When an underground cable faults, the expensive part is not the repair but finding where to dig. This project models a cable as a chain of series resistors, each representing one kilometre, and detects a short between a line and ground by measuring the resistance from the sending end up to the fault. A microcontroller converts that resistance into a distance and displays which line has faulted and how far along it, so the fault is located without excavating the whole route.
Not just the parts. Teams budget from a component list, then run out in week six on wire, connectors and the driver board they destroyed. These are the lines that catch them.
| Line | Cost |
|---|---|
Components and materials From the bill of materials | Rs 1,355 to Rs 3,500 |
Spares and replacements 15 % — you will destroy something | Rs 203 to Rs 525 |
Consumables and hardware Wire, connectors, headers, screws, heatshrink | Rs 250 to Rs 420 |
Perfboard and assembly | Rs 150 to Rs 400 |
Report, printing and binding Two or three bound copies, plots and the plagiarism check | Rs 400 to Rs 1,200 |
| Total | Rs 2,358 to Rs 6,045 |
| Each, split 3 ways | Rs 786 to Rs 2,015 |
Indicative bands last checked in August 2026 — a guide, not a quotation. Prices move and vary by seller, and anything you can borrow from the lab comes straight off the total. The 2.2 week figure assumes 5 person-weeks of work shared between 3; students past 4 add coordination rather than output, so the estimate stops improving there.
The same chain in words
Each line of the model cable is a series chain of equal resistors. Closing a fault switch connects that node to ground, exactly as a short to earth would in a real cable.
The controller drives one line at a time through a known reference resistor. The faulted length and the reference resistor form a potential divider, so the junction voltage depends on how much cable lies between the sending end and the fault.
The ADC reads that voltage, the controller converts it back to a resistance, divides by the resistance per kilometre and displays the distance.
With no fault present the line is open, the divider node sits at the supply rail, and the controller reports that line as healthy.
This is the chapter that separates an engineering project from an assembly job. Every value below carries the formula that produced it and the assumptions it rests on — check them against your own ratings before you use them, because your motor is not this motor.
Resistance per km chosen so the whole route fits the ADC range
Real XLPE cable is closer to 0.2 Ohm per km per core, far too small for a 10-bit ADC to resolve. Scaling to 100 Ohm per km is a modelling choice and the report has to say so, rather than implying the hardware measures real cable.
Vnode = Vcc x Rline / (Rref + Rline), with Rref = 100 Ohm
5 V supply, 100 Ohm reference. The steps shrink as the fault moves away: 833 mV between 1 and 2 km, but only 250 mV between 3 and 4 km.
step = Vref / 2^n
The smallest gap above, 250 mV, is about 51 ADC counts wide, so even the worst case resolves comfortably. This calculation is what justifies the choice of reference resistor and belongs in the design chapter.
Vnode / Vcc = 1 / (1 + Rref/Rline)
The relationship is a hyperbola, not a straight line. Either use a lookup table, or drive a known constant current through the line and measure the voltage across it — the constant-current version is linear and is the better engineering answer.
| Item | Qty | Unit cost |
|---|---|---|
Microcontroller board Arduino Uno or Nano | 1 | Rs 250 to Rs 500 |
Resistor chain 100 Ohm, 1 W, 1 % metal film | 12 | Rs 3 to Rs 12 |
Reference resistors 100 Ohm, 1 %, matched | 3 | Rs 3 to Rs 12 |
Fault simulation switches SPST DIP or toggle switches | 12 | Rs 10 to Rs 35 |
Relay module 4 channel, for line selection | 1 | Rs 180 to Rs 400 |
LCD display 16x2 with I2C backpack | 1 | Rs 140 to Rs 320 |
Power supply 5 V, 1 A adaptor | 1 | Rs 120 to Rs 280 |
Perfboard and hardware Perfboard, headers, standoffs, hookup wire | 1 | Rs 200 to Rs 500 |
Enclosure and panel Acrylic panel with the cable route printed on it | 1 | Rs 300 to Rs 900 |
Specifications are written as ratings rather than brands, so any equivalent part works. Where a line says to borrow from the lab, do — it is usually the largest number on the page, and the total drops to Rs 2,358 at the low end without them.
None of these blocks you — they are learnable inside a semester. Each one you do not have costs a couple of weeks, so count them into your plan.
Anything marked required is a blocker, not a difficulty. Arrange the access before you commit to the project, not after.
Use these when your guide says the scope is too small, or when you want something in the results chapter that nobody else in your batch will have.
The structure below is what a project report is marked against, with the mistake that costs marks in each chapter. There is no template to download and there will not be one: the writing is your work, and a site that did it for you would be helping you cheat rather than helping you pass.
A diploma report is typically 40 to 60 pages. The design and results chapters carry the marks; the literature survey can be short. A mini project report runs to about 40 to 50 pages, and the literature survey is usually brief. Guides expect one clear objective, met and measured.
The full report guide — front matter, conventions and page countsOne paragraph covering what the problem is, what you built, and what the result was. Written last, even though it appears first.
Loses marks: Describing the problem and the method but never stating a result. If there is no number in your abstract, it is not finished.
Why the problem matters, the context it sits in, and a clear statement of the objectives your project set out to meet.
Loses marks: Objectives written so vaguely that nobody can tell at the end whether they were met. Write objectives you can tick off in the conclusion.
What has already been done, what each approach achieved, and the specific gap your work addresses.
Loses marks: A list of paper summaries with no comparison and no gap. The survey exists to justify your design choice, so end it by saying what you chose and why.
The system as a whole: the block diagram, what each block does, and the signal or power path between them.
Loses marks: A block diagram copied from a datasheet or another report. Draw yours to match what you actually built, including the parts that are inconvenient.
Every component value and rating, with the formula, the assumptions and the arithmetic that produced it. This is the chapter that distinguishes an engineering project from an assembly job.
Loses marks: Component values with no justification. If a resistor is 10 kOhm, the report must say why it is not 1 kOhm.
The circuit as built, the PCB or wiring, the flowchart, and the parts of the code that carry the actual logic.
Loses marks: Twenty pages of pasted source listing. Include the flowchart and the few functions that matter, and put the full listing in an appendix.
What you measured, in tables and graphs, compared against what you predicted in the design chapter — including where they disagreed.
Loses marks: Photographs of the working model presented as results. A photograph is evidence that it exists, not evidence that it works. Results are measurements.
Whether each objective was met, what the measured performance was, and what the honest next step would be.
Loses marks: Future scope written as a wish list of unrelated features. It should follow from a limitation you actually hit.
Every source in a consistent style, plus datasheets, full code listings and the complete bill of materials.
Loses marks: Citing a blog or a video where a datasheet or a standard exists. Cite the primary source for anything you relied on.
The demonstration is half the assessment. These are the questions this project invites, and the answers are written the way you would give them out loud.
Low-resistance faults where a conductor is shorted to ground or to another conductor, because those give a defined resistance from the sending end to the fault. It cannot locate an open circuit, since there is no return path to measure, and it degrades badly on high-resistance faults where the fault resistance swamps the cable resistance.
Because it is a potential divider, and a divider output is a ratio, not a linear function of one leg. As the faulted length grows, the same extra kilometre changes the ratio by less and less. Driving a constant current through the cable and measuring the voltage across it gives a genuinely linear relationship, since V equals I times R with I fixed.
Usually in two stages. A pre-location method such as a Murray loop bridge or a time-domain reflectometer narrows the fault to within a few metres from one end, then a surge generator called a thumper discharges into the cable and the exact spot is pinpointed acoustically at the surface before digging.
It joins the faulted core to a healthy core at the far end to form a loop, then balances that loop in a Wheatstone bridge arrangement. At balance the ratio of the bridge arms equals the ratio of the two cable sections, so the distance to the fault follows from the total loop length without needing to know the resistance per kilometre precisely.
It is a deliberate scaling of the model so the fault positions are resolvable by a 10-bit ADC on a 5 V rail. Measuring a genuine 0.2 ohm per kilometre core needs a four-wire Kelvin measurement and a much higher resolution front end. The scaling is a limitation of the demonstration, not a claim about real cable.
Normally taken as a Diploma project (C-20, 6th sem) or B.E. mini project (5th/6th sem) project. If yours is a different course, the extensions above scope it up and the simpler half of the design scopes it down — the arithmetic does not change. Back to all projects.