Power Outage Averted : 3M Cable Joints Restore 3.3kV Mains Power For Drax

By Chris Dodds on 5th December, 2014

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BS5467 3.3kV Mains Power Cable Joints.

"Whilst your insurance policy may cover the cost of the damage to the underground services and legal costs attached to a claim, it will not extend to cover the cost of investigation, loss of contracts, insurance excesses, penalties and reduced bonuses" - Zurich Insurance plc.

All the above are financial costs, it is impossible to calculate reputational losses and the consequential losses associated with cable and power downtime. One thing is very clear - power outages are both catastrophic and very costly.

The need to restore power with an absolutely minimised outage period is crucial. The following demonstrates the "rapid-response" provided by 3M Electrical Product stockist, Thorne & Derrick.

Today, T&D made an emergency same-day dash delivery to Drax Power Station to enable restoration of the power supply to a 3.3kV cable network.

Accidental on-site cable damage placed the electrical circuit in a vulnerable position and required immediate cable jointing. The "cable strike" was caused by nearby civil engineering works which impacted upon the buried underground cable. The cable damage required a cable joint to be performed rather than a cable repair using 3M heat shrink wraparound sleeves - the mini-digger had struck the cable causing extensive damage into the cable sheath and down into cable wire armours.

The 3.3kV BS5467 multi-core power cables, including 3 core 185sqmm and 3 core 300sqmm, were jointed using 3M LVI-1 Scotchcast resin joint kits. The cable joints kits are complete including earth continuity for SWA cables and mechanical shearbolt connectors for quick and easy jointing of stranded copper conductors.

 

Need Cable Jointers ?  T&D can recommend LV HV Jointers.

 

• 3.3kV Cable Jointing - for cable jointing 3.3kV cables use 3M Scotch 23 self-amalgamating tape half lapped and stretched to 75% width over the crimp or mechanical connectors to increase the diameter by 8mm. For 3.3kV cable jointing the joint kit should not be energised for at least 2 hours. The completed cable joint should be left uncovered before back-filling for two hours to allow the cable jointing resin to fully set. Two part cable jointing resin has a tensile strength of 45MPA and electrical strength of 20kV/mm.

Pic : 3.3kV Power Cable :  3 Core Mains Cable BS5467 (Courtesy Cleveland Cable Company) 3.3kV 3 core mains cable is a medium voltage power cable designed to be buried for underground installation. BS5467 3.3kV cable can also be used indoors and outdoors and in underground cable ducting. The cable features stranded plain annealed copper conductors, XLPE insulation, PVC bedding, galvanised steel wire armour (SWA) and a black PVC outer sheath - despite medium voltage classification the cable is un-screened i.e. no copper tape screen.

 

Resin cable joints should be installed on de-energised ("dead") cables - for cable jointer safety, resin cable joints should not be installed in confined, unventilated areas and the LV cable jointer should avoid inhalation of vapours produced by resin cable joints during mixing and pouring.

Should the cable jointing application be located in a hazardous area zone with potentially explosive atmospheres, such as compressor houses or gas turbine power generation units, 3M can offer cold shrink cable joints which we require no "hot-working".

Category:  LV Cable Jointing & Terminating

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