CONCENTRIC WINDING In unbifurcated concentric windings, the first of the q coils which is the smallest is thrown. . Pole Pitch, Coil Span, Back Pitch, Front Pitch, Commutator Pitch in Armature Winding of DC Machines are explained in this video. The average pitch Y A = 2 B F Y Y +. When the coil span is less than pole pitch (180 deg electrical), the winding is called short pitched or chorded. the north pole, the other coil side should be under the center of the south pole. It is always 180° electrical. generator, the back pitch of the winding must equal the number of (a) commutator bars per pole (b) winding elements (c) armature conductors per path (d) armature parallel paths. 1. A 144-slot stator has a whole coiled 12-pole three-phase winding. , Y = 2/3 τ p. Only 100% coil pitch in a two pole machine means half the air-gap circumference. ∴ e = E 1 + E 2 = 2E. Study now. ; It means one side of the coil in a particular slot, after how many conjugative slots, the other side of the same coil is placed. Hence, the total e. (c)Find the number of coils in a coil group, m. Identify the approximate diameter and length of stator core,. In this. Pole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical Degree - YouTube Hey Aspirants. Here we can define one more term related to a coil called coil span. 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. If the coil-span (or coil-pitch) is equal to the pole-pitch, then the coil is termed a full-pitch coil. 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. Cogging torque was minimized by finding an optimum magnet pole arc length and torque ripples were minimized by finding. The formula for pitch factor is given by The pitch factor in the above equation is for fundamental component of emf. At this situation, two opposite sides of the coil lie under two opposite poles. . Determine the phase andline values of emf if the machine runs at 600 rpm and the flux per poleis 0. In this case, the coil sides lie under opposite poles, hence the induced e. c. advertisement. poles, 18 slots alternator, the pole pitch is n = 18/2 = 9 slots. Place the arrows according to the slot pitch. A resultant air-gap flux of a 16-pole, 3-phase alternator is 0. Hence, the coil span in three phase AC machines must be (frac{5}{6}th) of pole pitch. pole pitch = 180 electrical degrees or π electrical radians. 05 Wb, sinusoidally distributed. A six pole, three phase alternator has 72 slots and a coil span of 1 to 10, is the pitch factor? A. 11. 60o groups, 2-layer winding is used. Now coil is shorted by 1 slot i. Pole pitch is the peripheral distance between two adjacent poles. Short-pitched coils are deliberately used because of the following advantages: 1. #Alternator #Protectionofalternator#elect. • Pitch of a Winding (Y) In general, it may be defined as the distance round the armature between. EXAMPLE: Calculate the pitch factor for a alternator winding with 36 slots, 4. In other words, the distance between the two coil sides of a coil will be equal to the distance. Obtain a full-pitch winding. Coil Span: It is the angular distance between the two sides of the coil. 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. The pole pitch is 35 cm, the core length 32 cm, and the stator coil span coil span four fifth of the pole pitch. ISBN: 9780073373843. Each phase in this case consists of four coils (two per slot). e. Normally the nearest whole number is selected which is 6 in present case. , the case of short-pitch coil, the voltages generated in each coil side are not in phase. Calculate the rms value of the induced emf per phase of a 10-pole, 3-φ, 50-Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. It has key variables such as Pole Pitch (back and front pitch, resultant pitch and communicator pitch, Coil Span, Commutator Pitch. 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. 86 O 119. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical DegreeThere are many people who want to. The arc diagram contains all the necessary information for connecting the pole-groups correctly. K pn = cos nα/2. M. Compared to the overlapping winding above we need only 3 slots for the two poles. For a full pitch coil, the value of pitch factor is unity whereas for its value is also unity for concentrated coils. e. As shown in Fig. For alternator having fractional pitch winding of 8/14 the coil span is 102. Figure below shows a short pitched coil. Sketch the winding over a pole pitch, indicating the location of the conductor of each phase. 5 ≤ q ≤ 3, are presented in Section 3. K p = cos (nα/2) Where n is the nth harmonic. 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. The coil span equal to 180 electrical degrees: The coil span is less than 180 electrical degrees. Calculation:A coil rotated in a magnetic field induces current. It falls short by 1/6 pole-pitch or by 180°/6 = 30°. . the coil-span needs to be increased, so as to link a higher flux. 10 are one pole pitch or n slots or 180° electrical apart, the coil is called full pitch coil. Calculate the pitch factor for (a) fundamental (b) 3rd harmonic (c) 5th harmonic (d) 7th harmonic. The highest winding factor can be obtained with 4-solt span coil (the coil span is closest to pole pitch 3. In this case, the coil sides lie under opposite poles, hence the induced e. 25 slots. C. C. Use: (Y) =) 2. P. An alternator having 10-poles, 3-phase, and 60 Hz has 8 conductors per slot in single layer arrangement with 4 slots/pole/phase. If the maximum flux per pole, with a sinusoidal distribution, is 0. N st 2p r; 12 14 16 18 20 22; 12:. Coil–span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. 6. In a 4-pole, 35 slot d. 3. in. m. Alternatively, this type of coil is also called a short-pitch or chorded coil. 2 sin 30+0. The phase spread is 60° and the flux per pole is 25·8 × 10–3 weber. It is using an armature winding which is short pitched by one slot. 3. Correction for this is done by multiplying the voltage equation by Kp, called pitch factor. 1. The displacement between the sides of the coil is called the coil span. 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. After updating the table, the drop-down list below lets you select whether to display the number of slots per pole per phase, the maximum possible fundamental winding factor, the number of winding symmetries,. 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. 339 IC function as. For a coil span of 13/15 of a pole pitch, the phase winding factor is: K_p = cos(π * 13 / (2 * 15)) = 0. The maximum pole flux is 8. the coils cannot be full - pitched; they may be short - pitched with 15 slots, or long - pitched with 16 slots. 96 stator slots, 6poles, coil span 1to 12. 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). The coil span is 10 slots. Note. 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). ISBN: 9780133923605. Figure 2 illustrates a full pitch winding. 2. The pole pitch is 35 cm. If the coil. Coil span σ, winding factor k w, pole ratio G r and N c for possible pole-slot combinations in the proposed FMPM machine. round the coil which is the vector sum of e. The flux per pole is 80 m Wb and the coil span is 160° electrical. Number of Commutator Segments - Number of Commutator Segments is the count of cylindrical assembly of insulated segments that are mounted on the shaft. Back Pitch. 0. Coil–span or coil-pitch. MMF OF ARMATURE A. Pole pitch is the peripheral distance between two adjacent poles. in the two coil sides. 851: D) 0. 25 O 5. Alternator connections: star or delta connections of alternators suppress triplen harmonics from appearing across the lines 1. 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. *. y=Coil span τ=Z/2P is the Pole pitch or full span II. pdf from CSE 302 at World University of Bangladesh. • Coil span is nothing but the spacing between the two coil sides of a coil. The phase spread is 60° and the flux per pole is 25-8 x 10 weber. Calculared the flux per pole required to give Il kV line voltage on open circuit voltage. In this study, the electromagnetic performances of dual 3-phase permanent magnet (PM) machines with coil span of two slot-pitches are comparatively investigated. Coil is 12 slots. . What is meant by a full pitch winding a fractional pitch winding? If the coil span is equal to the pole pitch, then the armature winding is said to be full pitched. Coil–span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. In a 4-pole, 35 slot d. The flux per pole has a fundamental component of 0. Lap and Wave winding are explained. A coil is said to be fully pitched when the coil span is made equal to the pole pitch of the machine. It is usually measured in terms of teeth, slots or electrical degrees. Calculate the emf generated in each phase when the machine runs at 375 rpmHence, pitch factor or coil span factor K p = Cos(/2). 0. machines with. ( ) () ⎪ ⎪ ⎪ ⎩ ⎪⎪ ⎪ ⎨ ⎧ = − = − = − = − = sin 8 /5 sin 6 /5 sin. 25 O 5. Front pitch (Y f):. in them are additive. Despite its disadvantages, it is common in mass production. Determine the pitch (or coil span) factors for the winding ,24 Stator slots ,4 poles, coil span 1 to 5 12. 2:. Not ( I want a solution within 20 minutes because it is very urgent ) Q3//The armature of a 6600 volt, three-phase, 20-pole, 300 rpm star-connected alternator has 180 slots. 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. BUY. Publisher: McGraw-Hill Education. 6A. ISBN: 9780073373843. 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. However the waveform of the resultant emf can be improved by making the. Determine the coil and commutator pitches for a 72-slot 288-segment six-pole frog-leg armature winding. m. armature, 180 electrical-degree coil span will be obtained when coils occupy. because of that the pole pitch is 9/4 of the slot pitch, thus the three-phase symmetric distributed windings consist of 18 double-layer coils that can be used, in which each coil span. 967. The coil used in double layer winding are diamond shaped as in the dc windings. 13. 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~. (BTL-1) 4. 2. 25 = 6 and 1/4 slots. slots. If the coil span is less than the pole pitch (as in coil Fig. They are two basic physical types for the windings. , a pitch, or an pitch, etc. e. 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. ) Given: 120 slots, ,10 poles, double layer winding, coil pitch is shorted by 2 slots, f=60 Hz, Y connected. Answer: 0. It is possible to suppress the higher harmonics by using double-layer windings using shortened span coils. It may be the full pitched or short pitch. There are 2 coil sides per slot. m. e. What is the flux per pole if the voltage on open circuit is 1. 455 V D. To calculate the pitch factor, we need to consider the pole number and the fractional pitch. kp: 0. 951, 0. First. 👉 (2008-2018) With solution, BRANCH Wise Click the Link-ELECTRICAL. We will start Red at slot 1. 125 Wb and a. If the coil span is from slot 1 to slot 21, and the flux per pole has a fundamental component of 0. Last Answer : If the coil span is equal to pole pitch, the winding is called as full pitched winding. A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. If the machine gives 3300 V between lines on open circuit sinusoidal flux distribution, determine. Q1/ Calculate the voltage per phase for a 3-phase 1500 rpm, 4-pole alternator having a 16 conductors per slot connected in two layers. The fundamental pitch. I need answer within 20 minutes please please with my best wishes. 0. (5/6) of a pole pitch. See solution. The coil span is 150 , the flux/pole has a fundamental components of 0. d5. If the high speed coil span was 1/2 of pole pitch, then there would be roughly equal airgap circumference for induced poles as exists for the driven poles in slow speed, and no need for homopolar flux in the shaft. Sanfoundry Certification Contest of the Month is Live. Power System Analysis and Design (MindTap Course List) 6th Edition. Supposing that each coil under the pole pitch has. Publisher: McGraw-Hill Education. 1-9 coil span A SIMPLE explanation of what a pole pitch is in a generator or rotating machine. . Calculate the distribu factor for a 36-slot. TABLE I Winding factors for different combinations of pole numbers p and slot numbers Qs Qs p 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42. If t he coil pitch is y =3, the diame tral w inding w ill have the f. p. 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. If the coil span is. 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. It. Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. The coils are made up of 8 turns, and the windings are double layer. . Coil span is simply a peripheral distance between two sides of a coil. 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. less than 180° electrical, the coils are called, short pitched coils or fractional pitched coils. 150° is (frac{5}{6}) parts of 180° i. The coil span is 150 electrical degrees. – Comparator. 966the coil span of the two slot‐pitch technique has been pro-posed, based on the ‘stator shifting’ concept [8, 9]. In this paper, the influence of changing the span of the concentrated coil for a certain pole pitch on the harmonic content in the output voltage. If the coil-span (or coil-pitch) is equal to the pole-pitch, then the coil is termed a full-pitch coil. The coil-span is 144° (electrical). The distance between the two coil-sides of a coil is called coil-span or coil-pitch. air. Since this machine has 8 poles and a pole-pitch of 48/8 = 6 slots, the coil pitch here is 5/6 = 0·833 p. Register to editPitch factor problem. It equals pole pitch = Z P . 150 degrees c. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch. The Separation between the top and bottom sides of a coil is known as back pitch and is represented by (Y b). A: slot angle = 180slot per pole = 18015 = 12 pole pitch = no. 2 sin 50 +0. The coil span A. Emf induced per coil side is E. Expert Solution. However in practise this often isn’t the best choise because of the high harmonic content. Each of these coil spans is five slots, so this choice of winding pattern is referred to as “Five-Sixths” pitch. If the coil span is equal to the pole pitch, then the armature winding is said to be full – pitched. Zoom In Zoom Out Reset image size. Armature Currents and MMF of 5-Phase Machine The armature currents of 5-phase machine can be expressed with formula (1). 10. It is always 180° electrical. The pole pitch is 35cm, the core length is 32cm & sta- 4th tor coil span is of pole pitch. The flux per pole has a fundamental component of 0. Front Pitch-The number of armature conductors or elements spanned by a coil on the front is called front pitch. Looking at the diagram in the question. The coil span should be minimum of about 8. 7. B. The alternator has 18 slots per pole and the first coil lies in slots 1 and 16. The coils are place in 60 uniformly distributed slots around the inner perimeter of the stator. Here, e = E 1 = E 2 = E. Allow 10 ampere for the field current and assume a voltage drop of 4 volts for the armature circuit. 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. A 4-pole, 50 Hz alternator has double layer winding with 10 turns per coil and number of slots are 60. Every coil is connected to the commutator. Q: For alternator having fractional pitch winding of 8/14 the coil span is 102. Coil Span:The angular distance between the centers of two adjacent poles on a machine is known as pole pitch or pole span. of slots per pole = 15 but coil span is… question_answer Q: A synchronous generator is generating 320 V at 55 Hz at a field current of 3. The coil span is 160°. Coil Span: It is the angular distance between the two sides of the coil. 587, 0, khi 9. coils having span which is equal to one pole-pitch i. All coils in a phase are connected in series. Coil span is defined as the peripheral distance between two sides of a coil. . K P = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2. of poles, P= 4 No, of slots = 24; No. Pole pitch is always equal to 180o electrical. When the coil is having a span of less than 180° electrical, it is known as a short-pitch coil. 1 times the pole arc. in the two sides of the coil. Hence, the pole pitch of that DC machine would be 24. Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8. The pitch of the coils is 2 slots less than the pole pitch. When the coil span is equal to pole pitch (180 deg electrical), the winding is called full pitched winding. e. 79. Publisher: PEARSON. The winding is 5/6 pitch. it is said to the a fractional-pitch. If the coil span is less than the pole pitch, then the winding is said to be short-pitched. A coil having a span equal to 180⁰ electrical is called a full pitch coil as shown in the figure below. In an alternator, for a coil having a span of 2/3 of pole pitch,. 🔥engineers platform App Link. However, the phase winding factor for short-pitched coils is different from that of full-pitch coils. It is always equal to 180° electrical. 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. 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. Coil span and commutato pitch b. Pole Pitch, Coil Span, Back Pitch, Front Pitch, Commutator Pitch in Armature Winding of DC Machines are explained in this video. 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. Figure 1. 9 and pf = 0. Step by step Solved in 4. Step by step Solved in 2. Solution : n = Slots/pole = 36/4 = 9. 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. Last edited by markadlerdallas. K pn = cos nα/2. The coil pitch is 12/15. In general, electrical degrees equals mechanical degrees times 1/2 the number of poles. 866. m. The slots per pole per phase are 8 and the coil span is 20 slots. To understand, it simply means that one parallel path is in N-Pole and another parallel path in S-pole. Pole pitch is always equal to 180o. There are 4conductors per slot and a sinusoidally distributed flux per pole of 36mWb. The width of the coils is 5/6 of the pole pitch. 60o / 90o = 2/3. It is using an armature winding which is short pitched by one slot. may or may not be exactly equal to pole pitch B. what is coil pitch or coil span. 8. Download these Free Coil Span or Coil Pitch MCQ Quiz Pdf and prepare for your upcoming exams Like Banking, SSC, Railway, UPSC, State PSC. 26. 2. Commutator pitch. 4. 06 weber distributed sinusoidally over the pole. 5, then the coil-span can be either 11 or 10 slots. 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. For a 3-phase winding with 6 slots per pole per phase and with coil span of 15 slot, the value of pitch factor is A. Then, the pitch factor will be equal. – Comparator. 09 O4. The pitch of the coil is 2 slot less than the pole pitch. Prelude to Synchronous Generator Induced E. Distribution factorA coil advances on the back of the armature.