Detecting underground cable theft
Detecting underground cable theft
(OP)
Hi!
We've been experiencing a lot of cable theft in past years. i would like find out what possible method i could deploy with numerical relays with SCADA system to overcome this challenge.
We've been experiencing a lot of cable theft in past years. i would like find out what possible method i could deploy with numerical relays with SCADA system to overcome this challenge.






RE: Detecting underground cable theft
We're going to need a lot more information than what you have provided.
RE: Detecting underground cable theft
RE: Detecting underground cable theft
If you make it difficult to steal, or less valuable, the thefts seems to go down.
RE: Detecting underground cable theft
You have to make it difficult and less valuable, but you also need to have salvage yards stop "taking a blind eye" to people bringing in questionable scrap metal.
RE: Detecting underground cable theft
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If we learn from our mistakes I'm getting a great education!
RE: Detecting underground cable theft
This are energized 11kV cables coming from a Substation supplying customers. Most of these cables are in trenches, so what this criminals do, dig them out.... then cut them or burn the cable first when they know that the distributor tripped then cut it, or just pull it out using a truck.
I though of ideas, of maybe using numerical relays that got functions such as negative sequence and negative to positive sequence ratio. But i had issues achieving it using negative sequence functionality since its the same as having earth fault.
RE: Detecting underground cable theft
RE: Detecting underground cable theft
It sounds like the only solution to this problem is your field crew's response time to an outage--try to catch them in the act.. Maybe, look into a fault location scheme to assist in reducing response time/ fault location.
--or you can add a reclosing scheme with, let's say a 60 min time delay, and reclose as they're cutting into the cable.
By the way...bare ground cables can have some serious circulating currents. I've seem pictures of dead hobos that snuck into distribution substations and got zapped while cutting into these cables with pliers.
RE: Detecting underground cable theft
RE: Detecting underground cable theft
Good on ya,
Goober Dave
RE: Detecting underground cable theft
We haven't had people digging up underground power, but we have had people digging up underground street light circuits.
We started placing junction boxes underground, and only bringingup the pig tails. So they would only get a few feet at the most.
RE: Detecting underground cable theft
After digging when they find is aluminium, they leave it the way it is. so mostly they want copper.
RE: Detecting underground cable theft
Are we talking single phase or threephase? If threephase, you may wish to consider an undercurrent alarm. If sections of a phase is removed nps functionality may help. This is, however, heavily dependant on the load current. Higher load current, the higher the nps current when a phase is removed. I have not done the analysis for when two phases are removed but have seen it presented in various textbooks.
Regards.