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• Topic: Embedded system, Relay, Power supply
• Pages : 40 (10324 words )
• Published : May 12, 2013

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1.INTRODUCTION

1.1 Overview
The proposed project an embedded system based project which will closely monitor and control the power imbalance, this system gives the constant supply of voltage to the load for the distribution system to show this we design the circuit where we show that how we make the constant voltage by changing the voltage using tap changer, we use instruments for making the constant voltage is micro controller.
The equipment used for this project are two transformers, one for power supply and another for tap changing, LCD is used for displaying the value, dc motor is used as load, MC is used for controlling voltage, relays are used for two tapings, variable resister, potentiometer, crystal oscillator,555timeretc. are used.

1555 TIMERS
MOTOR
MICROCONTROLLER (8051)
VOLTAGE REGULATOR
CAPACITOR
BRIDGE RECTIFIER
TRANSFORMER
AC SUPPLY
LCD DISPLAY
LM35
COMPARATOR
CT
.2 Block Diagram

Figure1.1:-Block diagram of On Load Tap Changer.

1.3 Circuit Diagram

Figure 1.2:-Circuit diagram of on load tap changer.
1.4 Steps of Working
Step 1:- 1A transformer is used for power supply.
Step 2:- Bridge rectifier is used for converting analog to digital signal. Step 3:-A transistor is used to regulate the voltage.
Step 4:-A capacitor is used for providing pure dc.
Step 5:- After that the power will supply to each component of the system. Step 6:- Another 500A transformer is used for changing the taps. Step 7:- Two relays are used for two tapings.
Step 8:- In first tapping the voltage is more than 10v but for tapping two the voltage less than 10v can be use but not more than 15v. Step 9:- The changing voltage is shown in the LCD screen.
Step 10:- There is a temperature is used to sense the temperature and that ac voltage which is converted to dc by using ADC. Step 11:- A MC controller is used and resisters are used for giving the constant voltage. Step 12:- The LCD displays shows the avg. value for both the taps which is taken as constant voltage for the system.

1.5 Description of the Circuit
Input supply of 230V is given to the transformer. The supply voltage is step-down to 5V by the step-down transformer because 5V is the voltage limit of the used equipment. Now the 5V passes through the bridge rectifier to get DC which is pulsating one. To get the pure DC the voltage passes through the capacitor. Another bypass capacitor is also used in conversion of pulsating DC to Pure DC. The pure DC is given to 7805 voltage regulator, which act as a main supply of the equipment. A LED is use for the indication of flow of current.

From the voltage regulator the voltage goes to different part. The voltage goes to the dc motor, IC and other equipment. The tap changer is to change the tap by using the 500A transformer here also a rectifier is used to convert ac to dc and a capacitor is used to get the pure dc a variable resister is used for giving the intensity of the signal.

A temperature sensor is used which sense the temperature in the form of ac voltage signal and that is converted into dc signal by using ADC. Then the signals goes to the micro controller to control the signal and that controlled signal shown in LCD screen for both the tapping there is a common value is shown that is 12.6 which so taken as constant value for the system.

Here we see that when the voltage fluctuation occurs in the transmission system how we make the voltage constant in the distribution system using controlling circuits.

2.INTRODUCTION TO EMBEDDED SYSTEM

2.1 Introduction
An embedded system can be defined as a computing device that does a specific focused job. Appliances such as the air-conditioner, VCD player, DVD player, printer, fax machine, mobile phone etc. are examples of embedded systems. Each of these appliances will have a processor and special hardware to meet the specific requirement of the application along with the...