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Water Trees – Too Big to Fail?

Q: We had three cable samples sent out for testing from different areas. Each area has suffered multiple failures. We would like to have your opinion as to whether the injection process will be able to revive cables that have deterioration to this extent. Please send us any literature that you have, which can illustrate the extent of damaged cables and their successful rejuvenation.

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Using TDR to Identify Neutral Corrosion and Splices

Q: The blog post titled Neutral Corrosion — How Much Is Too Much? includes a waveform from a TDR (time domain reflectometer, often called a radar) that is used to pinpoint bad sections of cable neutral. The TDR is also used to pinpoint splice locations on the cable. How does the TDR determine the neutral corrosion and splices on the cable? And how is the waveform read to tell them apart and to pinpoint their locations?

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Concordance of IEEE 400.2™ & Warranty

Concordance of IEEE 400.2™ & Warranty Q: The definition of “Discouraged Diagnostic Testing” found in your warranty language does not seem to allow VLF testing in accordance with IEEE 400.2™.* In the unlikely event that a rejuvenated cable fails in service, we would want to repair the fault and test the cable with one of…

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Neutral Ampacity & Re-closers

Q: In Exhibit E of your proposal you state that cable replacement should be utilized rather than cable injection if the “cable neutral has lower than required ampacity …” I was able to find on Novinium’s website the limits for neutral corrosion, but nothing on the neutral ampacity limits. What are the neutral ampacity limits? Keep in mind that on three phase cable installs we use one-third neutrals. In Exhibit F of your proposal you define “Abnormal Operational Excursion(s).” One of the identified excursions, item (3), is “repeated operations of re-closers.” We use re-closers on all of our circuits. Does this mean that the warranty is void?

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Integrated Rehabilitation

When it comes to rehabilitating aging underground power cables there are basically three tool choices: A good choice, a better choice, and the best choice. The only bad choice is to do nothing at all. Integrated Rehabilitation uses all of the available tools and applies them in the order: best, better, good.

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Crow

Crow Q: Can you explain the Crow-AMSAA graph on Novinium’s web site?   A: I present the Novinium failure statistics in the chart nearby. Crow was a guy that worked for the “Army Material Systems Analysis Activity” or AMSAA. Crow developed the statistical model that now bears his name and that of his employer. Crow-AMSAA…

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