TRANSMISSION LINE MULTIPLE FAULT DETECTION AND INDICATION TO EB

Introduction Detect faults in remote transmission lines Immediately transmit any fault information to the Electricity board. Monitor multiple parameters such as voltage, current and temperature simultaneously Transfer data through a wireless medium such as Zigbee.

Features No wires involved Can detect faults due to over current, under voltage, increased temperature etc.,. Can operate in any environment in a transmission line. Can monitor multiple transmission lines sitting in an office.

Voltage Conversion Circuit Block Diagram TRANSMISSION LINE Module LEDs Voltage Conversion Circuit Zigbee Transceiver Microcontroller Level converter Current Sensor Thermal Detector Level converter Voltage Sensing 5v Power supply to all components

VOLTAGE SENSING Voltage (potential) transformer steps down the voltage in the transmission line. It is converted into a dc voltage after rectifier and filter. This rectified dc voltage gives a proportional voltage of the transmission line. It is fed into the ADC of the microcontroller. This ADC value gives the voltage present in the transmission line.

CURRENT SENSING Current transformer senses current taken by the load in a transmission line The interfacing circuit converts ac current into ac voltage and converts into dc voltage. The DC voltage is then given to ADC inside microcontroller which calculates the exact current flowing through the line Depending upon the ADC value the microcontroller finds current in the transmission line.

Temperature Sensing LM35 is used for temperature sensing It is a linear centigrade sensor. The output voltage is given by 10mV/C Can measure temperatures upto 150’C Accuracy is within 0.5’C Integrated sensor in a simple 3pin package.

Voltage Conversion Ckt Block Diagram Control Room Module PC Interfacing Voltage Conversion Ckt PC Zigbee Transceiver 5v Power supply to all components

Microcontroller PIC16F877A is the microcontroller used in the project. The controller has peripheral features like inbuilt ADC, required to get the signals from the sensors. Maximum clock frequency is 20MHz and hence faster than 8051. Based on RISC and Harvard architecture and hence even more faster. Embedded C is used for programming the microcontroller.

Zigbee Transceiver Used to do wireless communication between transmission line and control room Xbee module is used in the project Frequency of operation is in the license free ISM band – 2.4GHz Distance of up to 100mts possible with the XBee module Is Zigbee compatible Maximum data rates of up to 250Kbps possible Uses DSSS and CSMA/CA technologies for reliable communication.

Voltage Conversion Is required because of the mismatch in the operating voltages for Xbee and microcontroller. Microcontroller operates at 5V and Xbee operates at 3.3V. Hence direct communication between the two is not possible. Voltage conversion reduces the voltage from 5V to 3.3V when microcontroller is transmitting. It increases the voltage from 3.3V to 5V when the Xbee is transmitting. It is also used in the control room module for the same purpose.

RS232 Interface The serial/Comm port of the computer is used for communication with the hardware. The serial port of the computer uses RS232 standard for communication. RS232 standard voltages are not compatible with conventional TTL / CMOS circuits. Hence IC MAX232 is used for voltage conversion between RS232 port and the microcontroller. MAX232 enables full duplex communications, while doing the necessary voltage conversions.

PC Application A PC is used to monitor the contactor status and the load status. On the PC a visual basic program will be used. VB is used because it offers a easy to use and program graphical interface. The PC displays all the values and also indicates to the user if there is any fault or not.

Hardware Components PIC 16F877A microcontroller Sensors Zigbee transceiver Max232 for PC interface PC

Software Tools MP Lab IDE for PIC programming Orcad 16 for schematic design Eagle layout Editor for PCB design Visual Basic for PC programming in EB office

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