coil span will be (180 -. fs. (Assume lap. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. (Elect. 1. Calculate the pitch factor for: (i) Fundamental (ii) 3 rd harmonic (iii. It means that coil span is 180 electrical degrees. m. Give the values of front pitch, back-pitch and commutator pitch. It is always less than unity. 7. 2 sin 50 +0. p. A pole pitch is always 180° electrical regardless of the number of poles on the machine. Chording: with coil-span less than pole pitch 5. of consecu- tive turns (c) distribute the winding. f. Where n is the nth harmonic. Distribution factor (K d): The ratio of induced emf in the coil group when the winding is distributed in number of. Define Pitch Factor /Distribution Factor and present the formula to calculate. Transcribed Image Text: (d) obtain a full-pitch winding. Pole pitch = 180 electrical degrees = S/P = 2C/P. Concept: Coil pitch or coil span: It is defined as the angular distance between the two coil sides of one coil. A 3-phase, 50 Hz, 2-pole, star connected turbo alternator has 54 slots with 4 conductor per slot. 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). Back pitch (Y b): It is the span of the coil from the back end. d5. A. If the coil span is less then one pole pitch than it is called short pitch coil. We must note that the coil-pitch and flux barriers of the NC2 are adjusted as shown in. A pole pitch is always 180° electrical regardless of the number of poles on the machine. Expert Solution. Coil Span or Coil pitch. It is possible to suppress the higher harmonics by using double-layer windings using shortened span coils. Coil Span: It is the angular distance between the two sides of the coil. If the coil span factor is 0. 0 C. If the coil span is exactly equal to the pole-pitch, then such a coil is called a full-pitch coil. a. The winding distribution factor of the alternator is. Zoom In Zoom Out Reset image size. 9 and the efficiency is 0. In a 4-pole, 35 slot dc armature, 180 electrical degree coil span will be obtained when coils occupy _____ slots. Coil Span:The angular distance between the centers of two adjacent poles on a machine is known as pole pitch or pole span. 4. 1 is connected to coil side in slot No. 363Wb and a 15% third harmonic. Since this machine has 8 poles and a pole-pitch of 48/8 = 6 slots, the coil pitch here is 5/6 = 0·833 p. 3, Fig. Coil span or coil pitch Ys: It is the distance between the two sides of a coil measured in terms of armature slots. At this situation, two opposite sides of the coil lie under two opposite poles. A. The primary reason for making the coil span of a d. There. u. because of that the pole pitch is 9/4 of the slot pitch, thus the three-phase symmetric distributed windings consist of 18 double-layer coils that can be used, in which each coil span. 2-pole star-connected, armature winding of a generator has 6 slots per phase. You can compare the maximum fundamental winding factor for different. fs. . If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. Hence, the pitch factor or the coil span factor for the n th harmonic is given by, kcn = cos nα 2. The coil pitch is 5/6th of the full pitch and the flux per pole is o. For alternator having fractional pitch winding of 8/14 the coil span is 102. The slots per pole per phase are 8 and the coil span is 20 slots. For n th harmonic. The distribution of upper-side voltage phasors is the same as that of coil voltage phasors,. The separation between the top and bottom sides of a coil is called Coil span. ; Coil Span: It is the angular distance between the two sides of the coil. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. m. 6-phase fractional-slot-per-pole-per-phase Interior Permanent Magnet (IPM) machine having a novel topology of 18-slot, 8-pole, and, 6-phase, 48-slot, 8-pole IPM with distributed windings, both. 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 ). In order to eliminate, for example, the third harmonic, as the most significant one, the coil span should be equal to 2/3 of the pole pitch, i. It is using an armature winding which is short pitched by one slot. Commutator bars per pole. I need answer within 20 minutes please please with my best wishes. Hence, the coil span in three phase AC machines must be (frac{5}{6}th) of pole pitch. 0. In a full pitch coil, the coil span will be 180° electrical (equal to pole pitch). 11. 587, 0, khi 9. Thus the total emf at the coil terminal A & B is the phasor sum of (E 1 +E 10), (E. Find the terminal voltageon open circuit. 24, and assume first a short-pitched coil spanning half a pole pitch, then a long-pitched coil spanning one and a half. 26. Advantages of short pitched,( chorded, fractional slot) windings are:-The amount of copper used in the overhang (end winding) reduced and hence a saving on copper,Based on pitch of the coil (i) full pitched (ii) short pitched windings. 015 Wb. Calculation:A coil rotated in a magnetic field induces current. ∴ e = E 1 + E 2 = 2E. K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. PITCH FACTOR OR COIL SPAN FACTOR Pitch Factor – the ratio of the voltage generated in the fractional pitch coil to the voltage generated in the full pitch coil. Draw the developed diagram andshow the positions of brushes. Calculate the pitch and distribution factors for the fundamental, the third, and the fifth harmonics in the phase voltage. When the parallel path is twice the number of poles then it is known as Duplex Lap Winding. , pole-pitch ) is known as 'Full Pitch'. 339 IC function as. . The alternator has 18 slots per pole and the first coil lies in slots 1 and 16. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. ’s of consecutive turns c. It is expressed in terms of electrical space degree. Study now. Calculate the coil span factor or the pitch factor for the following windings: ( a) 54 stator slots, six-poles, when coil spans 1 to 8. It is in fact the periphery of the armature spanned by the two sides of the coil. It is usually measured in terms of teeth, slots or electrical degrees. 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. Sanfoundry Certification Contest of the Month is Live. Figure 4 shows the flux distribution linked to a short-pitch coil. winding is fractional-pitched. What is the short pitch in electrical degrees. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. Please see Electrical 4 U site for article on Armature Windings: Pole Pitch, Coil Span And Commutator Pitch. Full Pitch and. 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. Normally the nearest whole number is selected which is 6 in present case. 1993) Example 37. Here ξ is the chorded angle or short pitch angle. – Comparator. If the coil-span (or coil-pitch) is equal to the pole-pitch, then the coil is termed a full-pitch coil. D. 2. Pitch factor. Both, 7/9 and 8/9, are equally close to 5/6 but I would select 8/9 for better flux utilization. The coils are place in 60 uniformly distributed slots around the inner perimeter of the stator. The induced emf in each coil side. When a coil is having a span of 180° electrical, it is called a full-pitch coil. Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. The pitch factor corresponds to the mean span of the coils of the winding with respect to the pole pitch while the distribution factor quantifies the flux reduction due do the winding distribution inside a finite number of slots. Commutator pitch Y C = ±1. 8. e. 160 degrees b. ( c) 96 stator slots, six-poles, coil spans 1 to 13. Calculation: Given that, Slots S = 72. Let us assume that, a coil is short pitched by an angle α (electrical degree). 👉 (2008-2018) With solution, BRANCH Wise Click the Link-ELECTRICAL. If coil span is equal to pole pitch then it is called full pitch coil. b) 96 stator slots, 6 pole, coil span 1 to…. Pole pitch is always equal to 180o. It is expressed in terms of number of slots per pole. Pole – pitch. 1. Coil Span or Coil Pitch Question 1: For a 6 pole DC armature with 14 Slots having 2 coil sides per slot. Explanation: Pole pitch is called as center to center distance between two adjacent poles. voltage wave form which resembles a sinusoid to a better degree than that in a full pitch winding Example 1: Calculate the K d for a machine having 9 slots per pole for the following cases: a) A 3 phase winding with 120 0phase groups b) A 3 phase winding with 60 0 phase groups Solution: 0 209 180 a) Since one phase occupies. 85 lagging. Result- ant flux in the air-gap is 5 ´ 10– 2 webers per pole sinusoidally distributed. ∴ e = E 1 + E 2 = 2E. *. If the angular distances between the two coil sides are less than one pole pitch, it is termed short pitch or fractional pitch coil. The armature coils are all-connected in series. The commutator is also known as a reverser. The harmonic reduction in the voltage waveform of concentrated winding axial field PM machines is the subject of interest for many researchers. e. 2. The four coils of Phase A would span between slots 1 and 6, slots 2 and 7, slots 7 and 12 and slots 8 and 1. It may be the full pitched or short pitch. 1NP2. m. Pole – pitch. by 20o to full pitch distance. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . Step by step Solved in 2. See answer (1) Best Answer. coil pitch in terms of slots4. Wiki User. Coils 1, 2 and 3 shown in Fig. 1. Calculate the RMS value of the induced emf per phase. Electrical Engineering questions and answers. is known as coil span. You can read more about Full Pitch and Short Pitch Winding at:. in the two coil sides. 16 wb/pole and is distributed sinusoidally over the pole. Since slot pitch is 6, 6 slots have upward arrows, 6 down and so on. 1. Share on Whatsapp Latest UPSC IES Updates. 2 sin 30+0. 1. m. , Y R = Y B − Y F . the coil will be in 180o. Author: Robert L. pitch factorThe flux distribution Curve of a smooth-core 50 c/s generator is. e. 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. In a 4 pole, 3 phase alternator, armature has 36 slots. Download Solution PDF. Coil Span: It is the angular distance between the two sides of the coil. Last edited by markadlerdallas. in the two sides of the coil. 2 are short-pitched, full-pitched and over-pitched coils respectively. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. Power System Analysis and Design (MindTap Course List) 6th Edition. Looking at the diagram in the question. 6. We will start Red at slot 1. 125 Wb and a. 951: C) 0. This distance is measured in terms of armature slots or armature conductors that come between two adjacent pole centers. c. Where n is the nth harmonic. m. α = Angle of short pitch = 20o. Hence emf induced in one side of. Supposing that each coil under the pole pitch has. If t he coil pitch is y =3, the diame tral w inding w ill have the f. Coil-span or Coil pitch (Y s) It is the distance, measured in terms of armature slots (or armature conductors) between two sides of a coil. 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. TABLE I Winding factors for different combinations of pole numbers p and slot numbers Qs Qs p 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42. The dc armature winding in which coil sides are a pole pitch apart is called ____ winding – Full- pitch. 4. The resultant coil voltage $𝐸_{𝐶}$ is equal to the phasor sum of $𝐸_{𝐶1}$ and $𝐸_{𝐶2}$. Coil span σ, winding factor k w, pole ratio G r and N c for possible pole-slot combinations in the proposed FMPM machine. 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. It is expressed in terms of electrical space degree. Obtain a coil span of 180 degrees (electrical) b. • Winding pitch is the coil span divided by the pole pitch, e. This answer is:Full-pitch windings have a coil pitch of 1, which means the coil span is equal to the pole pitch. Calculate the emf generated in each phase when the machine runs at 375 rpmHence, pitch factor or coil span factor K p = Cos(/2). The commutation is improved in short-pitched coil, but the emf induced will be less compared to full-pitch. 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. The separation between the top and bottom sides of a coil is called Coil span. The reduction fraction is the pitch factor. Pole pitch is always equal to 180o. Electricity for Refrigeration, Heating, and Air Conditioning (MindTap Course List). 7. If the coil pitch is shortened by 1/n of the pole pitch then the nth harmonic will be suppressed or the harmonics near to n will be with low voltage, because of the. • In double layer windings used in. g. The distance between the two sides of a coil is called the coil. Publisher: McGraw-Hill Education. 50Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. 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. 966 Distribution factor = 0. A 3 phase 1800 kVA, 3 kV, 50 Hz, 250 rpm, salient pole. Calculate the emf generated in each phase when the machine runs at 375 rpmHey Aspirants. ISBN: 9780073373843. When the coil span is less than 180 electrical degrees, the winding is called short pitched or fractional pitch or chorded winding as shown in Fig. 10. K pn = cos nα/2. 23. It is always 180° electrical. Alternatively, this type of coil is also called a short-pitch or chorded coil. y=Coil span τ=Z/2P is the Pole pitch or full span II. What is the flux per pole if the voltage on open circuit is 1. Draw the double layer winding layout for a 24 slot stator and 4 pole alternator 3. It is usually measured in terms of teeth, slots or electrical degrees. 6. . 6. In this paper, the influence of changing the span of the concentrated coil for a certain pole pitch on the harmonic content in the output voltage. Where n is the nth harmonic. The arithmetic sum of induced emfs is 2E. ’s of consecutive turns c. arrow_forward A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. Full pitch winding. The flux per pole is 0. Each of these coil spans is five slots, so this choice of winding pattern is referred to as “Five-Sixths” pitch. 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. Calculation:The angular distance between the two coil sides is less than one pole pitch, it is termed short pitch or fractional pitch coil. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. Pole Pitch, Coil Span, Back Pitch, Front Pitch, Commutator Pitch in Armature Winding of DC Machines are explained in this video. It is usually measured in terms of teeth, slots or electrical degrees. The slots per pole per phase are 8 and the coil span is 20 slots. Coil – span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. Copy. Duplex Lap Winding. Here we have a 4-pole alternator with a 48 slot stator. . the core length 32 cm, and the stator coil span four fifth of the pole pitch. 125 Wb and a 25% third component. In this case, the coil sides lie under opposite poles, hence the induced e. This lecture will discuss;1. The coil pitch is 12/15. coil pitch in terms of slots4. fs. In a 4 pole, 54 slot dc armature, calculate the coil span. in. The armature winding is housed in 360 stors with 6 conductors per slot. 13. 85 lagging. Distribute the winding uniformly under different poles d. Author: Frank D. This lecture will discuss;1. c. 5. Por a full-pitch coil, Kr = I (unity) r:or a fractional-pitch coil, Kr < 1 6. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers. Front pitch (Y f):. Use a diagram like that shown in fig. ; Here, e = E 1 = E 2 = E. First. Type your question here Calculate the voltage per phase for a 3-phase 1500 rpm, 4-pole alternator having a 16 conductors per slot connected in two layers. Here, e = E 1 = E 2 = E. ( b) 42 stator slots, four-poles, coil. Not ( I want a solution within 20 minutes. 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. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. 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. It may be the full pitched or short pitch. . Then, the pitch factor will be equal. Chorded-coil. Calculate the distribu factor for a 36-slot. Hence emf induced in one side of the coil will be in 180 phase shift with emf induced in the other side of the coil. It is usually measured in terms of teeth, slots or electrical degrees. Download these Free Coil Span or Coil Pitch MCQ Quiz Pdf and prepare for your upcoming exams Like Banking, SSC, Railway, UPSC, State PSC. Question.