Detection of fault location in underground cable using arduino

DETECTION OF FAULT LOCATION IN UNDERGROUND CABLE USING
ARDUINO

Flow of Presentation
• Introduction to Project
• Underground cable v/s Overhead cables
• Faults in underground cables
• Methods for the Detection of faults
• Introduction to the Circuit
• Working of the Circuit
• Different circuit components

Introduction
• The objective of this project is to determine the distance of
underground cable fault from base station in kilometers using an
Arduino board.
• Many time faults occur due to construction works and other reasons.
• Cables have some resistance. We are mainly focusing that resistance.
Resistance can vary with respect to the length of the cable.

• If the length of the cable is increase, the value of the resistance will also
increase.
• If any deviation occurs in the resistance value, we will call that is fault point
and finding that place through Arduino technology.
• That fault point represents the standard of distance (kilometre) from the
base station.This value displayed by display unit.
• Before attempting to locate underground cable faults on cable, it is
necessary to know where the cable is located and what route it takes. If the
fault is on secondary cable, knowing the exact route is even more critical.

• Since it is extremely difficult to find a cable fault without knowing
where the cable is, it makes sense to master cable locating and
tracing and to do a cable trace before beginning the fault locating
process.
• Success in locating or tracing the route of electrical cable and metal
pipe depends upon knowledge, skill, and perhaps, most of all,
experience.
• Although locating can be a complex job, it will very likely become
even more complex as more and more underground plant is installed.
It is just as important to understand how the equipment works as it is
to be thoroughly familiar with the exact equipment being used.

UNDER
GROUND
CABLES
Suitable for congested urban
areas where overhead lines may
be difficult or impossible to
install
Low maintenance
Required
Small voltage drops
Fewer faults
Not susceptible to shaking and
shorting due to vibrations, wind,
accidents, etc.
No interference with
communication system
Posses no danger to
wildlife or low flying
aircraft
It is more Expensive
Fault point cannot
be easily located
Can not be easily
Repaired
It can work only upto
66 kv due to insulation
difficulties
Erection cost of high voltage
cable is very high

Faults in Underground cables
• When there is a break in the
conductor of a cable, it is
called open circuit fault.
• The open-circuit fault can
check by a megger.
• The megger will indicate zero
resistance in the circuit of the
conductor that is not broken.
• However if a conductor is
broken the megger will
indicate an infinite resistance
Open circuit Fault Earth FaultShort circuit Fault
• When two conductors of a
multi core cable come in
critical contact with each
other due to insulation
failure, it is so called as short
circuit fault.
• The two terminals of a
megger are connected to any
two conductors.
• If the megger gives a zero
reading it indicates short-
circuit fault between these
conductors.
• When the conductor of a cable
comes in contact with earth
• To identify this fault, one terminal
of the megger is connected to the
conductor and the other terminal
connected to the earth.
• The megger indicates zero
reading; it means the conductor
is earthed.

Methods for the Detection of Faults
• Online method uses and
process the sampled
current and voltages to
determine the fault
points.
Online Method Off-Line Method
• This method uses a special instrument to test
out service of cable in the field. Offline method
is classified into two methods such as tracer
method and terminal method.
Terminal Methods Tracer Method
• Terminal method is used to detect the location of
the fault in a cable from one end or both the
ends without tracking. This method is used to
find general areas of the fault to accelerate
tracking on buried cable.
• In this method fault of the cable can be
detected by walking on the cable lines.
Fault location is denoted from
electromagnetic signal or audible signal.
This method is used to find the fault
location very accurately.

Time domain reflectometry (TDR):
• The TDR sends a low-energy signal through the cable, causing no insulation degradation.
A theoretically perfect cable returns that signal in a known time and in a known profile.
• Impedance variations in a “real-world” cable alter both the time and profile, which the
TDR screen or printout graphically represents.
• One weakness of TDR is that it does not pinpoint faults. TDR is accurate to within about
1% of testing range.

Spark-induced Electromagnetic Signals
• During a voltage break-down in a conductor of length l, a spark-induced
electromagnetic signal is generated exactly where the break-down takes place.
• Two waves will propagate in both directions with a constant signal propagation
velocity, denoted v, towards the direction of the extremities of the conductor
(denoted A and B).
• The time difference ∆t measured between the two signals arriving at the
extremities of the conductor allows calculating the distance lf of the fault from
the extremity A by the simple relation,

Terminal Methods
1) Blavier Test (For a Single Cable Faults):
• When a ground fault occurs in a single cable and there is no other cables (without
faulty one), then blavier test can be performed to locate the fault in a single cable.
• Suppose-
• Fault to ground resistance = r
• Resistance from the Far end to the
cable fault = r2
• Resistance from the testing end of
the cable to the fault = r1

• First of all, We will insulate the far end of the cable to determine the
resistance between line to ground,
which is ;
𝑅1 = 𝑟1 + r
• Now, we will ground or earth the far end of the cable to find the
resistance between line to ground again.
𝑅2 = 𝑟1 +
𝑟 × 𝑟2
𝑟 + 𝑟2
• But the total resistance (before occurring the fault) was
R = 𝑟1 + 𝑟2
• Solving the above equations for r2 (fault location or distance), we get
𝑥 = 𝑅2 − (𝑅1 − 𝑅2)(𝑅 − 𝑅2)

2) Murray Loop Test:
• Wheatstone bridge’s principle is used in murray loop test to find the cable faults.
• The Wheatstone bridge is kept in balance by adjusting resistance of the ratio
arms Ra and Rb until the galvanometer deflection is zero.

Tracer Method
• In this method fault of the cable can be detected by walking on the cable lines.
Fault location is denoted from electromagnetic signal or audible signal. This
method is used to find the fault location very accurately.
• Transmitter create electromagnetic signals
on metallic conductors by producing output current.
• This electromagnetic field radiates from
the line is sense by receiver and we can
find exact location of fault as well as
depth of the cable.

• Cable locating test sets, often referred to as cable tracers, may be
grouped as follows:
i. Low frequency — usually less than 20 kHz sometimes referred to as
audio frequency (AF).
ii. High frequency — usually higher than 20 kHz and in the radio
frequency (RF) range to about 80 kHz.
iii. 60 Hz — most tracers provide this mode to allowtracing of
energized cables.
• Low frequency (AF) is considered the general-purpose selection
because it is more effective in tracing the route of cables located in
congested areas due to less capacitive coupling to everything else in
the ground. Low frequency can be more effective over greater
distances due to less capacitive leakage and because higher signal
power is allowed

Introduction to circuit Diagram
• 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.
• This project uses Ohms Law concept, when a low voltage DC is applied to the feeder end
through a series resistor, then the current would differ based on the location of fault
occurred in the cable.
• In case is there any short circuit occurred from line to ground, then the voltage across
series resistor alters accordingly, then it is fed to an analog to digital converter to develop
exact data, which the pre programmed Arduino module will display in kilometres.
• The proposed system is designed with a set of resistors to signifying the length of a cable
in kilometers, and the fault creation is designed with a set of switches at every known
kilometer (KM) to cross check the exactness of the same. The fault happening at a specific
distance and the particular phase is displayed on an LCD interfaced to the 8051
microcontroller.

Working of Circuit
• The project uses a set of resistances in series i.e. R10,R11,R12,R13 and
R14,R15,R16,R17, & R18,R19,R20,R21, 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 R10, R14 & R18 being the 3 phase cable input.
• 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 Arduino board.

Circuit Components
1) 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.

• 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

2) Relay driver ULN2003A
• 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.

• The ULN2003A functions as an inverter.
• If the logic at input 1B is high then the output at its corresponding pin
1C will be low.

START
Initialize the LCD display pins
2,3,4,5,11,12
Define variable
Distance=input voltage
If input voltage
>=890 and <920
12
Yes
No

1
Output
Distance=8
2
If input
voltage
>=850 and
<890
Output
Distance=6
Output
Distance=4
If input
voltage
>=750 and
<850
Yes
No
Yes
3
No
Display
“Distance=6”
Display
“Distance=8”
Display
“Distance=4”

3
If input
voltage
>=600 and
<750
Output
Distance=2
Yes
Output
Distance=0
No
END
Display
“Distance=0”
Display
“Distance=2”

Arduino Code
// include the library code:
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
// define phase control pins
int phase[3] = {7, 8, 9};
//********************************************************
*
int distance(int inputVoltage) {
if (inputVoltage >= 890 && inputVoltage < 920) {
return 8;
}
else if (inputVoltage >= 850 && inputVoltage < 890) {
return 6;
}
return 4;
}
return 2;
}

else return 0 ;
}
//*****************************************************
****
void setup() {
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// set pin mode for phase relays
for (int j = 0; j < 3; j++) {
pinMode(phase[j], OUTPUT);
}
}
void loop() {
digitalWrite(phase[0], HIGH);
delay(1000);
int dist1 = distance(analogRead(A0));
if (dist1 == 0) {
lcd.setCursor(0, 0);
lcd.write("R: ");
lcd.write("NF ");
}
else {
lcd.write("R: ");
lcd.print(dist1);
lcd.write(" KM");
}
digitalWrite(phase[0], LOW);
//===============================================
=
delay(1000);
if (dist2 == 0) {
lcd.write("Y: ");
lcd.write("NF ");
}

else {
lcd.write("Y: ");
lcd.print(dist2);
lcd.write(" KM");
}
//==================================================
delay(1000);
if (dist3 == 0) {
lcd.write("B: ");
lcd.write("NF ");
}
else {
lcd.write("B: ");
lcd.print(dist3);
lcd.write(" KM");
}
}

References
• http://www.edgefxkits.com
• https://www.elprocus.com
• http://electrical-engineering-portal.com
• http://ieeexplore.ieee.org
• http://www.electrical4u.com

Detection of fault location in underground cable using arduino

Detection of fault location in underground cable using arduino

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