There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. 75), the lowest 2-solt coil span. The armature coils are all-connected in series. A coil whose sides are separated by one pole pitch (i. poles, 18 slots alternator, the pole pitch is n = 18/2 = 9 slots. coil span, slip-ring voltage on open circuit, approximate full load current per phase in rotor. A four-pole three-phase 50 hertz, star connected AC generator has 12 stator slots. In this case, the coil sides lie under opposite poles, hence the induced e. Cogging torque was minimized by finding an optimum magnet pole arc length and torque ripples were minimized by finding. Here we can define one more term related to a coil called coil span. A pole pitch is always 180 electrical degrees, regardless of the number of poles on the machine. If the maximum flux per pole, with a sinusoidal distribution, is 0. You can read more about Full Pitch and Short Pitch Winding at:. slots. The coil span is 160°. Hence emf induced in one side of. g. . in. • In double layer windings used in. Determine the phase and line voltages if the coil is full pitched. 6. ∙ 10y ago. If the coil span is reduced by one slot, then the phase angle α between the induced EMFs in the two sides of the coil is given as. Lap winding • Suppose we want to make a lap winding for a P = 4 pole D. It is always 180° electrical. Thus coil span of either 6 or 7 may be selected. 0. Pole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical Degree - YouTube Hey Aspirants. Cogging torque was minimized by finding an optimum magnet pole arc length and torque ripples were minimized by finding. 259 C. B. Hence, the coil span in three phase AC machines must be (frac{5}{6}th) of pole pitch. the core length 32 cm, and. When a coil. The resultant coil voltage $𝐸_{𝐶}$ is equal to the phasor sum of $𝐸_{𝐶1}$ and $𝐸_{𝐶2}$. A 6-pole, 3-phase, 60 cycle alternator has 12 slots per pole and four conductors per slot. 707. 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. 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. Example: the throw could be to 9 meaning that one side of the coil is inserted in slot #1, and the other side in slot #9. of consecu- tive turns (c) distribute the winding. round the coil which is the vector sum of e. 26. This is naturally equal to the total number of armature slots divided by the number of poles in the machine. Use a diagram like that shown in fig. 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. frame. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. Each phase in this case consists of four coils (two per slot). 24 B where coil pitch is 3/4th of the pole pitch), then the D. 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. ∴ e = E 1 + E 2 = 2E. Determine the pitch (or coil span) factors for the winding , 96 Stator slots ,4 poles, coil span 1 to 18 13. The skew factor reflects the flux reduction if the winding is angularly twisted along the axis. 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. The primary reason for making the coil span of a d. Prelude to Synchronous Generator Induced E. 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. 3 mWb and the total number of armature conductors is 1000. Answer: a. It means that coil span is 180 electrical degrees. For n th harmonic. Pole pitch. Front connections 8+7=15; 30+7-30=7 8. We must note that the coil-pitch and flux barriers of the NC2 are adjusted as shown in. Similarly, for a coil having a span of 2/3 pole-pitch, kc = cos 60°/2 = cos 30° = 0. 0. When two capacitors of reactances 10ohms and 20 ohms are connected in parallel across a 100 V supply, total VAR drawn will be _. arrow_forward. The arithmetic sum of induced emfs is 2E. Pole Pitch: It is the angular distance between the two adjacent poles. If the coil span is from slot 1 to slot 21, and the flux per pole has a fundamental component of 0. The value of α will usually be given in the question, if not, then assume kc = 1. where B is the flux density, µ is permeability of material, A is the area of the magnetic field path, whereas the same subscript used in is used thought the paper. The induced emf in each coil side. Answer: c Explanation: Pole pitch is called as center to center distance between two adjacent poles. , a pitch, or an pitch, etc. Boylestad. 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. Calculate the distribu factor for a 36-slot. . 0. (Assume lap. pole pitch5. 09 O4. The coil span is 150°. 086 Wb, what will be the values of the emfs? phase. Emf induced per coil side is E. Coil Span: The number of core slots spanned by the sides of the coil. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. 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. Solution for For alternator having fractional pitch of 11/12 the coil span is a. 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. It falls short by 1/6 pole-pitch or by 180°/6 = 30°. 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. This distance is measured in terms of armature slots or armature conductors that come between two. As shown in Fig. Both Y B and Y F should be nearly equal to a pole pitch. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. A coil span less than 2/3 pole pitch is not used in practice. In this case, there is a phase difference between the e. . In this video lecture you will learn about electrical angle,mechani. arrow_forward. 2. (a) Describe armature reaction and explain its effect on terminal voltage (b) Calculate the speed and open circuit line and phase voltages of a 4-pole, 3-3 pitch factor or coil span factor in alternator tutorialspoint web oct 1 2021 1 2 if the coil span of a single coil is less than the pole pitch of 180A two pole three-phase 50 hz wye-connected AC generator has 9 slots per pole and 6 conductors per slot . e. 9780133923605. Number of slots: 3 Number of poles: 2 Number of phases: 3 Number of layers: 1 Coil span : 1 Number of slots per pole per phase: 1/2. 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 coil pitch is 5/6th of the full pitch and the flux per pole is o. Thus the total emf at the coil terminal A & B is the phasor sum of (E 1 +E 10), (E. Coil span or coil pitch Ys: It is the distance between the two sides of a coil measured in terms of armature slots. 5. . Where n is the nth harmonic. 025 Wb entering the armature from each north pole, and this flux is sinusoidally distributed along the air gap. So if coil side in slot No. 6. The skew by one slot pitch gives the value of fundamental skew factor of 0. In a 4-pole, 35 slot d. Sketch the winding over a pole pitch, indicating the location of the conductor of each phase. On the other hand, if its span is less than a pole-pitch. Pole pitch = 180 electrical degrees = S/P = 2C/P. See answer (1) Best Answer. At this situation, two opposite sides of the coil lie under two opposite poles. Hence, the total e. 14. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. e. 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. 10 A three-phase, wye-connected alternator has 15 slots/pole. m. BUY. c. 851: D) 0. Question: 2 Problem 2: The flux distribution curve of a smooth core 50HZ generator is B(0) = sin 8 +0. Pole pitch is always equal to 180o electrical. Distribution factor (K d): The ratio of induced emf in the coil group when the winding is distributed in number of. Back Pitch. Assume the coil span as 150° electrical. ∴ e = E 1 + E 2 = 2E. For the n th harmonic, the chording angle becomes nα° electrical. For alternator having fractional pitch winding of 8/14 the coil span is 102. If we used short pitched winding for armature winding than pitched factor is included in EMF equation in Alternator. 6. If coil span is equal to pole pitch then it is called full pitch coil. Coil Span Factor: In a full pitch winding the coil span or coil pitch is always equal to the pole pitch which is equal to 180 electrical degrees. Download Solution PDF. Corresponds to 180/12 i. Calculate the emf generated in each phase when the machine runs at 375 rpmHence, pitch factor or coil span factor K p = Cos(/2). The coil span is 150°. How do you calculate winding pitch? Pitch Factor is calculated by dividing the coil throw (–) 1 (coil span) , by the number of slots per pole. Draw the double layer winding layout for a 24 slot stator and 4 pole alternator 3. The distribution of upper-side voltage phasors is the same as that of coil voltage phasors,. Calculate the RMS value of the induced emf per phase. 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. The coil span or coil pitch for short or fractional pitch coil is less than 180 electrical degree. Note. A 4-pole, 50-Hz, star-connected alternator has 15 slots per pole and each slot has 10 conductors. 11. 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. Fig. 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. 24 where polepitch of 4 has been assumed), then winding is called full-pitched. In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch, back pitch, pole pitch, coil pitch, etc. in the two coil sides. Supposing that each coil under the pole pitch has. Determine the equation for the. Hence emf induced in one side of. This distance is measured in terms of armature slots or armature conductors that come between two adjacent pole centers. 1K 39K views 2 years ago AC Electrical Machines Jimit Tutorials In this video basic terminologies related to AC armature winding like coil, conductor, coil side, front pitch,. If the coil span is less than the pole pitch, then the winding is said to be short-pitched. This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. In this. Hence, the coil span in three phase AC machines must be (frac{5}{6}th) of pole pitch. Determine both the winding factor and the effective turns per phase. 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. ISBN: 9780073373843. o5Wb. Winding Question 9. 2. You can read more. However, the coil span may be less than a pole pitch, in which case the coil is described as short pitched or chorded. 150° is (frac{5}{6}) parts of 180° i. Coil span Pole pitch Periodicities Winding factor. 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. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . • Coil span is nothing but the spacing between the two coil sides of a coil. 1, or nonsalient (flush with the surface of the rotor), as shown in Fig. Q3- A/ 10 MVA, 11 KV, 50 Hz, 3-phase star-connected alternator s driven at 300 RPM. 1993) Example 37. The number of segments lying between the ends of the coil is known as the commutator pitch. (a) commutator bars per pole (b) winding elements (c) armature conductors per path (d) armature parallel paths. a coil. Alternator connections: star or delta connections of alternators suppress triplen harmonics from appearing across the lines 1. Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Solution : n = Slots/pole = 36/4 = 9. ∴ Coil span factor, Where β is the angle through which the coil is short pitched. 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. 7. A 3-phase, 4 pole, Y- connected alternator has 72 slots with two conductors per slot. A pole pitch in an electrical machine is equal to 180° electrical. To get a coil around every tooth, we need two winding layers (double layer winding). For making coil span equal to a pole pitch in the armature winding of a d. It is always less than unity. . Electricity for Refrigeration, Heating, and Air Conditioning (MindTap Course List). 0. Find equation of 5 EMF induced in one turn and its RMS valueIn this study, the electromagnetic performances of dual 3-phase permanent magnet (PM) machines with coil span of two slot-pitches are comparatively investigated. This is shown in the figure to left. The reduction fraction is the pitch factor. For a full pitch coil, the value of pitch factor is unity whereas for its value is also unity for concentrated coils. Relation between frequency, speed and number of poles: Fig: 1. 0 C. The electrical space angle between the active coil length or coil side is equal to one pole pitch. ( b) 42 stator slots, four-poles, coil spans 1 to 10. Obtain a full-pitch winding. A pole pitch is always 180° electrical regardless of the number of poles on the machine. Back pitch: The distance between the two sides of a coil in the back of the armature is called back pitch. As against this if coils are used in such a way that coil span is slightly less than a pole pitch i. in the two sides of the coil. it is said to the a fractional-pitch. 86 O 119. The highest flux we get, if we define the coil span equal to the pole pitch . 26. Where n is the nth harmonic. 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. M. Wheres is the number of slots, and 2p is the number of poles [19]. When a coil is having a span of 180° electrical, it is called a full-pitch coil. by 20o to full pitch distance. of slots / slots per pole. What is the coil span for a 2 pole 18 slot machine? a) 9 b) 4. 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 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. 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. 4, Fig. 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. is B = 10 sin theta + 2 sin 3 theta + 2 sin 7 theta kilo - gauss, when theta is measured from the neutral axis. 2 Selecting the coil span for a given pole pitch. Give the values of front pitch, back-pitch and commutator pitch. 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. This chapter covers the calculation of winding factors and armature MMFs, harmonic analysis of armature MMFs. Normally the nearest whole number is selected which is 6 in present case. A six pole, three phase alternator has 72 slots and a coil span of 1 to 10, is the pitch factor? A. 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. 36K subscribers Subscribe 9. 75 times the slot pitch), the lowest with 2-solt span coil. ) Given: 120 slots, ,10 poles, double layer winding, coil pitch is shorted by 2 slots, f=60 Hz, Y connected. (5/6) of a pole pitch. The pitch factor [3], [6], [7], [8] is the ratio of coil voltages for a fractional-pitch winding to those for a full-pitch one. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. View 26 DC Generator. 1 the coil span should be approximately equal to a pole pitch. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical DegreeThere are many people who want to. Figure 8 compares computed waveforms of phase back emf. K pn = cos nα/2. BUY Delmar's Standard Textbook Of ElectricityThe slots per pole per phase are 8 and the coil span is 20 slots. 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. Step by step Solved in 2. 9; 21. In a 4-pole, 35 slot d. Calculation:The angular distance between the two coil sides is less than one pole pitch, it is termed short pitch or fractional pitch coil. 0. Explanation: Pole pitch is called as center to center distance between two adjacent poles. e. f. fs. Now coil is shorted by 1 slot i. 23. • Pitch of a Winding (Y) In general, it may be defined as the distance round the armature between. 2 are short-pitched, full-pitched and over-pitched coils respectively. Wc is the coil span , and is the pole pitch measured in the number of coil sides, which is . 2. In a 4-pole, 35 slot d. See solution. Calculate the average voltage generated in a six-turn full pitch coil of a 25 cycle alternator if the. The distance between the two sides of an individual coil of and AC armature winding id termed the coil pitch. the north pole, the other coil side should be under the center of the south pole. In SWAT-EM we can set the coil span explicite. 966 and 0. In this study, the electromagnetic performances of dual 3-phase permanent magnet (PM) machines with coil span of two slot-pitches are comparatively investigated. Compared to the overlapping winding above we need only 3 slots for the two poles. It. The pole arc should be about 70% of pole pitch and length of core about 1. b) 96 stator slots, 6 pole, coil span 1 to…. , the case of short-pitch coil, the voltages generated in each coil side are not in phase. There are 2 coil sides per slot. IMs designed by utilising the winding configurations given in Section 3 are analysed and both SS and FW performance characteristics are presented. of slots per pole = 2 = 6 saree tensed gOSeaee Slot pitch, a = oF slow/pole > No. K p = cos (nα/2) Where n is the nth harmonic. 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). 1kv. 2. Here, e = E 1 = E 2 = E. 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. The flux per pole is 0. 8. You can compare the maximum fundamental winding factor for different. Calculate the pitch factor of the coil for 3 rd harmonic. Duplex Lap Winding. Pole pitch is always equal to 180o. is known as coil span. D. m. 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. Now labeling the starting end of each coil is easy, assuming an RYB phase sequence taking red as the reference. phase shift with emf induced in the other side of the coil. It is usually measured in terms of teeth, slots or electrical degrees. If the generator is running at 1200 rpm, find the average voltage generated between brushes for wave winding. Pole Pitch: It is the angular distance between the two adjacent poles. e. A 4 pole, 12 slot lap wound dc armature has two coil side/slot. Full Pitch and. If the angular distances between the two coil sides are less than one pole pitch, it is termed short pitch or fractional pitch coil. 1. Draw the developed diagram andshow the positions of brushes. *. p. The coil span is 10 slots. 5, then the coil-span can be either 11 or 10 slots. 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. For n th harmonic. To understand, it simply means that one parallel path is in N-Pole and another parallel path in S-pole. Fig. 6. 1 is connected to coil side in slot No. The pole pitch is 10 slots, and the coil pitch is 9 slots. Here, e = E 1 = E 2 = E. The fundamental pitch. The pole pitch is 35 cm. A. 24 D. Coil span is defined as the peripheral distance between two sides of a coil. If the coil span is less then one pole pitch than it is called short pitch coil. , or 5/6 × 180° = 150 electrical degrees. e. 12. of slots/pole/phase, m = 4 ma 2x30 ata Soest 0-9659 (Ans. α = Angle of short pitch = 20o. 7. 339 IC function as. Here we have a 4-pole alternator with a 48 slot stator. 40 O 2. It is defined as the angular distance between the central line of one pole to the central line of the next pole. Back. e. ); and k y is the short pitch factor. If t he coil pitch is y =3, the diame tral w inding w ill have the f. Better emf waveform in case of generators 6. When the. 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. Comparator. 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. 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.