BUY. Hence, the pole pitch of that DC machine would be 24. Figure 1. Chorded-coil. e. The harmonic reduction in the voltage waveform of concentrated winding axial field PM machines is the subject of interest for many researchers. Emf induced per coil side is E. 0. 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: (b) A 4 pole AC machine has its winding housed in 48 slots with coils of span 11/12 th of a pole…A pole pitch is always 180 electrical degrees, regardless of the number of poles on the machine. Here, e = E 1 = E 2 = E. round the coil which is the vector sum of e. The pole pitch, S/P, is also fractional, so that the coil-span cannot be of full-pitch. 31. 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. Figure 4 shows the flux distribution linked to a short-pitch coil. 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. 2-pole star-connected, armature winding of a generator has 6 slots per phase. Where n is the nth harmonic. (8) A SIMPLE explanation of Full Pitch and Short Pitch Winding. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. The separation between the top and bottom sides of a coil is called Coil span. F. 966the coil span of the two slot‐pitch technique has been pro-posed, based on the ‘stator shifting’ concept [8, 9]. 10 are one pole pitch or n slots or 180° electrical apart, the coil is called full pitch coil. Full pitch winding. Place the arrows according to the slot pitch. Winding Question 9. Comparator. frame. Now coil is shorted by 1 slot i. . 60 hz, 10-pole alternator has 120 slots and 4 turns in every coil. Determine the equation for the. 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. For n th harmonic. The dc armature winding in which coil sides are a pole pitch apart is called ____ winding – Full- pitch. (a) multiplex (b) fractional-pitch (c) full-pitch (d) pole-pitch 3. The coil span is 150°. 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. 2 are short-pitched, full-pitched and over-pitched coils respectively. 50Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. ISBN: 9780073373843. 0 i D. Theta (electrical)=p/2 (theta (mechanical)) What is the formula for electrical angle. phase shift with emf induced in the other side of the coil. . 50Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. Expert Solution. The coil-span is 144° (electrical). Answer: 0. See answer (1) Best Answer. e. What is the coil span for a 2 pole 18 slot machine? a) 9 b) 4. There. Here’s the best way to solve it. This distance is measured in terms of armature slots or armature conductors that come between two. Fractional slot winding 6. the coil span is (180-ε), therefore the emf induced in these coil sides will also be separated by this angle. In this. You can read more. If the coil span is from slot 1 to slot 21, and the flux per pole has a fundamental component of 0. 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. 160 degrees b. A 4-pole, 50 Hz alternator has double layer winding with 10 turns per coil and number of slots are 60. The flux distribution curve of a smooth - core 50 c/s generator is B = 10 sin theta + 2 sin 3 theta + 2 sin 7 theta kilo - gauss, when theta is measured from the neutral axis. ) A 6-pole, 3-phase, 60-Hz alternator has 12 slots per pole and four conductors per slot. In SWAT-EM the coil span is given in number of slots. 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. the coil will be in 180o. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. At this situation, two opposite sides of the coil lie under two opposite poles. DARWIN M. ) 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. 339 IC function as. The winding spans all11. 0. The primary reason for making the coil span of a d. ∴ e = E 1 + E 2 = 2E. armature, 180 electrical-degree coil span will be obtained when coils occupy. 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. 05 Wb, sinusoidally distributed. The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degrees. of a 10-pole three-phase 50Hz alternator with 2 slots per pole per phase and 4 conductors. Answer: c Explanation: Pole pitch is called as center to center distance between two adjacent poles. . fs. Find the pitch factor for an alternator having 48 stator slots, 6 poles, coil span 1-6 Option 1: cos 45 ° Option 2: cos 24 ° Option 3: cos 34 °. 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. Publisher: PEARSON. It is always 180° electrical. There is a formula for calculating electromagnetic torque based on magnetic flux, distribution factor, and pitch factor [18] as equation 8. 7. c. If the coil span is equal to the Pole pitch then it is called a full pitch coil. phase shift with emf induced in the other side of the coil. 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. Coil–span or coil-pitch. Determine the phase andline values of emf if the machine runs at 600 rpm and the flux per poleis 0. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. 125 Wb and a 25% third component. Assume = 0. Draw the double layer winding layout for a 24 slot stator and 4 pole alternator 3. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. 707 B. Hence, the total e. 3- Determine the coil span for 3-phase, two pole alternator, the pole pitch is equal to 18 slots and the coil span factor is. What is the coil span for a 4 pole 48 slot machine? Explanation: Slots per pole = 48/4=12, for a coil span of 10 slots, the coil is short pitched by 2 slots and the chording angle is ε=2γ and γ=180/12 ⇒ ε = 30° ⇒ Kp=cosε/2=0. fs. (16) k p1 = sin β 2 <1 where β is the coil span in °electrical, β=sα; s is the coil span in slots. 7 slots c. C. Download these Free Coil Span or Coil Pitch MCQ Quiz Pdf and prepare for your upcoming exams Like Banking, SSC, Railway, UPSC, State PSC. This distance is measured in terms of armature slots or armature conductors that come between two adjacent pole centers. Emf induced per coil side is E. The winding calculator allows you to find the optimum winding layout for your electric motor in a fast and convenient way. Pole pitch is always equal to 180. Use a diagram like that shown in fig. Pole pitch is the mechanical angle between adjacent poles, e. Obtain a full-pitch winding. Generally. 956 1. The pole pitch is 35 cm. , or 5/6 × 180° = 150 electrical degrees. m. Find the terminal voltageon open circuit. of slots / slots per pole. B. In a fractional pitch winding, the coil span is made less than 180 degrees electrical space. full, s. The primary reason for making the coil span of a d. e. Share on Whatsapp Latest UPSC IES Updates. IMs designed by utilising the winding configurations given in Section 3 are analysed and both SS and FW performance characteristics are presented. 967. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. 2. 339 IC function as. 7. The coil-span is 144° (electrical). The term “winding pitch” refers to the ratio of the number of winding slots enclosed by each coil in the alternator stator to the number of winding slots per generator pole. When the coil span is less than pole pitch (180 deg electrical), the winding is called short pitched or chorded. The width of the coils is 5/6 of the pole pitch. Determine the generated. 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. 772 x 10-3 Wb. 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. 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. Relation between frequency, speed and number of poles: Fig: 1. 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 or Coil Pitch. 5 c) 18 d) 6 View Answer. This winding has 12 slots per pole per phase. arrow_forward. Determine the equation for the emf induced in one turn, and its RMS value. Machine, Nagpur Univ. The armature coils are all-connected in series. The coil span is 150°. 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. 98: 61. 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;. Pole arc/ pole pitch = core length/ pole pitch = 0. The winding is wye-connected. The distance between the two sides of a coil is called the coil. it is defined as the peripheral distance between the center of two adjacent poles in a DC machine. 1. 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. 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. A coil having a span equal to 180⁰ electrical is called a full pitch coil as shown in the figure below: A coil having a span less than 180⁰ electrical is called a short pitch coil or fractional pitch coil. m. Coil Span Factor: In a full pitch winding the coil span or coil pitch is always equal to the pole pitch which is equal to 180 electrical degrees. This is naturally equal to the total number of armature slots divided by the number of poles in the machine. There are 2,500,000 Maxwells entering the armature from each North Pole, and this flux is sinusoidally distributed along the air gap. b. To get a coil around every tooth, we need two winding layers (double layer winding). arrow_forward. The arc diagram contains all the necessary information for connecting the pole-groups correctly. fs. 2. 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. Identify number of rotor slots, number conductors / slot, coil span, number of slots per pole. Concept: Coil pitch or coil span: It is defined as the angular distance between the two coil sides of one coil. 9780133923605. 50 Q 1. If t he coil pitch is y =3, the diame tral w inding w ill have the f. Calculate the pitch factor of the coil for 3 rd harmonic. Get Coil Span or Coil Pitch Multiple Choice Questions (MCQ Quiz) with answers and detailed solutions. Study with Quizlet and memorize flashcards containing terms like A lap winding, Twice, Full-pitch and more. † ‡ ˆ ‰ Š ‹ Œ Ž ‘ ’ “ ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿPitch factor: Full-pitched coils i. Generators 897 winding is fractional-pitched. Short-pitched coils are deliberately used because of the following advantages: 1. D. The armature windings conduct AC even on DC machines, due to the commutator action (which. Problem 1 : Develop the layout of a lap winding for a 3 phase ac machine having 4 pole and 24 slots. The pitch of the coil is 2 slot less than the pole pitch. Step by step Solved in 2. 0 D. A 3-phase, 8-pole, 60-Hz, star-connected alternator has 96 slots with 10 turns per coil. 025 Wb entering the armature from each north pole, and this flux is sinusoidally distributed along the air gap. It may be the full pitched or short pitch. Question. 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. e. Determine the pitch (or coil span) factors for the winding ,24 Stator slots ,4 poles, coil span 1 to 5 12. Lap and Wave winding. 150° is (frac{5}{6}) parts of 180° i. A Three-phase four-pole AC machine has 60 coils in the stator and each coil has 100 turns. Better emf waveform in case of generators 6. 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. In this video lecture you will learn about electrical angle,mechani. However in practise this often isn’t the best choise because of the high harmonic content. Fig. A) 1. 966 and 0. Most windings have < . Then, the pitch factor will be equal. * This angle is known as chording angle and the winding employing short-pitched coils is called chorded winding. BUY Delmar's Standard Textbook Of ElectricityThe slots per pole per phase are 8 and the coil span is 20 slots. In this case, we have a 10 pole alternator with coils wound in a fractional pitch of 18/21. It is usually measured in terms of teeth, slots or electrical degrees. 15 Consider the armature conductor marked X in Fig 1. Coil Span: It is the angular distance between the two sides of the coil. (5/6) of a pole pitch. A. The coils are place in 60 uniformly distributed slots around the inner perimeter of the stator. To calculate the pitch factor, we need to consider the pole number and the fractional pitch. Table 1 lists suitable combinations of stator slots and rotor poles for six-phase windings and gives the corresponding number of slots per pole per phase q6~. The back pitch and front pitch adopted could be respectively. It is always less than unity. Also note that the diagram gives no information about the coil-span or pitch; thus for example in the 36-slot case a full-pitch winding would have a coil-span of 9, but 8, 7 or 6 could also be used (all with 2 coil-sides per slot). Front Pitch-The number of armature conductors or elements spanned by a coil on the front is called front pitch. The primary reason for making the coil span of a d. Assuming double turn coil, Calculate the back pitch for progressive and retrogressive winding. 86. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . First. 10 A three-phase, wye-connected alternator has 15 slots/pole. ) Given: 120 slots, ,10 poles, double layer winding, coil pitch is shorted by 2 slots, f=60 Hz, Y connected. The number of segments lying between the ends of the coil is known as the commutator pitch. Hence emf induced in one side of. Step by step Solved in 4. SEE MORE TEXTBOOKS. The pole pitch is 35 cm. ed = electrical degree Example 2: Calculate the pole pitch for a three phase 4 pole ac machine having 36 stator slots. Hence emf induced in one side of. 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. 12Wb and a third harmonic component. Coil–span or coil. 135 degrees d. Thus, the total. Resultant pitch Y R is even, being the arithmetical difference of two odd numbers, i. The slots per pole per phase are 8 and the coil span is 20 slots. armature winding equal to a pole pitch is to (a) obtain a coil span of 180° (electrical) (b) ensure the addition of e. 60o groups, 2-layer winding is used. 25 slots. 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. It is usually measured in terms of teeth, slots or electrical degrees. Question. M. For the n th harmonic, the chording angle becomes nα° electrical. Download Solution PDF. 7. • Winding pitch is the coil span divided by the pole pitch, e. ISBN: 9780073373843. In practice, coil pitch (or Span) as low as eight-tenths of a Pole Pitch, is employed without much serious reduction in emf. Por a full-pitch coil, Kr = I (unity) r:or a fractional-pitch coil, Kr < 1 6. The coil-span chosen is of course less than the full-pitch. ISBN: 9780133923605. Pole pitch is always equal to 180o electrical. The rotor is a large electromagnet. armature, 180 electrical-degree coil span will be obtained when coils occupy. Coil span is defined as the peripheral distance between two sides of a coil. Back pitch (Y b): It is the span of the coil from the back end. Its magnetic poles can be salient (protruding or sticking out from the surface of the rotor), as shown in Fig. 12. They save copper of end connections. Fig. 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. c. If the coil-pitch is one pole pitch, it is called the full-pitch coil. For n th harmonic. Calculate the emf generated in each phase when the machine runs at 375 rpmHey Aspirants. 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. The coil span should be minimum of about 8. P˚ Kp = sin [(90°)(pitch)] Kp = sin 𝟐 PROBLEM 1: A 6 pole, 3Φ AC generated has 72 slots, the coil span is 12. 086 Wb, what will be the values of the emfs? phase and line? I need the procedure to get to that answer. It is equal to the number difference of the conductor connected to a given segment of the commutator. 0. Both Y B and Y F should be nearly equal to a pole pitch. round the coil which is the vector sum of e. K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. Chording: with coil-span less than pole pitch 5. Here, e = E 1 = E 2 = E. Based on number of layers (i) Single layer. Then the coil span value is _____. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Where n is the nth harmonic. m. . View full document. • So coil span is 16/4 = 4. Wiki User. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. In a synchronous generator, what do fractional pitch and fractional slot windings mean?• (e) The coil span must be odd integer. (BTL-1) 4. coil pitch in terms of slots4. Similarly, for a coil having a span of 2/3 pole-pitch, kc = cos 60°/2 = cos 30° = 0. A pole pitch is always 180° electrical regardless of the number of poles on the machine. the distance between the two sides of coil is called the coil-pitch. Pole pitch is always equal to 180o. EXAMPLE: Calculate the pitch factor for a alternator winding with 36 slots, 4. Calculate the no-load terminal voltage, if the speed of the alternator is 1500r. Let E 1, E 2 and E R be the emf induced in coil side lying under North Pole, South Pole and resultant of emf generated in both the active lengths of coil. The coil span is 160°. It is lesser than the value in the first case. The skew by one slot pitch gives the value of fundamental skew factor of 0. In this case, there is a phase difference between the e. It is always 180° electrical. , Y = 2/3 τ p. View 26 DC Generator. For 20 slots, 4 polesThe winding of a 4-pole alternator having 36 slots and coils and a coil span of 1 to 8. 16 wb/pole and is distributed sinusoidally over the pole. 0. Because a chording more than 1/3 pole pitch would noticeably reduce the phase emf. of consecutive turns (c) distribute the winding uniformly under different poles (d) obtain a full-pitch winding. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. It is using an armature winding which is short pitched by one slot. 1 is connected to coil side in slot No. The pole pitch is defined as the distance between two consecutive poles. Assuming single turn coil, calculate the back pitch for progressive and retrogressive winding. coil pitch in terms of electrical angle3. If fractional pitch is used, the emfs in the two coil sides are out of phase, which reduces the emf. b) 96 stator slots, 6 pole, coil span 1 to…. 4 pole three phase winding. Share on Whatsapp India’s #1 Learning Platform Start Complete Exam Preparation Daily Live MasterClasses. Winding pitch is the coil span divided by the pole pitch, e. d5. For a 3-phase winding with 6 slots per pole per phase and with coil span of 15 slot, the value of pitch factor is A. #Alternator #Protectionofalternator#elect. Obtain a full-pitch winding. N st 2p r; 12 14 16 18 20 22; 12:. In an alternator, for a coil having a span of 2/3 of pole pitch,. is B = 10 sin theta + 2 sin 3 theta + 2 sin 7 theta kilo - gauss, when theta is measured from the neutral axis. CONCENTRIC WINDING In unbifurcated concentric windings, the first of the q coils which is the smallest is thrown. Design a suitable double-layer lap winding for a 6-pole armature with 18 slots and two coil-sides per slot. 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. Copy. 5. A. 4. Determine the coil and commutator pitches for a 72-slot 288-segment six-pole frog-leg armature winding. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. The arc diagram contains all the necessary information for connecting the pole-groups correctly. It is given by K p = cos (α/2) Where α is the short pitch or chording angle. 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. 75), the lowest 2-solt coil span. 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. Equation () represents the operating magnetic load line of the PMSG, which is a function of machine dimensions; such as radius, stack length, air gap length and PM thickness. b) 96 stator slots, 6 pole, coil span 1 to…. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. c. Front connections 8+7=15; 30+7-30=7 8. 11. o. This advancement is measured in terms of armature conductors and is called back pitch. Calculate the pitch factor for: (i) Fundamental (ii) 3 rd harmonic (iii. On the other hand, if its span is less than a pole-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. Calculation: Given that,For making coil span equal to a pole pitch in the armature winding of a d. Pole Pitch: It is the angular distance between the two adjacent poles. . Example: the throw could be to 9 meaning that one side of the coil is. spanning over 180° (electrical). 0. Coil span or Coil Pitch. A 4 pole AC machine has its winding housed in 48 slots with coils of span 11/12 th of a pole. 0. In a 4 pole, 3 phase alternator, armature has 36 slots. The two sides of a coil are places in two slots on stator surface. 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 3rd harmonics. Since the winding is full pitched coil, so the pitch of each. Transcribed Image Text: (d) obtain a full-pitch winding. A six pole, three phase alternator has 72 slots and a coil span of 1 to 10, is the pitch factor? A. Coil–span or coil-pitch. Petruzella. Thus the total emf at the coil terminal A & B is the phasor sum of (E 1 +E 10), (E. 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. 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. Each phase in this case consists of four coils (two per slot). A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. 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. m. #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 core length 32 cm, and the stator coil span four fifth of the pole pitch. Only 100% coil pitch in a two pole machine means half the air-gap circumference. 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. M. 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). Pole – pitch. pole pitch5.