Abstract, introduction , block diagram , construction and working principal , funtion of each part , refrence conclusion

underground cable fault distance locator pdf

The objective of this project is to determine the distance of underground cable fault from base station in kilometers. The underground cable system is a common practice followed in many urban areas.While a fault occurs for some reason, at that time the repairing process related to that particular cable is difficult due to not knowing the exact location of the cable fault. The proposed system is to find the exact location of the fault.The project uses the standard concept of Ohms law i.e., when a low DC voltage is applied at the feeder end through a series resistor (Cable lines), then current would vary depending upon the location of fault in the cable.In case there is a short circuit (Line to Ground), the voltage across series resistors changes accordingly, which is then fed to an ADC to develop precise digital data which the programmed microcontroller of 8051 family would display in kilometers.The project is assembled with a set of resistors representing cable length in KM’s and fault creation is made by a set of switches at every known KM to cross check the accuracy of the same. The fault occurring at a particular distance and the respective phase is displayed on a LCD interfaced to the microcontroller.Further this project can be enhanced by using capacitor in an ac circuit to measure the impedance which can even locate the open circuited cable, unlike the short circuited fault only using resistors in DC circuit as followed in the above proposed project. This paper proposes fault location model for underground power cable using microcontroller. The aim of this project is to determine the distance of underground cable fault from base station in kilometers. This project uses the simple concept of ohm’s law.When any fault like short circuit occurs, voltage drop will vary depending on the length of fault in cable,since the current varies. A set of resistors are therefore used to represent the cable and a dc voltage is fed at one end and the fault is detected by detecting the change in voltage using a analog to voltage converter and a microcontroller is used to make the necessary calculations so that the fault distance is displayed on the LCD display.This project is intended to detect the location of fault in underground cable lines. It is actually not feasible to keep a check on the fault of the cables. This project gives a digital way to detect the fault location, i.e. the distance of the fault from the feeder end, so that it is easy to rectify that fault. This uses the fact that when any fault like a short circuit occurs, the voltage drop varies as the resistance between that distance changes since the current varies. A set of resistors are therefore used to represent the cable and a dc voltage is fed at one end and the fault is detected by detecting the change in voltage using a analog to voltage converter and a microcontroller is used to make the necessary calculations so that the fault distance is displayed on the LCD display.

CIRCUIT EXPLANATION:

The circuit is prepared using a set of resistors arranged in 4 rows representing the cable line. A set of three rows represent the three phases (assuming to be the R,Y and B phases). Each of three rows is scanned through a relay for any fault occurrence, thus using a total of three relays which are driven by a relay driver operated by a microcontroller. Each series resistor represents the resistance of the cable at certain distance. The 4th row of resistors is connected to a +5V supply through a resistor. The common point of the resistor and the cable series resistor is connected to an analog to digital converter. A switch is connected in series with each resistor to represent the fault condition.
CONCLUSION:

This project has been developed to demonstrate the detection of fault in cable lines. The fault location is determined and the distance is displayed on the LCD screen. Thus by getting to know the location of the fault, the technician can easily repair the fault.

FUTURE SCOPE:

This project can also be modified to locate the open circuit fault in the cable lines. Here, at present, we are concentrating only on the short circuit fault. For open circuited case, a capacitor can be used in an AC circuit to measure the change impedance and then calculate the distance.

CIRCUIT OPERATION:

When the microcontroller sends a logic high signal to one of the input pins of the relay driver, the corresponding output pin goes low. This low logic signal energizes the relay connected to the output. Eventually the set of resistors connected to that relay gets connected to ground incase a switch is in on state, representing the fault. That particular resistors get connected to the –ve 5V supply representing a short circuit condition (line to ground connection).

As different resistors get added in series with the resistors of the 4th row (connected to the ADC) through the fault switch, the current flowing through the resistors changes and eventually the voltage drop changes. The ADC converts the analog value of this voltage drop into an 8bit digital data. This digital signal is fed to the microcontroller. The microcontroller is programmed to read the ADC values to detect the fault which has occurred at that exact location. The microcontroller is interfaced to a LCD display which displays the distance of the cable in kilometers at which the fault has occurred and the particular phase. In case of no fault, the display will show all the phases are in no fault state.