Calculate the pitch factor for (a) fundamental (b) 3rd harmonic (c) 5th harmonic (d) 7th harmonic. Most windings have < . Cogging torque was minimized by finding an optimum magnet pole arc length and torque ripples were minimized by finding. 85. Calculate the emf generated in each phase when the machine runs at 375 rpmHence, pitch factor or coil span factor K p = Cos(/2). 15. , Y = 2/3 τ p. . Compared to the overlapping winding above we need only 3 slots for the two poles. p. Thus the total emf at the coil terminal A & B is the phasor sum of (E 1 +E 10), (E. 96 stator slots, 6poles, coil span 1to 12. K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. On the other hand, if its span is less than a pole-pitch. The armature windings conduct AC even on DC machines, due to the commutator action (which. 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. The back pitch and front pitch adopted could be respectively. 36 stator slots, 4-pole, coil span 1to 8 ii. 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 C. There are 2 coil sides per slot. the distance between the two sides of coil is called the coil-pitch. A pole pitch is always 180° electrical regardless of the number of poles on the machine. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. 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. C. If the coil-span (or coil-pitch) is equal to the pole-pitch, then the coil is termed a full-pitch coil. 587, 0, khi 9. m. In such coils, the two coil sides are not under the poles. As against this if coils are used in such a way that coil span is slightly less than a pole pitch i. 3. 339 IC function as. g. MMF OF ARMATURE A. 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. When two capacitors of reactances 10ohms and 20 ohms are connected in parallel across a 100 V supply, total VAR drawn will be _. When the winding is full pitched, coil span is equal to the pole pitch. K pn = cos nα/2. round the coil which is the vector sum of e. The coil pitch is short by 2 slots. The Separation between the top and bottom sides of a coil is known as back pitch and is represented by (Y b). If the coil span is equal to the Pole pitch then it is called a full pitch coil. 50Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. The resultant coil voltage $𝐸_{𝐶}$ is equal to the phasor sum of $𝐸_{𝐶1}$ and $𝐸_{𝐶2}$. m. 5. 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. ∴ Coil span factor, Where β is the angle through which the coil is short pitched. Now labeling the starting end of each coil is easy, assuming an RYB phase sequence taking red as the reference. 05: B) 0. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. less than 180° electrical, the coils are called, short pitched coils or fractional pitched coils. They save copper of end connections. 339 IC function as. Calculate the sinusoidally distributed flux per pole required to give a line voltage of 11 kV on open circuit, and the full. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. Allow 10 ampere for the field current and assume a voltage drop of 4 volts for the armature circuit. Pole – pitch. ∴ e = E 1 + E 2 = 2E. The average pitch Y A = 2 B F Y Y +. the coil will be in 180o. m. Coil span σ, winding factor k w, pole ratio G r and N c for possible pole-slot combinations in the proposed FMPM machine. If the coil span is less than the pole pitch (as in coil Fig. A six pole, three phase alternator has 72 slots and a coil span of 1 to 10, is the pitch factor? A. A) 1. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. fs. Comparator. It may be the full pitched or short pitch. 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. It is usually measured in terms of teeth, slots or electrical degrees. e. Q: For alternator having fractional pitch winding of 8/14 the coil span is 102. Pole pitch is always equal to 180o. 339 IC function as. . situation, two opposite sides of the coil lie under two opposite poles. Key. 16 wb/pole and is distributed sinusoidally over the pole. Solution for Calculate the pitch factor for the following windings: a) 72 stator slots, 6 pole, coil span 1 to 10. It may be the full pitched or short pitch. 3K views. a. C machines short pitch winding is generally used to reduce harmonic and. • Winding pitch is the coil span divided by the pole pitch, e. the coil span is (180-ε), therefore the emf induced in these coil sides will also be separated by this angle. View full document. * This angle is known as chording angle and the winding employing short-pitched coils is called chorded winding. u. (Elect. When measured in electrical degrees one pole itch is equal to 1800. Zoom In Zoom Out Reset image size. 363Wb and a 15% third harmonic. e. fs. 6. e. It. 8. Coil Span:The angular distance between the centers of two adjacent poles on a machine is known as pole pitch or pole span. 26. Pole pitch is the peripheral distance between two adjacent poles. Hence emf induced in one side of. A pitch in the "region" of 5/6 is most effective to reduce 5th and 7th harmonics. The pole arc should be about 70% of pole pitch and length of core about 1. 772 x 10-3 Wb. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. The coil-span chosen is of course less than the full-pitch. BUY. Example: the throw could be to 9 meaning that one side of the coil is. This lecture will discuss;1. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. It is sometimes convenient to speak of an armature coil span as having a fractional pitch expressed as a fraction e. 31. To calculate the pitch factor, we need to consider the pole number and the fractional pitch. Pole pitch = 180 electrical degrees = S/P = 2C/P. 150 degree (electrical). • To view the coil sides / coils, we must look below from above the slots as depicted in figure. 363Wb and a 15% third harmonic. arrow_forward How to calculate the pitch factor of a 8 pole alternator with an armature wound coils having 18 / 24 fractioanl pitch. 👉 (2008-2018) With solution, BRANCH Wise Click the Link-ELECTRICAL. The random wire placement leads to a wider distribution of resulting wire length on the coil body and consequently a wider range of electric coil resistances. The pole pitch is defined as the distance between two consecutive poles. 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. • Coil span is nothing but the spacing between the two coil sides of a coil. Distribute the winding uniformly under different poles d. of slots per pole = 2 = 6 saree tensed gOSeaee Slot pitch, a = oF slow/pole > No. 1kv. Y-connected alternator has 9 slots per pole and a full-pitch. Expert Solution. . 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. Determine the useful flux per pole. If the coil. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. Petruzella. I need answer within 20 minutes please please with my best wishes. K pn = cos nα/2. 12Wb and a third harmonic component. Please see Electrical 4 U site for article on Armature Windings: Pole Pitch, Coil Span And Commutator Pitch. 2. Degree of Reentrancy c. The. c. If the coil span is reduced by one slot, then the phase angle α between the induced EMFs in the two sides of the coil is given as. When the parallel path is twice the number of poles then it is known as Duplex Lap Winding. Pitch Factor·· the ratio of the voltage generated in ti1e fractional-pitch coil to the voltage generated in the full-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. 455 V D. The flux per pole has a fundamental component of 0. A coil is said to be fully pitched when the coil span is made equal to the pole pitch of the machine. You can read more. Better emf waveform in case of generators 6. However, the coil span may be less than a pole pitch, in which case the coil is described as short pitched or chorded. First. P˚ Kp = sin [(90°)(pitch)] Kp = sin 𝟐 PROBLEM 1: A 6 pole, 3Φ AC generated has 72 slots, the coil span is 12. P i t c h f a c t o r = W i n d i n g f a c t o r P o l e p i t c h. It may be the full pitched or short pitch. 13. The skew factor reflects the flux reduction if the winding is angularly twisted along the axis. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. in. C. 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. #10 A 4-pole,3-phase, y-connected induction motor has 48 stator slots 8 series conductors per slot and coil pitch of 83. The coil span is five-sixth of a pole pitch. a coil. The distribution of upper-side voltage phasors is the same as that of coil voltage phasors,. Problem. A pole pitch is always 180° electrical regardless of the number of poles on the machine. 163Wb. Download these Free Coil Span or Coil Pitch MCQ Quiz Pdf and prepare for your upcoming exams Like Banking, SSC, Railway, UPSC, State PSC. pole pitch5. Each of these coil spans is five slots, so this choice of winding pattern is referred to as “Five-Sixths” pitch. . The coil span is 150 electrical degrees. Calculate the no-load terminal voltage, if the speed of the alternator is 1500r. ) A 6-pole, 3-phase, 60-Hz alternator has 12 slots per pole and four conductors per slot. 851: D) 0. the north pole, the other coil side should be under the center of the south pole. In a 4 pole, 3 phase alternator, armature has 36 slots. Short pitch coil: If the angular distances between the two coil sides are less than one pole pitch, it is termed a short pitch or fractional pitch coil. Publisher: McGraw-Hill Education. winding is fractional-pitched. Then the coil span value is _____. In a 4 pole, 3 phase alternator, armature has 36 slots. Result Number of. c. Calculation: Given that, Slots S = 72. 5 are the stator low-order voltage harmonics for the different motors with 120°, 140°, 160° and 180° coil pitch at half load, full load and overload, respectively. 98: 61. where: coil. For n th harmonic. Chorded-coil. A. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. Coil Span (ii) Resultant Pitch. Resultant pitch Y R is even, being the arithmetical difference of two odd numbers, i. 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. The armature has double layers winding. 951, 0. When a coil is having a span of 180° electrical, it is called a full-pitch coil. Last Answer : If the coil span is equal to pole pitch, the winding is called as full pitched winding. 25 O 5. The pole pitch is 35 cm, the core length 32 cm, and the stator coil span four fifth of the pole pitch. (A) Determine the pitch and distribution factors. The coil span is 150°. of slots / slots per pole. the coils cannot be full - pitched; they may be short - pitched with 15 slots, or long - pitched with 16 slots. Calculate the pitch factor for an alternator winding with 36 slots, 4 poles, and coil span of 1 to 8. It falls short by 1/6 pole-pitch or by 180°/6 = 30°. So if coil span is ‘n’ slots or 180° electrical the coil is called 180° full pitch coil. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. Not ( I want a solution within 20 minutes. 2 Winding design with star of slots The star of slots is a collection of phasors which illustrates allIf α be the angle in electrical degrees, by which the span of the coil is less than a pole pitch in the alternator, then mathematically pitch factor is defined as. three factors: the pitch factor (also called chording or coil-span factor), the distribution factor (also called breadth, spread or zone factor) and the skew factor. arrow_forward. 7. 165 degrees. Pole pitch is always equal to 180o electrical. The theoretical coil pitch yp (or span) is the number of slot pitches between the two coil-sides of the same coil. 707 B. Here, the 1This means, if E 1 and E 10 are the emf induced in respective coil sides then the total emf induced will be E 1 +E 10. Design a suitable double-layer lap winding for a 6-pole armature with 18 slots and two coil-sides per slot. is known as coil span. 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). 26. Solution : Coil groups per phase = 3 x 4 = 12 Slots per pole per phase, m =24/12 =2 Angle between adjacent slots, â =180/24 =30 For full pitch coils, the coil span, á = 0, ie. Coil is 12 slots. c. In such coils, the two coil sides are not under the poles. Winding table. 8. 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. When a coil is having a span of 180° electrical, it is called a full-pitch coil. Back Pitch. For 20 slots, 4 polesThe winding of a 4-pole alternator having 36 slots and coils and a coil span of 1 to 8. If the maximum flux per pole, with a sinusoidal distribution, is 0. Question For a 3-phase stator winding having 6 slots per pole per phase and coil span of 13 slot pitch, the value of pitch factor will be: BUY. (16) k p1 = sin β 2 <1 where β is the coil span in °electrical, β=sα; s is the coil span in slots. 16 wb/pole and is distributed sinusoidally over the pole. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. For a coil span of 13/15 of a pole pitch, the phase winding factor is: K_p = cos(π * 13 / (2 * 15)) = 0. K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. m. 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. 1NP2. Machine, Nagpur Univ. The fundamental pitch. Sanfoundry Certification Contest of the Month is Live. Prob. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. Problem 1 : Develop the layout of a lap winding for a 3 phase ac machine having 4 pole and 24 slots. The coils are place in 60 uniformly distributed slots around the inner perimeter of the stator. The number of segments lying between the ends of the coil is known as the commutator pitch. An alternator has 18 slots per pole and the first coil lies in slots 1 and 16. , pole-pitch ) is known as 'Full Pitch'. ISBN: 9780133923605. A 4 pole AC machine has its winding housed in 48 slots with coils of span 11/12 th of a pole. The coil span should be minimum of about 8. If the coil span factor is 0. Where it is called an over-pitched coil if the coil span is greater than the pole pitch. Pitch factor:Concept: Pole Pitch: It is the angular distance between the two adjacent poles. 025 Wb entering the armature from each north pole, and this flux is sinusoidally distributed along the air gap. Assuming double turn coil, Calculate the back pitch for progressive and retrogressive winding. In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch, back pitch, pole pitch, coil pitch, etc. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . A. y=Coil span τ=Z/2P is the Pole pitch or full span II. P˚ = Pitch = coil span in no. the flux per pole has a fundamental component of 0. 10. If the coil span is less then one pole pitch than it is called short pitch coil. m. 13. armature, 180 electrical-degree coil span will be obtained when coils occupy. The value of α will usually be given in the question, if not, then assume kc = 1. The flux per pole is 0. Where n is the nth harmonic. Study with Quizlet and memorize flashcards containing terms like A lap winding, Twice, Full-pitch and more. Full Pitch and. ) 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. , coil span is 180º electrical) is called a full-pitch coil. Study now. Note. (5/6) of a pole pitch. L = πD/p = πD/ = 43 x 24 = 1048 ( satisfactory) Ex. 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 example, the 24‐slot/10‐pole PM machine in Figure 1a can be derived from two 12‐slot/10‐pole PM machines with the stator shift of 75 mechanical degrees (i. 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. 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. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. Hence, the total e. A 3-phase, 8-pole, 60-Hz, star-connected alternator has 96 slots with 10 turns per coil. 9 and pf = 0. Answer: a. ∴ e = E 1 + E 2 = 2E. Fractional pitched windings are purposely used to effect a substantial saving in copper of the end connection and for improving commutation . 80The coil pitch of such distributed windings is normally at least three slots which brings about a high winding resistance and occupies much space for the end windings. For a full pitch coil, the value of pitch factor is unity whereas for its value is also unity for concentrated coils. 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. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. 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. Coil span or Coil Pitch. 1. , coil span is 180º electrical) is called a full-pitch coil. 924 359. Determine both the winding factor and the effective turns per phase. The coil-span is 144° (electrical). However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. a. There are 2,500,000 Maxwells entering the armature from each North Pole, and this flux is sinusoidally distributed along the air gap. For A. Display and compare winding harmonicsElectrical Engineering. m. ∴ e = E 1 + E 2 = 2E. To get a coil around every tooth, we need two winding layers (double layer winding). Front Pitch-The number of armature conductors or elements spanned by a coil on the front is called front pitch. 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. 11. It is always equal to 180° electrical. 1822 V C. The primary reason for making the coil span of a d. The pole arc should be about 70% of pole pitch and length of core about 1. armature, 180 electrical-degree coil span will be obtained when coils occupy. The coil pitch is 12/15. Where n is the nth harmonic. poles, 18 slots alternator, the pole pitch is n = 18/2 = 9 slots. Lap and Wave winding are explained. Short-pitched coils are deliberately used because of the following advantages: 1. , angle between the two sides of. At this situation, two opposite sides of the coil lie under two opposite poles. electrical-engineering Three factors responsible for the change in voltage as load is applied to an AC generator are: 1) the drop in resistance in the armature circuit, 2) the change in flux, and 3) the ____________. At this situation, two opposite sides of the coil lie under two opposite poles. 1. Place the arrows according to the slot pitch. 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. It is one pole pitch. 6. To get a coil around every tooth, we need two winding layers (double layer winding). In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch, back pitch, pole pitch, coil pitch, etc. Assume a coil span of unity. Author: Frank D. 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. For a short pitch coil KC. It is usually measured in terms of teeth, slots or electrical degrees. coil pitch in terms of electrical angle3. 12. .