what is coil pitch or coil span. 13. 9780133923605. Back Pitch. , pole-pitch ) is known as 'Full Pitch'. They are two basic physical types for the windings. 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. Thus coil span of either 6 or 7 may be selected. What is the coil span for a 2 pole 18 slot machine? a) 9 b) 4. If the coil span is equal to the Pole pitch then it is called a full pitch coil. Back Pitch Question 2: A 36-slot, 4-pole, dc machine has a simplex lap winding with two conductors per slot. ISBN: 9780133923605. Here, e = E 1 = E 2 = E. 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. Similarly, for a coil having a span of 2/3 pole-pitch, kc = cos 60°/2 = cos 30° = 0. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. 75), the lowest 2-solt coil span. The coil span is 160°. the coils cannot be full - pitched; they may be short - pitched with 15 slots, or long - pitched with 16 slots. arrow_forward. Slots/pole/ph = m = 72/ (8×3) = 3. 9: Rated speed (rpm) 170: Rated current (Arms) 3. 6 turns. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. 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. You can read more. CONCENTRIC WINDING In unbifurcated concentric windings, the first of the q coils which is the smallest is thrown. of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a. it is said to the a fractional-pitch coil. Wheres is the number of slots, and 2p is the number of poles [19]. 1. Since the winding is full pitched coil, so the pitch of each. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. c. There. 6. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. 06 weber distributed sinusoidally over the pole. Assume = 0. Here, e = E 1 = E 2 = E. 6. It is always less than unity. The skew by one slot pitch gives the value of fundamental skew factor of 0. Answer: c Explanation: Pole pitch is called as center to center distance between two adjacent poles. The Separation between the top and bottom sides of a coil is known as back pitch and is represented by (Y b). It is usually measured in terms of teeth, slots or electrical degrees. It is always 180° electrical. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. A. The two sides of a coil are places in two slots on stator surface. 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. If the coil span is equal to the Pole pitch then it is called a full pitch coil. 0. 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. Generators 897 winding is fractional-pitched. If 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. can never be equal to pole pitch D. 2. The coil span is 150°. g. Last edited by markadlerdallas. 12. I need answer within 20 minutes please please with my best wishes. 10. Not ( I want a solution within 20 minutes. 0:00 / 15:33 What is Coil Pitch and Pole Pitch /what is electrical and mechanical angle in Urdu/Hindi IK LECTURES 2. 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. EXAMPLE: Calculate the pitch factor for a alternator winding with 36 slots, 4. See answer (1) Best Answer. Armature Windings: Pole Pitch, Coil Span And Commutator Pitch. Obtain a coil span of 180 degrees (electrical) b. The winding calculator allows you to find the optimum winding layout for your electric motor in a fast and convenient way. Alternator connections: star or delta connections of alternators suppress triplen harmonics from appearing across the lines 1. 1. 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. Determine the useful flux per pole. The arithmetic sum of induced emfs is 2E. Download Solution PDF. This is shown in the figure to left. pole pitch. Calculate the no-load terminal voltage, if the speed of the alternator is 1500r. Pole pitch is the peripheral distance between two adjacent poles. . Petruzella. Calculate the average voltage generated in a six-turn full pitch coil of a 25 cycle alternator if the. 15. A. The formula for pitch factor is given by The pitch factor in the above equation is for fundamental component of emf. In a 10 pole, lap wound de armature, the number of active armature conductor per pole is 50. It may be the full pitched or short pitch. 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. Obtain a full-pitch winding. 3. 9 and the efficiency is 0. ) 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. 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. Y-connected alternator has 9 slots per pole and a full-pitch. round the coil which is the vector sum of e. Machine, Nagpur Univ. For a short pitch coil KC. 15 situated at the center of an N pole rotating in clockwise direction. Front connections 8+7=15; 30+7-30=7 8. Coil span or Coil Pitch. ∙ 10y ago. Allow 10 ampere for the field current and assume a voltage drop of 4 volts for the armature circuit. The coil pitch is 12/15. 165 degrees. fs. armature, 180 electrical-degree coil span will be obtained when coils occupy. Assume that the coil span is 150° electrical. Step by step Solved in 2. In a 4 pole, 3 phase alternator, armature has 36 slots. Similarly, for a coil having a span of 2/3 pole-pitch, kc = cos 60°/2 = cos 30° =. Pole arc/ pole pitch = core length/ pole pitch = 0. e. The value of α will usually be given in the question, if not, then assume kc = 1. This answer is:Full-pitch windings have a coil pitch of 1, which means the coil span is equal to the pole pitch. Robert L. , Y = 2/3 τ p. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. Solution for Calculate the pitch factor for the following windings: a) 72 stator slots, 6 pole, coil span 1 to 10. Boylestad. This lecture will discuss;1. Determine the pitch (or coil span) factors for the winding ,24 Stator slots ,4 poles, coil span 1 to 5 12. Boylestad. o. Pitch Factor is calculated by dividing the coil throw (–) 1 (coil span), by the number of slots per pole. 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~. (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. arrow_forward. There are 0. A 3-phase, 50 Hz, 2-pole, star connected turbo alternator has 54 slots with 4 conductor per slot. It is usually measured in terms of teeth, slots or electrical degrees. α = Angle of short pitch = 20o. You can compare the maximum fundamental winding factor for different. 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. If the coil span is from slot 1 to slot 21, and the flux per pole has a fundamental component of 0. Since slot pitch is 6, 6 slots have upward arrows, 6 down and so on. Comparator. Fractional pitched windings are purposely used to effect a substantial saving in copper of the end connection and for improving commutation . In other words, the distance between the two coil sides of a coil will be equal to the distance. m. It is always 180° electrical. Coil Span: It is the angular distance between the two sides of the coil. Then, the pitch factor will be equal. 707 B. 1993) Example 37. When the coil span is lower than pole pitch, the phasor sum of conductor voltages is less than the arithmetic sum, because of vector addition. 🔥engineers platform App Link. 5. In a 4 pole, 54 slot dc armature, calculate the coil span. (2) 𝑘 𝑐 𝑛 = c o s 𝑛 α 2. Coil–span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. 4. The separation between the top and bottom sides of a coil is called Coil span. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch. = pitch factor or coil span factor ? = ratio of coil span and pole pitch ? = angle of short pitch ? = slots per pole ? = slots? = poles? = short pitch 𝑐 = coil span Distribution Factor, Breadth Factor, Winding Factor, Spread Factor (Kd) Similar to full pitch coils, concentrated winding is also rare in practice. The coil is also short-pitched (eg spam of two sides of. 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. The distance between the two sides of an individual coil of and AC armature winding id termed the coil pitch. Pitch factor. The Separation between the top and bottom sides of a coil is known as back pitch and is represented by (Y b). Coil span is simply a peripheral distance between two sides of a coil. 2 Selecting the coil span for a given pole pitch. 50 Q… A: Find the coil span Fractional pitch winding = 8/14 Q: For alternator having fractional pitch winding of 10/15 the coil span is O 2. 0 C. 40 O 2. It is possible to suppress the higher harmonics by using double-layer windings using shortened span coils. The pitch of the coil has 4 slots less than the pole pitch. Electrical Engineering. A pitch in the "region" of 5/6 is most effective to reduce 5th and 7th harmonics. ∴ e = E 1 + E 2 = 2E. Obtain a coil span of 180 degrees (electrical) b. Calculate the distribu factor for a 36-slot. 16 wb/pole and is distributed sinusoidally over the pole. • To view the coil sides / coils, we must look below from above the slots as depicted in figure. 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. The pitch factor. At this situation, two opposite sides of the coil lie under two opposite poles. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . Coil–span or coil-pitch. Calculate the distribution factor for a single layer 36 slots 2-pole three-phase stator winding. 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. Commutator pitch of a progressive lap winding is yc = +1. Coil Span or Coil Pitch Question 1: For a 6 pole DC armature with 14 Slots having 2 coil sides per slot. 6 Pole pitch Coil span y=Z/2P + 1, y=Z/2P - 1 7 Conditions of P/C ϵ N, meaning P cannot be 1 and for three phase C/m N symmetry Single layer fractional slot winding with Z=30, and 2P=4 q 2 1 or q 5 D. The flux per pole has a fundamental component of 0. 1. Calculate the pitch factor for (a) fundamental (b) 3rd harmonic (c) 5th harmonic (d) 7th harmonic. Publisher: McGraw-Hill Education. Example: the throw could be to 9 meaning that one side of the coil is. 85 lagging. PITCH FACTOR OR COIL SPAN FACTOR Pitch Factor – the ratio of the voltage generated in the fractional pitch coil to the voltage generated in the full pitch coil. 31. A. For alternator having fractional pitch winding of 8/14 the coil span is 102. 12Wb. 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 0. Use a diagram like that shown in fig. A coil is said to be fully pitched when the coil span is made equal to the pole pitch of the machine. View full document. 2. It has key variables such as Pole Pitch (back and front pitch, resultant pitch and communicator pitch, Coil Span, Commutator Pitch. Better emf waveform in case of generators 6. Back pitch (Y b): It is the span of the coil from the back end. is B = 10 sin theta + 2 sin 3 theta + 2 sin 7 theta kilo - gauss, when theta is measured from the neutral axis. In a 4 pole, 3 phase alternator, armature has 36 slots. When the coil is having a span of less than 180. The arc diagram contains all the necessary information for connecting the pole-groups correctly. BUY. Explanation: Pole pitch is called as center to center distance between two adjacent poles. Discuss the effect of making the coil span very different from the pole pitch on (a) the coil emf and (b) the coil torque. If each coil is short pitched by an angle of 36 ∘ electrical. ∴ e = E 1 + E 2 = 2E. 6. Now labeling the starting end of each coil is easy, assuming an RYB phase sequence taking red as the reference. Type your question here Calculate the voltage per phase for a 3-phase 1500 rpm, 4-pole alternator having a 16 conductors per slot connected in two layers. It is expressed in terms of electrical space degree. 10 are one pole pitch or n slots or 180° electrical apart, the coil is called full pitch coil. 135 degrees d. The distribution of upper-side voltage phasors is the same as that of coil voltage phasors,. In this alternator one pole spans twelve slots. A 3-phase, 8-pole, 60-Hz, star-connected alternator has 96 slots with 10 turns per coil. 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). y=Coil span τ=Z/2P is the Pole pitch or full span II. SEE MORE TEXTBOOKS. There are 2,500,000 Maxwells entering the armature from each North Pole, and this flux is sinusoidally distributed along the air gap. 4. If the coil. m. situation, two opposite sides of the coil lie under two opposite poles. Result Number of. Sketch the winding over a pole pitch, indicating the location of the conductor of each phase. In SWAT-EM we can set the coil span explicite. In practice, coil pitch (or Span) as low as eight-tenths of a Pole Pitch, is employed without much serious reduction in emf. The pitch of the coil has 4 slots less than the pole pitch. It is equal to the number difference of the conductor connected to a given segment of the commutator. ) Given: 120 slots, ,10 poles, double layer winding, coil pitch is shorted by 2 slots, f=60 Hz, Y connected. TYPES OF AC MACHINES WINDINGS. 015 Wb. The winding is wye-connected. Hence emf induced in one side of. The line to line induced emf for a 3 ϕ star connection is approximatelyCompute the phase and line voltage of a wye-connected three-phase, five-pole alternating current generator that runs at a speed of 1440rpm has a total slots of 135 slots with 4turns/coil. lt is also known as coil pitch. 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). The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degree. The usefulness of winding distribution and chording in reducing or eliminating harmonics will be touched on in. 60o / 90o = 2/3. 5, then the coil-span can be either 11 or 10 slots. e. e. The coil span is 150 electrical degrees. 0. The coils are place in 60 uniformly distributed slots around the inner perimeter of the stator. An alternator has 18 slots per pole and the first coil lies in slots 1 and 16. Transcribed Image Text: (d) obtain a full-pitch winding. Resultant pitch Y R is even, being the arithmetical difference of two odd numbers, i. 1, or nonsalient (flush with the surface of the rotor), as shown in Fig. Armature Currents and MMF of 5-Phase Machine The armature currents of 5-phase machine can be expressed with formula (1). ) A 6-pole, 3-phase, 60-Hz alternator has 12 slots per pole and four conductors per slot. 3K views. 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. M. Coil pitch or coil span is defined as the angular distance between the two coil sides of one coil. Figure below shows a short pitched coil. 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. 14. 15 Consider the armature conductor marked X in Fig 1. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. A 3-phase, 4 pole, Y- connected alternator has 72 slots with two conductors per slot. ; Here, e = E 1 = E 2 = E. The pitch factor, in rotating electrical machinery, is. 1-9 coil span A SIMPLE explanation of what a pole pitch is in a generator or rotating machine. Correction for this is done by multiplying the voltage equation by Kp, called pitch factor. Publisher: PEARSON. The armature has double layers winding. 1. slots. View 26 DC Generator. A 4-pole, 50 Hz alternator has double layer winding with 10 turns per coil and number of slots are 60. – Comparator. m. The coil span is five-sixth of a pole pitch. Because a chording more than 1/3 pole pitch would noticeably reduce the phase emf. it is said to the a fractional-pitch coil. A. 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). 8 slots b. 4. The flux per pole has a fundamental component of 0. To improve the wave form only 80% of the pole pitch is wound. Coil Span: The number of core slots spanned by the sides of the coil. 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 ). The winding is wye-connected. 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. 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. 36 stator slots, 4-pole, coil span 1to 8 ii. Winding table. Since 1 pole pitch is the angular distance between the two. Where it is called an over-pitched coil if the coil span is greater than the pole pitch. 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. First. 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. Display and compare winding harmonicsElectrical Engineering. Alternatively, this type of coil is also called a short-pitch or chorded coil. 7. 2. ( ) () ⎪ ⎪ ⎪ ⎩ ⎪⎪ ⎪ ⎨ ⎧ = − = − = − = − = sin 8 /5 sin 6 /5 sin. M. For making coil span equal to a pole pitch in the armature winding of a d. If the coil span is equal to the Pole pitch then it is called a full pitch coil. Commutator pitch Y C = ±1. Back pitch: The distance between the two sides of a coil in the back of the armature is called back pitch. The windings are arranged as 5 conductors per layer. Each of these coil spans is five slots, so this choice of winding. If the coil sides are placed in slots 1 and 6, then it is short-pitched or fractional-pitched because coil span is equal to 5/6 of a pole-pitch. The pole pitch is 35 cm. 24, and assume first a short-pitched coil spanning half a pole pitch, then a long-pitched coil spanning one and a half. 0 C. c. 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. 4. m. a. We make the coil span less than 180 degrees electrical space degrees in a fractional pitch winding. 1 and No. It is usually measured in terms of teeth, slots or electrical degrees. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. armature, 180 electrical-degree coil span will be obtained when coils occupy. The coil span is 10 slots. (a)Find the total number of coil groups in the machine. 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). The conductor being situated at the place of maximum flux density will have maximum emf induced in it. As the two coil sides are separated in space by an angle of (180-ε) i. For the n th harmonic, the chording angle becomes nα° electrical. It is using an armature winding which is short pitched by one slot. Expert Solution. 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). round the coil which is the vector sum of e. Coil–span or coil-pitch. 12. Coil Span Factor - Coil Span Factor is defined as the peripheral distance between two sides of a coil, measured in terms of the number of armature slots between them. of phases = 3; No. pole pitch. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. If the coil span is exactly equal to the pole-pitch, then such a coil is called a full-pitch coil. DARWIN M. Hence, the coil span in three phase AC machines must be (frac{5}{6}th) of pole pitch. 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. 96 stator slots, 6poles, coil span 1to 12. #Alternator #Protectionofalternator#elect. Note that although the span of a full-pitch coil is not an integer in a fractional-slot winding, the full-pitch coil is nevertheless an im- The correct answer is option 3. Power System Analysis and Design (MindTap Course List) 6th Edition. g. A 144-slot stator has a whole coiled 12-pole three-phase winding. It means that coil span is 180 electrical degrees. Most windings have < . Hence, during rotation when one side of the coil comes under north pole, the other side of the coil comes under south pole. 75 times the slot pitch), the lowest with 2-solt span coil. Coil span and commutato pitch b. m. e. A 3-phase, 4 pole, Y- connected alternator has 72 slots with two conductors per slot. coil pitch in terms of slots4. 4 pole = 90o. For a simplex lap winding, the commutator pitch YC = 1 and coil span YS ~ pole pitch. 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 highest flux we get, if we define the coil span equal to the pole pitch . 086 Wb, what will be the values of the emfs? phase and line? I need the procedure to get to that answer. Pole and slot numbers. Calculate its coil span factor. m. It may be the full pitched or short pitch. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers. To get a coil around every tooth, we need two winding layers (double layer winding). must be exactly equal to pole pitch C. Distribution factorA coil advances on the back of the armature. Its value may be calculated by the equation kp=sin p°/ Where kp =pitch factor (always decimal for fractional-pitch winding) p° = span of coil in electrical degrees ( coil span/slot/pole x180°) Example: Calculate the. 0. What is. 1. For n th harmonic. . The armature coils are all connected in series. If the coil span is less then one pole pitch than it is called short pitch coil. u. 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.