UNIVERSITY OF NAIROBI FACULTY OF ENGINEERING DEPARTMENT OF ELECTRICAL AND INFORMATION ENGINEEERING DESIGN AND FABRICATION OF SINGLE PHASE INDUCTION MOTOR FOR NUMERICAL MACHINE COMPLEX PROJECT INDEX: 107 SUBMITTED BY: CHRISTOPHER OKEYO OKELLO F17/1373/2010 SUPERVISOR: DR. C. WEKESA EXAMINER: DR. W. MWEMA PROJECT REPORT SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OFTHE DEGREEOF BACHELOR OF SCIENCE IN ELECTRICAL AND ELECTRONICENGINEERING OF THEUNIVERSITY OF NAIROBI 2014 SUBMITTED ON: 24th April, 2015 1 DECLARATION OF ORIGINALITY NAME OF STUDENT: CHRISTOPHER OKEYO OKELLO REGISTRATION NUMBER: F17/1373/2010 COLLEGE: Architecture and Engineering FACULTY/SCHOOL/INSTITUTE: Engineering DEPARTMENT: Electrical and Information Engineering COURSE NAME: Bachelor of Science in Electrical and Electronic Engineering TITLE OF WORK: DESIGN AND FABRICATION OF SINGLE PHASE INDUCTION MOTOR FOR NUMERICAL MACHINE COMPLEX 1) I understand what plagiarism is and I am aware of the university policy in this regard. 2) I declare that this final year project report is my original work and has not been submitted elsewhere for examination, award of a degree or publication. Where other people’s work or my own work has been used, this has properly been acknowledged and referenced in accordance with the University of Nairobi’s requirements. 3) I have not sought or used the services of any professional agencies to produce this work 4) I have not allowed, and shall not allow anyone to copy my work with the intention of passing it off as his/her own work. 5) I understand that any false claim in respect of this work shall result in disciplinary action, in accordance with University anti-plagiarism policy. Signature: …………………………………………………………………………………… Date: ……………………………………………………………………………………… I CERTIFICATION This report has been submitted to the Department of Electrical and Information Eng. University of Nairobi with my approval as supervisor: Dr. C. WEKESA Date: 24/04/2015 ……………… II DEDICATION To my loving mother, Mary Okello. III ACKNOWLEDGEMENTS I would like to thank the Almighty God for his guidance throughout the five years of my undergraduate studies I would like to thank my supervisor, Dr. C. Wekesa for his unending motivation;insight and supervisory role in making this project a success I would like to express my gratitude towards my parents for their prayers, encouragement and support throughout this time. Lastly, I am highly indebted to my classmates, Dennis Lubanga, Bana Clifford , Kimani Mugo, Billy Ochieng’, Doreen Mutekhele and Atanasio Maugambi for their insight into the project. It wouldn’t have been possible without your support IV TABLE OF CONTENTS DECLARATION OF ORIGINALITY ............................................................................................ I CERTIFICATION .......................................................................................................................... II DEDICATION .............................................................................................................................. III ACKNOWLEDGEMENTS .......................................................................................................... IV LIST OF TABLES ....................................................................................................................... VII LIST OF FIGURES ................................................................................................................... VIII LIST OF ABBREVIATIONS ....................................................................................................... IX CHAPTER 1 ................................................................................................................................... 1 INTRODUCTION ....................................................................................................................... 1 1.1 BACKGROUND INFORMATION .................................................................................. 1 1.2 Problem statement ............................................................................................................. 1 1.2.1 Project Organization ....................................................................................................... 2 CHAPTER 2 ................................................................................................................................... 3 LITERATURE REVIEW ............................................................................................................ 3 2.1 What is Motor? .................................................................................................................. 3 2.2 Basic Parts of a motor ........................................................................................................ 3 2.4 Single Phase Motors .......................................................................................................... 5 CHAPTER 3 ................................................................................................................................. 11 DESIGN OF SINGLE PHASE INDUCTION MOTOR .......................................................... 11 3.2 The Design Procedure ..................................................................................................... 12 3.3 Single Phase Induction Motor Design Specifications Determination ............................. 14 3.3.1 Motor specifications ..................................................................................................... 14 3.6 Design of starting winding for resistance split phone ..................................................... 30 CHAPTER 4 ................................................................................................................................. 32 RESULTS AND ANALYSIS ................................................................................................... 32 4.1 Results ............................................................................................................................. 32 4.2 Result Analysis ................................................................................................................ 34 CHAPTER 5 ................................................................................................................................. 35 CONCLUSIONS AND RECOMMENDATIONS ................................................................... 35 5.1 Conclusion ....................................................................................................................... 35 V 5.2 Recommendation ............................................................................................................. 36 References ..................................................................................................................................... 37 VI LIST OF TABLES Table 4. 1 Results .......................................................................................................................... 32 Appendix Table 1 Standard Load Efficiency and Power Factor For Small Single Phase, 50hz Cage - Motors ............................................................................................................................... 38 Appendix Table 2 The Standard Approximate Values For Co.η.Cos For Different Values Of Watts/R.P.S. .................................................................................................................................. 39 VII LIST OF FIGURES Fig. 2. 1 Parts of a Motor ................................................................................................................ 4 Fig. 2. 2 Diagram showing the operation of a D.C Motor .............................................................. 5 Fig. 3. 1 Design Flow Chart Diagram .......................................................................................... 11 Fig. 3. 2 Arrangement of Stator Coils ........................................................................................... 19 Fig. 3. 3 Rotor Set ......................................................................................................................... 24 VIII LIST OF ABBREVIATIONS Li – Iron Length F = Flux per Pole Kw=Winding Factor f=Frequency V=Rated voltage I=Full load current in the main winding, A Tm=Number of turns of the main winding P=Number of poles D=stator bore diameter, m L=Stator core length, m τP=Pole Pitch ns=Synchronous speed, r.p.s Bav=Average value of flux density in the air gap, Wb/m2 (Specific magnetic loading) ac= Ampere-conductor per meter of arm. Periphery, ac/m (specific electric loading) η=Full load efficiency Cos F= Full load power factor dcs – Depth of Stator Core dss-Depth of Stator slot Ss- Stator Slots Lg – Length of air gap Dr – Rotor diameter am- Area of main conductor IX Lmt - Length of mean turn Xom- Open circuit reactance Xk- Auxiliary Winding reactance Xm- Magnetising reactance Xo – Overhang reactance Xlm- Leakage reactance Kr-Leakage factor π - Peripheral Velocity Lb- Length of bar yss– Stator slot pitch ysr X ABSTRACT The energy sector plays a major role in driving Kenya’s economy. The need to conceive, develop and sustain energy generating sources cannot be underestimated. Being a growing economy, Kenya therefore needs to redirect her effort in production of selfsustaining energy generating sources. It is in this line that the government through the ministry of industrialization, energy and vision 2030 sought to establish the Numerical Machine Complex, which serves as a hub for fabrication, assembling and servicing small to medium scale moving machines. Since its conception NMC has been used majorly for assembling small motors and generators from the imported machine parts. The economic burden of importing already fabricated parts in addition to the high assembling costs, is considerably high for a growing economy which not only strives to self- sustain itself but also seeks to create employment for a semi-skilled workforce. It is in this line that the NMC management decided to look into a more economical option which involves fabrication of the single phase induction motor. Single phase induction motors have a wide range of application in small loads fromfridges, water pumps, fans, washing machines etc. This project seeks to provide solutionsto the required design specifications for 2.2 KW, 240 V SINGLE PHASE INDUCTION MOTOR forNumerical Machine Complex XI CHAPTER 1 INTRODUCTION 1.1 BACKGROUND INFORMATION Today, single-phase induction motors are used in a wide range of applications.Single-phase induction motors are used in small loads from fridges, water pumps, fans, washing machines. Even though the three-phase induction motor has taken up the larger portion of the market, the need to cater for all the consumers of different levels of energy demand has ensured that the single phase induction motors continue to exist within the market.Additionally, most domestic applications use only one line, this therefore makes single-phase induction motors the most suitable for these applications.Generally, induction motors are easy to fabricate and more efficient than other types of motors of the same rating, this makes it easy to readily initiate the induction motor fabrication projects. Owing to the existing demand and need to derive the advantages that come with producing local products, NMC initiated the single-phase induction motor design and fabrication I Kenya. 1.2 Problem statement 1.2.1Project objectives The objectives of this project is to come with the required desired design specifications for the single phase induction motor for fabrication by the Numerical Machine Complex. In wake of the increasing demand to locally fabricate the low rated induction motors, this project seeks to solve the design problem by presenting an easy to use design specification generating program to be used in the fabrication process. 1 1.2.1 Project Organization The project has been organized in to five chapters as follows; In Chapter 1, the project objectives and scope is introduced. In Chapter 2, a literature review on motors, motor action, and single phase motor operation is reviewed. Additionally, methods of starting a single-phase induction motor are introduced. In Chapter 3, the design procedure of single phase induction motor is introduced and applied. The pseudo code has been generated for simulating design specification is implemented and a flow chart is provided. In Chapter 4, the simulated results are tabulated and in-depth analysis on the results is presented In Chapter 5, a discussion and a conclusion on the project is presented. 2 CHAPTER 2 LITERATURE REVIEW 2.1 What isMotor? An electric motor is a machine that converts electric energy into mechanical energy. [1] 2.2 Basic Parts of a motor 2.2.1Stator The stator is the stationary part of the motor. 2.2.2 Rotor The rotor is the rotating member of the motor. 2.2.3FIELD SYSTEM The field system functions to produce a uniform magnetic field within which the armature rotates 2.2.4 Armature winding Armature winding consists of insulated conductors that are connected in a suitable manner. 2.2.5 Commutator A commutator which is a mechanical rectifier found in D.C.machines which convert thealternating voltage supplied to the armature winding into direct voltage across the brushes. 2.2.6 Brushes The purpose of the brushes is to ensure electrical connections between the stationary commutator and the rotating armature conductors. 3 Diagram illustrating the parts of a motor Fig. 2. 1Parts of a Motor A motor operates on the principle that a current- conductor placed in a magnetic field experiences a magnetic force whose direction is defined by the Fleming’s Left – hand Rule and whose magnitude is given by the expression , F=BIl Newton [1,2] Consider the DC motor shown below; for the DC motor shown, when the field magnets are excited and the armature conductor is supplied with the current, the conductor experiences a force whose direction is defined by the Fleming’s left hand rule. This force tends to rotate the armature conductor [2, 3] When the armature rotates, the conductors also rotate and hence cut the flux. An e.m.f is induced in the armature conductors whose direction is opposite to the applied voltage as defined by the Fleming’s Right hand Rule. This voltage is referred to as the counter e.m.f. or back e.m.f. [2] The voltage applied at the motor terminals therefore has to force the current against the back e.m.f. The electric work done in overcoming and causing the current to flow against the back 4 e.m.f. is converted into mechanical energy usually developed in the armature [1]. Therefore, it is clear that the energy conversion in dc motor is only possible due to the production of back e.m.f. The presence of back e.m.f. in dc motors regulates the flow of armature current i.e., it automatically changes the armature current to meet the load requirement. Fig. 2. 2Diagram showing the operation of a D.C Motor 2.4 Single Phase Motors Single phase motors are used on single-phase power supplies. Types of single phase motors Single phase motors are generally built I the fractional-horsepower range and may be classified into the following for basic categories [1] 1. Single-phase induction motors i. Split-phase type ii. Shaded-pole type 5 iii. Capacitor type 2. A.C. series motor 3. Repulsion Motors i. Repulsion-start induction-run motor ii. Repulsion-induction motor 4. Synchronous motors iv. Reluctance motor v. Hysteresis motor 2.4.1 AC SERIES MOTOR The a.c. series motor is also known as the universal motor. The a.c. series motor works on the same principle as the D.C. series motor, however, with little modification on the specific part of the motor [1]. These modifications include; i) Completely laminated magnetic circuit in order to reduce the eddy current loss. ii) Reduced number of turns of the series field winding to reduce the reactance of the field winding to a minimum. This reduces the voltage drop across the field winding. iii) It incorporates a low- reluctance magnetic circuit which ensures a high field flux within the set-up. Operation of a.c. series motor When the motor is connected to the single phase a.c. supply, the same alternating current flows through the field and armature windings. The field windings produce an alternating flux that reacts with the current flowing in the armature to produce a torque [1, 2]. The torque developed always acts in the same direction as both the armature current and the flux reverse 6 simultaneously [1]. The motor, therefore, does not enjoy the influence of a rotating flux. As such it operates on the same principle as the D.C. motor. 2.4.2 Single phase Repulsion Motor A single phase repulsion motor is a modified a.c. series motor with short- circuited brushes i.e. brushes are not connected to the supply. It also has a field structure with non-salient pole construction [2]. The short- circuited brushes allow the currents to be induced in the armature conductors by the transformer action. The starting torque in the motor is developed by adjusting the position of the short-circuited brushes on the commutator [1]. Principle of operation A single phase Ac motor with transformer action coupling between the windings of the stator and rotor. The stator is of non-salient pole design and has two series-connected windings, whose axes form a 90 degrees angle. The rotor is similar in design to the armature of the DC machine. The commutator brushes are short circuited, and the brush holder can be turned with respect to the axis of the motor. If the brush axis is aligned with the axis of one of the stator windings a current is induced in the rotor winding, as in the secondary winding of the transformer. This current interacts with the magnetic flux of the secondary stator winding and creates a torque that causes the rotor to rotate. By shifting the brushes around the commutator, the torque can be varied from zero to a maximum value [1]. These motors have the advantage that their rotational speed can be varied within limits without the use of auxiliary apparatus [2] 2.4.3 Single Phase Synchronous Motors These are very small single-phase motors which run at real synchronous speed [1]. 7 These small motors characteristically do not require D.C. excitation of the rotor. As a result they are also referred to as the unexcited single-phase synchronous motor [1, 3]. They are of two types: i) Reluctance Motors ii) Hysteresis motors 2.4.4 Single phase induction motor Generally, the conversion of electrical power into mechanical power takes place in the rotating part of an electric motor [2]. In a.c motors the rotor of the machine receives electric power by induction in a similar manner as the energy is transferred from the primary part to the secondary part of the transformer [1, 2]. 2.4.4.1 Construction of an Induction motor An induction motor consists essentially of two main parts: I) Stator II) Rotor i) The Stator The stator of an induction consists of a number of stampings, which are strategically placed to house the windings. The windings are wound for a definite number of poles which is determined by the required speed of the motor [1, 2, and 3]. The greater the number of poles, the lower the speed of the motor [2].When supplied with the current, the stator windings produce a rotating fluxwhich is of constant magnitude but which rotates at synchronous speed. The revolving flux induces an e.m.f in the rotor by induction. ii) Rotor 8 A single phase induction motor has a squirrel- cage rotor. The squirrel-cage rotor consists of a cylindrical laminated core with parallel slots for carrying the rotor conductors (heavy bars of copper or aluminum). The rotor bars are electrically welded to two shortcircuiting end-rings thereby forming a squirrel case construction. The rotor bars are not aligned straight to the rotor bar but are skewed to reduce the locking tendency of the rotor and to reduce the magnetic hum hence allowing the motor to run quietly [2]. 2.4.4.2 Single phase induction motor operation When the motor is fed from a single-phase supply, the stator winding produces a flux which only alternates along one space axis only, i.e. the flux produced does not rotate [1, 2 and 3]. A single – phase induction motor is therefore not self-starting. However, if the rotor is given a push in either direction, it accelerates to its final speed and continues to rotate in the given direction even after the force has been removed. 2.4.4.3 Making a single phase induction motor self-starting Single phase induction motors are not self- starting, therefore to make them self-starting they are temporarily converted into two phase and then reverted to single phase upon gaining the desired motion in the desired direction. There are several methods of making a single phase self-starting. These include:1. Split-phase induction motors In split phase induction motor, the stator has twowindings- main and auxiliary- which are used to start up the motor. The main winding has low resistance but high reactance whereas the starting winding has a high resistance but low reactance [1, 2]. At starting the winding current Im lags the applied voltage by about 70-80 degrees, the auxiliary winding current Ia by about 30-40 degrees. This result in a non-uniform travelling –wave field and consequently a rotor torque proportional 9 to ImIaSinα where α is the difference between the two angles of lag [5]. A starting torque of between 2.5-2 times the full load value is generated. After reaching 75% of the rated speed, the auxiliary winding may be open circuited with the help of centrifugal switch and the motor would still continue to run. 2. Capacitor split phase motor. Capacitor split phase motors incorporates capacitors in the auxiliary winding so as to greatly vary the phase difference between the auxiliary and the main winding [2]. There are two types: I. Capacitor start motor- In these types of single phase induction motor, the starting winding along with the capacitor is isolated when the motor has attained the desired speed. II. Capacitor-run motor- In these type of single phase induction motors, the starting winding (winding with the capacitor) remains in the rotor circuit after starting the motor. The starting winding helps improve the power factor. 10 CHAPTER 3 DESIGN OF SINGLE PHASE INDUCTION MOTOR START (Human decisions) Specifications, constraints, output requirements, initial machine dimensions, winding parameters, objective function Input Run the equivalent machine program and analyze the results Output (Examine Result) Are specified constraints/ condition satisfied? Are performance specifications satisfied? Print all the machine design values and expected performance values STOP Fig. 3. 1Design Flow Chart Diagram 11 Change machine directions and winding parameters 3.2 The Design Procedure The purpose of design is to obtain the dimensions and electrical particulars of a given machine to satisfy a given set of specifications covering the starting characteristics to output ratings. The main specifications for a single phase induction motor for design purposes are:1. Rated output in W or K.W. 2. Rated Voltage V 3. Rated current A 4. Rated speed r.p.m. 5. Frequency HZ 6. Poles, P 7. Pull out torque Nm 8. Starting torque Nm 9. Efficiency % 10. Power-factor % 11. Motor – type : split phase a) Resistance start induction run (low starting torque) b) Capacitor start induction run (medium starting torque) c) Capacitor start capacitor run (High starting torque) I. One capacitor II. Two capacitor Optimum characteristics, starting as well as running 12 3.2.1 Output Equation The output equation relates the desired output characteristics of the induction motor to the machine’ main determining specifications to which the motor should be designed based on. The following standard nomenclature will be adopted in the derivation of the output equation; F = Flux per Pole Kw=Winding Factor f=Frequency V=Rated voltage I=Full load current in the main winding, A Tm=Number of turns of the main winding P=Number of poles D=stator bore diameter, m L=Stator core length, m τP=Pole Pitch ns=Synchronous speed, r.p.s Bav=Average value of flux density in the air gap, Wb/m2 (Specific magnetic loading) ac= Ampere-conductor per meter of arm. Periphery, ac/m (specific electric loading) η=Full load efficiency Cos F= Full load power factor The KVA rating of a single phase induction motor is given by; KVA= VI*10-3 3.1 V=4.44KWfΟTm 3.2 Ο=BavL(πD/p) 3.3 13 Ac= (2TmI)/ (πD) 3.4 f= nsP/2 3.5 Substituting for the value of V in equation (1); then KVA= 4.44Kwf FTm I*10-3 3.6 Substituting for the values of f, F, and Tm ππ D KVA =4.44KW ( 2 ) (Bavππ L) ( ππππ· 2 )*10-3 3.7 = (1.11vπ2KWBavac*10-3) D2Lns 3.8 Again this can be expressed as; KVA=COD2Lns 3.9 Where; Co=1.11vπ2KWBavac*10-3 3.10 3.3 Single Phase Induction Motor Design Specifications Determination 3.3.1 Motor specifications πΎπ = 2.2 πΎπ π = 240 π π = 3 π»π πΉ = 50 π»π§ ππ = 2900 π ππ Take full load efficiency to be 80% and power factor 85% 3.4 Design solution 3.4.1 Main dimension Watts output = 3 π»π = 3 × 746 14 = 2238 πππ‘π‘π Actual speed = 2900 π ππ Nearest synchronous speed= 3000 πππ Number of poles P = 120 ×f 3.11 ns 120 × 50 3000 π = =2 3000 ππ (πππ ) = ( ) = 50 πππ 60 πππ‘π‘π − ππ’π‘ππ’π‘ 2238 =( ) π. π. π 50 = 44.76 From the graph, the value of πΆπ. π. πΆππ is given by; = 27 Therefore the main dimension of the motor is given by; π.π×0.746 π·2 πΏ = πΆπ.π.πΆππ π.π = 3.12 π 3 × 0.746 27 × 50 = 0.00165778π3 Since the motor is in high demand; We take πΏ = 1.5 ππ Hence for a 2-pole machine; πΏ×2 = 1.5 ; πΏ = 2.3562 ππ· π·2 πΏ = 0.00165778 2.356π·3 = 0.00165778π3 3 π·=√ 0.00165778 2.356 π· = 0.08894 π π· = 8.894 ππ 15 πΏ = 8.894 × 2.3562 = 20.956 ππ π· = 8.894 ππ ππ 3.50157 πΌππβππ From the standard stamping taste Selecting size 138 M of Guest Keen Williams then the bore diameter 1 π· = 3 " ≅ 8.9 ππ 2 Core length, πΏ = π·2 πΏ π·2 = 1657.78 (8.9)2 3.13 = 20.929 ππ Pole pitch ππ = π×8.9 2 = 13.98 ππ ππ ≅ 14.00ππ 3.4.2 Net iron length Li; Choosing a stacking factor of 0.9 then; The stacking factor is the ratio of electrical steel along the axial length of the iron core. It is important to account for the stacking factor when designing an electrical machine, since a stacking factor of less than 1.0 reduces the flux carrying capacity of the iron core accordingly. The stacking factor is low for very thin iron laminations and is approaching unity as the lamination thickness increases. The stacking factor is sometimes also called lamination factor or space factor. πΏπ = 0.9 πΏ = 0.9 × 20.929 = 18.836 ππ Check for peripheral velocity π π = ππ·π = π × 0.089 × 50 = 13.98π/π ππ The maximum permissible peripheral velocity for normal construction is 30m/sec. therefore the chosen D is within the permissible limit The selected stamping has 28 stator slots with parallel sided teeth and tapered slots. 16 The width of stator tooth = 0.1425" ≅ 0.362 ππ = 0.1425" = 0.362 ππ Flux density in the stator slot The stator tooth density π΅π‘π is within the range of 1.4 to 1.7 ππ /π2 π΅π‘π = ∅ 3.14 π ( π )×πΏπ ×ππ‘π π π ∅π = π΅π‘π {( ππ ) × πΏπ × ππ‘π } 3.15 = 1.4 {(28/2) × 0.00362 × 0.188} = 13.339 × 10−3 ππ The selected stamping has outer diameter 7 π·0 = 5 16"=13.81 Depth of stator slotsππ π = 0.573” ≅ 1.455 ππ Depth of stator core, πππ 1 πππ = 2 [π·0 − (π· + 2ππ π )] = 3.16 1 [13.81 − (8.9 + 2.91)] 2 = 1 ππ Check for flux density in the stator case ∅π π΅ππ = 2π 3.17 ππ ×πΏπ 13.339 × 10−3 = 2 × 1 × 10−2 × 18.836 × 10−2 = 3.5408π₯π₯π₯/π2 3.4.3 Stator winding Assuming winding factor for mail winding to be πΎπ€π = 0.8 Stator induced e.m.f πΈ ≅ 0.95 π ≅ 228 π£πππ‘π Number of turns in the main winding πΈ ππ = 4.44 πΎπ€π π∅ = 3.18 π 228 4.44 × 0.8 × 50 × 13.339 × 10−3 = 96.243 17 ≅ 96 Turns in series per pole = 48 3.4.4Winding arrangement Number of stator slots (total) = 28 28 Number of stator slots per pole = ( 2 ) = 14 Therefore selecting the number of coils for main winding = 7 18 Fig. 3. 2Arrangement of Stator Coils 19 For sinusoidal distribution the number of turns of each coil are calculated as; 2 πΆπππ 7 − 9; πππ ππ ½ ππππ π πππ = π ππ ( × 900 ) = 0.2225 14 4 πΆπππ 6 − 10; πππ ππ ½ ππππ π πππ = π ππ ( × 900 ) = 0.4339 14 6 πΆπππ (5 − 11); πππ ππ ½ ππππ π πππ = π ππ ( × 900 ) = 0.6235 14 8 πΆπππ (4 − 12); πππ ππ ½ ππππ π πππ = π ππ ( × 900 ) = 0.7818 14 10 πΆπππ (3 − 13); πππ ππ ½ ππππ π πππ = π ππ ( × 900 ) = 0.9009 14 12 πΆπππ (2 − 14); πππ ππ ½ ππππ π πππ = π ππ ( × 900 ) = 0.9749 14 14 πΆπππ (1 − 15); πππ ππ ½ ππππ π πππ = π ππ ( × 900 ) = 0.5000 14 = 4.4375 Percentage of turns in coil 7-9 0.2225 ( × 100) = 5.014 4.4375 Percentage of turns in coil 6-10 0.4339 ( × 100) = 9.778 4.4375 Percentage of turns in coil 5-11 ( 0.6235 × 100) = 14.051 4.4375 ( 0.7818 × 100) = 17.618 4.4375 ( 0.9009 × 100) = 20.302 4.4375 Percentage of turns in coil 4-12 Percentage of turns in coil 3-13 Percentage of turns in coil 2-14 ( 0.9749 × 100) = 21.9696 4.4375 20 Percentage of turns in coil 1-15 0.500 ( × 100) = 11.2676 4.4375 The turns in each coil will be πΆπππ 7 − 9 = (0.05014 × 48) = 2.406 ≈2 πΆπππ 6 − 10 = (0.09778 × 48) = 4.693 ≈5 πΆπππ 5 − 11 = (0.1405 × 48) = 6.744 ≈7 πΆπππ4 − 12 = (0.17618 × 48) = 8.456 ≈8 πΆπππ 3 − 13 = (0.20302 × 48) = 9.745 ≈ 10 πΆπππ 2 − 14 = (0.219696 × 48) = 10.545 ≈ 11 πΆπππ 1 − 15 = (0.112676 × 48) = 5.40 Total ≈5 48 Amended value of ππ = 2 × 48 = 96 The winding factor is calculated as; { (2 × 0.2225) + (5 × 0.4339) + (7 × 0.6235) + (8 × 0.7818) } +(10 × 0.9009) + (11 × 0.9749) + (5 × 0.500) 96 = 0.3695 ≈ 0.4 3.4.5Conductor size Main winding full current is given by πΌ= π».π×746 3.19 π£.π.πΆππ 21 = 3 × 746 240 × 0.85 × 0.80 πΌ = 13.713π΄ Assuming a current density of 5 π΄/ππ2 Area of main winding conductorππ is given by ππ = 13.713π΄ 5π΄/(ππ^2 ) = 2.7426/ππ2 Diameter of bare conductor √2.7426 × 4 π = 1.868 ππ From the conductor sizes available. The nearest size available has a bare conductor diameter 1.900 mm Therefore Area of main winding conductor ππ ; π ππ = × 2. 902 4 = 2.835ππ2 And diameter of insulated conductor = 2.4268ππ The largest number of turns per coil is 11 and therefore the largest number of main winding conductor in a slot is 11. Therefore the space occupied by 11 conductors is; π 11 × × 2. 42682 4 = 50.88 ππ 2 The average area of slot used 3.4.6 Length of mean turn The length of each of the coils per pole of a concentric winding is given by; πΏππ‘ = 8.4 (π·+ππ π ) ππ × π πππ‘π π ππππππ + 2πΏ 3.20 Where ππ π = ππππ‘β ππ π π‘ππ‘ππ π πππ‘ = 1.46 ππ 22 π· = π·πππππ‘ππ ππ π π‘ππ‘ππ = 8.9 ππ = ππ. ππ π π‘ππ‘ππ π πππ‘π = 28 πΏ = 20.956 ππ 8.4(8.9 + 1.46) × 14 + 2 × 20.656 = 85.424 ππ 28 8.4(8.9 + 1.46) πΏππ‘ πππ ππππ 2 − 14 = × 12 + 2 × 20.656 = 79.208 ππ 28 8.4(8.9 + 1.46) πΏππ‘ πππ ππππ 3 − 13 = × 10 + 2 × 20.656 = 72.992 ππ 28 8.4(8.9 + 1.46) πΏππ‘ πππ ππππ 4 − 12 = × 8 + 2 × 20.656 = 66.776 ππ 28 8.4(8.9 + 1.46) πΏππ‘ πππ ππππ 5 − 11 = × 6 + 2 × 20.656 = 60.56 ππ 28 8.4(8.9 + 1.46) πΏππ‘ πππ ππππ 6 − 10 = × 4 + 2 × 20.656 = 54.344 ππ 28 8.4(8.9 + 1.46) πΏππ‘ πππ ππππ 7 − 9 = × 2 + 2 × 20.656 = 48.128 ππ 28 πΏππ‘ πππ ππππ 1 − 15 = Length of mean turns of main winding (5 × 85.424 ) + (11 × 79.208) + (10 × 72.992) + (8 × 66.776) } (7 × 60.56) + (5 × 54.344) + (2 × 48.128) πΏππ‘ π = 48 { = 69.884 ππ Resistance of main winding; π΄π‘ 750 πΆ 0.021 96 × 0.69884 2.835 π = 0.021 0.49664Ω π΄π‘ 200 πΆ 0.017 96 × 0.69884 2.835 π = 0.017 0.402Ω 3.4.6 Rotor design Length of the air gap, πΏπ ππ πππ£ππ ππ¦ πΏπ = 0.2 + 2√π·πΏ ππ 3.21(a) Or 23 πΏπ = 0.2 + π· ππ 3.21(b) = 0.2 + 0.08894 = 0.289 ππ A length of air gap = 0.3 mm approximately can be taken 1 The selected stamping (pg. 598(138 m)) has rotor outer diameter 3 2 " ≅ 8.9 ππ and slots number 20 It has to be machined to create an air gap of 0.3 mm Thus making rotor diameter π·π = 8.9 − 2(0.3) = 8.84 ππ 3 Rotor inner diameter = 4 " = 1.9 ππ 3.5.7 Rotor slots The selected stamping has 20 slots in the rotor punching From the standard rotor sets; R-5 by Darydal Stainless steel is chosen (pg. 603); 0.145” 1”/16R 0. 3 0 0 0.145” Fig. 3. 3Rotor Set Area of the rotor slot is ” = 0.3 × 0.145 = 0.0435 π π. πππβππ = 0.280 ππ2 24 Allowing for rounding of corners and clearances, the area of the rotor bar can be taken as; ππ = 24ππ2 Total rotor copper section π΄π = ππ . ππ 3.22 20 × 24 = 480ππ2 And the total stator cooper section for main winding; π΄π = 2ππ ππ = 2 × 96 × 2.7426 = 526.5792mm2 ≅ 527ππ2 3.5.8 End Ring design π΄ πΏπ ) Area of each end = πΏπ = π π π 3.23 πΏπ 480 πΏπ = π×2 (TakingπΏπ = πΏπ ) πΏπ – ππ’πππππ‘ ππππ ππ‘π¦ ππ πππ ππππ 3.24 πΏπ − ππ’πππππ‘ ππππ ππ‘π¦ ππ πππ‘ππ πππ ≈ 76.394ππ2 Let end ring depth = 10 mm and emf thickness 5 mm Taking outer diameter of End ring Dero = 9.00 cm Inner diameter of endring Derl = 8.00 cm Mean diameter end ring De = 8.5cm 3.5.9 Gap extension coefficient Width of stator slot opening πππ = 0.065−11 = 1.65 ππ Ratio π πππ‘ πππππππ πππ πππππ‘β = Stator slot pitch π¦π π 1.65 0.3 = 5.5 ππ πΎ×8.9 28 3.25 = 0.9985 ππ Carter’s coefficient for semi-enclosed slots correspond to a ratio 5.5 from the standard taste [5] is 0.64 Therefore; πΎππ = π¦ π¦π π π π −πΎππ .πππ 0.9985 = 0.9985−0.64×0.165 3.26 25 = 1.118 ππππ πππππππ π‘βπ πππ‘ππ π πππ‘ π‘π βππ£π ππ πππππππ 1.0ππ πππ = 1.0 ππ π ππ‘ππ π πππ‘ πππππππ 1.0 = = 3.33 πππ πππππ‘β 0.3 For which πΎππ = 0.48 π × 8.84 = 1.3885 20 1.3885 = 1.3885 × 0.48 × 0.1 π¦π π = πΎππ π = 1.036 Therefore gap extension πΎπ = 1.118 × 1.036 = 1.158 3.5.10 Rotor resistance The rotor bars are assumed to be skewed through one slot pitch i.e. through 1.3885 cm Length of each bar; πΏπ = √(20.956)2 (1.3885)2 = 21.00 ππ Resistance of the rotor refereed to the main winding " πππ = 8ππ2 πΎ 2ππ [π πΏπ π ππ = 8(96) 2 π·π + π π2 π ] 2 (0.8)2 (0.04) 3.27 π 21.00 2 8.5 × 10−2 [ + ] 20 × 24 × 102 π 22 × 76.89 = 0.608Ω ππ‘ 75 π πΆ And ππ” = 0.017 0.021 × 0.336Ω = 0.0492 Ω at 20 0 πΆ 3.5.11 Reactances Slot leakage reactance 26 The specific performance for a slot is given by π π 2π ππ π = [π 2 π π+π1 ] 3.28 For the given case π1=0.26" π2=0.38” π = 0.533” π = 0 π = 0.04" π = 0.065" π1 /π2 = 0.684 From standard table [pf 390] π For π1 = 0.684 2 ∅ = 0.47 Therefore ππ π = [0.47 0.533 0.04 + ] 0.38 0.065 = 1.27 For rotor slot πΏ πΏ ππ π = [3π1 + π4 ] π 3.29 0 1 " Now; πΏ1 = 0.3" , πΏ4 = 0.042", ππ = 0.146", π0 = 1 ππ = (25.4) ππ π = [ 0.3 0.042 + 1 ] = 1.752 3 × 0.146 25.4 (π 2 +π 2 +π 2 ) 1 π πΆπ₯ = (π 1+π 2+π 3)2 × πΎ2 × 4ππ 1 2 3 3.30 π€π For π1 = 30 π2 = 54 , π3 = 68 πΎπ€π = 0.8 ππ = 28 πππ π = 2 Then πΆπ₯ = 302 +542 + 682 1 28 × × ≅ 2.0 (152)2 0.82 4 × 2 27 The slot leakage reactance in terms of the main winding; πΏ π πΆπ₯ = 16ππππ (ππ πΎπ€π )2 π (ππ π + ππ ππ π ) πΆπ₯ π π 3.31 π = 16 × π × 50 × 4π × 10−7 (96 × 0.8)2 × 20.956 × 10−2 28 × (1.27 + × 1.752) 2.0 28 20 ≈ 1.038Ω 3.5.11.1 Zigzag leakage reactanceπΏπ ; πΏ 16ππππ (ππ πΎπ€π )2 π ππ 3.32 π π ππ = 2 +π 2 ) ππ‘π (ππ‘π π‘π 3.33 2 12πΌπ π¦π π Where ππ‘π = 0.998 − 0.165 = 0.8329 ππ ππ‘π = 1.3885 − 0.1 = 1.2885π π¦π π = 0.998ππ π¦π π = 1.3885 πΌπ = 0.3ππ ππ = 0.8329 × 1.2885(0.88292 + 1.28852 ) 12 × 0.03 × (0.998)2 × (1.3885) = 5.07 ππ = 16 × π × 50 × 4π × 10−7 (96 × 0.8)2 × 20.956 × 10−2 28 = 0.15 28 3.511.2 Over hang reactance 1 π0 = 16ππππ (ππ πΎπ€π )2 6.4π π [π(π· + ππ π ) × ππ. ππππ π πππππ π πππ‘π ] π = 16 × π × 50 × 4π × 10−7 (96 × 0.8)2 × 3.34 1 × [π(0.0894 + 0.0146) × 8] 604 × 28 × 2 = 0.136 Ω 3.5.11.3 Magnetizing reactance ππ = 16ππππ (ππ πΎπ€π )2 10π πΏπΆπ 3.35 π πΎπ ππΉπ Assuming saturation factor πΉπ = 1.25 ππ = 16 × π × 50 × 4π × 10−7 (96 × 0.8)2 × 20.956 × 10−2 × 14.0 × 10−2 10 × 0.03 × 10−2 × 1.158 × 2 × 1.25 = 62.927 Ω 3.5.11.4 Skew Leakage Reactance The bars are skewed through one slot pitch Angle of skew, ππ = π 28 2 28 × 1 × 20 = 0.314πππππππ Skew leakage reactance π½π πΏππ = πΏπ πππ π²π 3.36 πΎπ = 0.95 πππ 62.92 × 0.13142 × 0.95 12 29 = 0.0895 Now the total leakage reactance πππ = ππ +ππ§ +ππ + ππ π 3.37 = 1.308 + 0.0895 + 0.15 + 0.136 = 1.06835 Ω π ππ‘ππ = 1 πππ 0.492 = = 0.2922 πππ 1.6835 3.5.11.5 Open circuit reactance π0π = ππ + πππ 2 = 62.927 + 1.6835 2 = 63.7687 Ω 3.38 Leakage factor = = π0π− πππ 3.39 π0π 62.927 − 1.6835 62.927 πΎπ = 0.973 πΎπ = √πΎπ = 0.986 3.6 Design of starting winding for resistance split phase The starting winding is designed for maximum torque per ampere of starting current. Therefore for purpose of calculating torque and current the rotor resistance is increased by 17.5% to take into account the skin effect The total resistance in terms of main winding 30 1 π π = ππ π + 1.75πππ ππ‘ 20π πΆ = 0.402 + 1.75 × 0.492 3.40 ππ‘ 20π πΆ = 1.263 Ω Total independence in terms of main winding at 200C 2 + π 2 = √1. 2632 + 1. 68352 ππ = √π π ππ 3.41 = 2.105 Ω Main winding locked Rotor current, πΌπ π π 240 πΌπ π = π = 2.105 = 114 3.42 π The starting current is not to exceed about 6 turns the full current i.e. 6 × 13.713 = 82.278 The starter current is hence taken as; 5 × 13.713 = 68.5654 πΌπ = 68.5654 πππ πΌπ 68.565 = = 0.601 πΌπ π 114 Auxiliary winding Reactanceππ = πππ 3.43 2 πΌ ( π ) −1 πΌπ π = 1.6835 0.6012 − 1 31 CHAPTER 4 RESULTS AND ANALYSIS 4.1 Results Table 4.1 Results DESIGN PARAMETER Rated Power Output, W Rated Voltage, V Rated Frequency, f Nearest Synchronous Speed, Ns Poles, P Speed in r.p.s , ns Wattsperrps ConCosPhi Main Diameter, D Length , L Standard Diameter, Ds Standard Length,Ls Standard Pole Pitch, Tps Length of Iron, Li Peripheral Velocity,V1 Width of Stator Slot, Wts Stator Tooth Density, Bts Number of Stator Slots, Ss Stator Flux Linkage, FM Stator Stamping Outer Diameter, Do Depth of Stator Core, dcs Depth of Stator Slots, dss Flux Density in the Stator Core, Bcs Winding Factor, Kwm Number of Turns in the Main Winding, Tm Turns in Series Per Pole, Tmp Power Factor, n Full Load Efficiency, ef Main Winding Current, I Current Density, Id Area of Main Winding Conductor, Am DESIGN VALUE 2238 240 50 3000 2 50 44.7600 W/r.p.s 27 8.894 cm 20.956cm 8.9 cm 20.929 cm 14.0 cm 18.836 cm 13.9857 0.362 cm 1.400 28 0.0135Wb 13.8100 cm 1.4550 cm 1 cm 0.0355 0.800 96 48 0.8500 0.800 13.7132 A 5 A/mm2 2.7426 mm2 32 Diameter of Bare Conductor, Dbc Length of Air Gap, Lg Rotor Outer Diameter, Dro Number of Rotor Slots,Nrs Rotor Inner Diameter, Dri Length of Chosen Rotor Stamping, Lrs Width of Chosen Rotor Stamping, Wrs Area of Rotor Slot, As Area with Allowance and Clearance Incorporated, Ar Total Copper Section for Main Winding, AM Current Density in End Ring, db Current Density in Rotor Bar, de Area of Each End Ring, Ae Length of bar, Lb Resistance of the Rotor Referred to the Main Winding, rrm Width of Stator Slot, Wos Slot Leakage Reactance, Xsr Stator Slot Pitch, Yss Zig Zag Leakage Reactance, Xz Magnetizing Reactance, Xm Skew leakage Reactance, Xsk Total Leakage Reactance, XTlm Open Circuit Reactance, Xom Gap Extension Coefficient, Kg 1.8683mm 0.3000 mm 8.9 cm 20 1.9 cm 0.3” 0.145” 24cm2 480 mm2 527 mm2 20 20 76.3636 mm2 21 cm 154.0094 0.362 cm 1.0814 0.9985cm 0.0031 62.927 0.0895 1.6835 63.7687 1.158 33 4.2 Result Analysis The design values obtained for the 2.2kw, 240V, 2900rpm, and 50Hz motor are within the desired values for the specified induction motor. The specified values for various motor parts ensure flow of the acceptable value of current within the rotor and stator windings. 34 CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 5.1 Conclusion This project applied the standard motor design procedures to determine the required design specifications for single phase induction motor for Numerical machine Complex. The objectives of the experiment were to come up with the proper design specifications for consideration of local fabrication of the small size single phase induction motor in Kenya. For the purpose of design, it was established that there exists standard dimensions for different motor parts especially as regard the stator and the rotor. Companies and governments seeking to set up fabrication industries will therefore have to consider the process of acquiring these standard existing parts for the purpose of fabricating the induction machine. In addition, the project presents a program that automatically generates the numerical approximations of the design specifications by accepting the input which are the desired machine output specifications and numerically generating the expected design values of the machine parts as output for the process of fabrication. The values generated from the program present an easier way of reducing the tedious numerical calculations and the chances of occurrence of the errors arising from numerical calculations. As captured in the workings, this project only provides solutions to the design phase of the Motor fabrication process. There exists a lot more to be done especially as entails assembling machines, acquisition of well -trained human labor and procurement of the required materials for fabrication of motor casing, coils, rotor and the stator. It is, however, a greater step in the right direction as it provides a basis of reference for the fabrication process. Whatever good or bad 35 that results thereof this stage of the fabrication process determines whether or not the final product is within the market expectation or demand. 5.2 Recommendation Industrialization remains a challenge to many developing countries. Lack of adequate finances, technical know-how and lack of government initiatives are but a few of challenges to the industrialization process. However, the greater good that comes with initiating the process is immense. From job creation, increase in revenue, to self-sustainability, industrialization is an investment worth making. Through this project, it is recommended that; 1. The Numerical Machine Complex initiates the process of designing and fabricating local made single phase induction motors 2. That the company invests in assembling the necessary machines for the fabrication process 3. The company should equally invest in training her personnel for the purpose of cementing a better understanding of the fabrication process, and to ensure high quality products. 36 REFERENCES [1] M. V.K, Principles of Electrical Machines, India: S. Chand, 2002. [2] T. a. Chand, A Text Book of Electrical Technology, India : S. Chand , 2005. [3] F. A. S. U. Charles K., Electric Machinery, New York: Mc Graw Hill, 2003. [4] J. B., Electrical and Electronic Principles and Technology, New York: Oxford , 2003. [5] A. R.K., Principles of Electrical Machine Design, India: S.K. karataria &Son, 2007. 37 APPENDIX Appendix Table 1 Standard Load Efficiency and Power Factor for Small Single Phase, 50 Hz Cage - Motors RATING (W) FULL LOAD EFFICIENCY POWER FACTOR P.U 40 0.38 0.45 100 0.50 0.55 200 0.60 0.60 400 0.68 0.65 750 0.72 0.67 1000 0.75 0.70 1500 0.77 0.76 2000 0.79 0.81 2500 O.82 O.87 38 Appendix Table 2: The Standard Approximate Values for Co.η.Cos for Different Values of Watts/R.P.S. Watts/r.p.s πΆπ. π. πΆππ 3.6 7.2 12 18 9.5 12 15.5 18 39 %SINGLE PAHSE INDUCTION MOTOR DESIGN SPECIFACTION DETERMINATION PROGRAM Es=2.2e3 % Motor output rating V=240 % Motor Rated voltage HP=3 % Rated Output in horse power W=HP*746 % Motor output in Watts f=50 % Frequency Ns=3000 % speed in revolution per minute P=((120*f)/Ns) % Motor Poles ns=(Ns/60) % speed in revolution per second Wattsperrps=W/ns %Using the value of Watts/r.p.s read the value of the ConCosPhi from the %Watts/r.p.s versus ConCosPhi graph ConCosPhi=46 %Input the value of ConCosPhi from the graph %MAIN DIMENSIONS d2l=((HP*0.746)/(ConCosPhi)) %Determination of the length and Width of the motor %L/TP=1.5;%Input the desirable value depending on the demand of the motor %being designed %(L*2/PiD)=1.5; LTP=1.5 LPD=1.5 %Zout=LPD pi=22/7 %Zout=((L*P)/(pi*D)) D=8.9 %D=((LPD*pi)/(L*P)) %LPD=((L*P)/(pi*D))%Get the value of D and L from line 19 and 22 %From the values of the D & L obtained, choose the appropraiate stamping %from the standard stamping table %Taking the appropriate main dimensions values of the Chosen stamping as Ds %and Ls, then L=(d2l/(D*D)) %Length of the Motor Ds= 0.089 %Diameter of the chosen stamping Ls=((D*D*L)/(D*D)) %corelength of the desired stamping Tps= (((22/7)*D)/P) %Pole pitch %Net Iron Length Li=0.9*Ls%0.9 is the desirable stacking factor %CHECK FOR PEERIPHERAL VELOCITY Vl=(22/7)*Ds*ns %The permissible value of the peripheral velocity should be less than 30m/s Wts= 0.00362 %Enter the value of the Stator teeth from the selected Stamping Bts=1.4 %Stator 1.7 wb/m^2 tooth flux density should be withtin the range odf 1.4 to % Let (Phi)m=Bts((Ss/p)*Li*Wts) flux linkage in the motor be equivalent to FM Ss=28 %Stator slots FM=Bts*(Ss/P)*Li*Wts Do=13.81 %Enter the value of the outer diameter for the selected stamping dss=1.455 %Enter the value of the depth of the stator slots %for the selected stamping 40 dcs=0.5*(Do-(D+(2*dss))) %Depth of the stator core %CHECK FOR FLUX DENSITY IN THE STATOR CORE Bcs Bcs=FM/(2*dcs*Li) %STATOR WINDING Kwm=0.8 Kwm; E=228 Tm=E/(4.44*Kwm*f*FM) Tmp=Tm/P %Define the desirable winding factor for main winding %Stator Induced Voltage %Number of turns in the main winding %Turns in series per per pole %CONDUCTOR SIZE %MAIN WINDING FULL CURRENT I n=0.85 %Full load eficiency ef=0.80 %Power factor I=((3*746)/(V*n* ef)) %Main Winding Full current Id=5 %Enter the value of current density in the line Id %Area of the main winding conductor Am=I/Id %Diameter of bare conductor Dbc= ((Am*4*7)/22)^0.5 %ROTOR DESIGN Lg=0.3 %Desirable Length of the air gap' L %Enter the diamter and the number of slots of the chosen rotor stamping %the slectd stamping has the following maesurements Dro=0.00084 %rotor outer diamter Nrs= 20 %Nrs- Number of Rotor slots %Rotor inner diameter Dri= 0.019 %ROTOR SLOTS %Area of the rotor slot %From the standard rotor sets. Choose sppropriate stamping Lrs=0.003 %Length of the chosen rotor stamping Wrs=0.00145 %Width of the chosen rotor stamping As=Lrs*Wrs%Product of the length of the rotor slot and the width of the rotor slot %Area with clarence and allowance for end corners incorporated Ab=24 Ar=Nrs*Ab %TOTAL STATOR COPPER SECTION FOR MAIN WINDING AM=2*Tm*Am 41 %END RING DESIGN %Area of each end ring ,Ae db=20 de=20 Ae=(Ar*7*db)/(22*P*de) %GAP EXTENSION COEFFICIENT Wos=0.000165; %Enter the value of the width of the stator slot opening %lg=O.OOO3;%Gap Length GP= Wos/Lg;%Gap ratio- this is the ratio of the %Slot openiningWo at the gap surface and the air gap length % This Ratio is used to determine the Carter's coefficient from the % standard tables yss=(pi*8.9)/Ss; %Stator Slot pitch, yss Kcs=0.64; %Carters' coefficient for semi-closed slots %Gap Extension factor Kg is given by Kgs=((yss)/(yss-(Kcs*Wos))); %ROTOR RESISTANCE Lb=21.00 %Length of the rotor bar rho=0.021 %Density of the material Rrm=8*Tm*Kwm*Kwm*rho*((Lb)/(Nrs*Ab))+((2*de)/(pi*P*P*Ae)) %Resistance of %the rotor as reffered to the main winding %REACTANCES a1=0.26 a2=0.38 b=0.0533 c=0 d=0.04 e=0.065 Ra1a2=a1/12 % Form the ratio of a1/a2 determined we estmate %the value of Phi used in determining the value of the %slot leakage reactance from the standard tables provided phi=0.47 Xss=((phi*(a2/b))+(d/e)+((2*c)/(e+a1)))%The specific Perfomance for %a slot L1=0.3 Ws=0.146 h4=0.042 Wo=1/25.4 Xsr=((L1/3*Ws)+(h4/Wo)) ysr=1.3885 Wtr=ysr-0.1 mhu=4*pi*10e-3 %ZIG ZAG REACTANCE LEAKAGE REACTANCE Xz=(Wts*Wtr*(Wtr*Wtr+Wtr*Wtr))/(12*Lg*yss*yss*ysr) Xzl=16*pi*f*mhu*(Tm*Kwm*Tm*Kwm)*(L/Ss)*Xz %OVERHANG REACTANCE cp=8 %Avrage coil span %Ss=28; 42 Xo=16*pi*f*mhu*(Tm*Kwm*Tm*Kwm)*((1/6.4)*Ss*P)*(pi*(D+dss)*cp) %MAGNETISING REACTANCE tao=14e-2 Fs=1.25 %saturation factor Kg=2*1.158 Xm=16*pi*f*mhu*(Tm*Kwm*Tm*Kwm)*((L*tao)/(10*Lg*Kg*P*Fs)) %SKEW LEAKAGE REACTANCE PhiS=0.134 %Rotor bar Skew Anglein radians k1=0.95 Xsk=Xm*((PhiS*PhiS)/12)*k1 %TOTAL LEAKAGE REACTANCE XTlm=Xm+Xo+Xzl+Xsr %OPEN CIRCUIT REACTANCE REFFERED TO MAIN WINDING Xom=Xm+(XTlm/2) 43