Boylestad. The winding is wye-connected. The armature coils are all connected in series. I need answer within 20 minutes please please with my best wishes. P˚ Kp = sin [(90°)(pitch)] Kp = sin 𝟐 PROBLEM 1: A 6 pole, 3Φ AC generated has 72 slots, the coil span is 12. #Alternator #Protectionofalternator#elect. Hence, the coil span in three phase AC machines must be (frac{5}{6}th) of pole pitch. Two-and four-pole rotors have normally nonsalient poles, while rotors with more than four poles have salient poles. 12Wb. 31. Then, the pitch factor will be equal. 75 times the slot pitch), the lowest with 2-solt span coil. Transcribed Image Text: (d) obtain a full-pitch winding. arrow_forward. 50Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a full-pitch winding. Here, e = E 1 = E 2 = E. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. View the full answer. Distribute the winding uniformly under different poles d. Please see Electrical 4 U site for article on Armature Windings: Pole Pitch, Coil Span And Commutator Pitch. It is lesser than the value in the first case. 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 . 150 degree (electrical). the coil-span needs to be increased, so as to link a higher flux. Obtain a coil span of 180 degrees (electrical) b. air. Answer: 0. The random wire placement leads to a wider distribution of resulting wire length on the coil body and consequently a wider range of electric coil resistances. ) A 6-pole, 3-phase, 60-Hz alternator has 12 slots per pole. Each phase in this case consists of four coils (two per slot). [8+8] 2. CONTENTS CONTENTS + 0 ) 2 6 - 4 Lear ningPole – pitch. * This angle is known as chording angle and the winding employing short-pitched coils is called chorded winding. The width of the coils is 5/6 of the pole pitch. Assume the coil span as 150° electrical. armature, 180 electrical-degree coil span will be obtained when coils occupy. Pole pitch is always equal to 180o. 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). Table of Contents Terms used in the armature winding Conductor Turn Coil Coil Side Front end and Back end connector Pole. When the coil span of the winding is equal to pole pitch, the coils are called the full pitched coils. For the n th harmonic, the chording angle becomes nα° electrical. The winding is wye-connected. #Alternator #Protectionofalternator#elect. The term “winding pitch” refers to the ratio of the number of winding slots enclosed by each coil in the alternator stator to the number of winding slots per generator pole. Here ξ is the chorded angle or short pitch angle. Answer: a. The pole pitch is 35 cm, the core length 32 cm, and the stator coil span four fifth of the pole pitch. , 5 slot‐pitches in Figure 2a) [8, 9]. 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. fs. Electrical Engineering questions and answers. First. The value of α will usually be given in the question, if not, then assume kc = 1. Give the values of front pitch, back-pitch and commutator pitch. c. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. It is possible to suppress the higher harmonics by using double-layer windings using shortened span coils. F = 0. If the generator is running at 1200 rpm, find the average voltage generated between brushes for wave winding. 0. Design a suitable double-layer lap winding for a 6-pole armature with 18 slots and two coil-sides per slot. Relation between frequency, speed and number of poles: Fig: 1. EXAMPLE: Calculate the pitch factor for a alternator winding with 36 slots, 4. In a fractional pitch winding, the coil span is made less than 180 degrees electrical space. 60 hz, 10-pole alternator has 120 slots and 4 turns in every coil. 4 pole = 90º. Calculation:The angular distance between the two coil sides is less than one pole pitch, it is termed short pitch or fractional pitch coil. Where it is called an over-pitched coil if the coil span is greater than the pole pitch. Coil Span:The angular distance between the centers of two adjacent poles on a machine is known as pole pitch or pole span. Calculate the distribu factor for a 36-slot. Pole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical Degree - YouTube Hey Aspirants. slots. B. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. Lap and Wave winding. The coil span is 160°. 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. A pole pitch is always 180° electrical regardless of the number of poles on the machine. Por a full-pitch coil, Kr = I (unity) r:or a fractional-pitch coil, Kr < 1 6. It is always equal to 180° electrical. ( c) 96 stator slots, six-poles, coil spans 1 to 13. 12. The fundamental pitch. Coil Span or Coil Pitch Question 1: For a 6 pole DC armature with 14 Slots having 2 coil sides per slot. 951, 0. C machines short pitch winding is generally used to reduce harmonic and. There are B coil groups of (A+1) coils, that is, 1 coilIf the pole span or coil pitch is equal to the pole pitch (as in the case of coil A in Fig. It. 05 Wb, sinusoidally distributed. 1. 25 = 6 and 1/4 slots. Pole pitch is always equal to 180o electrical. If the maximum flux per pole, with a sinusoidal distribution, is 0. Hence E. Assume = 0. 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). 4. It is defined as the angular distance between the central line of one pole to the central line of the next pole. Fig. it is said to the a fractional-pitch coil. If we used short pitched winding for armature winding than pitched factor is included in EMF equation in Alternator. The coil span is 150°. Cogging torque was minimized by finding an optimum magnet pole arc length and torque ripples were minimized by finding. 851: D) 0. ∙ 10y ago. In a 4 pole, 3 phase alternator, armature has 36 slots. Assuming single turn coil, calculate the back pitch for progressive and retrogressive winding. 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. 12 Wb and a 20% 3 rd harmonics. 0. 3- Determine the coil span for 3-phase, two pole alternator, the pole pitch is equal to 18 slots and the coil span factor is. Based on number of layers (i) Single layer. TERMS Coil Throw: The location in an armature core of the sides of a coil starting in slot number one (1). 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. Sanfoundry Certification Contest of the Month is Live. 26. of phases = 3; No. 2. 86. Pole pitch is the peripheral distance between two adjacent poles. 1. Use a diagram like that shown in fig. F. Find the breadth factor for 3-Iwinding with 2 slots per pole per phase. It falls short by 1/6 pole-pitch or by 180°/6 = 30°. 5 are the stator low-order voltage harmonics for the different motors with 120°, 140°, 160° and 180° coil pitch at half load, full load and overload, respectively. c. fs. pdf from CSE 302 at World University of Bangladesh. 2. Register to editPitch factor problem. 966The pole pitch, mQ ′ ∕ p, is also fractional, so that the coil-span cannot be of full-pitch. In an alternator, for a coil having a span of 2/3 of pole pitch,. 0. As shown in Fig. 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. Hence emf induced in one side of. A coil whose sides are separated by one pole pitch (i. 966 Distribution factor = 0. In such coils, the two coil sides are not under the poles. 09 O4. The induced emf in each coil side. Prob. g. Chording: with coil-span less than pole pitch 5. The displacement between the sides of the coil is called the coil span. 1: How to get flux, based on the rotor, through a coilspan coil (the coil span is closest to pole pitch, 3. Explain the following armature winding terminologies (i)commutator Pitch (ii)Coil Side (iii)Pole Pitch. m. 16. e. Q: 3- Determine the coil span for 3-phase, two pole alternator, the pole pitch is equal to 18 slots and… A: For a two-pole alternator,Pole pitch = 18 slotsCoil span factor =32 Q: A 4 pole, three-phase, star-connected alternator has an armature with 120 slots and 4 conductors per…The winding pitch of a generator is the number of slots spanned by each coil in the stator winding divided by the number of slots per pole. • So coil span is 16/4 = 4. 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. slots. 36 stator slots, 4-pole, coil span 1to 8 ii. Fractional slot winding 6. It is usually measured in terms of teeth, slots or electrical degrees. 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. K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. The coil span is 150 electrical degrees. 3. armature, 180 electrical-degree coil span will be obtained when coils occupy. The commutation is improved in short-pitched coil, but the emf induced will be less compared to full-pitch. The highest flux we get, if we define the coil span equal to the pole pitch . Figure 1. Kr ==sink 2 · Kp =pitch factor in dcci111al p" =span of the coil in electrical degrees. Distribute the winding uniformly under different poles d. Step by step Solved in 3 steps. It is usually measured in terms of teeth, slots or electrical degrees. winding is fractional-pitched. frame. The pole pitch is always 180 degrees electrical regardless of the number of poles in a machine. ; Coil Span: It is the angular distance between the two sides of the coil. F induced in the other side of the coil. Full Pitch and. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. Understand what Full Pitch and Short Pitch Windings are, and what Coil Span is. If the coil span is less than the pole pitch (as in coil B where coil pitch is 3/4th of the pole pitch), then the Fig. Share on Whatsapp Latest UPSC IES Updates. 6. In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch, back pitch, pole pitch, coil pitch, etc. Therefore one coil, such as coil 1 which traverses slot 1 and 7 falls under the north and south pole exactly because they are 180º apart as seen in the image above. 24 where pole- pitch of 4 has been assumed), then winding is called full-pitched. Publisher: McGraw-Hill Education. In this case, we have a 10 pole alternator with coils wound in a fractional pitch of 18/21. We will start Red at slot 1. The distance between the two sides of a coil is called the coil. e. 866. In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch, back pitch, pole pitch, coil pitch, etc. 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. in them are additive. 7. e. 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. $$\mathrm{Slot\:per\:pole =\frac{90}{6}= 15}$$ For a full-pitch coil, the coil span is 15 slots. This answer is:Full-pitch windings have a coil pitch of 1, which means the coil span is equal to the pole pitch. Pole – pitch. 16 wb/pole and is distributed sinusoidally over the pole. Generators 897 winding is fractional-pitched. 165 degrees. 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. (d)Find the number of turns per phase, Tph. 2. e. d5. Back Pitch. 5. of slots per pole = 15 but coil span is… Q: A synchronous generator has 9 slots per pole. Author: Frank D. phase shift with emf induced in the other side of the coil. A. Coil Span (ii) Resultant Pitch. Theta (electrical)=p/2 (theta (mechanical)) What is the formula for electrical angle. A 3-phase, 12-pole, star-connected alternator has 180 slots with 10conductors per slot and the conductors of each phase are connectedin series. slots. . C machine having a total number slots S = 16. The winding spans all11. 1 the coil span should be approximately equal to a pole pitch. Pitch factor. 7. f. Condition for designing a Mush winding:- 21. The pole pitch is 10 slots, and the coil pitch is 9 slots. Since one pole presents 180 electrical space degrees so the slots pitch. arrow_forward. If coil span is 6 and if top coil side of a coil lies in slot 1 then the. 259 C. 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. 4, Fig. 2. 956 1. P˚ = Pitch = coil span in no. A 10 MVA, I KV, 50 Hz, 3-phase, star-connected synchronous seberatur is driven ur 300 r. What is a coil span? The coil span is the distance between one conductor of a certain phase and the corresponding return conductor. Coilspan or coil-pitch. 2 are short-pitched, full-pitched and over-pitched coils respectively. View full document. Discuss the effect of making the coil span very different from the pole pitch on (a) the coil emf and (b) the coil torque. Find the terminal voltageon open circuit. Coil span or coil pitch Ys: It is the distance between the two sides of a coil measured in terms of armature slots. As the two coil sides are separated in space by an angle of (180-ε) i. The coil span is 150 electrical degrees. If the coil-span (or coil-pitch) is equal to the pole-pitch, then the coil is termed a full-pitch coil. In a 4 pole, 54 slot dc armature, calculate the coil span. Ensure the addition of e. This. 10 are one pole pitch or n slots or 180° electrical apart, the coil is called full pitch coil. The distance between the two sides of an individual coil of and AC armature winding id termed the coil pitch. 5. 0:00 / 15:33 What is Coil Pitch and Pole Pitch /what is electrical and mechanical angle in Urdu/Hindi IK LECTURES 2. Figure 8 compares computed waveforms of phase back emf. A 4 pole AC machine has its winding housed in 48 slots with coils of span 11/12 th of a pole. Now coil is shorted by 1 slot i. Three kinds of coil spans are used, they are 4-solt pitch, 3-solt pitch, and 2-solt pitch. The pole pitch is defined as the distance between two consecutive poles. The coil span is 160°. Alternatively, this type of coil is also called a short-pitch or chorded coil. The windings are arranged as 5 conductors per layer. 0. Hence, the pole pitch of that DC machine would be 24. 7. Problem 1 : Develop the layout of a lap winding for a 3 phase ac machine having 4 pole and 24 slots. 60o / 90o = 2/3. Coil Span or Coil pitch. armature, 180 electrical-degree coil span will be obtained when coils occupy. Calculared the flux per pole required to give Il kV line voltage on open circuit voltage. (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. e. Full pitch winding. Thus coil span of either 6 or 7 may be selected. e. 958] (B) Determine the maximum flux per'pole when connected to a' 220-volt,60-cycle line, neglecting local resistance and reactance drops. placed in the top layer of the slot & the other side of the coil is placed in the bottom layer of another slot nearly a pole pitch apart. 85 lagging. 0 C. 125 Wb and a 25% third component. 0. Here, e = E 1 = E 2 = E. Let us consider, the coil has a pitch short by an angle α electrical degrees from the full pitch. To calculate the pitch factor, we need to consider the pole number and the fractional pitch. 966 and 0. e. If the coil span is equal to the Pole pitch then it is called a full pitch coil. Pole – pitch. To get a coil around every tooth, we need two winding layers (double layer winding). Slots/pole/ph = m = 72/ (8×3) = 3. Pole pitch is always equal to 180o. 1. Coil span Coil span (also known as coil pitch) is the angular distance between two sides of a coil, measured in terms of armature slots. A. 1 . It is usually measured in terms of teeth, slots or electrical degrees. Determine the phase andline values of emf if the machine runs at 600 rpm and the flux per poleis 0. 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. 5. A 4-pole, 3-phase synchronous machine has 48 slots. Obtain a full-pitch winding. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. arrow_forward. M. A coil having a span equal to 180⁰ electrical is called a full pitch coil as shown in the figure below. ( b) 42 stator slots, four-poles, coil. 6. The slots per pole per phase are 8 and the coil span is 20 slots. In this study, the electromagnetic performances of dual 3-phase permanent magnet (PM) machines with coil span of two slot-pitches are comparatively investigated. e. In SWAT-EM the coil span is given in number of slots. A Three-phase four-pole AC machine has 60 coils in the stator and each coil has 100 turns. However the waveform of the resultant emf can be improved by making the. The individual coils may have a span greater or less than a pole pitch but the average coil-span equals one pole-pitch. . what is coil pitch or coil span. Armature Currents and MMF of 5-Phase Machine The armature currents of 5-phase machine can be expressed with formula (1). Obtain a full-pitch winding. If t he coil pitch is y =3, the diame tral w inding w ill have the f. Solution for Calculate the pitch factor for the following windings: a) 72 stator slots, 6 pole, coil span 1 to 10. Coil Span: The number of core slots spanned by the sides of the coil. Coil pitch: The distance measured in terms of armature slots or armature conductors between two sides of a coilQuiz # Solve the following problems. If fractional pitch is used, the emfs in the two coil sides are out of phase, which reduces the emf. *. The stator has two slots/pole/phase and 4 conductors per slot are accommodated in two layers. m. It is one pole pitch. Pole and slot numbers. TYPES OF AC MACHINES WINDINGS. A coil whose sides are separated by one pole pitch (i. ) 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 may be the full pitched or short pitch. A pitch in the "region" of 5/6 is most effective to reduce 5th and 7th harmonics. 025 Wb entering the armature from each north pole, and this flux is sinusoidally distributed along the air gap. 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. (c)Find the number of coils in a coil group, m. It is lesser than the value in the first case. 85 lagging. The slots per pole per phase are 8 and the coil span is 20 slots. In SWAT-EM we can set the coil span explicite. The skew factor reflects the flux reduction if the winding is angularly twisted along the axis. The winding is housed in 360 slots and has 6 conductors per slot, the coils spanning (5/6) of a pole pitch. m. Calculate the emf generated in each phase when the machine runs at 375 rpm Hence, pitch factor or coil span factor K p = Cos(/2). Boylestad. An alternator having 10-poles, 3-phase, and 60 Hz has 8 conductors per slot in single layer arrangement with 4 slots/pole/phase. A 3-phase, 4 pole, Y- connected alternator has 72 slots with two conductors per slot. 11. β = 180o/ = 20o. the coil will be in 180o. M. At this situation, two opposite sides of the coil lie under two opposite poles. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers. 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. Discuss the effect of making the coil span very different from the pole pitch on (a) the coil emf and (b) the coil torque. 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. In such coils, the two coil sides are not under the poles. It is always less than unity. 9780133923605. Hence, the total e. The harmonic reduction in the voltage waveform of concentrated winding axial field PM machines is the subject of interest for many researchers. fs. It is using an armature winding which is short pitched by one slot.