Fabric Tape Conductor Shield

Dear Amiable Amphibian,

I am wondering if you can provide some thoughts or comments on a cloth fabric semi-con we have here on some older #2 Cu cables, 15kV. Does the Ultrinium fluid harm this fabric?  Does the fluid react with any semi-conducting materials like carbon? Does Novinium think the injection process disturbs or harms the fabric?

Conducting Query

Dear Conducting-

The fabric tapes used on pre-1980 vintage cables were carbon-black dispersed on cotton fibers. Neither the cotton nor the carbon black in these semiconducting tapes react with the silanes used with Ultrinium™ fluid or Perficio™ fluid. In fact, cables with fabric tapes have been treated with alkoxysilane rejuvenation fluid for over two decades. Novinium has not experienced a single failure of a cable with a taped conductor shield.

The use of taped conductor shields in medium voltage distribution applications all but halted by the mid-1970’s in North America. Bartnikas and Srivastava relate in Power and Communication Cables, page 83 …

“Semiconducting carbon black tapes were … used as shields in the early linear polyethylene (PE) insulated cables. Due to poor adhesion between the tapes and the PE as well as occasional breaks or gaps between butting edges of carbon black tapes themselves, partial discharges often occurred within the voids formed at these faults. Polyethylene cables using carbon black shielding tapes were also found to be highly susceptible to tree growth.”

The fact that you have some of these cables in service today is testament to the absence of partial discharge and hence these particular cables do not suffer from the poor adhesion, occasional breaks or gaps which Bartnikas and Srivastava warned about in their book. However, there are certainly water trees and I’ll bet they’re doozies.  Fortunately, ameliorating the pernicious effects of water trees is precisely what Ultrinium and Perficio fluids are designed to do.

There are two operational considerations when injecting taped conductor shield cables. First, there is much more room in the strand interstices, so the fluid will flow faster and the cable will hold more fluid – these are both good things.  Second, when fluid flows through the strands it will entrain some un-adhered carbon black, so the outlet fluid will be black. Not to worry, there is much more where that came from and there is no need to try to flush it all out either.

Yours truly,

Thermo B. Frog

Suitable for Treatment

Dear B.F.

We’ve taken some photographs of cable samples identified with off-line PD testing.  I was hoping to get your opinion of the cable and if injection would be able to address these issues.

·        On two samples, we found the XLP insulation was a greenish color.  We’ve never found cables discolored before and it had an odd odor.  Upon wafering and dying the sample, quite a few trees were found.

·        On three samples, we found spots where a hole was burned through the semi-con layer and dirt had gotten between the semi-con and insulation, causing some deep pitting.

I’ve attached some photos of the issues.  Neither of these cables has been treated, but can they? Let me know what you think.

Wishing you well,

Wisconsin

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Dear Wisconsin-

First off – green is a lovely color and you should be proud of your sample’s hue. The green color proves that the insulation compound manufacturer included anti-oxidants in its formulation and is generally an indication of recent heat exposure. The sulfur-based anti-oxidants break into by-products as they do their job. Some of these by-products absorb red light, leaving a predominantly yellow to green hue. The insulation may by 4201 made by Union Carbide, now Dow Wire & Cable. Click here to check out a fact sheet put out by the Dow folks called:

Color Indicates Presence of Antioxidants in XLPE Insulation Compounds

With regard to the odor, I can’t answer definitively for two reasons. One, you did not send me a sample and two, frogs are not known for their olfactory prowess. I can, however, speculate. The sulfur-containing anti-oxidant by-products are called thiols or mercaptans and have strong garlic-like odor. I have a cat at my house with an exceptionally keen nose. If you send me a stinky sample I can ask her to identify the chemistry involved. I hope it does not smell like tuna fish — she might gnaw on it. See "rats" below.

With regard to the water trees, you will find those in every solid dielectric cable. Water trees are the predominant cause of solid dielectric cable failure. Fortunately, Novinium provides fluids that can reverse the damage caused by water trees and replace the anti-oxidants that have been consumed over decades of field aging.

·        Click here to learn how you can know that water trees are the predominant cause of cable failures.

·        Click here to learn how you can be confident that rejuvenation will reverse the damage caused by water trees.

·        Click here to learn how Novinium^®-brand Ultrinium™ fluid can replenish the anti-oxidants in aged cable.

Deep Pitting

I don’t know if the cable with the holes in it smelled like garlic, but the rodents that chewed on it must have liked the odor.  I doubt that the meal was satisfying. I am fond of rodents. An adult mouse fills my belly for the better part of a week, but I might have taken a pass on the gal that was chewing on your cable. Shreds of polyethylene in her belly would end up in mine and would undoubtedly upset my delicate digestion. I suspect the rat stopped chewing when she started to feel a tingling in her mouth – those were partial discharges. Persistence would have led to an untimely end. That’s how I know the rat was a female. A male rat would not have been smart enough to back off when he felt the tingles … in fact they probably would have only encouraged him more.

Here is a question for you, Wisconsin. How many cables had to be examined to find these rodent bites? If rodent damage is rampant in your service territory, off-line partial discharge testing might be a useful tool to find where the rats reside. It is true, that rejuvenation cannot address rodent damage, but how prevalent is this failure mode? For some insight on that question check out my three-part postings of January 2012 …

Failure Causes I, Failure Causes II, and Failure Causes III.

The Novinium masters of reliability have been involved in the injection of many millions of cable feet. Cables with water trees, with or without interesting color and odor, are handled easily and these represent the frog’s share of the root causes of cable failure. Add in component issues addressed by rejuvenation and a tiny minority of potential issues are left unaddressed. It is for this reason that more than 99.4% of all cable treated by Novinium enjoy failure-free reliability.

Never put anything in your mouth that can kill you,

T. B. F.

Integrated Diagnostics 

Dear BF,

My firm will consider and evaluate additional services beyond rejuvenation that will add quality or value to a requested proposal.  Additional options for cable testing services would be of particular interest.  An explanation of services and associated costs must be included with all additional service offerings.  Information submitted for this may lead to additional evaluation points in the “services to be provided” category.

Please help me with my decision matrix,

Tahoma

Dear Tahoma-

For my readers who are not local to the Pacific Northwest, like you and I, Tahoma is a local Indian name, which means “snow peak” and designates Mt. Rainier, the snow covered volcano close to Seattle and Tacoma.  I have a view of Tahoma from my pond too – feel free to visit me anytime and I will be happy to share my grubs.  I’m all for decision matrices.  Every time one of these has been used Novinium comes out on top – safer, faster, better.

Your query suggests that you have a particular interest in cable testing services.  I have provided several posts in the past that describe the issues and challenges associated with diagnostic testing.  I list several of them below for your review:

In short, this frog is skeptical of claims of efficacy for any of the commercially available diagnostic tests.  Compare the double-digit false positives and double-digit false negatives inherent in testing with this single digit – one percent.  That’s the number of post treatment failures that have occurred in all cables proactively treated with any of the globally commercialized rejuvenation technologies.  Novinium’s post-treatment reliability record is even better than the average!

Occasionally there are cases where diagnostics are appropriate.

Novinium’s diagnostic tool box includes several kinds of instruments including infrared imaging and three kinds of on-line partial discharge detectors.  Novinium uses infrared imaging technology to identify improperly installed compression connectors.  The picture nearby shows a side-by-side image of two splices, one installed properly and the other suffering from thermal runaway.  Three different on-line partial discharge detectors are available to pinpoint discharges in terminations, splices and cables.  A high frequency current transformer can be clipped around a cable or its neutrals to detect discharges in the cable or connected equipment.  A Transient Earth Voltage (TEV) sensor allows the pinpointing of local discharges.  For applications where it is not prudent to approach a piece of operating equipment such as air operated switchgear, an airborne acoustic sensor can locate discharges inaudible to the human ear.

In addition to these instruments, Novinium provides consulting services to circuit owners to diagnose problem areas using failure data.  This approach is the lowest cost and most accurate diagnostic available.  The method was documented in a DEIS (Dielectrics and Electrical Insulation Society) Feature Article in the March/April 2009 issue of IEEE Electrical Insulation Magazine, Diagnostic Testing of Stochastic Cables.

Diagnostically yours,

Thermo B.F.

 On-line Diagnostic Testing

Dear Ms. Conducting-

Thank you for your comment of May 13, 2011 to Middle East Query – Diagnostic Testing Timing.  Click here to see the original post and comment.  In short, Ms. Conducting wanted to dive deeper into the data. Below I have reproduced slide number 281 from the CDFI (Cable Diagnostic Focused Initiative) Regional meeting presented by NEETRAC (The National Electric Energy Testing Research & Application Center at Georgia Tech’s College of Engineering) and hosted by American Electric Power (AEP).  The meeting was held on October 13-14, 2009 in Columbus, Ohio, U.S.A. The entirety of the presentation slides are available by clicking here. The figure below (from slide 278) shows the failure results tracked for over three years on 114 feeder cable miles tested using online PD on cables that included EPR, XLPE, and PILC cables. After the testing was completed, the cables and attached accessories were allowed to fail – that is, no rehabilitation actions were taken.  There were about 85 accessory failures; there were about 90 cable failures.

 The online PD testing indicated the need for action (i.e. imminent failure) on 45 accessories.  Of the identified 45, 14, or 31%, actually failed.  The false positives were 69%. The results on the cable were marginally better. Of the 52 cables, which were diagnosed as “bad,” 23 actually failed or about 44%.  The false positives were 56%.  For both accessories and cables the number of faults that occurred on plant, that had been deemed “good” by the testing firm, far outnumbered those identified as “bad.”  There were about 71 and 67 false negative failures for accessories and cable respectively.

Not only did the observations show that the testing was unable to provide reasonable discrimination between bad and good, the raw number of failures that occurred in the presumably “good” sub-population was about 3 to 5 times higher. Because the researchers did not provide population statistics beyond the total mileage of cable installed, it is not possible to determine with precision the relative false negative performance. However, I can make some frogstimates. If the average three-phase feeder run length were 1760 feet (typical for North America) and there were 2.2 components per cable segment (also typical), there would have been approximately 343 cable segments (or about 114 three-phase cables, termination to termination) and about 750 accessories.  The relative failure rate over the three-year period would have been 11% (i.e. 85/750) for accessories and 26% (i.e. 90/343) for cables. My frogstimate of the false negatives are 9.5% (i.e. (85-14)/750) and 19.5% (i.e. (90-23)/343) for accessories and cables respectively.

Amazingly, these profoundly dismal results are spun by testing proponents as proof that a testing program is a fruitful endeavor. It’s no wonder to me why humans get sucked into tulip and real-estate bubbles and Ponzi schemes – no frog has ever been so duped.  There have been a few would-be-princesses that have been duped by a frog, but never the other way around.  Alas, wishing that a frog is a prince does not make him so. Wishing that a diagnostic provides useful information does not make it so.

There are two immutable reasons and their “anti-synergy” that explain why the current generation of diagnostics cannot work. These two reasons are:

1.   The economics of aged circuit rehabilitation, and

2.   The second law of thermodynamics.

Further, without some technological breakthrough that reduces the cost of applying diagnostics by an order of magnitude, it is unlikely these immutable and anti-synergetic forces will ever be reconciled. To inoculate yourself from these ill-conceived schemes, read and understand the DEIS (Dielectric and Electrical Insulation Society) feature article, “Diagnostic Testing of Stochastic Cables” published in the March/April 2009 pages of IEEE’s Electrical Insulation Magazine.  Click here to learn.

Data and Frogs don’t lie (unless you’re a fly),

T. B. Frog

Really Long Term Life

In my December 29, 2010 post at …

Crazy-Competitor-Claims

Wonderer in the Wilderness inquired …

1. How can Novinium get the same cable life extension without a soak period?  It would seem to me that Novinium puts less fluid into the cable than one would get with a soak period.

In my first post addressing this question I provided an abbreviated answer. We learned from the abbreviated answer that that when Novinium founders conceived of the first generation of treatment fluid over two decades ago, there was a failure to check the relative diffusion rates of the phenylmethyldimethoxysilane (PMDMS) monomer and the condensation catalyst we had chosen to provide long life.  This turned out to be a grave mistake, which we have corrected.  In a subsequent post on January 3, 2011 at …

Catalytic Considerations – Component I

… I provided a more comprehensive answer, but I promised five new posts that would explain the functional improvement of the five kinds of ingredients in Ultrinium™ 732 and Ultrinium™ 733 fluids.  In this last of those five sub-posts, I explain how a component with a really ugly name provides extraordinarily long life.  Chemists call the material found in Ultrinium™ fluids cyanobutylmethyldimethoxysilane (Pronounced: Sigh-an-Oh•butte-ill•meth-ill•die-meth-ox-ee•sigh-lane); we will call it CBMDMS for short.

In the graph nearby I explain the first dimension of why CBMDMS works so well for so long.  The graph plots the “permeation product” of the three most commercially important rejuvenation silanes.  Permeation is the product of the diffusion coefficient and the solubility of the material in cross-linked polyethylene (XLPE).  The rate of fluid exudation from a cable is directly proportional to this permeation product.  Remember that if a fluid exudes out of the cable, it is not providing any life extension benefit.  The lower the permeation value, the longer the fluid will stay in the cable.  The permeation of the primary ingredient in Novinium’s Perficio™ 011 fluid and other older technology fluids is illustrated by the light-blue-colored (upper-most) line over the range of 15 to 90°C.  This fluid is called phenylmethyldimethoxysilane (Pronounced: Fen-ill•meth-ill•die-meth-ox-ee•sigh-lane) by chemists; we will call it PMDMS.  In a recent post, Chain Entanglement, I explained how extending the length of the side chains entangled the silicone in the polyethylene polymer chains and slowed the diffusion.  The orange line shows the advantage enjoyed by tolylethylmethyldimethoxysilane (Pronounced: Tall-ill•eth-ill•die-meth-ox-ee•sigh-lane by chemists) or TEMDMS, which is a result of this chain entanglement.  The permeation rate and proportional exudation rate of TEMDMS, is always lower than that of PMDMS.  At low temperature they are about the same, but at 75°C, the TEMDMS permeates about 5-times slower.  But the focus of this post is the amazing CBMDMS, which enjoys a 25-fold to 45-fold permeation advantage over the PMDMS.  That’s a really big deal!  At 75°C CBMDMS will outlast PMDMS by a factor of 45!

TEMDMS and CBMDMS are available only from Novinium, as their use is protected by U.S. Patent 7,643,977, other pending applications, and their foreign equivalents.

The cyano-group, found only in Novinium rejuvenation products, grades stress in the same way, but at the nano-scale.    Before I explain how this works we need to define a thermonuclear-sized word:  dielectrophoresis, pronounced die-EE-lek-trow-for-EE-sis or DEP for short.  DEP is a phenomenon in which a force is exerted on a dielectric molecule when it is subjected to a non-uniform electric field – the greater the dielectric constant of the material, the greater the force.  The illustration nearby explains how the diverging electrical field near an imperfection imparts a force upon CBMDMS molecules and draws them into the local-region of highest electrical stress.  The presence of the high dielectric constant material smoothes the electrical stress and interferes in several ways with dielectric failure mechanisms:

1.    The local AC stress is reduced, and water trees grow more slowly.

2.    The high electrical fields around space charges are reduced, which reduces the likelihood of UV photon creation and the inception of free electrons.

3.    Any free electrons will not be accelerated to the same energy as they would have been in a greater field.

4.    The reduced local field increases both the partial discharge inception and extinction voltages.

Greater persistence in the insulation and stress grading provide longer post-injection life even in demanding applications.  Performance at high temperature and performance in cables with constrained geometry that limit the amount of fluid that can be supplied, are greatly enhanced by the presence of CBMDMS.

Longer life through better chemistry,

Thermonuclear B.F.