The coil pitch is 5/6th of the full pitch and the flux per pole is o. 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 °. To understand, it simply means that one parallel path is in N-Pole and another parallel path in S-pole. This number is known as coil span. Q: For alternator having fractional pitch winding of 8/14 the coil span is 102. coil span, slip-ring voltage on open circuit, approximate full load current per phase in rotor. The flux per pole has a fundamental component of 0. Pitch: Pole and Winding • Pole pitch is the mechanical angle between adjacent poles, e. ’s of consecutive turns c. 9 slots . Draw the developed diagram andshow the positions of brushes. 05 Wb, sinusoidally distributed. In practice, coil pitch (or Span) as low as eight-tenths of a Pole Pitch, is employed without much serious reduction in emf. Commutator pitch of a progressive lap winding is yc = +1. Full pitch winding. 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. 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. If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. less than 180° electrical, the coils are called, short pitched coils or fractional pitched coils. Short-pitch windings have a coil pitch of less than 1, which means the coil span is shorter than. D. It is usually measured in terms of teeth, slots or electrical degrees. Kr ==sink 2 · Kp =pitch factor in dcci111al p" =span of the coil in electrical degrees. Winding table. What is the short pitch in electrical degrees. Hence, during rotation when one side of the coil comes under north pole, the other side of the coil comes under south pole. Coil span σ, winding factor k w, pole ratio G r and N c for possible pole-slot combinations in the proposed FMPM machine. A. Coil–span or coil-pitch. The commutator is also known as a reverser. 12Wb and a third harmonic component. The pitch of the coils is 2 slots less than the pole pitch. 707. . The coil-span is 144° (electrical). Introductory Circuit Analysis (13th Edition) 13th Edition. may or may not be exactly equal to pole pitch B. 16 wb/pole and is distributed sinusoidally over the pole. 966 Distribution factor = 0. The phase spread is 60° and the flux per pole is 25·8 × 10–3 weber. Copy. Therefore one coil, such as coil 1 which traverses slot 1 and 7 falls under the north and south pole exactly because they are 180º apart as seen in the image above. 24 D. The windings are arranged as 5 conductors per layer. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. 9; 21. of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a full-pitch winding. 24 O 128. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. In SWAT-EM we can set the coil span explicite. #Alternator #Protectionofalternator#elect. g. p Number of pole-pairs q Ratio of pole-width to pole-pitch Q Least number of slots in a doubly slotted machine Qs Number of coils per phase of distributed winding Ru Resistance of phase-belt, u = a,b,c R Matrix of branch resistances Sn Cross-sectional area of nth coil T Time-period vu Supply voltage of uth phase-belt, u = a,b,c α Mechanical. 15 Consider the armature conductor marked X in Fig 1. A 4-pole, 50-Hz, star-connected alternator has 15 slots per pole and each slot has 10 conductors. Here we can define one more term related to a coil called coil span. The width of the coils is 5/6 of the pole pitch. Coil Span: It is the angular distance between the two sides of the coil. The pole pitch is defined as the distance between two consecutive poles. e. For a coil span of 13/15 of a pole pitch, the phase winding factor is: K_p = cos(π * 13 / (2 * 15)) = 0. Calculate the pitch factor for: (i) Fundamental (ii) 3 rd harmonic (iii. The coil-span chosen is of course less than the full-pitch. If 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. In this case, there is a phase difference between the e. 6. pdf from CSE 302 at World University of Bangladesh. of slots per pole = 2 = 6 saree tensed gOSeaee Slot pitch, a = oF slow/pole > No. 1. of slots/pole/phase, m = 4 ma 2x30 ata Soest 0-9659 (Ans. The part of the coil in which EMF is generated is known as _____. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. In a 4-pole, 35 slot d. F = 0. 8 slots b. phase shift with emf induced in the other side of the coil. The coil span is 150 electrical degrees. Determine the equation for the emf induced in one turn, and its RMS value. ) A 6-pole, 3-phase, 60-Hz alternator has 12 slots per pole. Fractional slot winding 6. An alternator has 18 slots per pole and the first coil lies in slots 1 and 16. fs. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. The distance between the two sides of an individual coil of and AC armature winding id termed the coil pitch. The coil span is 150 electrical degrees. #Alternator #Protectionofalternator#elect. 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. 2. If coil span is equal to pole pitch then it is called full pitch coil. BUY. Understand what Full Pitch and Short Pitch Windings are, and what Coil Span is. 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. 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. In this case, the coil sides lie under opposite poles, hence the induced e. m. There is a formula for calculating electromagnetic torque based on magnetic flux, distribution factor, and pitch factor [18] as equation 8. So if coil side in slot No. 15 situated at the center of an N pole rotating in clockwise direction. It is usually measured in terms of teeth, slots or electrical degrees. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers. 259 C. ( c) 96 stator slots, six-poles, coil spans 1 to 13. When the. Transcribed image text: 1. If the coil span is equal to the Pole pitch then it is called a full pitch coil. electrical degrees indicate the amount the currents in conductors has changed. In a 10 pole, lap wound de armature, the number of active armature conductor per pole is 50. 3 percent. Calculate the pitch factor of the coil for 3 rd harmonic. A chording angle ε is defined as the angle by which coil span departs from _____ a) 90° electrical space degrees b) 180° electrical space degrees c) 360° electrical space degreesSolution: No. where: coil. The skew by one slot pitch gives the value of fundamental skew factor of 0. 0. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. 4. When two capacitors of reactances 10ohms and 20 ohms are connected in parallel across a 100 V supply, total VAR drawn will be _. 25 slots. It is using an armature winding which is short pitched by one slot. Hence, the total e. It. Slots/pole/ph = m = 72/ (8×3) = 3. Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. 23. Calculate the pitch factor for an alternator winding with 36 slots, 4 poles, and coil span of 1 to 8. Now labeling the starting end of each coil is easy, assuming an RYB phase sequence taking red as the reference. ∴ e = E 1 + E 2 = 2E. 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. Question. For example, in a 6-pole armature having 96 slots, a coil spanning 15 teeth would obviously be a fractional-pitch or chorded coil (since pole-pitch is 16). m. Expert Solution. On the other hand, if its span is less than a pole-pitch. For a simplex lap winding, the commutator pitch YC = 1 and coil span YS ~ pole pitch. 1. 24 where polepitch of 4 has been assumed), then winding is called full-pitched. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. 0 C. The coil span should be minimum of about 8. Place the arrows according to the slot pitch. is known as coil span. 2. The harmonic reduction in the voltage waveform of concentrated winding axial field PM machines is the subject of interest for many researchers. Distribute the winding uniformly under different poles d. Calculate the rms value of the induced emf per phase of a 10-pole, 3-φ, 50-Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. Coil span is the number of slots between the two sides of the same coil. e. The armature coils are all connected in series. If the span of the coil is reduced by an angle 'α' of electrical, then the. Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature. Ratio of the pole arc to pole pitch: 0. Use: (Y) =) 2. A: slot angle = 180slot per pole = 18015 = 12 pole pitch = no. Pole pitch is always equal to 180o electrical. No matter how many poles, each pole always spans exactly 180 electrical degrees, and it is called pole pitch. Coil Span: It is the angular distance between the two sides of the coil. m. a coil. ed = electrical degree Example 2: Calculate the pole pitch for a three phase 4 pole ac machine having 36 stator slots. 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. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. Identify the approximate diameter and length of stator core,. Back Pitch. A. Alternatively, this type of coil is also called a short-pitch or chorded coil. 125 Wb and a. Then, the pitch factor will be equal. c. 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. Each phase in this case consists of four coils (two per slot). fs. Coil–span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. c. Its magnetic poles can be salient (protruding or sticking out from the surface of the rotor), as shown in Fig. fs. Assume the coil span as 150° electrical. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. 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. Calculate the average voltage generated in a six-turn full pitch coil of a 25 cycle alternator if the. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. 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. Chorded-coil. A coil having a span equal to 180⁰ electrical is called a full pitch coil as shown in the figure below. In a fractional pitch winding, the coil span is made less than 180 degrees electrical space. 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. 15. Result- ant flux in the air-gap is 5 ´ 10– 2 webers per pole sinusoidally distributed. 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. Find the EMF produced by a DC generator connected to a 6 poles coil rotating at 1200 RPM. SEE MORE TEXTBOOKS. Pole pitch is always equal to 180o electrical. The primary reason for making the coil span of a d. Calculate the pitch factor for (a) fundamental (b) 3rd harmonic (c) 5th harmonic (d) 7th harmonic. Calculation:When the coil sides forming a coil are spaced exactly one pole pitch a part they are said to be of full-pitch. $$\mathrm{Slot\:per\:pole =\frac{90}{6}= 15}$$ For a full-pitch coil, the coil span is 15 slots. The dc armature winding in which coil sides are a pole pitch apart is called ____ winding – Full- pitch. However the waveform of the resultant emf can be improved by making the. Distribute the winding uniformly under different poles d. The armature winding is housed in 360 stors with 6 conductors per slot. For alternator having fractional pitch winding of 8/14 the coil span is 102. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Last edited by markadlerdallas. The pole pitch is 35 cm. Question. After updating the table, the drop-down list below lets you select whether to display the number of slots per pole per phase, the maximum possible fundamental winding factor, the number of winding symmetries,. If the coil span of a single coil is less than the pole pitch of 180° electrical, i. If each coil spans 8 slot pitches, what is the value…Front pitch: The distance between the last side of the first coil and first side of the second coil is called the front pitch. IMs designed by utilising the winding configurations given in Section 3 are analysed and both SS and FW performance characteristics are presented. in them are additive. 26. 8. Transcribed Image Text: (d) obtain a full-pitch winding. If the coil span is equal to the Pole pitch then it is called a full pitch coil. c. The coil-span is 144° (electrical). in the two sides of the coil. 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. ∴ e = E 1 + E 2 = 2E. 5. 1NP2. An 8-pole lap wound DC generator has 120 slots having 4 conductors per slot. 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. 966The pole pitch, mQ ′ ∕ p, is also fractional, so that the coil-span cannot be of full-pitch. Problem. 86 O 119. Now coil is shorted by 1 slot i. Armature Currents and MMF of 5-Phase Machine The armature currents of 5-phase machine can be expressed with formula (1). Petruzella. Coil pitch or coil span is defined as the angular distance between the two coil sides of one coil. Pole pitch is defined as the angular distance between the central line of one pole to the central line of the next pole. the core length 32 cm, and the stator coil span four fifth of the pole pitch. 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. Problem 1 : Develop the layout of a lap winding for a 3 phase ac machine having 4 pole and 24 slots. 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. Pole pitch = 180 electrical degrees = S/P = 2C/P. 0. is B = 10 sin theta + 2 sin 3 theta + 2 sin 7 theta kilo - gauss, when theta is measured from the neutral axis. It is always equal to 180° electrical. Hence, the total e. 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. of slots per pole = 15 but coil span is… Q: A synchronous generator has 9 slots per pole. Calculation: Given that, Slots S = 72. Therefore one coil, such as coil 1 which traverses slot 1 and 7 falls under the north and south pole exactly because they are 180º apart as seen in the image above. Solution for For alternator having fractional pitch of 11/12 the coil span is a. In a 4 pole, 35 slot dc armature, calculate the coil span a. The individual coils may have a span greater or less than a pole pitch but the average coil-span equals one pole-pitch. Emf induced per coil side is E. It may be the full pitched or short pitch. arrow_forward. Calculate the distribution factor for a single layer 36 slots 2-pole three-phase stator winding. Wiki User. First, a double-layer winding is investigated with the number of slots Q, pole pairs p and a constant coil pitch . Solution for Calculate the pitch factor for the following windings: a) 72 stator slots, 6 pole, coil span 1 to 10. It is sometimes convenient to speak of an armature coil span as having a fractional pitch expressed as a fraction e. How many comparators does a 339 IC contains? 4. 4. If the coil span is less than the pole pitch (as in coil Fig. 12 Wb and a 20% 3 rd harmonics. The width of the coils is 5/6 of the pole pitch. Determine the phase andline values of emf if the machine runs at 600 rpm and the flux per poleis 0. 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. c. The primary reason for making the coil span of a d. It may be the full pitched or short pitch. . . The slots per pole per phase are 8 and the coil span is 20 slots. 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. What is meant by a full pitch winding a fractional pitch winding? If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. (a) commutator bars per pole (b) winding elements (c) armature conductors per path (d) armature parallel paths. It indicates how the coils are spaced out on the armature core. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. 0. BUY Delmar's Standard Textbook Of ElectricityThe slots per pole per phase are 8 and the coil span is 20 slots. If the coil. The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degrees. Both, 7/9 and 8/9, are equally close to 5/6 but I would select 8/9 for better flux utilization. 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. Power System Analysis and Design (MindTap Course List) 6th Edition. It is generally denoted by K c and its value is always less than unity. Chording: with coil-span less than pole pitch 5. a. 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 ). 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. 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. 851: D) 0. The skew factor reflects the flux reduction if the winding is angularly twisted along the axis. Download Solution PDF. Assume the coil span as 150° electrical. Similarly, if the emf induced in coil sides 2 and 11 are E 2 & E 11, then the total emf in coil 2-11 is given as arithmetic sum of E 2 and E 11. 05: B) 0. The rotor is a large electromagnet. Note. Assuming double turn coil, Calculate the back pitch for progressive and retrogressive winding. If the maximum flux per pole, with a sinusoidal distribution, is 0. 8. arrow_forward. Get Coil Span or Coil Pitch Multiple Choice Questions (MCQ Quiz) with answers and detailed solutions. 14. Draw the double layer winding layout for a 24 slot stator and 4 pole alternator 3. 363Wb and a 15% third harmonic. 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. Since one pole presents 180 electrical space degrees so the slots pitch. Pole pitch = 180 electrical degrees = S/P = 2C/P. 1kv. Alternator connections: star or delta connections of alternators suppress triplen harmonics from appearing across the lines 1. 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. in the two coil sides. MMF OF ARMATURE A. 24, and assume first a short-pitched coil spanning half a pole pitch, then a long-pitched coil spanning one and a half. armature, 180 electrical-degree coil span will be obtained when coils occupy. Thus the total emf at the coil terminal A & B is the phasor sum of (E 1 +E 10), (E. P˚ Kp = sin [(90°)(pitch)] Kp = sin 𝟐 PROBLEM 1: A 6 pole, 3Φ AC generated has 72 slots, the coil span is 12. 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. 60º / 90º = 2/3. Coil Span:The angular distance between the centers of two adjacent poles on a machine is known as pole pitch or pole span. If each coil is short pitched by an angle of 36 ∘ electrical. m. 31. 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. Pole pitch is always equal to 180o. Coil–span or coil. Three kinds of coil spans are used, they are 4-solt pitch, 3-solt pitch, and 2-solt pitch. 866. 455 V D. Key. m. C. e. A 4 pole, 12 slot lap wound dc armature has two coil side per slot. 85 lagging. ( b) 42 stator slots, four-poles, coil spans 1 to 10. Its flux per pole is 0. The resultant coil voltage $𝐸_{𝐶}$ is equal to the phasor sum of $𝐸_{𝐶1}$ and $𝐸_{𝐶2}$. 163Wb. Since slot pitch is 6, 6 slots have upward arrows, 6 down and so on. The line to line induced emf for a 3 ϕ star connection is approximatelyCompute the phase and line voltage of a wye-connected three-phase, five-pole alternating current generator that runs at a speed of 1440rpm has a total slots of 135 slots with 4turns/coil. Machine, Nagpur Univ. *. 31. The winding is double-layer. Answer: a. Pole Pitch: It is the angular distance between the two adjacent poles. IV. Pole Pitch, Coil Span, Back Pitch, Front Pitch, Commutator Pitch in Armature Winding of DC Machines are explained in this video. Give the values of front pitch, back-pitch and commutator pitch. 5. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. 125 Wb and a 25% third component. It is given by K p = cos (α/2) Where α is the short pitch or chording angle. The fundamental flux per pole is 0. If the coil span is less then one pole pitch than it is called short pitch coil. It is lesser than the value in the first case. 15. It is usually measured in terms of teeth, slots or electrical degrees. The pole arc should be about 70% of pole pitch and length of core about 1. The pole pitch, S/P, is also fractional, so that the coil-span cannot be of full-pitch. 339 IC function as. In a 4-pole, 35 slot d. • To view the coil sides / coils, we must look below from above the slots as depicted in figure. In other words, the distance between the two coil sides of a coil will be equal to the distance. 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. of slots / slots per pole. It is usually measured in terms of teeth, slots or electrical degrees. the flux per. full, s. 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.