ARDUINO BASED UNDERGROUND CABLE FAULT DETECTION Submitted by:

Contents Project overview Block diagram Power supply Arduino Duemalinove. Relay Relay driver LCD Software requirements Schematic & Working of the project Advantages Applications Future scope Conclusion

Project overview The project uses the simple concept of OHMs law where a low DC voltage is applied at the feeder end through a series resistor. The current would vary depending upon the length of fault of the cable in case there is a short circuit of LL or 3L or LG etc. The series resistor voltage drop changes accordingly which is then fed to analog input of programmed microcontroller would display the same in Kilo meters. The project is assembled with a set of resistors representing cable length in KMs and fault creation is made by a set of switches at every known KM to cross check the accuracy of the same.

Block diagram

Power supply

Contd.. The 230V AC supply is first stepped down to 12V AC using a step down transformer. This is then converted to DC using bridge rectifier. The AC ripples is filtered out by using a capacitor and given to the input pin of voltage regulator 7805. At output pin of this regulator we get a constant 5V DC which is used for MC and other ICs in this project.

ARDUINO The Arduino microcontroller is an easy to use yet powerful single board computer that has gained considerable traction in the hobby and professional market. The Arduino is open-source, which means hardware is reasonably priced and development software is free.

Image of development board

Features of Duemalinove The Duemalinove board features an Atmel ATmega328 microcontroller operating at 5 V with 2 Kb of RAM, 32 Kb of flash memory for storing programs and 1 Kb of EEPROM for storing parameters. The clock speed is 16 MHz, which translates to about executing about 300,000 lines of C source code per second

…..contd The Arduino programming language is a simplified version of C/C++. If you know C, programming the Arduino will be familiar. If you do not know C, no need to worry as only a few commands are needed to perform useful functions.

Relay A relay is an electrically operated switch. Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and have double throw (changeover) switch contacts as shown in the diagram.

Contd.. Relays allow one circuit to switch a second circuit which can be completely separate from the first. For example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit. There is no electrical connection inside the relay between the two circuits, the link is magnetic and mechanical. To drive relay through MC ULN2003 relay driver IC is used

Relay driver ULN2003 ULN is Relay driver application The ULN2003 is a monolithic high voltage and high current Darlington transistor arrays. It consists of seven NPN Darlington pairs that features high-voltage outputs with common-cathode clamp diode for switching inductive loads. The collector-current rating of a single Darlington pair is 500mA. The Darlington pairs may be paralleled for higher current capability.

Contd.. The ULN functions as an inverter. If the logic at input 1B is high then the output at its corresponding pin 1C will be low.

Liquid crystal display (lcd) Most common LCDs connected to the microcontrollers are 16x2 and 20x2 displays. This means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively. The standard is referred to as HD44780U, which refers to the controller chip which receives data from an external source (and communicates directly with the LCD.

Contd.. If an 8-bit data bus is used the LCD will require 11 data lines(3 control lines plus the 8 lines for the data bus) The three control lines are referred to as EN, RS, and RW EN=Enable (used to tell the LCD that you are sending it data) RS=Register Select. When RS=0; data is treated as a command & When RS=1; data being sent is text data. R/W=Read/Write . When RW=0; the data written to the LCD & When RW=0; the data reading to the LCD.

Software requirements Arduino software which can be freely available on Arduino Forum http://arduino.cc/en/Guide/HomePage.

Working of project The project uses a set of resistances in series i.e. R10,R11,R12,R13 and R17,R16,R14,R21, R20,R19,R18,R25,R22 as shown in the circuit diagram, one set for each phase. Each series resistors represents the resistance of the underground cable for a specific distance thus 4 such resistances in series represent 1-4kms. 3 relays are used to common point of their contacts are grounded while the NO points are connected to the input of the R17, R21 & R25 being the 3 phase cable input. R10 is fed with a series resistor R1 to 5v supply. The common point of R10 & R1 is given to input pin 0 of arduino duely wired as explained above.