Submerged Power Cable

Probably going to need some scuba gear too!

If you knew the transmission line impedance you might be able to do a TDR from one end or the other to find a break. But you're probably not using a coaxial cable for power transmission so that wouldn't work.

We might be able to help if you specified why you believe you have a failure; e.g. water found between jacket and conductor, bright glowing blue light in lake, circuit breaker blows open an hour after throwing switch, massive fish kill, every time the bungalow on the island looses power we see a boater checking the propeller on his outboard.

To avoid guess answers,kindly take the trouble to provide more details on the existing cable (length,new or old ) and its installation.It is an expensive and troublesome work.

Locating cable fault is a specialised job that require an experience tester with an advance cable fault locating device.In my experience of cable faults on 11 and 22kv 3-core,PILCSTA&S,XLPESWAPE copper and alluminium conductor cables,installed between 1 to 1.5 metre in depth underground,I employed good and not so good specialist.For directly short-through fault between phase to ground and at straight through joints ( most of the cases ) the best result was one which send out electrical pulses and measure (with an expensive electronic device) the returning signals.I do not know the detail but it could be the traveling time of the returning signal.He was able to calculate the location of the fault accurate to +- 8 metres.For partially shorted or high resistance fault,it is more difficult and uncertain.We had to "thump" the cable,and hope to "burnt" through the fault and create a proper short or open fault that can be measured.Meanwhile you can walk along the line with a sensitive microphone (place close to the ground ) and listen with headphone the intermitant sparking sound in the U/G cable.We did this after midnight when trafic noise was less.Once I had to switch on the VCB energing the faulty line with 11kv in the hope to create a real damage that can be detected.This is a dangerous operation unless you Know your multi stages of protection scheme and conditions of your installations absolutely well.

The resistance loop measurement method is very inaccurate and unreliable.I remember one tester with "Seaward brand ?" resistance bridge cable locator which resulted with several cuts and many joints.The accuracy was + - 50 metres.

Good luck,

Khor