Project Body:



1.1     Background of the study

A voltage regulator is an electrical device designs to automatically to maintain a constant voltage level. It may use an electro mechanical system, or passive and active electronic components depending on the design. It is use to regulate fluctuating AC or DC voltage from one level of voltage to another with exception of passive short regulators.

1.2     Objectives of the study

The aims and objectives of this project “automatic voltage regulator” is to provide protection to electronic/electrical appliances.

1.3     Scope of the study

This research work covers the entire aspect of voltage regulator contributing towards the prevention of recurring damage due to voltage fluctuation in order to maintain constant voltage supply to electrical electronics appliances. It is used to prevent electrical/electronic appliances from damage, if the voltage is below 170 vac the relay will not trigger to produce any output. This type of regulator used a continuous auto-transformer to maintain AC output that is close to the standard or normal main voltage as possible under condition of fluctuation.

1.4     Limitation of the study

A study of this nature would be influences by other limitations such as time constraint, financial factor and inadequate record keeping to enable the power examination of the research work. Most importantly, automatic voltage regulators are design for electrical/electronic appliance as such it is not an AVR used in by generating sets to give out steady power supply.

1.5     Definition of terms

A circuit provides an output which is proportional to the rate of the change of the input voltage and is obtained by interchanging the resistor and capacitor of the integrator circuit.


Resistor is component that is specifically designed to have a certain amount of resistance. The principle applications of resistor here are to limit current, to divide voltage and, in certain cases, to generate heat.


A capacitor stores electrical energy in the form of an electro static field. Capacitors are widely used to filter AC signal from a variety of circuits. A capacitor stored energy in form of capacitance measured in farad.


A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit.


A relay is an electronically operated switch, many relays use an electromagnet to operate a switching mechanism, but other operating principles are also used. A simple electromagnetic relay consist of a coil of wire surrounding a soft iron core, an iron yoke, which provide a low reluctance path for magnetic flux, a hinged to the yoke, and a set or sets of contacts; the armature is hinged to the yoke and mechanically linked to a moving contact (s).

The Transformer

The transformer changes the magnitude of an A-C voltage. It consist simply of two insulated coils P an S, called primary and secondary coils, wound round a soft-iron core (figure 2.9 the core is made of laminae or sheets of soft iron, insulated by varnish from each other.

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