AC TRANSFORMER

Southern Luzon State University
College of Industrial Technology
September 2015
TABLE OF CONTENTS

I. Title Page
II. Table of Contents
III. Abstract
IV. Introduction
V. Statement of the Objective
VI. Records of Data, Sketch, Photos of Lab Project
VII. Result/Output of test
VIII. Conclusion
IX. Recommendation
X. References
XI Appendix

Abstract

A transformer is an electrical device that is used to change the voltage in alternating current (AC) electrical circuits. The ability of this device to change voltage is a major advantage of AC electricity over direct current (DC). A transformer needs an alternating current that will create a changing magnetic field. A changing magnetic field also induces a changing voltage in a coil. This is the basis of how a transformer works: The primary coil is connected to an AC supply.
Wrap two, equal-length bars of steel with a thin layer of electrically-insulating tape. Wrap several hundred turns of magnet wire around these two bars. You may make these windings with an equal or unequal number of turns, depending on whether or not you want the transformer to be able to “step” voltage up or down. I recommend equal turns to begin with, and then experiment later with coils of unequal turn count.
Join those bars together in a rectangle with two other, shorter, bars of steel. Use bolts to secure the bars together (it is recommended that you drill bolt holes through the bars before you wrap wire around them).
Check for shorted windings (ohmmeter reading between wire ends and steel bar) after you’re finished wrapping the windings. There should be no continuity (infinite resistance) between the winding and the steel bar. Check for continuity between winding ends to ensure that the wire isn’t broken open somewhere within the coil. If either resistance measurements indicate a problem, the winding must be re-made.
Power your transformer with the low-voltage output of the “power supply” described at the beginning of this chapter. Do not power your transformer directly from wall-socket voltage (120 volts), as your home-made windings really aren’t rated for any significant voltage!
Measure the output voltage (secondary winding) of your transformer with an AC voltmeter. Connect a load of some kind (light bulbs are good!) to the secondary winding and re-measure voltage. Note the degree of voltage “sag” at the secondary winding as load current is increased.
Loosen or remove the connecting bolts from one of the short bar pieces, thus increasing the reluctance (analogous to resistance) of the magnetic “circuit” coupling the two windings together. Note the effect on output voltage and voltage “sag” under load.
If you will make a transformer with unequal turn windings, try it in step-up versus step-down mode, powering different AC loads.

Introduction

A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Commonly, transformers are used to increase or decrease the voltages of alternating current in electric power applications.
A varying current in the transformer's primary winding creates a varying magnetic flux in the transformer core and a varying magnetic field impinging on the transformer's secondary winding. This varying magnetic field at the secondary winding induces a varying electromotive force (EMF) or voltage in the secondary winding. Making use of Faraday's Law in conjunction with high magnetic permeability core properties, transformers can thus be designed to efficiently change AC voltages from one voltage level to another within power networks.
Since the invention of the first constant potential transformer in 1885, transformers have become essential for the AC transmission, distribution, and utilization of electrical energy. A wide range of transformer designs is encountered in electronic and electric power applications. Transformers range in size from RF transformers less than a cubic centimeter in volume to units interconnecting the power grid weighing hundreds of tons.

Statement of the objective

This study is aimed to:
1. Describe how a transformer is constructed
2. What are some uses of transformers?
3. How a transformer works?

Records of Data, Sketch, and Photos of Lab Project

N1 = 276 Turns V1 =
N2 = 36 Turns V2 =

Figure: The AC Transformer

Result/Output of Test

Conclusions

In view of the fact that an attempt has been made to present all the major features involved, from a construction as well as a design viewpoint. We learned winding a transformers and how to use a AC transformer. We construct a transformer and how will it convert to rectifier and diode.

Recommendations

Use proper tools to construct a transformer. You must have a rectifier, fishpaper and all the device and equipment needed to build a transformer

.References Knowlton, A.E. (Ed.) (1949). Standard Handbook for Electrical Engineers (8th ed.). McGraw-Hill. p. 597, Fig. 6–42.

Appendix