Off-Line Field Diagnostics for MV and HV Oil-Paper Insulated Cables

Banerjee, Sarajit; Jahromi, Ali Naderian; Sedding, H.G.

doi:10.5324/nordis.v0i24.2304

Cited by 2 publications

(2 citation statements)

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“…The rise of cable core and cable surface temperature as the tan δ increase is illustrated in Figure 11. It was reported that for oil-impregnated paper cable (see Table 2) in [22], when tan δ is greater than 0.01, the cable insulation is assessed as being in bad condition and needing urgent action. Analysis shows that when tan δ values are 0.0017 and 0.009, which correspond to good and considerably aged insulation conditions respectively, the corresponding cable surface temperatures are 5.8 and 11°C higher than ambient temperature correspondingly.…”

Section: Reason 1 -Insulation Degradationmentioning

confidence: 99%

“…Therefore, the tan δ value of the cable insulation should be greater at an ambient temperature of 6 °C. Consequently it can be concluded that a local surface temperature rise of 5.2 °C could be the result of locally aged insulation, and the degradation is under the threshold of moderately aged by the standards provided in [22].…”

Section: Reason 1 -Insulation Degradationmentioning

confidence: 99%

See 1 more Smart Citation

Diagnosis of abnormal temperature rise observed on a 275 kV oil-filled cable surface — A case study

Zhou

Hepburn

et al. 2019

IEEE Trans. Dielect. Electr. Insul.

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This paper presents a case study on a 275 kV oil-filled cable. The condition assessment and diagnosis are based on analysis of cable surface temperature in relation to its current load and insulation dielectric loss. The work was initiated by a local abnormal temperature rise of 5.2 °C in cable surface temperature, which was observed during a routine inspection. The temperature rise occurred at bend area with a length of approximately one metre in the Blue Phase. No PD activity was identified using on-line PD measurement. The relation between cable surface temperature, cable core temperature and cable insulation condition was then simulated based on the thermal model of power cables. According to simulation analysis, poor condition of cable insulation or oil from an oil duct penetrating a region under the cable surface were identified as possible reasons for the problem observed. An in service X-ray scanning technique was employed for further investigation and to aid diagnosis. The X-ray images revealed a slight distortion of the PVC sheath and the presence of multiple voids between cable insulation paper and the lead sheath. It was concluded that an oil leakage from the oil duct to the voids under the cable lead sheath was responsible for the local cable surface temperature rise. The result removed the concern of incipient cable breakdown, and a potential unplanned outage.

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Section: Reason 1 -Insulation Degradationmentioning

confidence: 99%

Section: Reason 1 -Insulation Degradationmentioning

confidence: 99%