(BTL-1) 4. Coil Span: It is the angular distance between the two sides of the coil. So if coil span is ‘n’ slots or 180° electrical the coil is called 180° full pitch coil. 10 are one pole pitch or n slots or 180° electrical apart, the coil is called full pitch coil. Hence, the pole pitch of that DC machine would be 24. Machine, Nagpur Univ. C. Prob. Petruzella. ( b) 42 stator slots, four-poles, coil. 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 three phase, 50 Hz, 8 pole alternator has a star connected winding with 120 slots and 6 conductor per slot. In this case, there is a phase difference between the e. Calculate the emf generated in each phase when the machine runs at 375 rpmHey Aspirants. In other words, the distance between the two coil sides of a coil will be equal to the distance. 15 Consider the armature conductor marked X in Fig 1. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. ∴ e = E 1 + E 2 = 2E. It indicates how the coils are spaced out on the armature core. CONTENTS CONTENTS + 0 ) 2 6 - 4 Lear ningPole – pitch. In such coils, the two coil sides are not under the poles. 71 O 120. Pitch factor:Concept: Pole Pitch: It is the angular distance between the two adjacent poles. 6. Boylestad. Use a diagram like that shown in fig. In this. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. If the coil span is less then one pole pitch than it is called short pitch coil. In general, if the coil span falls short of full-pitch by an angle α (electrical)*, then kc = cos α/2. 09 O4. 0. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical DegreeThere are many people who want to. 1822 V 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. 40 O 2. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. Publisher: McGraw-Hill Education. Ans. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. A 4 pole, 12 slot lap wound dc armature has two coil side per slot. The arithmetic sum of induced emfs is 2E. 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. 57 O 127. Transcribed Image Text: 9. In this case, the coil sides lie under opposite poles, hence the induced e. It may be the full pitched or short pitch. F induced in the other side of the coil. It is usually measured in terms of teeth, slots or electrical degrees. ∴ Coil span factor, Where β is the angle through which the coil is short pitched. I need answer within 20 minutes please please with my best wishes. 60o groups, 2-layer winding is used. 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. . of consecutive turns (c) distribute the winding uniformly under different poles (d) obtain a full-pitch winding. The commutator is also known as a reverser. Identify number of rotor slots, number conductors / slot, coil span, number of slots per pole. e. For alternator having fractional pitch winding of 8/14 the coil span is 102. 1 the coil span should be approximately equal to a pole pitch. TYPES OF AC MACHINES WINDINGS. The coil used in double layer winding are diamond shaped as in the dc windings. It equals pole pitch = Z P . You can compare the maximum fundamental winding factor for different combinations of number of poles and number of slots, display the winding layout for different coil spans,. 2:. Share on Whatsapp Latest UPSC IES Updates. a. 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. α = Angle of short pitch = 20o. Define Pitch Factor /Distribution Factor and present the formula to calculate. (Elect. armature, 180 electrical-degree coil span will be obtained when coils occupy. When the parallel path is twice the number of poles then it is known as Duplex Lap Winding. , pole-pitch ) is known as 'Full Pitch'. Pole Pitch, Coil Span, Back Pitch, Front Pitch, Commutator Pitch in Armature Winding of DC Machines are explained in this video. Determine the coil and commutator pitches for a 72-slot 288-segment six-pole frog-leg armature winding. DARWIN M. 0. 9 slots . In this case, there is a phase difference between the e. It is expressed in terms of number of slots per pole. The flux per pole has a fundamental component of 0. armature, 180 electrical-degree coil span will be obtained when coils occupy. , Y = 2/3 τ p. Distribute the winding uniformly under different poles d. The coil span is 160°. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch. D. Calculate its coil span factor. 11. A pole pitch is always 180° electrical regardless of the number of poles on the machine. Q3- A/ 10 MVA, 11 KV, 50 Hz, 3-phase star-connected alternator s driven at 300 RPM. You can investigate three-phase integer-slot, fractional-slot and concentrated windings, both with single and double winding layers where appropriate. Electrical Engineering questions and answers. Calculate the average voltage generated in a six-turn full pitch coil of a 25 cycle alternator if the. Emf induced per coil side is E. 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,. Determine the equation for the emf induced in one turn, and its RMS value. This lecture will discuss;1. In an alternator, for a coil having a span of 2/3 of pole pitch,. As shown in Fig. The armature winding is housed in 360 stors with 6 conductors per slot. Hence emf induced in one side of. An alternator has 18 slots per pole and the first coil lies in slots 1 and 16. 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. 2. Pole – pitch. ( c) 96 stator slots, six-poles, coil spans 1 to 13. The rotor is a large electromagnet. 0. 6. 259 C. Solution for Calculate the pitch factor for the following windings: a) 72 stator slots, 6 pole, coil span 1 to 10. 10. The flux per pole has a fundamental component of 0. Generators 897 winding is fractional-pitched. In a 10 pole, lap wound de armature, the number of active armature conductor per pole is 50. 7. 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. Calculate the emf generated in each phase when the machine runs at 375 rpmHence, pitch factor or coil span factor K p = Cos(/2). First. K pn = cos nα/2. Answer: c Explanation: Pole pitch is called as center to center distance between two adjacent poles. Coil Span (ii) Resultant Pitch. The pole arc should be about 70% of pole pitch and length of core about 1. 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. If the coil span is. 4. p. Coil pitch or coil span is defined as the angular distance between the two coil sides of one coil. 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. 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. 0 i D. [Answer: 0. ISBN: 9780133923605. If the maximum flux per pole, with a sinusoidal distribution, is 0. 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. Pitch factor. In this alternator one pole spans twelve slots. 05 Wb, sinusoidally distributed. 75 times the slot pitch), the lowest with 2-solt span coil. You can read more about Full Pitch and Short Pitch Winding at:. ISBN: 9780073373843. Calculate the no-load terminal voltage, if the speed of the alternator is 1500r. Commutator bars per pole. In a 4-pole, 35 slot dc armature, 180 electrical degree coil span will be obtained when coils occupy _____ slots. The part of the coil in which EMF is generated is known as _____. When a coil is having a span of 180° electrical, it is called a full-pitch coil. The coil span is 150°. A pole pitch in an electrical machine is equal to 180° electrical. 15, 13; 19, 17; 21, 19; 23, 21;150° is (frac{5}{6}) parts of 180° i. Power System Analysis and Design (MindTap Course List) 6th Edition. Answer: 0. arrow_forward. If the coil span is equal to the Pole pitch then it is called a full pitch coil. For a three-phase winding with 6 slots per pole per phase and with a coil span of 15 slots, the value of pitch factor is This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. The pole pitch is 35cm, the core length is 32cm & sta- 4th tor coil span is of pole pitch. In a synchronous generator, what do fractional pitch and fractional slot windings mean?• (e) The coil span must be odd integer. Study with Quizlet and memorize flashcards containing terms like A lap winding, Twice, Full-pitch and more. Here, e = E 1 = E 2 = E. Question. This distance is measured in terms of armature slots or armature conductors that come between two. The pitch of the coils is 2 slots less than the pole pitch. I need answer within 20 minutes please please with my best wishes. Transcribed Image Text: (d) obtain a full-pitch 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. in the two sides of the coil. The pole pitch is always 180 degrees electrical regardless of the number of poles in a machine. If the coil span is equal to the Pole pitch then it is called a full pitch coil. 7. 0. 6. o. Thus, the total. It means that coil span is 180 electrical degrees. Muthu RE: How. The flux per pole is 0. Pole pitch is always equal to 180o. belt factor. We make the coil span less than 180 degrees electrical space degrees in a fractional pitch winding. Assume the coil span as 150° electrical. 98: 61. If the coil span is from slot 1 to slot 21, and the flux per pole has a fundamental component of 0. Hence, the total e. Generators 897 winding is fractional-pitched. Here’s the best way to solve it. Solution : n = Slots/pole = 36/4 = 9. A. Relation between frequency, speed and number of poles: Fig: 1. 0 C. 3. 25 O 5. • Coil span is nothing but the spacing between the two coil sides of a coil. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. In general, electrical degrees equals mechanical degrees times 1/2 the number of poles. Now labeling the starting end of each coil is easy,. ’s of consecutive turns c. Pole – pitch. 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. 5. Figure 2 illustrates a full pitch winding. 2 sin 30+0. In a 4-pole, 35 slot dc armature, 180 electrical degree coil span will be obtained when coils occupy _____ slots. Coil span and commutato pitch b. The winding is housed in 360 slots and has 6 conductors per slot, the coils spanning (5/6) of a pole pitch. 587, 0, khi 9. If the coil span is equal to the Pole pitch then it is called a full pitch coil. 16 wb/pole and is distributed sinusoidally over the pole. 2. Because a chording more than 1/3 pole pitch would noticeably reduce the phase emf. M. Calculate the distribution factor for a single layer 36 slots 2-pole three-phase stator winding. 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). It is lesser than the value in the first case. Similarly, for a coil having a span of 2/3 pole-pitch, kc = cos 60°/2 = cos 30° =. what is coil pitch or coil span. Full pitch winding. c. in. Determine the equation for the emf induced in one turn, and its RMS value. Assume the coil span as 150° electrical. $$\mathrm{Slot\:per\:pole =\frac{90}{6}= 15}$$ For a full-pitch coil, the coil span is 15 slots. Obtain a coil span of 180 degrees (electrical) b. 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 . coil span, slip-ring voltage on open circuit, approximate full load current per phase in rotor. 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. The armature has double layers winding. It is given by K p = cos (α/2) Where α is the short pitch or chording angle. 1. Display and compare winding harmonicsElectrical Engineering. There. 1. 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). 1 the coil span should be approximately equal to a pole pitch. the flux per pole has a fundamental component of 0. Slots/pole/ph = m = 72/ (8×3) = 3. 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. Assuming double turn coil, Calculate the back pitch for progressive and retrogressive winding. 9: Rated speed (rpm) 170: Rated current (Arms) 3. If the machine gives 3300 V between lines on open circuit sinusoidal flux distribution, determine. Commutator pitch. If the coil-pitch is one pole pitch, it is called the full-pitch coil. . A pitch in the "region" of 5/6 is most effective to reduce 5th and 7th harmonics. f. It falls short by 1/6 pole-pitch or by 180°/6 = 30°. It is using an armature winding which is short pitched by one slot. may or may not be exactly equal to pole pitch B. Lap winding • Suppose we want to make a lap winding for a P = 4 pole D. The distribution of upper-side voltage phasors is the same as that of coil voltage phasors,. For n th harmonic. An 8-pole lap wound DC generator has 120 slots having 4 conductors per slot. The winding calculator allows you to find the optimum winding layout for your electric motor in a fast and convenient way. 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. If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. When measured in electrical degrees one pole itch is equal to 1800. Then, the pitch factor will be equal. They are two basic physical types for the windings. m. Pole pitch is always equal to 180o. K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. The armature windings conduct AC even on DC machines, due to the commutator action (which. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. 455 V D. 966The pole pitch, mQ ′ ∕ p, is also fractional, so that the coil-span cannot be of full-pitch. A coil having a span equal to 180⁰ electrical is called a full pitch coil as shown in the figure below. The coils are place in 60 uniformly distributed slots around the inner perimeter of the stator. Lap and Wave winding. Sketch the winding over a pole pitch, indicating the location of the conductor of each phase. It is generally denoted by K c and its value is always less than unity. Coil Span:The angular distance between the centers of two adjacent poles on a machine is known as pole pitch or pole span. 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 1P: Visit your local library (at school or home) and describe the extent to which it provides literature. It is possible to suppress the higher harmonics by using double-layer windings using shortened span coils. fs. Similarly, for a coil having a span of 2/3 pole-pitch, kc = cos 60°/2 = cos 30° = 0. m. y=Coil span τ=Z/2P is the Pole pitch or full span II. However in practise this often isn’t the best choise because of the high harmonic content. 2. 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. A 4 pole, 12 slot lap wound dc armature has two coil side/slot. It is always 180° electrical. A winding constituting a basic unit under a pole-pair (N and S) is repeated for any number of pole pairs when q is integral. The pole pitch is 35 cm. The coil pitch is short by 2 slots. Determine the pitch (or coil span) factors for the winding , 96 Stator slots ,4 poles, coil span 1 to 18 13. Solution for For alternator having fractional pitch winding of 10/14 the coil span is 4. First, a double-layer winding is investigated with the number of slots Q, pole pairs p and a constant coil pitch . 135 degrees d. 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. Discuss the effect of making the coil span very different from the pole pitch on (a) the coil emf and (b) the coil torque. Transcribed Image Text: (d) obtain a full-pitch winding. 0. 5. The ratio of phasor (vector) sum of induced emfs per coil to the arithmetic sum of induced emfs per coil is known as pitch factor (Kp)or coil span factor (Kc) which is always less than unity. A. It is lesser than the value in the first case. SEE MORE TEXTBOOKS. Two-and four-pole rotors have normally nonsalient poles, while rotors with more than four poles have salient poles. Correction for this is done by multiplying the voltage equation by Kp, called pitch factor. I need answer within 20 minutes please please with my best wishes. For example if S/P = 10. For making coil span equal to a pole pitch in the armature winding of a d. (8) A SIMPLE explanation of Full Pitch and Short Pitch Winding. where B is the flux density, µ is permeability of material, A is the area of the magnetic field path, whereas the same subscript used in is used thought the paper. The winding is 5/6 pitch. a. 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. Ensure the addition of e. Coil–span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. The Separation between the top and bottom sides of a coil is known as back pitch and is represented by (Y b). Pole pitch is always equal to 180. , Y R = Y B − Y F . Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Assume = 0. Solution for Calculate the pitch factor for the following windings: a) 72 stator slots, 6 pole, coil span 1 to 10. Hence E. of poles, P= 4 No, of slots = 24; No. Here ξ is the chorded angle or short pitch angle. The slots per pole per phase are 8 and the coil span is 20 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. (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. † ‡ ˆ ‰ Š ‹ Œ Ž ‘ ’ “ ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿPitch factor: Full-pitched coils i. Pole pitch = 180 electrical degrees = S/P = 2C/P. Coil–span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. 31. It is usually measured in terms of teeth, slots or 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. Coil span is the number of slots between the two sides of the same coil. Assume that the coil span is 150° electrical. In a fractional pitch winding, the coil span is made less than 180 degrees electrical space. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. Ensure the addition of e. 1 times the pole arc. When the winding is full pitched, coil span is equal to the pole pitch. m. The winding distribution factor of the alternator is. Where n is the nth harmonic. Coil – span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. Problem. Y-connected alternator has 9 slots per pole and a full-pitch. The use of windings with a coil span of two slots promises a better balance between ohmic losses and end windings space on the one hand and harmonic content. m. 50 Q 1. 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. The highest winding factor can be obtained with 4-solt span coil (the coil span is closest to pole pitch 3. Fractional pitched windings are purposely used to effect a substantial saving in copper of the end connection and for improving commutation . This type of winding is mainly used for. This number is known as coil span. 5, then the coil-span can be either 11 or 10 slots. coils having span which is equal to one pole-pitch i. (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. 924 359. number of slots and a coil span of two slots require at least 18 slots. Coil span Pole pitch Periodicities Winding factor. 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. Coils 1, 2 and 3 shown in Fig. Hence, the total e. Pole pitch is always equal to 180o. It may be the full pitched or short pitch. The pole pitch is 35 cm, the core length 32 cm, and the stator coil span four fifth of the pole pitch. 163Wb. ÐÏ à¡± á> þÿ ” — þÿÿÿt u v w x y z { | } ~ € ‚ ƒ „.