Let us assume that, a coil is short pitched by an angle α (electrical degree). The primary reason for making the coil span of a d. 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. spanning over 180° (electrical). 951: C) 0. Short-pitched coils are deliberately used because of the following advantages: 1. 587, 0, khi 9. Pole arc/ pole pitch = core length/ pole pitch = 0. A coil whose sides are separated by one pole pitch (i. 0. 150° is (frac{5}{6}) parts of 180° i. (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. 125 Wb and a. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. Pole Pitch, Coil Span, Back Pitch, Front Pitch, Commutator Pitch in Armature Winding of DC Machines are explained in this video. e. pitch factorThe flux distribution Curve of a smooth-core 50 c/s generator is. A 3-phase, 12-pole, star-connected alternator has 180 slots with 10conductors per slot and the conductors of each phase are connectedin series. The arc diagram contains all the necessary information for connecting the pole-groups correctly. If the coil span is equal to the Pole pitch then it is called a full pitch coil. , coil span is 180º electrical) is called a full-pitch coil. armature, 180 electrical-degree coil span will be obtained when coils occupy. Calculate the pitch factor for: (i) Fundamental (ii) 3 rd harmonic (iii. You can read more about Full Pitch and Short Pitch Winding at:. Pole pitch = 180 electrical degrees = S/P = 2C/P. Calculate the emf generated in each phase when the machine runs at 375 rpmHence, pitch factor or coil span factor K p = Cos(/2). In a 4-pole, 35 slot dc armature, 180 electrical degree coil span will be obtained when coils occupy _____ slots. The skew by one slot pitch gives the value of fundamental skew factor of 0. round the coil which is the vector sum of e. In a fractional pitch winding, the coil span is made less than 180 degrees electrical space. The distribution of upper-side voltage phasors is the same as that of coil voltage phasors,. 80The coil pitch of such distributed windings is normally at least three slots which brings about a high winding resistance and occupies much space for the end windings. The conductor being situated at the place of maximum flux density will have maximum emf induced in it. 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. For a simplex lap winding, the commutator pitch YC = 1 and coil span YS ~ pole pitch. ISBN: 9780133923605. To get a coil around every tooth, we need two winding layers (double layer winding). 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. Here, e = E 1 = E 2 = E. 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,. 60o / 90o = 2/3. Coil span Pole pitch Periodicities Winding factor. 160 degrees b. e. Figure below shows a short pitched coil. Pole pitch is always equal to 180o electrical. A 10 MVA, I KV, 50 Hz, 3-phase, star-connected synchronous seberatur is driven ur 300 r. 12Wb and a third harmonic component. 7. 086 Wb, what will be the values of the emfs? phase and line? I need the procedure to get to that answer. Coil Span: It is the angular distance between the two sides of the coil. 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. In a 4 pole, 3 phase alternator, armature has 36 slots. It indicates how the coils are spaced out on the armature core. ; Coil Span: It is the angular distance between the two sides of the coil. Ensure the addition of e. MMF OF ARMATURE A. 10. 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 pitch factor corresponds to the mean span of the coils of the winding with respect to the pole pitch while the distribution factor quantifies the flux reduction due do the winding distribution inside a finite number of slots. Duplex Lap Winding. Here, e = E 1 = E 2 = E. Note. Let us consider, the coil has a pitch short by an angle α electrical degrees from the full pitch. Zoom In Zoom Out Reset image size. It is equal to the number difference of the conductor connected to a given segment of the commutator. 10 A three-phase, wye-connected alternator has 15 slots/pole. ; Here, e = E 1 = E 2 = E. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. Solution for For alternator having fractional pitch winding of 10/14 the coil span is 4. Use a diagram like that shown in fig. a. But, the given coil is short-pitched so that the coil span is $$\mathrm{coil\:span = (14 − 1)β = 13β}$$ $$\mathrm{∴\:α = (15 − 13)β = 2β = 2 × 12° = 24°}$$ Winding factor for fundamental component Pole pitchis defined as the peripheral distance between the center of two adjacent poles in a DC machine. ( 2) The harmonic voltages decrease in a short pitch coil, thereby improving the waveform of the induced voltage in the winding. 8 slots b. When measured in electrical degrees one pole itch is equal to 1800. A Three-phase four-pole AC machine has 60 coils in the stator and each coil has 100 turns. 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. If the high speed coil span was 1/2 of pole pitch, then there would be roughly equal airgap circumference for induced poles as exists for the driven poles in slow speed, and no need for homopolar flux in the shaft. 26. 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. The reduction fraction is the pitch factor. The coil span is 10 slots. . Determine the generated. The Separation between the top and bottom sides of a coil is known as back pitch and is represented by (Y b). Since this machine has 8 poles and a pole-pitch of 48/8 = 6 slots, the coil pitch here is 5/6 = 0·833 p. Draw the double layer winding layout for a 24 slot stator and 4 pole alternator 3. Determine the equation for the emf induced in one turn, and its RMS value. If the coil span is less then one pole pitch than it is called short pitch coil. Hence, the total e. 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. 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. Pole pitch is the peripheral distance between two adjacent poles. Similarly, for a coil having a span of 2/3 pole-pitch, kc = cos 60°/2 = cos 30° = 0. ISBN: 9780073373843. ; Here, e = E 1 = E 2 = E. For example if S/P = 10. 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. D. Boylestad. Coil spanA: slot angle = 180slot per pole = 18015 = 12 pole pitch = no. 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. fs. β = 180o/ = 20o. Hence emf induced in one side of. If the coil span is from slot 1 to slot 21, and the flux per pole has a fundamental component of 0. Draw the developed diagram andshow the positions of brushes. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . Calculation: Given that, Number of coils = 16Q2: 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. Author: Robert L. It is usually measured in terms of teeth, slots or electrical degrees. must be exactly equal to pole pitch C. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical DegreeThere are many people who want to. Calculation:The angular distance between the two coil sides is less than one pole pitch, it is termed short pitch or fractional pitch coil. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. DARWIN M. Where n is the nth harmonic. • In double layer windings used in. With a full-pitch coil, the emfs induced in the two coil sides are. Please see Electrical 4 U site for article on Armature Windings: Pole Pitch, Coil Span And Commutator Pitch. TYPES OF AC MACHINES WINDINGS. 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. Each of these coil spans is five slots, so this choice of winding. ; 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. Wiki User. In this study, the electromagnetic performances of dual 3-phase permanent magnet (PM) machines with coil span of two slot-pitches are comparatively investigated. o. 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. Back pitch: The distance between the two sides of a coil in the back of the armature is called back pitch. 911 V B. Distribution factor (K d): The ratio of induced emf in the coil group when the winding is distributed in number of. Each of these coil spans is five slots, so this choice of winding pattern is referred to as “Five-Sixths” pitch. Power System Analysis and Design (MindTap Course List) 6th Edition. Full Pitch and. This lecture will discuss;1. 363Wb and a 15% third harmonic. 14. of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a. It is expressed in terms of electrical space degree. The distance between the two sides of a coil is called the coil. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. In a 4 pole, 3 phase alternator, armature has 36 slots. Publisher: PEARSON. A. ’s of consecutive turns c. The skew factor reflects the flux reduction if the winding is angularly twisted along the axis. of phases = 3; No. Identify the approximate diameter and length of stator core,. Then, the pitch factor will be equal. B. 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. The winding calculator allows you to find the optimum winding layout for your electric motor in a fast and convenient way. Resultant pitch Y R is even, being the arithmetical difference of two odd numbers, i. The flux per pole has a fundamental component of 0. b) 96 stator slots, 6 pole, coil span 1 to…. Emf induced per coil side is E. The value of α will usually be given in the question, if not, then assume kc = 1. Pitch factor or coil-span factor In general, if the coil span falls short of full-pitch by an angle (electrical)*, then kc = cosα/2. It may be the full pitched or short pitch. round the coil which is the vector sum of e. 339 IC function as. of slots / slots per pole. m. Also note that the diagram gives no information about the coil-span or pitch; thus for example in the 36-slot case a full-pitch winding would have a coil-span of 9, but 8, 7 or 6 could also be used (all with 2 coil-sides per slot). m. 36 stator slots, 4-pole, coil span 1to 8 ii. The electrical space angle between the active coil length or coil side is equal to one pole pitch. ∴ e = E 1 + E 2 = 2E. 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. 15. 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. The pitch factor for third harmonic in an alternator having 18 slots per pole and coil span 5/6 of pole pitch is _. Also note that the diagram gives no information about the coil-span or pitch; thus for example in the 36-slot case a full-pitch winding would have a coil-span of 9, but 8, 7 or 6 could also be used (all with 2 coil-sides per slot). Looking at the diagram in the question. F induced in the other side of the coil. You can read more. 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. coil pitch in terms of slots4. In such coils, the two coil sides are not under the poles. S 36 Solution From equation 5, pole pitch = P = 4 =9 Coil Span or coil pitch: It is the distance between the two active sides of the same coil under adjacent opposite poles. 6. Figure 8 compares computed waveforms of phase back emf. 13. What is the short pitch in electrical degrees. Pole pitch is always equal to 180o electrical. 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). e. The pitch factor of an alternator is a measure of the winding distribution along the armature. 958] (B) Determine the maximum flux per'pole when connected to a' 220-volt,60-cycle line, neglecting local resistance and reactance drops. Based on the prototype of the long stator LSM we designed, the effect of different short-pitch factors on the propulsive force was studied: (8) {y p θ = τ π k y = sin θ 2 where y p is the short pitch, denoted by length; θ is the short pitch angle (rad. Calculate the pitch factor for (a) fundamental (b) 3rd harmonic (c) 5th harmonic (d) 7th harmonic. The flux per pole is 0. Coil span is 16 – 1 = 15 slots. The coil span factor is represented as For full pitch coil, the value of α will be 0⁰, cos α/2 = 1 and KC = 1. 4, Fig. , the case of short-pitch coil, the voltages generated in each coil side are not in phase. 339 IC function as. ed = electrical degree Example 2: Calculate the pole pitch for a three phase 4 pole ac machine having 36 stator slots. In a 4-pole, 35 slot dc armature, 180 electrical degree coil span will be obtained when coils occupy _____ slots. Pole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical Degree - YouTube Hey Aspirants. c. is known as coil span. Pole and slot numbers. Pole pitch is the electrical angle between the north pole and. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. e. 1 . The pole pitch is 35 cm, the core length 32 cm, and the stator coil span four fifth of the pole pitch. They save copper of end connections. If the coil span is. it is defined as the peripheral distance between the center of two adjacent poles in a DC machine. The commutation is. 16 wb/pole and is distributed sinusoidally over the pole. 2. 26. In an alternator, for a coil having a span of 2/3 of pole pitch,. lt is also known as coil pitch. (a) commutator bars per pole (b) winding elements (c) armature conductors per path (d) armature parallel paths. Step by step Solved in 3 steps. 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. Determine the pitch (or coil span) factors for the winding ,24 Stator slots ,4 poles, coil span 1 to 5 12. Hence pole pitch is equal to total numbers of armature slots divided by total numbers of poles, we alternatively refer to it as armature slots per pole. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. 24 B where coil pitch is 3/4th of the pole pitch), then the D. fs. armature, 180 electrical-degree coil span will be obtained when coils occupy. The coil span of a full pitch coil is always 180° electrical. 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. of slots per pole = 2 = 6 saree tensed gOSeaee Slot pitch, a = oF slow/pole > No. Coil span is simply a peripheral distance between two sides of a coil. 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. When the coil span is less than pole pitch (180 deg electrical), the winding is called short pitched or chorded. A. – Comparator. 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. 4 pole = 90o. It is usually measured in terms of teeth, slots or electrical degrees. m. Calculate the emf generated in each phase when the machine runs at 375 rpm Hey Aspirants. α = Angle of short pitch = 20o. Front Pitch-The number of armature conductors or elements spanned by a coil on the front is called front pitch. 6-phase fractional-slot-per-pole-per-phase Interior Permanent Magnet (IPM) machine having a novel topology of 18-slot, 8-pole, and, 6-phase, 48-slot, 8-pole IPM with distributed windings, both. The dc armature winding in which coil sides are a pole pitch apart is called ____ winding – Full- pitch. 16 wb/pole and is distributed sinusoidally over the pole. f. Then, the pitch factor will be equal. Coil–span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. Distribute the winding uniformly under different poles d. If the coil. A 3-phase, 50 Hz, 2-pole, star connected turbo alternator has 54 slots with 4 conductor per slot. 71 O 120. 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. 7. Hence, the pole pitch of that DC machine would be 24. L = πD/p = πD/ = 43 x 24 = 1048 ( satisfactory) Ex. 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. In this. 339 IC function as. 1 the coil span should be approximately equal to a pole pitch. It. If the pole span or coil pitch is equal to the pole pitch (as in the case of coil A where pole-pitch of 4 has been. The coil span of the alternator is 1 to 8. Since slot pitch is 6, 6 slots have upward arrows, 6 down and so on. C machine having a total number slots S = 16. Here we can define one more term related to a coil called coil span. (Assume lap. 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). 2 are short-pitched, full-pitched and over-pitched coils respectively. This distance is measured in terms of armature slots or armature conductors that come between two. When 40V DC voltage is applied to a single-phase AC motor, it draws 1A current. The winding is 5/6 pitch. Author: Frank D. Sanfoundry Certification Contest of the Month is Live. Distribute the winding uniformly under different poles d. e. Answer Coil span factor = 0. The coil pitch is short by 2 slots. pole pitch5. Get Coil Span or Coil Pitch Multiple Choice Questions (MCQ Quiz) with answers and detailed solutions. Correction for this is done by multiplying the voltage equation by Kp, called pitch factor. The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degrees. Note. Coil span is the number of slots between the two sides of the same coil. The displacement between the sides of the coil is called the coil span. In a 10 pole, lap wound de armature, the number of active armature conductor per pole is 50. 2. 1, or nonsalient (flush with the surface of the rotor), as shown in Fig. C machines short pitch winding is generally used to reduce harmonic and. 75), the lowest 2-solt coil span. b) 96 stator slots, 6 pole, coil span 1 to…. Pitch Factor or Coil Span Factor is defined as the ratio of EMF generated in the short-pitch coil to the EMF generated in the Whefull-pitch coil. 3. Publisher: McGraw-Hill Education. The number of segments lying between the ends of the coil is known as the commutator pitch. Lap winding • Suppose we want to make a lap winding for a P = 4 pole D. 125 Wb and a 25% third component. F. ’s of consecutive turns c. For A. C. of slots per pole = 15 but coil span is… Q: A synchronous generator has 9 slots per pole. If the coil span factor is 0. 9 and the efficiency is 0. Better emf waveform in case of generators 6. 9 slots . 1. The induced emf in each coil side. If the coil span is exactly equal to the pole-pitch, then such a coil is called a full-pitch coil. This lecture will discuss;1. 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~. Required: a. B. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. This distance is measured in terms of armature slots or armature conductors that come between two adjacent pole centers. 9 and pf = 0. BUY. Find the breadth factor for 3-Iwinding with 2 slots per pole per phase. ∙ 10y ago. C. 10. The coil-span chosen is less than the full-pitch because of the inherent advantages of chording. It may be the full pitched or short pitch. e. pitch factor and distribution factor in alternator | coil span factor in hindi | short pitch coilOTHER TOPICS 1) distribution factor in alternator the pole span or coil pitch is equal to the pole pitch (as in the case of coil A in Fig. † ‡ ˆ ‰ Š ‹ Œ Ž ‘ ’ “ ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿPitch factor: Full-pitched coils i. 5 c) 18 d) 6 View Answer. It may be the full pitched or short pitch. In this case, the coil sides lie under opposite poles, hence the induced e. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. Find the EMF produced by a DC generator connected to a 6 poles coil rotating at 1200 RPM. phase shift with emf induced in the other side of the coil. Place the arrows according to the slot pitch. Not ( I want a solution within 20 minutes. The highest winding factor can be obtained with 4-solt span coil (the coil span is closest to pole pitch 3. may or may not be exactly equal to pole pitch B. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. For a short pitch coil KC. BUY. A six pole, three phase alternator has 72 slots and a coil span of 1 to 10, is the pitch factor? A. K pn = cos nα/2. Calculate the pitch and distribution factors for the fundamental, the third, and the fifth harmonics in the phase voltage. The coil-span is 144° (electrical). The Separation between the top and bottom sides of a coil is known as back pitch and is represented by (Y b). Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . If coil span is equal to pole pitch then it is called full pitch coil. Here we have a 4-pole alternator with a 48 slot stator. The flux per pole is 0. If the coil span is from slot 1 to slot 21, and 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. See answer (1) Best Answer. If the angular distances between the two coil sides are less than one pole pitch, it is termed short pitch or fractional pitch coil. 16. If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. 4. 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. In a 4 pole, 54 slot dc armature, calculate the coil span. 2. When a coil is having a span of 180° electrical, it is called a full-pitch coil. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. 1822 V C. The pole pitch is 35 cm. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. The coil span is 150°. Coil Span: It is the angular distance between the two sides of the coil. Determine both the winding factor and the effective turns per phase. situation, two opposite sides of the coil lie under two opposite poles. The flux per pole has a fundamental component of 0. 5 ≤ q ≤ 3, are presented in Section 3. The slots per pole per phase are 8 and the coil span is 20 slots. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. 851: D) 0. If the coil-span (or coil-pitch) is equal to the pole-pitch, then the coil is termed a full-pitch coil. In this case, the coil sides lie under opposite poles, hence the induced e. Pole pitch. If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. If the machine gives 3300 V between lines on open circuit with sinusoidal flux distribution. The coil span is 150 , the flux/pole has a fundamental components of 0. pdf from CSE 302 at World University of Bangladesh. Commutator pitch. 12Wb. A. It is always less than unity. 0 i D. Fractional pitched windings are purposely used to effect a substantial saving in copper of the end connection and for improving commutation . 165 degrees. Hence E. Understand what Full Pitch and Short Pitch Windings are, and what Coil Span is. 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. g. However in practise this often isn’t the best choise because of the high harmonic content. Full pitch winding. K pn = cos nα/2.