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investigation on how to rewind a three-phase induction motor that will improve efficiency to reduce energy consumption

investigation on how to rewind a three-phase induction motor that will improve efficiency to reduce energy consumption

investigation on how to rewind a three-phase induction motor that will improve efficiency to reduce energy consumption

CHAPTER ONE

Introduction

A squirrel cage induction motor was designed according to IEC standard with related output three phase 2.2kW, 4poles, 1420rpm rated speed and rated voltage 415v, 50Hz fail to operate properly due to supply voltage hardly rise above 380v. Using the multimeter to check the continuity of the motor winding from phase to phase and one of the fail continuity test, so the motor got burnt out from sustained thermal overload.

In this case proper refurbishment work must be done to make the motor healthier, machine calculation and workshop testing of the machine after the refurbishment work.


CLASSIFICATION OF ELECTRIC MOTOR


Electric Motor

An electric motor Is divivded into A.C  and D.C motors in electric motor energy is converted from one form to another.


Principle of electric motors

If a current carrying conductor is placed perpendicular to the magnetic field it experiences a force.

A.C MOTOR

A.C motor is an alternating current motor. In A.C motor electrical energy is converted to mechanical energy. And is divided into three part.

Synchronous motor.

Induction motor .

Linear motor.

Induction Motor

Induction motor are classified into three phase and single phase .

It is also known as asynchronous motor, because it operate at speed less than it synchronous speed.

It is the most common used A.C eleectric motor i.e 90% of industrial motor are induction type and also common for residential/domestic application.

Synchronous speed

This is the speed of rotation of the magnetic field in rotary machine and it depends upon the frequency and number of poles of the machine.

Working principle of induction motor

When supply is given to the stator windings a magnetic flux is produced in the stator due to the flow of current in the coil.

Three phase induction motor

The 3 phase  phase  induction motor it is the must widely usde motor for different kind of industrial drive.


Advantages of 3 phase induction motor

Easy to build and id cheaper than D.C or synchronous motors.

Induction motor is robust 

Maintenance is easy and cost low. 

Stable operation under load

Range in size from watt to megawatt 

Disadvantage of 3 phase induction motor

it has low starting torque

draw large starting current

operate with a poor lagging power factor when lightly 

3 phase induction motor formulae

Synchronous speed= 120f/p

Rotor speed = (1-S)Ns

Slip speed = Ns-Nr

%Slip =( Ns-Nr/Ns)100

Frequency of the rotor = Sf

Torque = kE2I2Cosβ2

Rotor efficiency = N/Ns


Part of 3 phase squirrel cage induction motor

Stator

The first part is stator it is the static part of motor and the outer part of it is called a frame. A frame of induction motor is generally made up of cast iron, it means molten iron is made to cold down in a mold to form this type of shape.

                                                                    

Figure 1: Stator         Figure2: Frame

Stator core

The frame hold stator core made up of silicon steel to form the magnetic circuit of the stator

core, consist of slot on a inner periphery. However, this core look solid but it is formed by 

many layers, each layers is called a lamination, having thickness less than 0.5mm, complete

core is called laminated core. The core is laminated to reduce eddy current losses.

                        

Figure 3: stator core Figure4: Lamination Stator core

Stator winding

The stator consist of three winding, one for red, one for yellow, and one for red phase. All ends of the winding are brought together to the terminal box, so that they can be energize through external supply. The work of this winding is to produce rotating magnetic field.

  Figure5: stator winding

Rotor 

This is the rotating part of the motor and it develops mechanical power. There are two types of  rotor squirrel cage rotor and phase wound rotor.


Squirrel cage rotor

It is made from thin lamination, slot are made on the outer periphery of the lamination while the shaft hold in the middle. 



                             Figure6: Squirrel cage rotor


Rotor winding squirrel cage rotor

The winding is made from thin conductor bar which is of copper or aluminum and the both ends of the conductors are short circuited through circular rings, due to which the current generated in the winding remain circulated inside the circuit.



                           Figure8: Rotor winding squirrel cage rotor



Terminal box

This is where the end of the three windings are connected to the three phases supply at the terminal.


                       Figure 9: Terminal box



Covers  and bearings

The covers hold the shaft on both side of the rotor, so that the rotor can rotate in the middle of the stator core. Both the two ending consist of high grade steel bearing so that the rotor get almost zero mechanical friction when rotating.


                                     

Figure 10: Cover         Figure 11: Bearing




Fan and Cover

the fan helps the motor remain cool during working time and the blade are designed in such a way that they pull air from axial direction and throw it out in the radial direction.


             

Figure12: Fan Figure13: Fan Cover


connection of three phase induction motor

three phase induction motor can be connect in star connection as well as delta connection if there is six winding ends; R1,R2,Y1,Y2,B1,B2.


Delta connection

Connect U1 and W2 this fort line 1 

connect U2 and V1 this form  line 2

connect V2 and W1 this form  line 3



star connection

connect W2 with U2 and V2 this forms neutral connection.

Connect U1,V1, and W1 to their respective lines this forms three different lines.

If you want to your induction motor to start on star winding and run on delta then you may use star delta starter.



PROBLEM STATEMENT

A 2.2-kW, 3-phase, 50Hz squirrel-cage induction motor originally designed for 380 V (A.C.) application got burnt out from over voltage condition. Because local supply voltage is higher than the machine rated voltage. 

OBJECTIVES

The objectives of this research is 

To investigate how to rewind a three-phase induction motor that will improve efficiency to reduce energy consumption.

The provision of information of good practice guides for local electrical technicians.

To adopt winding parameters relative to 380V (A.C)

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.

The  lowest  cost  method  of  reducing  the  starting 

current for standard induction motors consists in applying 

the line  voltage to only a part of the  winding at first, and 

connecting  the  rest  of  the  winding  with  a  time  delay. 

Usually the three phase winding of the  motor is designed 

with two or more parallel circuits, either parallel paths or 

parallel  conductors,  for  each  phase.  The  voltage  is 

applied initially only to one part of the winding, the entire 

winding  being  energized few  seconds  later as  the motor 

started and attained the rated speed.


LIMITATION OF STUDY

Three phase 2.2kw, rated speed 1500rpm and related voltage 380v squirrel cage induction motor.

Based on traditional motor rewinding method.

Realization of 380v single layer lap types three phase stator winding.



















CHAPTER TWO

Literature review

Review of previous research

Single and three phase IMs represent 80% of electric motors (Yoon, Jeon&Kauh, 2002) and use up more than 54% of the world electric energy and more than 60% of the total U.S. electric energy (Yoon et al, 2002), (Fei, Fuchs & Huang, 1989). In addition, 60% of the electric power used in industry is consumed by three phase IMs (Kioskeridis&Margaris,1996). This large consumption is due to the large amount of reactive power required by IMs, hence high apparent power is drawn from the system and also due to the reduction in IMs efficiency and power factor (Razali, Abdalla, Ghoni&Venkataseshaiah, 2012), especially when they operate at light loads. Moreover, the wide spread use of re-wound IMs causes a large decrease in efficiency. Some winders use coils that have a number of turns or conductor cross-sectional area that is less than or greater than the origin ones (Prakash, Baskar, Sivakumar& Krishna, 2008). These winding deviations may lead to a decrease in motor impedance, which causes an increase in motor temperature. Improving the efficiency of three phase IMs, which is one of the objective of this research, plays a significant role in decreasing energy consumption. Different methods have been used for efficiency optimization. The simplest strategy to optimize three phase IM efficiency is to run and maintain the motor in star mode which results in reduction of input power. This simple method is not appropriate for high loads because when the motor runs at high loads with star connection, the motor current increases and the efficiency and power factor decrease (Ferreira &de Almeida, 2006). The magnetic material plays a big role in the efficiency enhancement of three phase IMs. using copper or premium steel rotor cage as an alternative to aluminum and standard steel cage results in improving three phase IMs performance. Also, this substitution lessens the stator coils temperature. (Parasiliti, Villani, Paris, Walti, Songini, Novello& Rossi, 2004). Consequently, less cooling effort will be needed. Internal and external methods are explained in (Yoon et al, 2002), where in the internal method; cooling air passes the air gap between the rotor and stator while passing over frame in the external method. This paper concludes that the effect of using the internal method is better compared to the external method in terms of reducing motor temperature, hence higher efficiency is obtained. The authors (Faiz&Sharifian, 1995) use a method called “Hooke-Jeeves” which is a computer program that finds an appropriate value of motor parameters such as outer and inner stator diameter, slot depth and stack length by adding small incremental changes to motor parameters. A comparison between initial and optimal parameters is explained in ( Faiz et al, 1995 ) where optimal parameters are better than the initial parameters in terms of efficiency and power factor optimization. Several control methods of three phase IMs have been applied to control motor speed. The scalar control or (v/f control) method that includes open and closed loop control is used in different research papers for the purpose of efficiency improvement (Famouri&Cathey, 1989).


Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative

Based on the applied techniques these 

methods  can be classified into two groups: 

traditional and alternative.

Traditional techniques generally last long, 

figure 7. To start the next phase one must wait 

for the end of the previous, which can take 

several hours. Traditional techniques require 

higher operating temperatures and thus higher 

insulation class rating. Higher operating 

temperatures also increases pressure on the 

mechanical components (such as bearings) 

shortening their lifetime [18]. The alternative






















CHAPTER THREE

Methodology

This chapter will cover the details explanation of methodology that will be used to make this research project complete and the method is use to achieve the objectives of the research project.

Data collection

They are two main source of data collection which are primary and secondary but for the purpose of this research work secondary data collection is use to gather data.

The secondary source of data collection comprise written literature studies, textbooks, journals and research papers gathered from libraries and internet. Within the data collection period I will find the study about rewinding three phase induction motor in the Internet and do some research about the project related and I will find out the component and other materials and some of equipment to be used.  


Motor measurement details

First principle approach to cage motor stator refurbishment often involves measurement of the stator axial length and bore diameter, together with the slot, tooth and core dimensions. Essential measurements are also normally taken on the rotor. Of course, these measurements usually precede the actual machine calculations.

Machine calculations

The calculations leading to the choice of the number of poles, number of coils per phase per pole, number of phase groups, number of turns-in-series per phase, amongst other quantities, necessary for the realization of a 380 V(a.c.) double-layer lap-type 3-phase stator winding with a diamond overhang will be carried out.

Refurbishment work proper

Rewinding of stator

Preparation of Slots

Coil Production

Coil Insertion into Slots & Arrangement

Coil Lead Connections/Pre-Impregnation Tests

Impregnation and Drying of Winding

Machine Assembly Processes


Workshop testing of motor



Pre-Commissioning Tests/Checks

S/N 

   ACTION 

            RESULT 

  STANDARD 

   REMARK 









Winding Insulation 

Resistance Measurement @ 300C for 1 minute, with test voltage of 500V(d.c.). 


i)Phase-to-Phase: 

U1–V1= 

V1–W1= 

W1–U1= 

ii)Phase-to-Frame: 

U1–Frame = 

V1–Frame =  

1 min. value @ 400C not 

less than (kV+1) MΩ                   or  

not less than 1.96(kV+1) MΩ @ 300C [Enyong, 2004]. 



Continuity Check  

U1 – U2 = 

V1 – V2 = 

W1 – W2 = 

Continuous Circuit. 


      . 




U1– V1&V2 = 

U1– W1&W2 =


Open-circuit. 




















Test-Running (or Commissioning)/Checks;

S/N 

ACTION 

RESULTS OBSERVED 

REMARKS 


1) 

330(a.c.) applied through ammeters to machine without load. This was the supply voltage level at the time.

i)   Starting Current:      





ii)  Running Current:    






iii) Running Speed:          



2) 

Watching out for unusual sound or vibration  






















 3) 

Checking for signs of overheating or burning  













Proposed contribution 

Voltage relay protection to protect supply system.

Vibration sensor to protect against bearing failure.

Check the temperature of the motor regularly and ensure the body of the motor is free from dust.







Reference

S. Sharma, B. Gaur and D. Punetha, "Optimization technique to mitigate the losses in single phase induction motor," 2016 International Conference on Advances in Computing, Communication, & Automation (ICACCA) (Spring), Dehradun, 2016, pp. 1-4. 

D. J. Rhees, "Electricity-" The greatest of all doctors": An introduction to" High frequency oscillators for electro-therapeutic and other purposes"," ProcIEEE,vol. 87, pp. 1277-1281, 1999. 

I. Takahashi, T. Koganezawa, G. Su and K. Ohyama, "A super high speed PM motor drive system by a quasi-current source inverter," in IEEE Transactions on Industry Applications, vol. 30, no. 3, pp. 683-690,May/Jun 1994. 

M. B. U. Bakshi, Transformers & Induction Machines. Technical Publications, 2009. 

J. Larabee, B. Pellegrino and B. Flick, "Induction motor starting methods and issues," Record of Conference Papers Industry Applications Society 52nd Annual Petroleum and Chemical Industry Conference, 2005, pp. 217-222. 

B. Theraja, A. Theraja, U. Patel, S. Uppal, J. Panchal, B. Oza, V. Thakar, M. Patel and R. Patel, "A Textbook of Electrical Technology Vol II," S.Chand Publishers, 2005. 

U. Bakshi and V. Bakshi, Electrical Circuits and Machines. Technical Publications, 2009. 

Mittle& Mittal, Basic ElecEngg, 2E. Tata McGraw-Hill Education, 2005. 

U. Bakshi and V. Bakshi, Electrical Machines - II. Technical Publications, 2009. 

M. Yoon, C. Jeon and S. K. Kauh, "Efficiency increase of an induction motor by improving cooling performance," IEEE Trans. Energy Convers., vol. 17, pp. 1-6, 2002. 

A. Sharma, R. Gupta and L. Srivastava, "Implementation of neural network in energy saving of induction motor drives with indirect vector control," Journal of Theoretical and Applied Information Technology, vol. 5, pp. 774-779, 2008. 

R. Fei, E. Fuchs and H. Huang, "Comparison of two optimization techniques as applied to three-phase induction motor design," IEEE Trans. Energy Convers., vol. 4, pp. 651-660, 1989. 

I. Kioskeridis and N. Margaris, "Loss minimization in induction motor adjustable-speed drives," IEEE Trans. Ind. Electron., vol. 43, pp. 226-231, 1996. 

R. Razali, A. N. Abdalla, R. Ghoni and C. Venkataseshaiah, "Improving squirrel cage induction motor efficiency: Technical review," International Journal of Physical Sciences,vol. 7, pp. 1129-1140, 2012. 

 V. Prakash, S. Baskar, S. Sivakumar and K. S. Krishna, "A novel efficiency improvement measure in three-phase induction motors, its conservation potential and economic analysis," Energy for Sustainable Development,vol. 12, pp. 78-87, 2008. 

F. J. Ferreira and A. T. de Almeida, "Method for in-field evaluation of the stator winding connection of three-phase induction motors to maximize efficiency and power factor," IEEE Trans. Energy Convers., vol. 21, pp. 370-379, 2006.

 F. Parasiliti, M. Villani, C. Paris, O. Walti, G. Songini, A. Novello and T. Rossi, "Three-phase induction motor efficiency improvements with die-cast copper rotor cage and premium steel," in Proceedings of SPEEDAM’04 Symposium, 2004.

 J. Faiz and M. Sharifian, "Optimum design of a three phase squirrel-cage induction motor based on efficiency maximization," Comput. Electr. Eng., vol. 21, pp. 367-373, 1995. 

P. Famouri and J. J. Cathey, "Loss minimization control of an induction motor drive," in Industry Applications Society Annual Meeting, 1989., Conference Record of the 1989 IEEE, 1989, pp. 226-231. 

P.M Enyong, C.A Anyaeji and F.I Izuagie, “Refurbishment of a Three-Phase Induction Motor Reflecting Local Voltage Condition,” Journal of Electrical and Eletronics Engineering, volume 8, pp 64-69, 2013.


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