This is naturally equal to the total number of armature slots divided by the number of poles in the machine. M. 10 are one pole pitch or n slots or 180° electrical apart, the coil is called full pitch coil. It falls short by 1/6 pole-pitch or by 180°/6 = 30°. . 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. The coil span is 150 electrical degrees. Pole pitch is always equal to 180o electrical. Get Coil Span or Coil Pitch Multiple Choice Questions (MCQ Quiz) with answers and detailed solutions. 79. The coil pitch is equivalent to the span, except that this term is used more often in a theoretical context and expressed in electrical degrees, or per-unit of a pole-pitch. 98: 61. the coil will be in 180o. Chorded-coil. A 144-slot stator has a whole coiled 12-pole three-phase winding. in. If the coil span is equal to the Pole pitch then it is called a full pitch coil. 33 percent of pole pitch to obtain the maximum reduction of harmonics. Identify number of rotor slots, number conductors / slot, coil span, number of slots per pole. Coil pitch or coil span is defined as the angular distance between the two coil sides of one coil. I need answer within 20 minutes please please with my best wishes. arrow_forward A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. Pole pitch is always equal to 180o. Pitch Factor is calculated by dividing the coil throw (–) 1 (coil span), by the number of slots per pole. For 20 slots, 4 polesThe winding of a 4-pole alternator having 36 slots and coils and a coil span of 1 to 8. Publisher: McGraw-Hill Education. Define Pitch Factor /Distribution Factor and present the formula to calculate. 60o groups, 2-layer winding is used. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. Pitch: Pole and Winding • Pole pitch is the mechanical angle between adjacent poles, e. c. of consecu- tive turns (c) distribute the winding. It. Pitch Factor·· the ratio of the voltage generated in ti1e fractional-pitch coil to the voltage generated in the full-pitch. In a 4 pole, 3 phase alternator, armature has 36 slots. . 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 armature coils are all-connected in series. 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. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. 60 hz, 10-pole alternator has 120 slots and 4 turns in every coil. A coil whose sides are separated by one pole pitch (i. Hence emf induced in one side of. arrow_forward A. o. 10 slots d. Find the EMF produced by a DC generator connected to a 6 poles coil rotating at 1200 RPM. 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. 6. The pole pitch is 35 cm, the core length 32 cm, and the stator coil span four fifth of the pole pitch. ed = electrical degree Example 2: Calculate the pole pitch for a three phase 4 pole ac machine having 36 stator slots. It means that coil span is 180 electrical degrees. If the coil span is less then one pole pitch than it is called short pitch coil. Last edited by markadlerdallas. Coil span is 16 – 1 = 15 slots. Learn what a pole pitch is, the pole pitch formula & definition, and how to. BUY. It. The arc diagram contains all the necessary information for connecting the pole-groups correctly. Obtain a full-pitch winding. #Alternator #Protectionofalternator#elect. It is defined as the angular distance between the central line of one pole to the central line of the next pole. 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. 7. . 🔥engineers platform App Link. in them are additive. Chording: with coil-span less than pole pitch 5. ; Here, e = E 1 = E 2 = E. For alternator having fractional pitch winding of 8/14 the coil span is 102. Let us consider, the coil has a pitch short by an angle α electrical degrees from the full pitch. 40 O 2. Explanation: Pole pitch is called as center to center distance between two adjacent poles. If t he coil pitch is y =3, the diame tral w inding w ill have the f. If the coil span is equal to the Pole pitch then it is called a full pitch coil. 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. 25 O 5. slots. lt is also known as coil pitch. Generators 897 winding is fractional-pitched. . In a 4-pole, 35 slot dc armature, 180 electrical degree coil span will be obtained when coils occupy _____ slots. armature, 180 electrical-degree coil span will be obtained when coils occupy. 2. it is said to the a fractional-pitch. because of that the pole pitch is 9/4 of the slot pitch, thus the three-phase symmetric distributed windings consist of 18 double-layer coils that can be used, in which each coil span. Now labeling the starting end of each coil is easy, assuming an RYB phase sequence taking red as the reference. 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. When two capacitors of reactances 10ohms and 20 ohms are connected in parallel across a 100 V supply, total VAR drawn will be _. It is also called a chorded coil. Pole Pitch: It is the angular distance between the two adjacent poles. Here, e = E 1 = E 2 = E. [8+8] 2. ) 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: It is the angular distance between the two sides of the coil. In practice, coil pitch (or Span) as low as eight-tenths of a Pole Pitch, is employed without much serious reduction in emf. 4 pole = 90º. Assuming double turn coil, Calculate the back pitch for progressive and retrogressive winding. 12 3-0. (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. armature, 180 electrical-degree coil span will be obtained when coils occupy. Author: Frank D. machines with. Calculate its coil span factor. Thus, the total. Here, e = E 1 = E 2 = E. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . Required: a. Compared to the overlapping winding above we need only 3 slots for the two poles. 967. As shown in Fig. Answer: c Explanation: Pole pitch is called as center to center distance between two adjacent poles. It is usually measured in terms of teeth, slots or electrical degrees. it is said to the a fractional-pitch coil. of a 10-pole three-phase 50Hz alternator with 2 slots per pole per phase and 4 conductors. D. If the coil span is equal to the Pole pitch then it is called a full pitch coil. The pole pitch is 10 slots, and the coil pitch is 9 slots. Note. Hence, during rotation when one side of the coil comes under north pole, the other side of the coil comes under south pole. For a coil span of 13/15 of a pole pitch, the phase winding factor is: K_p = cos(π * 13 / (2 * 15)) = 0. 707 B. Place the arrows according to the slot pitch. Explain the following armature winding terminologies (i)commutator Pitch (ii)Coil Side (iii)Pole Pitch. 966 and 0. m. Determine both the winding factor and the effective turns per phase. 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. 50Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. f. 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. Table of Contents Terms used in the armature winding Conductor Turn Coil Coil Side Front end and Back end connector Pole. 1. ∴ e = E 1 + E 2 = 2E. A 4 pole, 12 slot lap wound dc armature has two coil side per slot. The slots per pole per phase are 8 and the coil span is 20 slots. The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degree. Obtain a coil span of 180 degrees (electrical) b. 0 B. 1 the coil span should be approximately equal to a pole pitch. For a full pitch coil, the value of pitch factor is unity whereas for its value is also unity for concentrated coils. The maximum pole flux is 8. D. Coil span Pole pitch Periodicities Winding factor. F. (ii) Pole pitch: The over hang portion of the coils depend upon the coil. It is using an armature winding which is short pitched by one slot. less than 180° electrical, the coils are called, short pitched coils or fractional pitched coils. The spacing is expressed in terms of number of slots between the sides. Coil is 12 slots. Determine the phase andline values of emf if the machine runs at 600 rpm and the flux per poleis 0. 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. Question. 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. 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;. 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. 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. air. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. The armature has double layers winding. It is always less than unity. m. 0. ; It means one side of the coil in a particular slot, after how many conjugative slots, the other side of the same coil is placed. Winding table. 4. The flux per pole has a fundamental component of 0. A 4-pole, 50-Hz, star-connected alternator has 15 slots per pole and each slot has 10 conductors. Concept: Coil pitch or coil span: It is defined as the angular distance between the two coil sides of one coil. Figure 1. If the machine gives 3300 V between lines on open circuit sinusoidal flux distribution, determine. Answer: c Explanation: K p =cosε/2 (i) Slots per pole = 36/4=9, for a coil span of 8 slots, the coil is short pitched by 1 slot and the chording angle is ε=γ = 20° ⇒ K p =cos10°=0. Since one pole presents 180 electrical space degrees so the slots pitch. Generators 897 winding is fractional-pitched. . 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. Determine the pitch (or coil span) factors for the winding ,24 Stator slots ,4 poles, coil span 1 to 5 12. Study with Quizlet and memorize flashcards containing terms like A lap winding, Twice, Full-pitch and more. the coil will be in 180o. In a 4-pole, 35 slot d. Author: Frank D. What are the different types of stator windings in induction motor? Ø. 9; 21. 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. 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. In a 10 pole, lap wound de armature, the number of active armature conductor per pole is 50. 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. armature, 180 electrical. m. The pole pitch is always 180 degrees electrical regardless of the number of poles in a machine. The two sides of a coil are places in two slots on stator surface. A 3-phase, 4 pole, Y- connected alternator has 72 slots with two conductors per slot. This is shown in the figure to left. Expert Solution. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. 363Wb and a 15% third harmonic. Solution for Calculate the pitch factor for the following windings: a) 72 stator slots, 6 pole, coil span 1 to 10. It is usually measured in terms of teeth, slots or electrical degrees. 15 situated at the center of an N pole rotating in clockwise direction. Cogging torque was minimized by finding an optimum magnet pole arc length and torque ripples were minimized by finding. For making coil span equal to a pole pitch in the armature winding of a dc generator, the back pitch of the winding must equal the number of – Commutator bars per pole. A coil span less than 2/3 pole pitch is not used in practice. Find the terminal voltageon open circuit. Back pitch: The distance between the two sides of a coil in the back of the armature is called back pitch. it is defined as the peripheral distance between the center of two adjacent poles in a DC machine. K p = cos (nα/2) Where n is the nth harmonic. Number of Commutator Segments - Number of Commutator Segments is the count of cylindrical assembly of insulated segments that are mounted on the shaft. 9 and pf = 0. of consecutive turns (c) distribute the winding uniformly under different poles (d) obtain a full-pitch winding. The meaning of FULL-PITCH WINDING is the winding of an armature in which the two sides of the armature coil span a distance equal to the pole pitch. Coil span or Coil Pitch. Here, e = E 1 = E 2 = E. Sanfoundry Certification Contest of the Month is Live. If the coil span is from slot 1 to slot 21, and the flux per pole has a fundamental component of 0. 00 O…influence of slot/pole number (S/P) combinations on the rotor bar copper loss, a winding harmonic index is described in Section 2. In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch, back pitch, pole pitch, coil pitch, etc. 955, whilst the second option gives (k_{sk1}) equal to 0. 160 degrees b. . It is lesser than the value in the first case. 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. Each of these coil spans is five slots, so this choice of winding. advertisement. It may be the full pitched or short pitch. 6. 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. It is usually measured in terms of teeth, slots or electrical degrees. The total flux per pole is 10⁶ lines. p. In SWAT-EM the coil span is given in number of slots. Figure 4 shows the flux distribution linked to a short-pitch coil. 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. 2. What is the coil span for a 2 pole 18 slot machine? a) 9 b) 4. 0 C. (Elect. 1NP2. 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. A pitch in the "region" of 5/6 is most effective to reduce 5th and 7th harmonics. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. 1 is connected to coil side in slot No. We will start Red at slot 1. 14. 1, or nonsalient (flush with the surface of the rotor), as shown in Fig. Assume a coil span of unity. Machine, Nagpur Univ. ) A 6-pole, 3-phase, 60-Hz alternator has 12 slots per pole. Transcribed Image Text: (d) obtain a full-pitch winding. The dc armature winding in which coil sides are a pole pitch apart is called ____ winding – Full- pitch. If the coil span is. 50 Q 1. 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. In this case, the coil sides lie under opposite poles, hence the induced e. A=2, B=1 and C=2 and D=5. Its flux per pole is 0. e. 3. c. Coil Span: The number of core slots spanned by the sides of the coil. m. 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. (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. 31. This type of winding is mainly used for. Back pitch (Y b): It is the span of the coil from the back end. The. Pitch factor: Pitch factor is defined as the ratio of the induced emf per coil when the winding is short-pitched to the induced emf per coil when the winding is full pitched. In a 4-pole, 35 slot d. Question. 1 times the pole arc. Now coil is shorted by 1 slot i. • Pitch of a Winding (Y) In general, it may be defined as the distance round the armature between. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. Allow 10 ampere for the field current and assume a voltage drop of 4 volts for the armature circuit. The coil span is 150 electrical degrees. The first coil lies in slots 1 and 16. 2. K pn = cos nα/2. The Separation between the top and bottom sides of a coil is known as back pitch and is represented by (Y b). 5 c) 18 d) 6 View Answer. Calculate the sinusoidally distributed flux per pole required to give a line voltage of 11 kV on open circuit, and the full load current per conductor. Pole pitch is always equal to 180o. (b) Determine the pitch (or coil span) factors for the following windings: i. 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). Three kinds of coil spans are used, they are 4-solt pitch, 3-solt pitch, and 2-solt pitch. what is coil pitch or coil span. D 2 L = Q / C 0 ns = 500/( 153 x 8) = 0 m 3 Using round poles for the salient pole alternator and assuming ratio of pole arc to pole pitch as 0 and pole arc equal to core length. This advancement is measured in terms of armature conductors and is called back pitch. This chapter covers the calculation of winding factors and armature MMFs, harmonic analysis of armature MMFs. M. 3 percent. m. The coils are made up of 8 turns, and the windings are double layer. This video lecture provides full understanding of pole pitch and coil pitch with examples. The reduction fraction is the pitch factor. In a full pitch coil, the coil span will be 180° electrical (equal to pole pitch). phase shift with emf induced in the other side of the coil. g. ISBN: 9780073373843. A 4-pole, 3-phase synchronous machine has 48 slots. 8. It may be the full pitched or short pitch. 135 degrees d. 339 IC function as. 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 ). Publisher: McGraw-Hill Education. The slots per pole per phase are 8 and the coil span is 20 slots. Alternatively, this type of coil is also called a short-pitch or chorded coil. 2:. 3 mWb and the total number of armature conductors is 1000. In this case, we have a 10 pole alternator with coils wound in a fractional pitch of 18/21. Fractional slot winding 6. Coil–span or coil-pitch. 6. The coil span is 150 electrical degrees. 4 pole three phase winding. ( c) 96 stator slots, six-poles, coil spans 1 to 13. SEE MORE TEXTBOOKS. At this situation, two opposite sides of the coil lie under two opposite poles. The coil pitch is short by 2 slots. 956 1. 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. 7. Coil Span: It is the angular distance between the two sides of the coil. When a coil. Coil span and commutato pitch b. Back Pitch. MMF OF ARMATURE A. The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degrees. The separation between the top and bottom sides of a coil is called Coil span. ∙ 10y ago. 7. ( ) () ⎪ ⎪ ⎪ ⎩ ⎪⎪ ⎪ ⎨ ⎧ = − = − = − = − = sin 8 /5 sin 6 /5 sin. The pitch factor. The correct answer is option 2): 5 slots Concept: 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. When the. Find equation of 5 EMF induced in one turn and its RMS valueIn this study, the electromagnetic performances of dual 3-phase permanent magnet (PM) machines with coil span of two slot-pitches are comparatively investigated. , coil span is 180º electrical) is called a full-pitch coil. of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a full-pitch winding. View the full answer. 5. First, a double-layer winding is investigated with the number of slots Q, pole pairs p and a constant coil pitch . 75), the lowest 2-solt coil span. 5, then the coil-span can be either 11 or 10 slots. 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. Assuming single turn coil, calculate the back pitch for progressive and retrogressive winding. The flux per pole has a fundamental component of 0.