1 . Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Calculate the no-load terminal voltage, if the speed of the alternator is 1500r. Generally. e. A. The winding is double-layer. 125 Wb and a 25% third component. There’s just one step to solve this. m. a. 6 Pole pitch Coil span y=Z/2P + 1, y=Z/2P - 1 7 Conditions of P/C ϵ N, meaning P cannot be 1 and for three phase C/m N symmetry Single layer fractional slot winding with Z=30, and 2P=4 q 2 1 or q 5 D. Note. First, a double-layer winding is investigated with the number of slots Q, pole pairs p and a constant coil pitch . It is one pole pitch. Pole – pitch. A coil whose sides are separated by one pole pitch (i. . full, s. 10. Comparator. Cogging torque was minimized by finding an optimum magnet pole arc length and torque ripples were minimized by finding. A 3-phase, 4 pole, Y- connected alternator has 72 slots with two conductors per slot. Learn what a pole pitch is, the pole pitch formula & definition, and how to. of a 10-pole three-phase 50Hz alternator with 2 slots per pole per phase and 4 conductors. ( ) () ⎪ ⎪ ⎪ ⎩ ⎪⎪ ⎪ ⎨ ⎧ = − = − = − = − = sin 8 /5 sin 6 /5 sin. 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. Slots/pole/ph = m = 72/ (8×3) = 3. 0. The pitch factor, in rotating electrical machinery, is. e. 5 c) 18 d) 6 View Answer. Here, e = E 1 = E 2 = E. 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. The arc diagram contains all the necessary information for connecting the pole-groups correctly. pole pitch5. Display and compare winding harmonicsElectrical Engineering. The pitch factor [3], [6], [7], [8] is the ratio of coil voltages for a fractional-pitch winding to those for a full-pitch one. c. Calculation: Given that,For making coil span equal to a pole pitch in the armature winding of a d. Emf induced per coil side is E. arrow_forward How to calculate the pitch factor of a 8 pole alternator with an armature wound coils having 18 / 24 fractioanl pitch. generator, the back pitch of the winding must equal the number of (a) commutator bars per pole (b) winding elements (c) armature conductors per path (d) armature parallel paths. It may be the full pitched or short pitch. Sketch the winding over a pole pitch, indicating the location of the conductor of each phase. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. Hence, the coil span in three phase AC machines must be (frac{5}{6}th) of pole pitch. In this case, there is a phase difference between the e. 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). 10 slots d. 985 (ii) Slots per pole = 72/6=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° ⇒ K p =cos15°=0. fs. F. 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. It is usually measured in terms of teeth, slots or electrical degrees. This is shown in the figure to left. Step by step Solved in 2. Coil Span: The number of core slots spanned by the sides of the coil. c. Hence emf induced in one side of. 85 lagging. Hence, the total e. Wiki User. Pole pitch is the peripheral distance between two adjacent poles. It is expressed in terms of number of slots per pole. 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. 36K subscribers Subscribe 9. It has key variables such as Pole Pitch (back and front pitch, resultant pitch and communicator pitch, Coil Span, Commutator Pitch. 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. To get a coil around every tooth, we need two winding layers (double layer winding). e. Resultant pitch Y R is even, being the arithmetical difference of two odd numbers, i. If the coil span is less than the pole pitch, then the winding is said to be short-pitched. m. Get Coil Span or Coil Pitch Multiple Choice Questions (MCQ Quiz) with answers and detailed solutions. The pitch of the coils is 2 slots less than the pole pitch. Sanfoundry Certification Contest of the Month is Live. 6. Pole pitch is always equal to 180. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . Pole pitch is the mechanical angle between adjacent poles, e. If the coil span is equal to the Pole pitch then it is called a full pitch coil. (Assume lap. The flux per pole has a fundamental component of 0. L = πD/p = πD/ = 43 x 24 = 1048 ( satisfactory) Ex. (BTL-1) 4. If the coil-span (or coil-pitch) is equal to the pole-pitch, then the coil is termed a full-pitch coil. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. 10 such that two slots No. 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. 50 Q 1. The winding is wye-connected. coil pitch in terms of slots4. A 4 pole, 12 slot lap wound dc armature has two coil side/slot. The coil span should be minimum of about 8. b) 96 stator slots, 6 pole, coil span 1 to…. • So coil span is 16/4 = 4. For a full pitch coil, the value of pitch factor is unity whereas for its value is also unity for concentrated coils. Coil–span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. 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. Example: the throw could be to 9 meaning that one side of the coil is. 9659. fs. It is always 180° electrical. ) A 6-pole, 3-phase, 60-Hz alternator has 12 slots per pole. 2 are short-pitched, full-pitched and over-pitched coils respectively. We will start Red at slot 1. Similarly, for a coil having a span of 2/3 pole-pitch, kc = cos 60°/2 = cos 30° = 0. 6. Transcribed Image Text: (d) obtain a full-pitch winding. m. Front pitch (Y f):. Now labeling the starting end of each coil is easy, assuming an RYB phase sequence taking red as the reference. 0. e. Muthu RE: How. pole pitch = 180 electrical degrees or π electrical radians. 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. Since slot pitch is 6, 6 slots have upward arrows, 6 down and so on. In this case, the coil sides lie under opposite poles, hence the induced e. 33 percent of pole pitch to obtain the maximum reduction of harmonics. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch. A full-pitch coil is one whose pitch is equal to the pole-pitch at the working harmonic. 966 D. 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. ) 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. It is usually measured in terms of teeth, slots or electrical degrees. 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. The coil used in double layer winding are diamond shaped as in the dc windings. Here, e = E 1 = E 2 = E. Transcribed Image Text: 9. 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,. 26. 06 weber distributed sinusoidally over the pole. It is possible to suppress the higher harmonics by using double-layer windings using shortened span coils. 0. 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. 75), the lowest 2-solt coil span. e. 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. The flux per pole has a fundamental component of 0. the coil will be in 180o. e. Boylestad. Lap and Wave winding. 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. Each phase in this case consists of four coils (two per slot). (d)Find the number of turns per phase, Tph. It. The term "region" is important, because a design with 3 slots per pole and phase, for instance, can only be pitched 6/9 or 7/9 or 8/9. Fig. If the maximum flux per pole, with a sinusoidal distribution, is 0. 6. The distribution of upper-side voltage phasors is the same as that of coil voltage phasors,. View the full answer. 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. m. 0 i D. the coils cannot be full - pitched; they may be short - pitched with 15 slots, or long - pitched with 16 slots. Coil span factor (Kc): The ratio of emf induced in a short-pitched coil to emf induced in a full-pitched coil is called coil span factor or pitch factor or chorded factor. In a 4-pole, 35 slot d. 85. Ans. Por a full-pitch coil, Kr = I (unity) r:or a fractional-pitch coil, Kr < 1 6. The arithmetic sum of induced emfs is 2E. 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. What is the coil span for a 2 pole 18 slot machine? a) 9 b) 4. , coil span is 180º electrical) is called a full-pitch coil. 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. The coil span is 150°. a coil. Download Solution PDF. 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. Short-pitch windings have a coil pitch of less than 1, which means the coil span is shorter than. m. The armature winding is housed in 360 stors with 6 conductors per slot. Coil span or coil pitch Ys: It is the distance between the two sides of a coil measured in terms of armature slots. The induced emf in each coil side. K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. It is always 180° electrical. 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;. e. m. We make the coil span less than 180 degrees electrical space degrees in a fractional pitch winding. Commutator pitch of a progressive lap winding is yc = +1. The number of segments lying between the ends of the coil is known as the commutator pitch. Calculate the pitch factor for an alternator winding with 36 slots, 4 poles, and coil span of 1 to 8. • To view the coil sides / coils, we must look below from above the slots as depicted in figure. ) Given: 120 slots, ,10 poles, double layer winding, coil pitch is shorted by 2 slots, f=60 Hz, Y connected. The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degrees. In such coils, the two coil sides are not under the poles. At this situation, two opposite sides of the coil lie under two opposite poles. Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. round the coil which is the vector sum of e. situation, two opposite sides of the coil lie under two opposite poles. 85 lagging. Compared to the overlapping winding above we need only 3 slots for the two poles. of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a full-pitch winding. If coil span is 6 and if top coil side of a coil lies in slot 1 then the. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers. 339 IC function as. 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. Every coil is connected to the commutator. 10 are one pole pitch or n slots or 180° electrical apart, the coil is called full pitch coil. – Comparator. Since 1 pole pitch is the angular distance between the two. • In double layer windings used in. 9659When the coil span is lower than pole pitch, the phasor sum of conductor voltages is less than the arithmetic sum, because of vector addition. The pole pitch, S/P, is also fractional, so that the coil-span cannot be of full-pitch. Let us assume that, a coil is short pitched by an angle α (electrical degree). ; Here, e = E 1 = E 2 = E. Electrical Engineering. D. Pole pitch is always equal to 180o 7. in the two coil sides. coil pitch in terms of electrical angle3. 12 Wb and a 20% 3 rd harmonics. may or may not be exactly equal to pole pitch B. 6. The back pitch and front pitch adopted could be respectively. Problem. g. Here we can define one more term related to a coil called coil span. 50 Q… A: Find the coil span Fractional pitch winding = 8/14 Q: For alternator having fractional pitch winding of 10/15 the coil span is O 2. 31. 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. Calculate the distribu factor for a 36-slot. coil pitch in terms of slots4. Where it is called an over-pitched coil if the coil span is greater than the pole pitch. Number of Commutator Segments - Number of Commutator Segments is the count of cylindrical assembly of insulated segments that are mounted on the shaft. e. 125 Wb and a. 7. Expert Solution. 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. It falls short by 1/6 pole-pitch or by 180°/6 = 30°. ; Coil Span: It is the angular distance between the two sides of the coil. , coil span is 180º electrical) is called a full-pitch coil. Place the arrows according to the slot pitch. See solution. Expert Solution. M. 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. 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. P˚ = Pitch = coil span in no. arrow_forward. g. 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 separation between the top and bottom sides of a coil is called Coil span. 1. Copy. 1 and No. It is equal to the number difference of the conductor connected to a given segment of the commutator. 951: C) 0. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. pole pitch5. B. Not ( I want a solution within 20 minutes. The coil span of a full pitch coil is always 180° electrical. pitch factorThe flux distribution Curve of a smooth-core 50 c/s generator is. 150 degrees c. For a coil span of 13/15 of a pole pitch, the phase winding factor is: K_p = cos(π * 13 / (2 * 15)) = 0. Coil span is defined as the peripheral distance between two sides of a coil. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. 7 slots c. If the coil span is less than the pole pitch (as in coil Fig. p. 24 where pole- pitch of 4 has been assumed), then winding is called full-pitched. 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. . of poles, P= 4 No, of slots = 24; No. Pole pitch is always equal to 180o. Calculate the pitch and distribution factors for the fundamental, the third, and the fifth harmonics in the phase voltage. . 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. If the coil span is equal to the Pole pitch then it is called a full pitch coil. Back pitch (Y b): It is the span of the coil from the back end. It means that coil span is 180 electrical degrees. 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. This distance is measured in terms of armature slots or armature conductors that come between two adjacent pole centers. In other words, the distance between the two coil sides of a coil will be equal to the distance. 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. Calculation:When the coil sides forming a coil are spaced exactly one pole pitch a part they are said to be of full-pitch. 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 . 09 O4. 0 D. Author: Frank D. A. 15, 13; 19, 17; 21, 19; 23, 21;150° is (frac{5}{6}) parts of 180° i. 2:. a. Relation between frequency, speed and number of poles: Fig: 1. 150 degree (electrical). generator, the back pitch of the winding must equal the number of (a) commutator bars per pole (b) winding elements (c) armature conductors per path (d) armature parallel paths. Pole pitch is defined as the angular distance between the central line of one pole to the central line of the next pole. must be exactly equal to pole pitch C. Use: (Y) =) 2. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. Alternatively, this type of coil is also called a short-pitch or chorded coil. Calculate the pitch factor for (a) fundamental (b) 3rd harmonic (c) 5th harmonic (d) 7th harmonic. However, the coil span may be less than a pole pitch, in which case the coil is described as short pitched or chorded. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. A 3-phase, 8-pole, 60-Hz, star-connected alternator has 96 slots with 10 turns per coil. 7. Calculate the pitch factor for an alternator winding with 36 slots, 4 poles, and coil span of 1 to 8. ISBN: 9780073373843. Coils 1, 2 and 3 shown in Fig. 2. Hence, during rotation when one side of the coil comes under north pole, the other side of the coil comes under south pole. 1. If the coil span is equal to the Pole pitch then it is called a full pitch coil. The dc armature winding in which coil sides are a pole pitch apart is called ____ winding – Full- 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 coil span of the alternator is 1 to 8. A 4-pole, 3-phase synchronous machine has 48 slots. Back. 2 Selecting the coil span for a given pole pitch. 9: Rated speed (rpm) 170: Rated current (Arms) 3. Publisher: McGraw-Hill Education. 16 wb/pole and is distributed sinusoidally over the pole. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. 12 Wb and a. F induced in the other side of the coil. (ii) Pole pitch: The over hang portion of the coils depend upon the coil. For the n th harmonic, the chording angle becomes nα° electrical. Commutator bars per pole. A coil is said to be fully pitched when the coil span is made equal to the pole pitch of the machine. Pole – pitch. Coil span σ, winding factor k w, pole ratio G r and N c for possible pole-slot combinations in the proposed FMPM machine. 2. armature, 180 electrical. ∴ e = E 1 + E 2 = 2E. 86 O 119. of slots / slots per pole. 24, and assume first a short-pitched coil spanning half a pole pitch, then a long-pitched coil spanning one and a half. The spacing is expressed in terms of number of slots between the sides. An alternator having 10-poles, 3-phase, and 60 Hz has 8 conductors per slot in single layer arrangement with 4 slots/pole/phase. In a 4 pole, 3 phase alternator, armature has 36 slots. The two sides of a coil are placed in two slots on the stator surface. 96 stator slots, 6poles, coil span 1to 12. A six pole, three phase AC generator 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. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. Lap and Wave winding are explained. m. The fundamental flux per pole is 0. Use a diagram like that shown in fig. In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch, back pitch, pole pitch, coil pitch, etc. 3K views. 086 Wb, what will be the values of the emfs? phase and line? I need the procedure to get to that answer. . If the coil span factor is 0. It is always less than unity. Hence E. When the winding is full pitched, coil span is equal to the pole pitch. 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. , 5 slot‐pitches in Figure 2a) [8, 9]. If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched coil. c. Please see Electrical 4 U site for article on Armature Windings: Pole Pitch, Coil Span And Commutator Pitch. are e. Answer Coil span factor = 0. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. So if coil span is ‘n’ slots or 180° electrical the coil is called 180° full pitch coil. 1 times the pole arc. Short-pitched coils are deliberately used because of the following advantages: 1. The. 2. Number of empty slots = 18 – 15 = 3 slots ( herefore alpha = 180^circ imes frac{3}{{18}} = 30^circ). For example if S/P = 10. Determine the equation for the emf induced in one turn, and its RMS value. 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). The distance between the two sides of an individual coil of and AC armature winding id termed the coil pitch. 707.