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Middle East Query – Rejuvenation Time

April 27, 2011

Dweller of the Desert asked 22 questions in his post …

Middle East Query – 22 Questions

In this installment I address questions 4 and 5.

4.   How much time does it take to inject a certain length of cable?  What is the maximum cable length that can be injected?

The longest cable to date that Novinium has injected was 4,400 meters.  This was a 53 mm2 compact strand submarine cable out to an island.  Check out the aerial photograph.  The cable path was at a maximum depth of 500 meters.  We know how to go much longer.

Injection times are dependent on:

a.   Insulation material—XLPE injects faster than EPR
b.   Strand compaction—round strands faster than compact or compressed strands
c.    Cable size—larger cables inject faster than smaller ones, because there is more space between the strands
d.   In general, a 100 meter piece of cable injection requires less than 30 minutes.

If you have a specific long cable in mind, give me the particulars and I can show you how we calculate how long it will take. There is also a June 27, 2007 paper, “Advances in Chemical Rejuvenation of Submarine Cables” that explains the basics.

5.   How much time does it take to locate splices? Who will identify the splices? Is it the contractor or the customer?

Novinium provides the technology to identify the number and location of buried splices. The number and approximate location of splices can be determined in less than 15 minutes with a time domain reflectometer or TDR. Buried splices can be accurately located in 1-2 hours depending on access to the cable path and the number of other cables in the same area with a radio frequency locator or RF locator. We describe how this is accomplished in Novinium Rejuvenation Instructions TDR Diagnosis (NRI 260) and RF Locating (NRI 270).

A TDR sends an electronic pulse down the cable. Changes in impedance create reflections that are displayed on the instrument as wave forms. It is important to use an impedance streamliner (IS) to minimize the reflections at the connection between the TDR and the cable. The photograph nearby shows a Novinium proprietary IS and a high resolution TDR. The inset shows a TDR in use by a master craftsman.
RF Setup
The illustration shows how a splice is pinpointed with a RF locator. A signal is impressed between the conductor and the concentric neutral. The two signals are 180° out of phase, so they tend to cancel each other out. I say they tend to cancel, because the canceling is not perfect and some signal leaks through allowing the master craftsman to follow the cable path. The signal strength typically skyrockets when the craftsman nears a splice, because the concentricity of the neutral is generally disturbed at the splice.

For now, Ma’a salama (معالسلامة/Good bye)