Ground Electric Cable Faults, How to Detect them, a Discussion

The post discusses ground electric cable faults and the many methods to detect them through specialized devices.

In India and many other tropical countries the summer times are treacherous, and just imagine the situation if the conditions are accompanied by power cuts! That can be sheer punishment!

Power cuts in developing countries are mostly due to negligence and bad or wrong wiring implementations which results in cable faults in the form of shorts circuits or beaks.

Recently, one of the followers of this blog and my friend, Mr.Raj Mukherji, had to suffer similar situations, and he was interested to know regarding some electronic solutions which could be used for detecting such complex faults quickly, so that the residents don't have to suffer for long hours. Let's learn more about his query:

Discussing How to Find Underground Cable Faults Quickly

Dear Swagatam,

Hope you are doing well.

Following an incident which happened yesterday made me contact you again with the hope of getting some simple idea of a circuit/device from you which can revolutionize the present methods of detecting underground power cable faults. Perhaps it can also be used to predict any kind of faults that may occur in the near future!

Well, let me explain the incident clearly:

Yesterday, I was on a leave from my office and at about 1:30pm, suddenly there was a power cut in my locality. It was around 40 degrees with a relative humidity around 85; you can imagine our condition then. However, we came to know that the "Electric Supply Authority" have suspected some kind of cable faults and they are inspecting the same.

It is note worthy to mention here that we had been experiencing sudden power fluctuations since early May 2012. This was reported thrice at different times to the supplier by me but they could not provide a permanent solution. Every time they sent their men and did something outside and reported that the fault has been fixed. However, the same issue re-occurred after few days. So, finally the intermittent issue turned out to be a major problem yesterday.

There was no power in my locality between 1:30pm till 9:00pm. Then the power resumed (may be from another phase on a temporary basis) just to let us sleep till about 4am early this morning and the fans stopped again! So, finally at about five o'clock in the morning I went out to the actual spot to see the situation. I saw the workers were joining a segment of new cable about 10-12 meters long and about 2-3 meters deep which they finally "detected" and found to be burnt. Ultimately, the normal supply resumed at 8am and it relieved everyone.

So, the above incident gave me a clear impression of the following facts:

a. The supplier must be using some old method to pinpoint the fault which took them around 8-10 hrs

b. The supplier failed to locate the exact electrical short circuit earlier which was causing the supply voltage to fluctuate a lot at times when we had lodged several complaints in the last month. Had they done so, it would have certainly saved them and all of us from this trouble and inconvenience which lasted for about 18 hrs Therefore, considering the above I thought of contacting you with the idea of getting some kind of simple and yet very effective solution which will help in:

1. Reducing the downtime of such kinds of cable faults 2. Predicting a probable cable fault in the near future

I was Googling a little bit to find out if there are any such instruments/methods that are used in other countries to track these kinds of faults quickly and came up with this one:

https://ecmweb.com/mag/electric_locating_underground_cable/

It discusses quite comprehensively about the pros and cons of the various methods used to tackle an underground cable fault and out of the various methods discussed, the "Time Domain Reflectometer" drew my attention. However, who knows that the simple solution which you suggest becomes "UNIQUE" and also becomes the standard for the next generation cable fault detection?

The simplicity of your published circuits made me think that probably you can come up with something new and cheap and hence I decided to share my recent experience with you.

Considering the potentiality of this project (both from it's commercial value and usability) I would request you to think over this and not to rush at some conclusion immediately. You may also need to conduct a survey to find out the methods used by the power suppliers in Mumbai or in Delhi etc in order to design this project accordingly.

We should also keep this in mind that the required "detector/sensor" should be capable of detecting a cable fault which lies may be 2-10 meters below the ground.

Wishing you all the success for this project and also thanking you for spending your valuable time in going through this e-mail. Waiting for an acknowledgement.

Kind regards,

Raj Kumar Mukherji

My Reply: 
 
Thank you Raj,
I think the solution using a simple circuit idea isn't feasible here, I tried to investigate the TDR method of detecting ground fault and came across an interesting post, which can be read here:
https://www.epanorama.net/circuits/tdr.html
I have one intersting circuit which was invented by me a long time ago and I have already discussed it in this blog, this circuit can also be modified for identifying the above cable fault situations. You may read the circuit here:
https://www.homemade-circuits.com/2011/12/how-to-make-non-contact-ac-mains-phase.html
Though I am not sure how it could be implemented, it's definitely worth trying. Any input will be appreciated.

Leave a Comment