Problem. The commutation is improved in short-pitched coil, but the emf induced will be less compared to full-pitch. c. Pitch Factor is calculated by dividing the coil throw (–) 1 (coil span), by the number of slots per pole. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Determine the phase andline values of emf if the machine runs at 600 rpm and the flux per poleis 0. 0 C. You can read more about Full Pitch and Short Pitch Winding at:. 7. 16 wb/pole and is distributed sinusoidally over the pole. A 3-phase, 4 pole, Y- connected alternator has 72 slots with two conductors per slot. A 3-phase, 12-pole, star-connected alternator has 180 slots with 10conductors per slot and the conductors of each phase are connectedin series. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. The winding is wye-connected. I need answer within 20 minutes please please with my best wishes. For example, the 24‐slot/10‐pole PM machine in Figure 1a can be derived from two 12‐slot/10‐pole PM machines with the stator shift of 75 mechanical degrees (i. 5. coil pitch in terms of electrical angle3. Obtain a coil span of 180 degrees (electrical) b. The theoretical coil pitch yp (or span) is the number of slot pitches between the two coil-sides of the same coil. Pole pitch is always equal to 180o electrical. The fundamental pitch. Calculate the no-load terminal voltage, if the speed of the alternator is 1500r. The alternator has 18 slots per pole and the first coil lies in slots 1 and 16. 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. 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. The induced emf in each coil side. The commutation is. Coil span is 16 – 1 = 15 slots. Coil–span or coil-pitch. If the coil span is less then one pole pitch than it is called short pitch coil. 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. 0 D. 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. If the coil. If the coil span is equal to the Pole pitch then it is called a full pitch coil. The alternator has 18 slots per pole and the first coil lies in slots 1 and 16. Explanation: Pole pitch is called as center to center distance between two adjacent poles. They save copper of end connections. c. To understand, it simply means that one parallel path is in N-Pole and another parallel path in S-pole. 14. The armature has double layers winding. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. 4, Fig. 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. F. Short-pitched coils are deliberately used because of the following advantages: 1. 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. Calculate its coil span factor. Identify number of rotor slots, number conductors / slot, coil span, number of slots per pole. Example: the throw could be to 9 meaning that one side of the coil is. EE - 422 DC & AC MACHINERY 2nd Semester AY 2020-2021 ENGR. If the coil. , the case of short-pitch coil, the voltages generated in each coil side are not in phase. 15. Pole pitch is defined as the angular distance between the central line of one pole to the central line of the next pole. g. The distribution of upper-side voltage phasors is the same as that of coil voltage phasors,. 5, then the coil-span can be either 11 or 10 slots. 7. fs. What is the short pitch in electrical degrees. To calculate the pitch factor, we need to consider the pole number and the fractional pitch. Robert L. u. 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. Expert Solution. It is lesser than the value in the first case. It may be the full pitched or short pitch. When two capacitors of reactances 10ohms and 20 ohms are connected in parallel across a 100 V supply, total VAR drawn will be _. 956 1. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. • Coil span is nothing but the spacing between the two coil sides of a coil. Assume a coil span of unity. Obtain a full-pitch winding. 60o / 90o = 2/3. is known as coil span. A Three-phase four-pole AC machine has 60 coils in the stator and each coil has 100 turns. fs. Pitch Factor·· the ratio of the voltage generated in ti1e fractional-pitch coil to the voltage generated in the full-pitch. A pole pitch is always 180 electrical degrees, regardless of the number of poles on the machine. round the coil which is the vector sum of e. f. Emf induced per coil side is E. To get a coil around every tooth, we need two winding layers (double layer winding). Pole arc/ pole pitch = core length/ pole pitch = 0. Calculate the distribution factor for a single layer 36 slots 2-pole three-phase stator winding. Solution for For alternator having fractional pitch winding of 10/14 the coil span is 4. 09 O4. m. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers. situation, two opposite sides of the coil lie under two opposite poles. See moreIf the coil span is less than the pole pitch then the coil is said to be a short-pitched coil. Distribute the winding uniformly under different poles d. A) 1. However in practise this often isn’t the best choise because of the high harmonic content. #10 A 4-pole,3-phase, y-connected induction motor has 48 stator slots 8 series conductors per slot and coil pitch of 83. The primary reason for making the coil span of a d. arrow_forward A. The coil-span chosen is of course less than the full-pitch. 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. 163Wb. It is expressed in terms of electrical space degree. , 5 slot‐pitches in Figure 2a) [8, 9]. ; Coil Span: It is the angular distance between the two sides of the coil. g. The pole pitch is 35 cm. It is expressed in terms of electrical space degree. 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). 3, Fig. Determine the useful flux per pole. Ensure the addition of e. Correction for this is done by multiplying the voltage equation by Kp, called pitch factor. 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). (a) 1 and 10 (b) 1 and 9 (c) 2 and 11 (d) 3 and 12 (C) frog (d) mu 12. 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. Last edited by markadlerdallas. The coil span is 160°. The value of α will usually be given in the question, if not, then assume kc = 1. 967. 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. Condition for designing a Mush winding:- 21. If the maximum flux per pole, with a sinusoidal distribution, is 0. A coil having a span equal to 180⁰ electrical is called a full pitch coil as shown in the figure below. electrical degrees indicate the amount the currents in conductors has changed. Advantages of short pitched,( chorded, fractional slot) windings are:-The amount of copper used in the overhang (end winding) reduced and hence a saving on copper,Based on pitch of the coil (i) full pitched (ii) short pitched windings. The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degrees. The coil span is five-sixth of a pole pitch. Find the terminal voltageon open circuit. So if coil span is ‘n’ slots or 180° electrical the coil is called 180° full pitch coil. 0. Then, the pitch factor will be equal. the coil will be in 180o. What is. Wheres is the number of slots, and 2p is the number of poles [19]. Resultant pitch Y R is even, being the arithmetical difference of two odd numbers, i. 2 Winding design with star of slots The star of slots is a collection of phasors which illustrates allIf α be the angle in electrical degrees, by which the span of the coil is less than a pole pitch in the alternator, then mathematically pitch factor is defined as. 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. Looking at the diagram in the question. Ans. armature, 180 electrical-degree coil span will be obtained when coils occupy. A 3-phase, 8-pole, 60-Hz, star-connected alternator has 96 slots with 10 turns per coil. may or may not be exactly equal to pole pitch B. In this alternator one pole spans twelve slots. (a)Find the total number of coil groups in the machine. Study now. 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. full, s. Determine the phase and line voltages if the coil is full pitched. Generally. 06 weber distributed sinusoidally over the pole. The pole arc should be about 70% of pole pitch and length of core about 1. A coil whose sides are separated by one pole pitch (i. If the coil span is. The distance between the two sides of an individual coil of and AC armature winding id termed the coil pitch. 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 coil span is 150°. Back pitch (Y b): It is the span of the coil from the back end. less than 180° electrical, the coils are called, short pitched coils or fractional pitched coils. For a simplex lap winding, the commutator pitch YC = 1 and coil span YS ~ pole pitch. Coil Span: It is the angular distance between the two sides of the coil. A coil is said to be fully pitched when the coil span is made equal to the pole pitch of the machine. = 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. 956, 0,647 02A pole pitch covers 25/4 = 6. Pole pitch is always equal to 180o electrical. Determine the pitch (or coil span) factors for the winding , 96 Stator slots ,4 poles, coil span 1 to 18 13. 71 O 120. kp: 0. (Assume lap. It may be the full pitched or short pitch. TYPES OF AC MACHINES WINDINGS. m. Discuss the effect of making the coil span very different from the pole pitch on (a) the coil emf and (b) the coil torque. When the parallel path is twice the number of poles then it is known as Duplex Lap Winding. If we used short pitched winding for armature winding than pitched factor is included in EMF equation in Alternator. Coil spanA: slot angle = 180slot per pole = 18015 = 12 pole pitch = no. Coil Span: It is the angular distance between the two sides of the coil. 3K views. It is also called a chorded coil. 16 wb/pole and is distributed sinusoidally over the pole. Hence, during rotation when one side of the coil comes under north pole, the other side of the coil comes under south pole. The highest flux we get, if we define the coil span equal to the pole pitch . 2. 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. IMs designed by utilising the winding configurations given in Section 3 are analysed and both SS and FW performance characteristics are presented. Where it is called an over-pitched coil if the coil span is greater than the pole pitch. In other words, the distance between the two coil sides of a coil will be equal to the distance. The skew by one slot pitch gives the value of fundamental skew factor of 0. Ensure the addition of e. 4 pole three phase winding. . Define Pitch Factor /Distribution Factor and present the formula to calculate. Coil–span or coil-pitch. The pole pitch is 35 cm, the core length 32 cm, and the stator coil span four fifth of the pole pitch. Pole – pitch. The value of α will usually be given in the question, if not, then assume kc = 1. For a short pitch coil KC. 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). are e. Pole pitch is the electrical angle between the north pole and. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. The part of the coil in which EMF is generated is known as _____. Pole – pitch. 707 B. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . #Alternator #Protectionofalternator#elect. a. d5. A pole pitch in an electrical machine is equal to 180° electrical. C machines short pitch winding is generally used to reduce harmonic and. 50Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. You can investigate three-phase integer-slot, fractional-slot and concentrated windings, both with single and double winding layers where appropriate. Find the pitch factor for an alternator having 48 stator slots, 6 poles, coil span 1-6 Option 1: cos 45 ° Option 2: cos 24 ° Option 3: cos 34 °. ed = electrical degree Example 2: Calculate the pole pitch for a three phase 4 pole ac machine having 36 stator slots. The skew factor reflects the flux reduction if the winding is angularly twisted along the axis. (2006), “Distribution, coil-span and winding factors for PM. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. armature winding equal to a pole pitch is to (a) obtain a coil span of 180º (electrical) (b) ensure the addition of e. The coil span should be minimum of about 8. 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. 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. Figure below shows a short pitched coil. It is using an armature winding which is short pitched by one slot. 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. 26. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. . Pole pitch is always equal to 180o. ISBN: 9780073373843. Coil is 12 slots. Transcribed Image Text: (d) obtain a full-pitch winding. The flux per pole is 0. 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. The width of the coils is 5/6 of the pole pitch. In such coils, the two coil sides are not under the poles. The distance between the two coil-sides of a coil is called coil-span or coil-pitch. Only 100% coil pitch in a two pole machine means half the air-gap circumference. Back Pitch Question 2: A 36-slot, 4-pole, dc machine has a simplex lap winding with two conductors per slot. Explain the following armature winding terminologies (i)commutator Pitch (ii)Coil Side (iii)Pole Pitch. When coil sides are pole pitch apart, the DC armature winding is called as _____ a) Multiplex b) Fractional-pitch c) Full-pitch d) Pole-pitch View Answer. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. 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. 12Wb and a third harmonic component. 86. This winding has 12 slots per pole per phase. Design a suitable double-layer lap winding for a 6-pole armature with 18 slots and two coil-sides per slot. (Elect. y=Coil span τ=Z/2P is the Pole pitch or full span II. in. 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. 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). Show transcribed image text There are 3 steps to solve this one. Generators 897 winding is fractional-pitched. Prob. 1: How to get flux, based on the rotor, through a coilspan coil (the coil span is closest to pole pitch, 3. C. arrow_forward. The winding is wye-connected. c. pole pitch = 180 electrical degrees or π electrical radians. • Key design factors include number of poles, number of slots, and number of slots spanned by coils. Display and compare winding harmonicsElectrical Engineering. 12 3-0. 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. Pitch Factor or Coil Pitch. A. Expert Solution. Pole – pitch. , pole-pitch ) is known as 'Full Pitch'. 0. The pitch factor for third harmonic in an alternator having 18 slots per pole and coil span 5/6 of pole pitch is _. Q: For alternator having fractional pitch winding of 8/14 the coil span is 102. of consecu- tive turns (c) distribute the winding uniformly under different poles (d) obtain a. 2 sin 70 wb/m? where O is angle measured from neutral axis. e. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. 36 stator slots, 4-pole, coil span 1to 8 ii. It is given by K p = cos (α/2) Where α is the short pitch or chording angle. , angle between the two sides of. If each coil is short pitched by an angle of 36 ∘ electrical. The arithmetic sum of induced emfs is 2E. The coil span equal to 180 electrical degrees: The coil span is less than 180 electrical degrees. 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. Study with Quizlet and memorize flashcards containing terms like A lap winding, Twice, Full-pitch and more. The first coil lies in slots 1 and 16. in the two sides of the coil. What are the different types of stator windings in induction motor? Ø. 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. The pole pitch is 35 cm. It equals pole pitch = Z P . First. Hence, the total e. Coil Span: The number of core slots spanned by the sides of the coil. 24, and assume first a short-pitched coil spanning half a pole pitch, then a long-pitched coil spanning one and a half. It is always equal to 180° electrical. They save copper of end connections. A 4 pole, 12 slot lap wound dc armature has two coil side per slot. A coil whose sides are separated by one pole pitch (i. Draw the developed diagram andshow the positions of brushes. 7 slots c. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical DegreeThere are many people who want to. none of the aboveThe coil span generally varies from 2/3 pole pitch to full pole pitch. In SWAT-EM the coil span is given in number of slots. Pole pitch is always equal to 180o. It means that coil span is 180 electrical degrees. A 3-phase, 50 Hz, 2-pole, star connected turbo alternator has 54 slots with 4 conductor per slot. Q: Explain the following Armature Winding Terminologies (i) Coil Span (ii) Resultant Pitch A: In the following section, coil span and resultant pitch related to armature winding technology has… Q: Assume that a four-pole de machine has an armature with a radius of 15 cm and an effective length of…In the second example, with a pole pitch of 15. Most windings have < . Give the values of front pitch, back-pitch and commutator pitch. In general, electrical degrees equals mechanical degrees times 1/2 the number of poles. 924 359. of slots per pole = 2 = 6 saree tensed gOSeaee Slot pitch, a = oF slow/pole > No. 150° is (frac{5}{6}) parts of 180° i. We must note that the coil-pitch and flux barriers of the NC2 are adjusted as shown in. fs. The pitch of the coil is 2 slot less than the pole pitch. M. Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. If the coil span is equal to the Pole pitch then it is called a full pitch coil. Solution for Calculate the pitch factor for the following windings: a) 72 stator slots, 6 pole, coil span 1 to 10. 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. Determine the equation for the. Calculate the pitch and distribution factors for the fundamental, the third, and the fifth harmonics in the phase voltage. 9 slots . , Y = 2/3 τ p. The term "region" is important, because a design with 3 slots per pole and phase, for instance, can only be pitched 6/9 or 7/9 or 8/9. are e. 8 slots b. 1993) Example 37. Number of Commutator Segments - Number of Commutator Segments is the count of cylindrical assembly of insulated segments that are mounted on the shaft. Degree of Reentrancy c. Back. 6. 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. The formula for pitch factor is given by The pitch factor in the above equation is for fundamental component of emf. ISBN: 9780133923605. 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. 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. The winding calculator allows you to find the optimum winding layout for your electric motor in a fast and convenient way. Here, e = E 1 = E 2 = E. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. Electrical Engineering. . 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. Here we have a 4-pole alternator with a 48 slot stator. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical DegreeThere are many people who want to. 165 degrees. 12. Coil span or Coil Pitch. Each phase in this case consists of four coils (two per slot). The slots per pole per phase are 8 and the coil span is 20 slots. The coil span is 150 , the flux/pole has a fundamental components of 0. A 4-pole, 3-phase synchronous machine has 48 slots. A. TERMS Coil Throw: The location in an armature core of the sides of a coil starting in slot number one (1). frame. 866. When measured in electrical degrees one pole itch is equal to 1800. It has key variables such as Pole Pitch (back and front pitch, resultant pitch and communicator pitch, Coil Span, Commutator Pitch. View 26 DC Generator. Pole Pitch: It is the angular distance between the two adjacent poles. 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. , a pitch, or an pitch, etc. 3. Coilspan or coil-pitch. 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 3 rd harmonics. e. The coil pitch is 12/15. Here’s the best way to solve it.