Design And Construction Of A 2.2Kva Three Phase Induction Motor

ABSTRACT

Three phase induction motors are employed in almost all the industries because of its simple construction and easy operation. Efficiency of the induction motor is affected by its fixed losses and variable losses which mainly depend on the input supply voltage and load current respectively. An attempt is made to minimize the iron losses by using the permanent magnet ferrite. A new Three Phase Induction Motor Using Written Pole Technology is proposed in this paper whose stator consists of two three phase windings accommodated in the same core and rotor is used as squirrel cage rotor with ferrite material on its periphery.

Shaft loads are categorized as low, medium and high, Stator windings are energized through a controller based on the load demand. When compared to conventional induction motor, the motor efficiency and power factor are improved. Another approach of this machine is that the ferrite layer on the rotor periphery will reduce the motor losses which results in improving the motor efficiency. In this motor, one windings (main winding) is designed for the 220volt ac voltage.

TABLE OF CONTENTS

 TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

DEFINITION OF TERMS

TABLE OF CONTENT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• AIM OF THE PROJECT
• SIGNIFICANCE OF THE PROJECT
• LIMITATION OF THE PROJECT
• APPLICATION OF THE PROJECT

CHAPTER TWO

LITERATURE REVIEW

2.0      LITERATURE REVIEW

2.1      HISTORICAL BACKGROUND OF THE STUDY

2.2     PRINCIPLE OF OPERATION

2.3     TYPES OF THREE PHASE INDUCTION MOTOR

2.4      DIFFERENCE BETWEEN SLIP RING AND SQUIRREL CAGE INDUCTION MOTOR

2.4       REFERENCES

CHAPTER THREE

DESIGN METHODOLOGY

3.0      METHODOLOGY

3.1      CONSTRUCTIONAL DETAILS

3.2      DESIGN CONSIDERATIONS

3.3      DESIGN DESCRIPTION OF THE PROPOSED THREE PHASE INDUCTION MOTOR

3.4      DESIGN OUTPUT EQUATION

3.5      CHOICE OF SPECIFIC LOADINGS

3.6      POWER FACTOR AND EFFICIENCY

CHAPTER FOUR

4.0       TEST AND RESULT ANALYSIS

4.1        CONSTRUCTION PROCEDURE AND TESTING ANALYSIS

           4.2          ASSEMBLING OF SECTIONS

4.3         TESTING OF THREE PHASE INDUCTION MOTOR
4.4          TROUBLESHOOTING TECHNIQUES FOR AC INDUCTION MOTORS

4.5         BASIC DIAGNOSTIC TOOLS

4.6         MOTOR SELECTION AND MAINTENANCE

CHAPTER FIVE

• SUMMARY, CONCLUSION AND REFERENCES
• CONCLUSION
• RECOMMENDATION
• REFERENCES

 CHAPTER ONE

1.0                                                        INTRODUCTION

A 3 phase induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor can therefore be made without electrical connections to the rotor. An induction motor’s rotor can be either wound type or squirrel-cage type.

Three-phase squirrel-cage induction motors are widely used in industrial drives because they are rugged, reliable and economical. Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans. Although traditionally used in fixed-speed service, induction motors are increasingly being used with variable-frequency drives (VFDs) in variable-speed service. VFDs offer especially important energy savings opportunities for existing and prospective induction motors in variable-torque centrifugal fan, pump and compressor load applications. Squirrel cage induction motors are very widely used in both fixed-speed and variable-frequency drive (VFD) applications.

1.1                                         BACKGROUND OF THE PROJECT

Induction motors are employed in Textile mills, Agriculture and almost all the manufacturing industries to drive the loads because of its rugged in construction and ease of operation. The major limitation of induction motor is its efficiency and power factor. These two parameters depend on the shaft load. In conventional induction motor, only mechanical output is available and  hence, its power factor and efficiency is limited. Written pole induction motor with dual stator winding would be the better choice to overcome  these limitations. Written Pole Motors offer a revolutionary method for powering large horsepower applications in locations where only single-phase power is available. The Written-Pole motor is a hybrid concept, which utilizes basic concepts from induction, hysteresis and permanent magnet motors, with several important distinctions.  The primary feature which differentiates Written-Pole  motors from more conventional designs is a continuous layer of ferrite magnets on the surface of the rotor, along with a high-density exciter winding contained within the stator winding. This unique design matches the pole structure of the rotor to the rotational speed of the motor.The result is a motor that combines the desirable starting characteristics of a high-slip, high-power factor cage motor with the energy-efficient operation of an AC permanent magnet motor– without relying on power electronics, reduced voltage starters or phase converters.

Dual stator induction motor became popular since 1930. When a three phase supply is applied to one of the stator windings, a revolving magnetic field of constant magnitude is developed in the air gap and this field is shared by both the windings. The various possibilities in the design modification, speed control, efficiency, power factor improvement of induction motor and double winding induction motors are discussed below. Dual stator induction motor stator with two separate windings wound for a dissimilar number of poles is fed from an independent variable-frequency variable-voltage inverter.

This drive offers advantages as speed sensor less operation, Zero speed operation is achieved  by independently controlling the two sets of stator current and hence, maintaining a minimum electrical frequency independent of mechanical speed. This drive is suited for either constant volts per hertz or filed oriented operation. Circulating harmonics currents are eliminated by the dissimilar number of poles. Three-phase induction motors are designed to meet high starting torque, good operating efficiency and power factor. Optimization design of three-phase induction motor is formulated as a nonlinear multivariable programming problem to meet the above requirements. The simulated annealing algorithm was used to obtain an optimum design. Any significant improvement in the operating efficiency of induction motor will be effort at energy conservation. The optimized design of induction motor can be obtained  using Rosenbrock’s method  to minimize the cost of active materials, the annual energy consumed and the total annual cost. The stator of a double winding induction motor can be connected in star and delta, thereby active resistance  by 11% and  inductance by 13% can be reduced. The active resistance decreases to considerable value and hence copper losses are decreased. DWIM has increase of output power and torque of 10% and starting torque reduced by 3.5% [6]. A 3.7 kW three phase induction motors are widely used in agriculture and industries. During rewinding process, efficiency get reduced by five percentage points due to improper rewinding process in which the winding conductor size is reduced by 1 SWG or by reducing number of turns from the winding specification. This improper rewinding practice results in reduction of torque per ampere and increase in winding temperature for the given load. Efficiency of the induction motor can be optimized even at lightly loaded condition by means of TRIAC fed drive. Input voltage is adjusted based on the optimal- efficiency and power factor. More than 10% efficiency improvement is possible even at one fourth of the full load. Dual stator induction motor suggested for energy conservation consists of two sets of RUN windings. The main RUN winding is energized to have sufficient MMF in order to produce sufficient magnetic flux and to operate the motor at light loads with good power factor. In this machine reduced power is applied to the second set of RUN winding and hence, the  power consumed due to eddy currents, copper losses and poor power factor are considerably reduced. The efficiency of an induction motors 2.2 kW can be improved by means of die cast copper instead of aluminium cage rotor with premium steel core. In multi flux level of a three-phase squirrel-cage induction motor, the efficiency and power factor can be both maximized as a function of  load. The stator winding with two sets of turns, shares the same positions in the stator slots. Among all the possible stator winding connections, six modes were selected and analyzed. Efficiency of an induction motor can be improved by cutting the predefined arc-section of the rotor. Air gap over a periphery will not be uniform and causes edge effect. The redesign is focused on construction of the rotor with novel windings configurations. Optimal values of induction motor design parameters can be determined using Particle Swarm based approach to three-phase Induction Motor based on particle-swarm-optimization (PSO) technique. This method shows improvement in efficiency, active material cost, and performance under starting and full load conditions. Dual stator induction motor can be operated in power balancing mode and maximum efficiency mode for effective utilization of the machine. Second set of stator winding can feed electrical loads, thereby power factor and efficiency is improved.

1.2                                             OBJECTIVE OF THE PROJECT

An electric motor is used for the conversion of electrical energy into mechanical energy. This conversion of electrical power to mechanical energy takes place in the rotating part of the motor. A D.C. Motor is called as Conduction motor, but an A.C. Motor is called as Induction Motor. The aim of the work is to design an induction motion that is rated 2.2kva.

1.3                                              PURPOSE OF THE PROJECT

The main purpose of designing an induction motor is to obtain the complete physical dimensions of all the parts of the machine.

1.4                                         SIGNIFICANCE OF THE PROJECT

1. It has a simple design, low initial cost, rugged construction almost unbreakable
2. The operation is very simple with almost very less maintenance as there are no brushes.
3. The efficiency of these motors is very high, as there are no frictional losses, with reasonably good power factor.
4. The control gear for the starting purpose of these motors is minimum and thus simple and reliable operation.

1.5                                           LIMITATION OF THE PROJECT

1. The speed control of these motors is not easy without some loss in efficiency.
2. As the load on the motor increases, the speed decreases.
3. The starting torque is inferior when compared to D.C. Motors.

1.6                                          APPLICATION OF THE PROJECT

The AC induction motor is used more than any other means to power industrial equipment. Because there are so many applications, it is impossible to develop a list or guide for all the applications of AC induction motors. But the fewer application are as below:

1. Water supply
2. Pumps
3. Chemical pumps
4. Cooling towers
5. Compressors
6. Blowers and fans
7. Drilling machines
8. Grinders
9. Mixing machines, etc