Power cable failure Intake pumps 2

[sparkview]

Hi all,

Recently we experienced a failure on several 2.4 kV AC feeder cables and control DC cables as a result of a short circuit flash. The feeder cables are supplying power to high horsepower pumps which are used to maintain water level in an intake channel used for Steam Turbine systems. Attached, I included several pictures illustrating the failure and the location where the cables are located.

Several years prior the failure the conduits going to the pumps were revamped, however the contractor introduced several splices on the power and control cables. As a results water/ moisture may have entered the splices and caused the cable failures. Moreover, do to the cables (power and control) been so close to each other, it also damaged a feeder cable from another pump. The short circuit was so intense that it went also through the DC control system (125 VDC) shorting and burning other relays, circuit boards, etc.

I was wondering if the community may provide additional probable causes that may damage a power cable in such matter. Any recommendations to prevent such mishap is also appreciated.

In advance many thanks for your cooperation and support.

Kind regards,

Jairo

 

[HCBFlash]

The evident layout, workmanship, and maintenance conditions alone indicate that this sort of damage and collateral damage would happen, and will happen again. Shall I really discuss proximity, placement, fireproofing, securing of cables here? Need I point out collapsing vault walls, unbushed, unpacked conduit ends? Is anyone familiar with the forces and movements of cabling when subject to bolted or arcing fault conditions? Even normal environmental thermal movements don't appear to have been properly addressed.

This is not to say such lousy installations are entirely uncommon, but such failures are an expected consequence.

.

(Me,,,wrong? ...aw, just fine-tuning my sarcasm!)

 

[edison123]

A costly lesson for some bean-counter somewhere.

Muthu

http://www.edison.co.in

 

[sparkview]

Hi HCBFlash,

Thanks for your reply. Indeed, the pit is far from been adequate for the purpose of cables. On a short term what would you recommend as a corrective/ preventive measure?
Furthermore, the pit is also used for 125VDC control, not sure if protective devices on the DC system would been able to isolate the faults injected by the AC system.

Kind regards,

Jairo