*. Calculate the sinusoidally distributed flux per pole required to give a line voltage of 11 kV on open circuit, and the full. 10 A three-phase, wye-connected alternator has 15 slots/pole. The displacement between the sides of the coil is called the coil span. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. 11. Pitch factor. If the coil span is less than the pole pitch (as in coil Fig. are e. D 2 L = Q / C 0 ns = 500/( 153 x 8) = 0 m 3 Using round poles for the salient pole alternator and assuming ratio of pole arc to pole pitch as 0 and pole arc equal to core length. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. Learn what a pole pitch is, the pole pitch formula & definition, and how to. Table of Contents Terms used in the armature winding Conductor Turn Coil Coil Side Front end and Back end connector Pole Pitch Coil Pitch or Coil span Pitch of a winding or winding pitch Back Pitch Front Pitch Resultant Pitch Commutator Pitch Calculation of pitch values Terms used in the armature winding TERMS Coil Throw: The location in an armature core of the sides of a coil starting in slot number one (1). 455 V D. Use a diagram like that shown in fig. Download Solution PDF. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. When coil sides are pole pitch apart, the DC armature winding is called as _____ a) Multiplex b) Fractional-pitch c) Full-pitch d) Pole-pitch View Answer. 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. Note that although the span of a full-pitch coil is not an integer in a fractional-slot winding, the full-pitch coil is nevertheless an im- The correct answer is option 3. g. 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;. Download Solution PDF. Alternatively, this type of coil is also called a short-pitch or chorded coil. (a) multiplex (b) fractional-pitch (c) full-pitch (d) pole-pitch 3. 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 0. spanning over 180° (electrical). fs. 57 O 127. This is shown in the figure to left. 966 and 0. • Pitch of a Winding (Y) In general, it may be defined as the distance round the armature between. First, a double-layer winding is investigated with the number of slots Q, pole pairs p and a constant coil pitch . 24 B where coil pitch is 3/4th of the pole pitch), then the D. where B is the flux density, µ is permeability of material, A is the area of the magnetic field path, whereas the same subscript used in is used thought the paper. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. Participate Now!Since 1 pole pitch is the angular distance between the two consecutive poles which is equal to 180 electrical degree, therefore the coil span for full pitch coil is also equal to 180 electrical degree. For 20 slots, 4 polesThe winding of a 4-pole alternator having 36 slots and coils and a coil span of 1 to 8. ) 2 Angle by which the coil is short pitched, B = a = 30° Distribution factor, Ky = Pitch factor or coil span factor, K, = cos 6 = cos. 951: C) 0. 4 Winding Factor Both distribution factor (Kd) and pitch factor Kp together is known as winding factor Kw. ) A 6-pole, 3-phase, 60-Hz alternator has 12 slots per pole and four conductors per slot. Pole pitch = S/P. When the winding is full pitched, coil span is equal to the pole pitch. Figure 2 illustrates a full pitch winding. But, the given coil is short-pitched so that the coil span is $$\mathrm{coil\:span = (14 − 1)β = 13β}$$ $$\mathrm{∴\:α = (15 − 13)β = 2β = 2 × 12° = 24°}$$ Winding factor for fundamental component Pole pitchis defined as the peripheral distance between the center of two adjacent poles in a DC machine. arrow_forward A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. 125 Wb and a. Download these Free Coil Span or Coil Pitch MCQ Quiz Pdf and prepare for your upcoming exams Like Banking, SSC, Railway, UPSC, State PSC. They save copper of end connections. 1kv. ∴ e = E 1 + E 2 = 2E. 85. Fig. The pitch factor, in rotating electrical machinery, is defined as the ratio of resultant EMF of a _____ a) full-pitched coil to that of a chorded coil b) full-pitched coil to the phase EMF c) chorded coil to the phase EMF d) chorded coil to that of a full-pitched coil View AnswerCalculate the pitch factor for an alternator winding with 36 slots, 4 poles, and coil span of 1 to 8. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. Pole – pitch. Understand what Full Pitch and Short Pitch Windings are, and what Coil Span is. 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 . Question. Emf induced per coil side is E. What are the different types of stator windings in induction motor? Ø. m. At this situation, two opposite sides of the coil lie under two opposite poles. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. You can compare the maximum fundamental winding factor for different combinations of number of poles and number of slots, display the winding layout for different coil spans,. advertisement. Similarly, for a coil having a span of 2/3 pole-pitch, kc = cos 60°/2 = cos 30° = 0. In a 4-pole, 35 slot d. 1K 39K views 2 years ago AC Electrical Machines Jimit Tutorials In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch,. 25 O 5. A. It equals pole pitch = Z P . of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a. Armature Windings: Pole Pitch, Coil Span And Commutator Pitch. (16) k p1 = sin β 2 <1 where β is the coil span in °electrical, β=sα; s is the coil span in slots. full, s. e. A pole pitch in an electrical machine is equal to 180° electrical. Determine the phase andline values of emf if the machine runs at 600 rpm and the flux per poleis 0. Coil spanA: slot angle = 180slot per pole = 18015 = 12 pole pitch = no. 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. The armature coils are all connected in series. The winding is 5/6 pitch. 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. Two-and four-pole rotors have normally nonsalient poles, while rotors with more than four poles have salient poles. 7. Hence E. 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. Short-pitched coils are deliberately used because of the following advantages: 1. placed in the top layer of the slot & the other side of the coil is placed in the bottom layer of another slot nearly a pole pitch apart. Create a winding table for the given armature: Winding 1: 4 pole, 11 slots, 11 commutator segments, double layer, progressive, simplex WAVE winding Show the solutions. If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched coil. Distribute the winding uniformly under different poles d. 911 V B. Pole and slot numbers. For n th harmonic. ∴ e = E 1 + E 2 = 2E. 0 D. 16 wb/pole and is distributed sinusoidally over the pole. (A) Determine the pitch and distribution factors. It is always 180° electrical. To get a coil around every tooth, we need two winding layers (double layer winding). You can compare the maximum fundamental winding factor for different. arrow_forward. of consecutive turns (c) distribute the winding uniformly under different poles (d) obtain a full-pitch winding. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. A 4 pole, 12 slot lap wound dc armature has two coil side per slot. 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. arrow_forward. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. In a 4-pole, 35 slot dc armature, 180 electrical degree coil span will be obtained when coils occupy _____ slots. c. Table of Contents Terms used in the armature winding Conductor Turn Coil Coil Side Front end and Back end connector Pole. • In double layer windings used in. 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. arrow_forward A. 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 highest flux we get, if we define the coil span equal to the pole pitch . must be exactly equal to pole pitch C. C. Thus, the total. Last edited by markadlerdallas. 125 Wb and a 25% third component. When the coil span is less than pole pitch (180 deg electrical), the winding is called short pitched or chorded. If the coil span is equal to the Pole pitch then it is called a full pitch coil. For example, the below image shows the 2p6s machine with double layer winding with the coil span being 2 slots (120 degree electrical) instead of 3 slots (180. are e. 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. 12 Wb and a. Fig. B. As the two coil sides are separated in space by an angle of (180-ε) i. #Alternator #Protectionofalternator#elect. K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. [Answer: 0. Coil span σ, winding factor k w, pole ratio G r and N c for possible pole-slot combinations in the proposed FMPM machine. 0. Let us assume that, a coil is short pitched by an angle α (electrical degree). A) 1. TERMS Coil Throw: The location in an armature core of the sides of a coil starting in slot number one (1). There are 2,500,000 Maxwells entering the armature from each North Pole, and this flux is sinusoidally distributed along the air gap. I need answer within 20 minutes please please with my best wishes. It is using an armature winding which is short pitched by one slot. by 20o to full pitch distance. 2 Selecting the coil span for a given pole pitch. Step by step Solved in 4. However in practise this often isn’t the best choise because of the high harmonic content. Coil Span or Coil Pitch Question 1: For a 6 pole DC armature with 14 Slots having 2. The distance between the two sides of an individual coil of and AC armature winding id termed the coil pitch. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch. . The coil span is 150 electrical degrees. Where n is the nth harmonic. When 40V DC voltage is applied to a single-phase AC motor, it draws 1A current. e. View the full answer. If coil span is 6 and if top coil side of a coil lies in slot 1 then the. If coil span is equal to pole pitch then it is called full pitch coil. Pitch Factor or Coil Pitch. The arc diagram contains all the necessary information for connecting the pole-groups correctly. 1 times the pole arc. coil pitch in terms of slots4. 50Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. m. The coil span is 150°. Three kinds of coil spans are used, they are 4-solt pitch, 3-solt pitch, and 2-solt pitch. 10. The resultant coil voltage $𝐸_{𝐶}$ is equal to the phasor sum of $𝐸_{𝐶1}$ and $𝐸_{𝐶2}$. The coil-span chosen is of course less than the full-pitch. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Full pitched coils have the advantage of giving maximum emf induced in the coil. However the waveform of the resultant emf can be improved by making the. less than 180° electrical, the coils are called, short pitched coils or fractional pitched coils. K p = cos (nα/2) Where n is the nth harmonic. is B = 10 sin theta + 2 sin 3 theta + 2 sin 7 theta kilo - gauss, when theta is measured from the neutral axis. Its flux per pole is 0. (a) commutator bars per pole (b) winding elements (c) armature conductors per path (d) armature parallel paths. 24 O 128. 2. ; Coil Span: It is the angular distance between the two sides of the coil. If the angular distances between the two coil sides are less than one pole pitch, it is termed short pitch or fractional pitch coil. Zoom In Zoom Out Reset image size. g. Winding pitch is the coil span divided by the pole pitch, e. The reduction fraction is the pitch factor. 2. , a pitch, or an pitch, etc. c. number of slots and a coil span of two slots require at least 18 slots. ∙ 10y ago. Result Number of. of slots / slots per pole. The winding is wye-connected. If the maximum flux per pole, with a sinusoidal distribution, is 0. When the coil span is lower than pole pitch, the phasor sum of conductor voltages is less than the arithmetic sum, because of vector addition. 2 sin 30+0. Back Pitch. Expert Solution. it is said to the a fractional-pitch coil. 3K views. Degree of Reentrancy c. Each of these coil spans is five slots, so this choice of winding. Commutator pitch of a progressive lap winding is yc = +1. The coil pitch is short by 2 slots. Obtain a coil span of 180 degrees (electrical) b. A 4-pole, 50-Hz, star-connected alternator has 15 slots per pole and each slot has 10 conductors. The flux per pole is 0. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. c. 086 Wb, what will be the values of the emfs? phase. Commutator pitch Y C = ±1. 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. DARWIN M. . Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. m. Calculate the emf generated in each phase when the machine runs at 375 rpm Hey Aspirants. Back Pitch Question 2: A 36-slot, 4-pole, dc machine has a simplex lap winding with two conductors per slot. electrical degrees indicate the amount the currents in conductors has changed. 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. 36 stator slots, 4-pole, coil span 1to 8 ii. The pitch factor for third harmonic in an alternator having 18 slots per pole and coil span 5/6 of pole pitch is _. 26. 1 the coil span should be approximately equal to a pole pitch. If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. 135 degrees d. Coil pitch: The distance measured in terms of armature slots or armature conductors between two sides of a coilQuiz # Solve the following problems. 1 times the pole arc. Determine the useful flux per pole. It is expressed in terms of number of slots per pole. Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. 36K subscribers Subscribe 9. 160 degrees b. Y-connected alternator has 9 slots per pole and a full-pitch. none of the aboveThe coil span generally varies from 2/3 pole pitch to full pole pitch. Muthu RE: How. Transcribed Image Text: (d) obtain a full-pitch winding. Pitch Factor·· the ratio of the voltage generated in ti1e fractional-pitch coil to the voltage generated in the full-pitch. . Explanation: Pole pitch is called as center to center distance between two adjacent poles. Power System Analysis and Design (MindTap Course List) 6th Edition. phase shift with emf induced in the other side of the coil. 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. CONCENTRIC WINDING In unbifurcated concentric windings, the first of the q coils which is the smallest is thrown. Solution : n = Slots/pole = 36/4 = 9. Number of Commutator Segments - Number of Commutator Segments is the count of cylindrical assembly of insulated segments that are mounted on the shaft. Publisher: PEARSON. Coil Span (ii) Resultant Pitch. Here’s the best way to solve it. A six pole, three phase AC generator has 72 slots, the coil span is 12. You can investigate three-phase integer-slot, fractional-slot and concentrated windings, both with single and double winding layers where appropriate. The coil span factor is represented as For full pitch coil, the value of α will be 0⁰, cos α/2 = 1 and KC = 1. A 4-pole, 50 Hz alternator has double layer winding with 10 turns per coil and number of slots are 60. Pole pitch is the peripheral distance between two adjacent poles. 9; 21. Where it is called an over-pitched coil if the coil span is greater than the pole pitch. As against this if coils are used in such a way that coil span is slightly less than a pole pitch i. phase shift with emf induced in the other side of the coil. 26. 1. 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. † ‡ ˆ ‰ Š ‹ Œ Ž ‘ ’ “ ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿPitch factor: Full-pitched coils i. lt is also known as coil pitch. EXAMPLE: Calculate the pitch factor for a alternator winding with 36 slots, 4. Distribution factor (K d): The ratio of induced emf in the coil group when the winding is distributed in number of. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . Q: 3- Determine the coil span for 3-phase, two pole alternator, the pole pitch is equal to 18 slots and… A: For a two-pole alternator,Pole pitch = 18 slotsCoil span factor =32 Q: A 4 pole, three-phase, star-connected alternator has an armature with 120 slots and 4 conductors per…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. round the coil which is the vector sum of e. Condition for designing a Mush winding:- 21. 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. g. View full document. 707. Question: 2 Problem 2: The flux distribution curve of a smooth core 50HZ generator is B(0) = sin 8 +0. Distribute the winding uniformly under different poles d. M. 85 lagging. 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). There are 2 coil sides per slot. 2 sin 70 wb/m? where O is angle measured from neutral axis. Here, e = E 1 = E 2 = E. of slots per pole = 15 but coil span is… Q: A synchronous generator has 9 slots per pole. S 36 Solution From equation 5, pole pitch = P = 4 =9 Coil Span or coil pitch: It is the distance between the two active sides of the same coil under adjacent opposite poles. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. The winding is housed in 360 slots and has 6 conductors per slot, the coils spanning (5/6) of a pole pitch. m. 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. 4. e. . It is equal to the number difference of the conductor connected to a given segment of the commutator. ∴ e = E 1 + E 2 = 2E. Identify the approximate diameter and length of stator core,. 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. Calculate the rms value of the induced emf/phase of a 10 pole, 3 , 50 Hz alternator with and in 2 layers. We will start Red at slot 1. 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. 1993) Example 37. Expert Solution. Now labeling the starting end of each coil is easy, assuming an RYB phase sequence taking red as the reference. MMF OF ARMATURE A. . 1. , angle between the two sides of. slots. of phases = 3; No. Robert L. 0 B. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical DegreeThere are many people who want to. However, the coil span may be less than a pole pitch, in which case the coil is described as short pitched or chorded. It may be the full pitched or short pitch. It is defined as the angular distance between the central line of one pole to the central line of the next pole. For example, in a 4-pole generator with a 48-slot stator (12 slots per pole), if each coil in the stator winding spans 12 slots then the ratio is 1/1 and the winding is full pitch. The flux per pole has a fundamental component of 0. Calculate its coil span factor. 9659. the coil span is (180-ε), therefore the emf induced in these coil sides will also be separated by this angle. Author: Robert L. For A. 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). If S be the total number of slots and P be the total number of poles then coil span is S/P. Hence pole pitch is equal to total numbers of armature slots divided by total numbers of poles, we alternatively refer to it as armature slots per pole. Determine the phase and line voltages if the coil is full pitched. 4. Hence, the pitch factor or the coil span factor for the n th harmonic is given by, kcn = cos nα 2. Assuming double turn coil, Calculate the back pitch for progressive and retrogressive winding. ( b) 42 stator slots, four-poles, coil. situation, two opposite sides of the coil lie under two opposite poles. 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. 5. The coil span is 150°. Coil–span or coil-pitch. 163Wb. It may be the full pitched or short pitch. There are 0. f. Because a chording more than 1/3 pole pitch would noticeably reduce the phase emf. 2-pole star-connected, armature winding of a generator has 6 slots per phase. In general, electrical degrees equals mechanical degrees times 1/2 the number of poles. Pole pitch is always equal to 180o electrical. When the coil is having a span of less than 180° electrical, it is known as a short-pitch coil. Chording: with coil-span less than pole pitch 5. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical DegreeThere are many people who want to. 4 pole three phase winding. Calculate the distribu factor for a 36-slot. Pole Pitch, Coil Span, Back Pitch, Front Pitch, Commutator Pitch in Armature Winding of DC Machines are explained in this video. Electrical Engineering questions and answers. the coil-span needs to be increased, so as to link a higher flux. Calculate the pitch factor for (a) fundamental (b) 3rd harmonic (c) 5th harmonic (d) 7th harmonic. 33 percent of pole pitch to obtain the maximum reduction of harmonics. If the coil span is equal to the Pole pitch then it is called a full pitch coil. Cogging torque was minimized by finding an optimum magnet pole arc length and torque ripples were minimized by finding. Assume = 0. α = Angle of short pitch = 20o. , or 5/6 × 180° = 150 electrical degrees. 1 the coil span should be approximately equal to a pole pitch. Lap and Wave winding. 0. 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 ). Copy. 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. Here, e = E 1 = E 2 = E. How do you calculate winding pitch? Pitch Factor is calculated by dividing the coil throw (–) 1 (coil span) , by the number of slots per pole. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. pole pitch. 50 Q 1. When the coil span is equal to pole pitch (180 deg electrical), the winding is called full pitched winding. Let us consider, the coil has a pitch short by an angle α electrical degrees from the full pitch. This video lecture provides full understanding of pole pitch and coil pitch with examples. 0. Hence, the coil span in three phase AC machines must be (frac{5}{6}th) of pole pitch. Alternatively, this type of coil is also called a short-pitch or chorded coil. Sanfoundry Certification Contest of the Month is Live. Determine the equation for the emf induced in one turn, and its RMS value. This winding has 12 slots per pole per phase.