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Oil seepage through Cable cores

Mukund Pandurang Joshi

Hello Everyone,

One of our transformer supplier have supplied cable confirming to BS 7846 - F2. The cable size is 4 Core x 4 sq.mm. 

This cable is installed between transformer CT junction box till the Marshalling box. Recently, there was an oil leakage from the CT junction box. This cable witnessed oil seepage from interstices of the cable and the oil has reached the marshalling box at the other end. The transformer is having ERGON HYVOLT I oil.

Please advise if such cables can be used after satisfactory passing of insulation resistance measurement test. Also, please clarify if any traces of oil inside the cable can have any depleting effect on the cable.

Thanks in advance.

Mukund

  • 0

    To be clear - is this

    1) a cable normally filled with oil and it is coming out or

    2) a cable normally  dry now wetted by with oil spill from a transformer soaking in ?

    What follows assumes the latter, and that the oil is this one you mentioned    and this  short data  applies

    Some oils do attack certain types of insulation, but most modern oils are actually compatible with most modern plastics - the real problems related to older oils and rubberised insulation - so it may be time to look at the datasheet for whatever the oil is and maybe then to call the cable maker.

    That one does not look like it should be a problem for any polyethylene/polypropylene or PVC insulation. Nylon glands and or rubber grommets may not do so well.

    If the cable checks out OK, apart from being sticky and inconvenient, it is likely to be safe for continued operation, at least for a short time until the situation can be clarified wth the cable maker.

    More seriously, why has the oil come out in the first place and what was it doing , - is something now running without proper insulation or without cooling ?

    mike.

  • 0 in reply to mapj1

    Thanks Mike for your response. 

    To answer to your first query, the cable is normally dry and it is now soaked with oil.

    Preliminary observation suggests oil leak happened due at the CT terminal flange connection and seeped through the gasket. The transformer is not yet commissioned and hence the transformer supplier is carrying out root cause analysis. I have also approached the cable manufacturer to get confirmation.

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