DESIGN AND CONSTRUCTION OF AN ARC WELDING MACHINE

ABSTRACT

The machine is designed to serve with an output of 250A. it has two pats which are the primary and secondary parts. The primary part, through which voltage is supplied to the machine has 180 turns which is made of 2mm2 S.W.G 14 copper coil. The secondary part has 45 turns made of 4mm2 S.W.G 8 copper coil.
Both turns are wound on separate limb of the laminated core. The voltage from primary turns flows to the secondary turn by induction.
The machine contain a power switch through which the machine can be switched on or off when connected to the power source. The indication light simply shows when the machine is on or off which is equally controlled by the power switch.
The fan connected to the machine helps in the looking of the temperature of the machine, it gets started once the machine is on.
The welding current is adjusted by varying the spacing between the primary and secondary windings when the cranks is rotated, clockwise the insulating block between the two winding moves down, the magnetic flux leakage and the inductive impedance are increased, thereby reducing the welding current in the secondary windings. Also as the insulating block is moved upward, away between the two turns, the magnetic flux leakage and the inductive impedance are brought down, causing the welding current to rise.

CHAPTER ONE

INTRODUCTION
The Arc welding machine is the type that uses an electric power as an input, which is being supplied through the primary and then transferred to the secondary winding by induction which can the be used to carry out welding work by connecting to the output terminal the welding cables.
The output of the machine is designed in a way that it can be varied by adjusting the crank of the machines in clockwise or anti-clockwise direction in either to increase or decrease the output current respectively depending on the size of the material it is to be used on.

OBJECTIVES OF THE STUDY
This group agreed in bringing ideals together as one body to construct a functional 250Amp Arc welding machine, which will be fir in both industrial and agricultural field.
The machine takes an input ranging from 220volt to 230volts which will be induced to the secondary windings then giving out it’s output towards the output terminals of the secondary windings.
Due to the variation on the size of the metallic materials, the machine the machine is designed in such a way that it’s output current can be varied in other to suit the material it works one.

SCOPE/LIMITATIONS OF THE STUDY
The machine is designed to be supplied with an input ranging from 220volts to 240volts. It is a single phase machine which gives it’s output through the output terminal of it’s secondary windings. The machine with it’s maximum output as 250Amps can be re-adjusted to a lower value when such output is considered too high.
He machine is equally designed to work with electrodes with their gauge ranging from 8,10 and 12 depending on the nature of the material and in all cases, it is expected to serve continuously for about 48hours provided the required input voltage is being supplied to it.

DEFINITION OF TERMS
Listed below are the definition of some of the term used in this project:
Coil: This is a copper conductor used to form the primary and secondary windings from which current enters and leaves out of the transformer.
Insulator: This can be defined as those materials that do not allow the passage of electric current through them. They are used to insulate the windings from each other as well as the laminated core.
Windings: This is the copper wire used as the coil, which is then wound on the limb of the laminated core from which current enters and leaves the circuit.
Flux: This can be defined as the magnetic effect experienced in the circuit due to the flow of current in the windings.
Laminated core: This is the core lamination which is inform of strips joined in such a way that the joints in the alternate layers are staggered in such a way as to avoid the presence of narrow gaps right through the cross-section of the core. It is constructed with transformer sheet steel lamination assembled to provide a continuous magnetic path. It consists of the joke and the limb which are equally laminated to reduce the lost due to eddy current.
Limb: This can be defined as the vertical parts of the lamination core on which the primary and secondary windings are wound separately on the different limbs of the laminated core
Yoke: This is the outer horizontal parts of the lamination core, which help in the reduction of eddy current losses, as well as provide mechanical support to the windings. It also carries the magnetic flux produced by the poles.

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