High Voltage Electric Cables Research Articles

Impact of electrical cable insulating oil on the mineralisation of [1-(14)C]glucose in soil.

Subsurface high voltage electric cables are commonly insulated using dodecylbenzene in combination with mineral oil. This work assessed the impact of increasing concentrations of cable insulating oil (0-10% dry weight) on soil microbial respiration as determined by mineralisation of [1-(14)C]glucose (11 microg C g(-1) soil). Acute impact was assessed from 0 days to 21 days, and chronic impact was assessed after 300 days. This study found that cable insulating oil increased respiratory activity of soil microflora. The extent of impact was found to depend on both oil concentration and the length of oil-soil contact time. Following acute exposure (21-days oil-soil contact time), it was found that oil concentrations up to 1% promoted a significant (P<0.05) increase in the extent of [1-(14)C]glucose mineralisation to (14)CO(2) relative to the control. In contrast, higher concentrations of cable insulating oil (5% and 10%) promoted no significant (P0.05) increase in the extent of [1-(14)C]glucose mineralisation to (14)CO(2) relative to the control. Following chronic exposure (300-days oil-soil contact time), the extent of mineralisation was greater at all oil concentrations applied relative to the control. For oil concentrations up to and including 1%, there was a decrease in the extent of elevation in mineralisation relative to the values after 21-days exposure. At higher oil concentrations, namely 5% and 10%, the extent of elevation in mineralisation was comparable with that after 21-days oil-soil contact time. We suggest that the increase in mineralisation of glucose indicates that cable insulating oil is a readily available carbon source to the carbon-limited soil microflora.

Electrical burns caused by fishing rod contact with overhead electric cables: a potential hazard to fishermen

Three patients were admitted to the Burns Unit at Newcastle General Hospital suffering from varying degrees of electrical bum injuries. All were fishermen whose injuries had been caused by their highly conductive carbon fibre fishing rods touching overhead high voltage electrical cables. This paper also describes the information available to fishermen to assist in the prevention of this type of injury.

Performance of extrusion crossheads in multi‐layer cable covering

AbstractExperiments are reported concerning the performance of an extrusion crosshead used in the three‐layer covering of high voltage electrical cables. Both extrusion pressure requirements and circumferential distributions of polymer layer thicknesses in the finished cable were measured and compared with the results of a previously published finite element method of melt flow analysis within the crosshead. While agreement on pressure is good, it is necessary to allow for the effects of both gravity and slight misalignments of crosshead components if the thickness distributions are to be correlated satisfactorily. The latter effect emphasizes the need for a high degree of accuracy in crosshead design and manufacture.