Nov 2017
Electricity Distribution
Development of Oil-filled Cable Additive- Phase 2
Nov 2017
Dec 2019
UK Power Networks, Eastern Power Networks, London Power Networks and South Eastern Power Networks
Maxi Faridi
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Network Innovation Allowance
The aim of Phase 2 is to trial few circuits and confirm the satisfactory operation of the new SHFs in fluid filled cables representative of those in distribution networks and in FFC circuits. The project will also ensure SHF production and quality assurance at industrial production level.

Northern Power Grid is a project partner and will supply cable and oil samples from their network for testing in the project.

Stage 1 concerns the sourcing and preparation of cable test samples, equipment necessary to carry out rig and laboratory testing throughout the remainder of the project. During this stage, circuits will also be nominated for future circuit trials pending the completion of rig trials.

Stage 1 Objectives:

  • Scale-up, transfer, and qualification of the SHF formulation to a major cable oil supplier. This will ensure that sufficient volumes of SHF are available for circuit and rig trials.
  • Understand electrical characteristics, oxygen and particulate content of oil samples drawn from across the network.
  • Understand thermal ageing on cables with SHF. Preparation of cable aging trials to have cable samples filled with degassed SHF.
  • Construct and commission primary and secondary FFC test rigs in preparation for SHF rig trials.
  • Develop test geometries necessary to produce suitable leak rates for testing for both primary and secondary rigs.
  • Nominated circuits and sourcing of cable samples that match the design of the length for testing.

In Stage 2 SHF samples will be trialled on the primary and secondary FFC rigs. This period will also cover initial field trials which will commence upon the successful completion of a complete set of rig trials on a given circuit. Laboratory trials, including ageing studies will continue to progress.

Stage 2 Objectives:

  • Determine the effects of ageing on SHF-soaked cable samples. 
  • Planning and preparation for rig trial testing. Carry out contaminated testing and cable repair and jointing trials on secondary cable test rigs.
  • Prepare selected circuits for rig trial testing. Train cable operators in handling and injection of SHF blend.
  • Initial circuit trials, including flushing the cable with new SHF blend and assessment of both asset and SHF health.

The final stage is primarily concerned with the completion and collection of data from cable rig and circuit field trials, with the aim of demonstrating the efficacy of the selected SHF formulation under operational conditions prior to transfer to business as usual. During this period laboratory trials will also be completed, which will provide valuable information regarding the long-term stability of the selected formulation under operational conditions.

Stage 3 Objectives:

  • Removal and dissection of the final samples within the ageing study, to assess changes in the SHF blend and cable over the course of the trial.
  • Completion of assessment of selected samples within primary and secondary rigs. The rigs will still remain in place to allow for future testing if required.
  • Completion of field trials. This will include the long-term assessment of circuits treated with SHF during the course of Stage 2 as well as demonstrations of sheath repair and jointing. The completion of this work package will demonstrate the efficacy of the SHF formulation operating within a decommissioned cable including compatibility with common cable repair techniques.
The project will be deemed successful if following objectives are successfully delivered :

1- Development of a self-healing cable fluid formulation that proves successful in achieving FFC leaks repair and fluid containment in cable rigs and circuit trials.

2- Demonstrate that the SHF formulation can be produce in volumes necessary to meet demand and are compatible with cables under operational conditions and a wide range of temperatures.

3- Demonstrate that the SHF developed is capable of significantly reducing or eliminating leaks and widespread environmental contamination arising from damage to the cable sheath or plumb joints.