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.
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.
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.