Soaking I:  Diminishing Returns

Dear Greatest of Soakers,

It seems odd to me that for one who spends so much time soaking herself, that soaking cables is anathema to your firm’s culture.  When is it appropriate to soak a No.2 compressed URD cable?  If I do soak, for how long should I soak?

Geometrically constrained,

Alaskan Amber

Dear Amber-

You ask more questions than any of my other numerous fans.  I like that, except I have been told that some find the questions and the answers too technical.  My response to those critics is to ask your own questions.  If you ask a simple question, I will provide a simple answer.  This Amber guy is cool, his question is appropriate, and a proper answer it is going to require two posts.  Here is the first …

I can see why you might have been misled to believe that I am anti-soak, but that characterization is unfair.  Let’s set the facts straight:

1.   Novinium has a pile of patents that make soaking unnecessary, even for multi-decade life, for all but the most geometrically constrained cables.  I will define “geometrically constrained” later.  The following technological advancements, which I have expounded upon in past blogs, mean that even without a soak, Novinium technology will last longer than the two-decade old approach used by less enlightened purveyors of rejuvenation:

a.   Catalyst improvements were chronicled in Catalytic Considerations I and Catalytic Considerations II.

b.   Novinium Voltage Stabilizers are not present in older approaches.

c.    Our ultra-violet package, which retards the formation of electrical trees was laid out in “To UV or not to UV.”

d.   The tremendous power of effective anti-oxidants present only in Ultrinium™ brand fluids was described in “AO, AO … its home from work we go.”

e.   “Chain Entanglement” dramatically slows the exudation of treatment fluid from the cable and is another patented Novinium innovation.

f.     The “Really Long Term Life” afforded by still another patented Novinium innovation delivered by an ultralow permeability component.

2.   The folks at Novinium invented soaking over two decades ago.

3.   Novinium does soak cables under certain circumstances.

We do consider soaking as a last resort, however, because soaking has two drawbacks.  First, and in order of importance to us, there are safety compromises associated with leaving a hydraulic connection to an energized cable for a long period of time.  I enumerated these risks in my post:  “Greatest Rejuvenation Risks.”  For live-front applications, Novinium can greatly mitigate these risks with a piece of proprietary technology called an HVFI or high-voltage fluidic-interface.  Click here to view a HVFI test report.  Second, there are economic costs associated with a soak period.  In short, a soak bottle with an associated capital cost must be deployed for the duration of the soak period and the injection team has to be redeployed to the site to remove said soak bottle.

Despite these challenges we occasionally resort to soak periods.  The very first consideration is whether the cable to be rejuvenated has a severely constrained geometry.  The “Draft Guide for Rehabilitation and Rejuvenation of Extruded Dielectric Cable” defines constrained geometry in general and severely constrained geometry in particular as follows:

“When the available volume of fluid that can be held in the strand interstices at atmospheric pressure is less than the optimum quantity of fluid to treat the cable, the cable is said to be a constrained geometry cable.  Figure 3-1 [below] shows the three realms of geometry for round (or concentric), compressed, and compact strand cables, namely unconstrained (greater than 20 kg/km), moderately constrained (<20 kg/km and >10 kg/km), and severely constrained (<10 kg/km).”

In practice severely constrained cables are those with conductors of 7-strand and compact 19-strand construction.  If your cables do not have severely constrained conductors, four decades of life extension are possible without resorting to soak periods.

At Novinium we routinely employ soak periods on severely constrained geometry cables for high value circuits with live-front terminations.  Submarine cables provide an example of such high value circuits.  These cables can require 7-figures to replace, so the incremental cost of providing a soak is justified.  Can Novinium make soaking safe in the dead-front applications typical of residential distribution cable?  To answer that question check out my subsequent posts in this series:

Soaking II:  Safety First

Unconstrained by old paradigms,

Thermo

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.

It’s easy to be green™

Dear greenest of frogs,

On your blog masthead you declare that it is easy to be green, but you provide no explanation.  What’s the scoop?  What are your green credentials?

Leepin’ Leprechaun

Dear Greenest of Leprechauns-

This is my first inquiry from a real Leprechaun.  We share a love for all things green.  I don’t know about you, but I love St. Patrick’s Day for two reasons.  First, I get a chuckle out of all the humans dressing up as frogs.  I wear my birthday suit to work and I get compliments for my holiday spirit.  Humans can be so funny.  The second reason I love this holiday is I get to focus attention on why it is so very easy to be green.  Easy for me, of course – I was born green, but easy for circuit owners around the world.

When power cables come to the end of their useful life, circuit owners have two alternatives: replace or rejuvenate.  Novinium rejuvenation provides our customers the opportunity to reduce their environmental impact by avoiding the production of aluminum, copper, and plastics needed to manufacture power cables.  Thus, critical resources do not have to be consumed and energy does not have to be expended to produce these materials.  Additionally, our customers save diesel fuel normally used to install replacement cable.  All of these environmental benefits are achieved with no loss in cable life extension — Novinium rejuvenation provides a 40-year life extension, the same as the life expectancy of a new cable.  Over the last several years, Novinium has rejuvenated millions of feet of underground power cable.

It is possible to calculate the net positive environmental impact of rejuvenation.  I refer to a 2010 paper in Environmental Science Technology (44, 5587-5593) by researchers¹ at the Bren School of Environmental Science and Management at the University of California, Santa Barbara, and Southern California Edison, titled, “Life Cycle Assessment of Overhead and Underground Primary Power Distribution.”  The baseline life cycle impact assessment for underground cable per circuit mile per year is very high, even assuming the cable is recycled.  Over 95% of cable, which is replaced instead of being rejuvenated, is not recycled, but rather abandoned in place.  Hence the values in the table nearby understate the actual environmental savings afforded by the in situ recycling delivered by Novinium’s cable rejuvenation process.

A typical 10 mile rejuvenation project extends cable life by 40 years and reduces global warming potential by at least 3,000 metric tons of CO₂ equivalent.

It’s easy to be green,

Thermo

¹Sarah Bumby, Ekaterina Druzhinina, Rebe Feraldi, Danae Werthmann, Roland Geyer, and Jack Sahl.

Chain Entanglement

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, we failed 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 fourth of five sub-posts, I explain the concept of chain entanglement.

I use one of the tailored molecules found in Ultrinium™ fluids called tolylethylmethyldimethoxysilane or TEM for short.  I was not willing to go on a diet of any kind, but because I desired to better illustrate chain entanglement, I had to create a much smaller clone of myself.  I call my clone Nano-me, because she will be exploring molecular interactions in the nanometer range.  Do not let her diminutive size fool you; she is as clever as I.

On Frogograph 1, Nano-me shows the rather boring structure of cross-linked polyethylene (XLPE).  The carbon-carbon chains are typically several thousand carbon atoms long.  About once every one-thousand carbons there is a cross link site, which Nano-me is illuminating with her green laser.

On Frogograph 2, an electron micrograph¹ at 40,000X magnification illustrates the structure of the crystalline and amorphous phases of the polymer.  Roughly half of the PE is crystalline; the balance is amorphous.  If you had frog eyes you would be able to see the lightly shaded, generally parallel lines that are crystalline platelets.  The darker areas between the crystalline regions are amorphous.

On Frogograph 3, Nano-me is illuminating a representation of a carbon-carbon polymer chain – the squiggly line.  The chains are tightly packed serpentines in the crystalline region and wander randomly in the amorphous region.  Each crystalline platelet is about 10 nano-meters thick, or about 75 carbon-carbon bonds.  The amorphous layer sandwiched between platelets is roughly the same thickness.  The vast majority of diffusion that occurs, does so in the amorphous region, but even crystalline polymers are not impervious to diffusion.

Frogograph 4 shows a 3D-section of two crystalline platelets and an anatomically accurate representation of the tangle of carbon-carbon chains that make up the amorphous cream filling – think about one of those chocolate cookies with the sugary white filling.  In the upper right-hand corner and to the same scale – a water molecule is illustrated.  It is pretty easy to visualize the water diffusing through the intra-molecular spaces of the amorphous polymer.  On the left of the cream filling is a monomer of the aforementioned tolylethylmethyldimethoxysilane or TEM monomer.  Considerably larger than water, the TEM monomer can squeeze through the amorphous layer, but it must bend and rotate tortuously to diffuse.  As we have previously explored in Catalytic Considerations I and Catalytic Considerations II, the monomer reacts with water it encounters, and it grows as it does so.  Nano-me is pushing gently on a typical hexamer.  Six monomers, plus seven waters, yield a hexamer.  Nano-me is encountering a great deal of resistance because of chain entanglement.  If you look closely at the TEM molecules you will notice rings of six carbon atoms.  These rings include what chemist call conjugated double bonds.  This ring structure is quite rigid.  Furthermore, the rings have a two-carbon chain to the silicone backbone and another carbon hanging off the end of the ring.  These structures stick out from the molecule and slow diffusion.  It is a bit like sticking your paws straight out to the side of your body and then pushing your way through a crowd.  Movement is retarded and you are unlikely to make any friends.  These “rude sidearms” were tailored for entanglement … specifically for the rejuvenation application.  The TEM-class of materials is available only in Novinium’s Ultrinium formulations and is protected by U.S. Patent 7,643,977, other pending applications, and foreign equivalents.

TEM is a custom designed molecule for the rejuvenation application.  It has no other commercial uses.  This is in contrast to the legacy class of materials in use prior to the introduction of Ultrinium fluids.  Those older materials, which have dozens of applications and hence were readily available, are not optimized for the cable life extension application.  The molecular optimization included in TEM facilitates a significant increase in post-injection anticipated life or reduces the volume of fluid required for more modest life extension periods.  Longer life through better chemistry!

Encouraging entanglements,

Thermonuclear

¹Kindly provided by Fred Steennis of KEMA in the Netherlands.

AO, AO … it’s home from work we go

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 we failed 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 third of five sub-posts we will explore the role of the anti-oxidants (AO).  Every human knows the benefits of including anti-oxidants in their diets.  I am not as susceptible to oxidative damage, because I keep my temperature lower – that way I do not have to consume foul tasting raspberries and blueberries.  Besides their sickening sweet taste, the antioxidants found in berries are single-shot deals.  A single anti-oxidant molecule consumes a single oxidizer.  What we need for cables is a molecule that quenches the nasty oxidizer and then regenerates itself – indefinitely.  It would be nice for people too, but don’t hold your breath.  For cables the folks at BASF^® and Novinium have a solution.

The primary AO in Novinium’s Ultrinium™ fluid formulations is BASF’s Irgastab^® Cable KV10.  Furthermore all of the components of the Ultrinium UV package have anti-oxidant properties.  These materials were described in To UV or not to UV.  In the vernacular, these UV components are “two-fers” or “two-for-one” ingredients, because they fulfill at least two¹ independent and important life-extension functions.

Antioxidants are included in virtually all modern cable compound formulations.  Originally deployed by polymer compound manufacturers to prevent oxidation during cable extrusion, it has been shown by

Cold blooded and not oxidized,

Thermonuclear

¹Ferrocene and Tinuvin^® 123 are “three-fers.”  Ferrocene is an anti-oxidant (AO), an ultra-violet absorber (UVA), and a voltage stabilizer.  Tinuvin^® 123 is an anti-oxidant (AO), a hindered amine light stabilizer (HALS), and a methanolic corrosion inhibitor.

Flux Weighted Temperature

In my two previous posts (“Why does load matter?” & “Projecting Future Load – Compound Growth”), I used the phrase, “Flux Weighted Temperature.”   Since we coined that term at Novinium, I have an obligation to define it.  In mass transfer, flux is the mass that flows through a unit area per unit time.  In the illustration nearby, the arrows show the flux of fluid through the cable radius as it exudes out of the insulation shield into the adjacent soil.  Exudation flux is the flux at the insulation shield outside diameter¹ and is a one-way affair.  Once fluid hits the infinite dilution of the soil, it is quickly transported away and metabolized by the flora and fauna in the soil.  The cable manufacturers call this exudation flux “sweat-out.”  Certain volatile components may sweat-out of the insulation shortly after the cable is manufactured, leaving beads of fluid on the surface.  Within the field of rejuvenation, sweat-out is not a good metaphor, because the exudation flux is so very small, there is no obvious indication that it is occurring at all.

Flux is a non-linear function (Tech translation:  That means it’s complicated!) of the dynamic temperature profile across the radius of the cable, the geometry of the cable, the materials of which the various layers of a cable are made, and the dynamic chemistry of the rejuvenation fluid.  At Novinium we use a tool, which enjoys two U.S. patents, 7,643,977 and 7,848,912, to provide accurate estimates of the flux.  We call this tool, MFlux.  I introduced MFlux in an August 3, 2010 post, “40-year Life.”

The alternative to a flux weighted temperature would be a time weighted temperature.  Assume for example that a cable spent 12 hours at a radially uniform 40°C and 12 hours at 20°C, the time weighted temperature would be 30°C.  Time weighting would lead you grossly astray, because the exudation flux, while the cable is at 40°C, is almost an order of magnitude greater than the flux at 20°C.  This is because permetion rates change by about a factor of 3 for each 10°C.  If we apply flux weighting to this example the flux weighted temperature would be 39°C [(40°C x 12 hrs x 10 flux-weight + 30°C x 12 hrs x 1 FW) ∕ (12 hrs x 10 FW + 12 hrs x 1 flux-weight)].

It is fortunate that cables do not have a radially uniform temperature profile as in the example of the previous paragraph.  If they did, treatment fluids would exude much faster than they actually do.  In fact, for all direct-buried cables with non-zero loads it is always warmer in the inner portions of the cable than the surrounding soil.  Since the solubility in insulation and shield polymers of fluids in general, and rejuvenation fluids in particular, is greater at higher temperature, the exudation flux is greatly reduced.  This is so, because the exudation flux is proportional to the difference in chemical potential or the fugacity² of the fluid in the polymer.  The fugacity gradient mitigates the inside-out concentration gradient.  Let’s take that in pieces – last piece first.  The concentration of the rejuvenation fluid in the soil around the cable is zero and has some value greater than zero inside the cable.  The concentration gradient provides a second law³ driving force for fluid exudation.  A healthy radial temperature profile reduces the chemical potential in the inner portions of the cable, but the exudation flux must still always be greater than zero.

Only Novinium can calculate the flux weighted temperature.  Only Novinium can use that knowledge to tailor the fluid delivery and fluid formulation to the requirements of an individual cable as described by U.S. Patent 7,611,748.  Only from Novinium can you learn so much from a frog!

Resting on my flux weighted belly,

Thermo

¹If there were a jacket present, the exudation flux would be at the outside diameter of the jacket.

²To learn more about fugacity in cables, check out “Molecular Thermodynamics of Water in Direct-buried Power Cables,” from the Nov/Dec issue of IEEE Electrical Insulation Magazine.

³The second law of thermodynamics provides that entropy of a system always increases.  In common language, systems become more disordered with time – if only it were not so.  The concentration of rejuvenation fluid within a cable is an ordered state, compared to the disordered state of infinite dilution outside of the cable.

Projecting Future Load – Compound Growth

Dear Thermo,

Thanks for your insightful answer in your previous post, “Why does the load matter?”  How important is the future load growth?  Our planning team gives me a range instead of a single value; they suggest 2-3%.  I have sent you some real data for several of our circuits.  Teach me oh webbed one!

Still Overworked in Ohio

P.S.  Steve is actually very helpful once you get used to him.

Dear Overworked- 

Albert Einstein is said to have once quipped, “The most powerful force in the universe is compound interest.”  He was talking about money, but the same principle applies to compound growth of any kind as you shall see if you read on.

Your planners undoubtedly consider whether the geography served by the circuit is mature or whether there is still new development likely.  On top of the growth rate from new services, how are existing customer electrical demands changing?  In general, more and more electrical applications are being deployed, but greener, more energy efficient appliances may mitigate or even reverse that load growth.  Also demand management may reduce peak loads.  I picture the planners pulling out their crystal balls to determine how fast plug-in hybrid cars will be deployed.  These are just a few of the considerations in estimating future load growth.  The impact is huge, so the exercise is well worth considering.

To test that impact, let’s do a sensitivity analysis on a single 3-phase feeder circuit, your Carrollton AM-1215.  Nearby, I have plotted estimated temperature data for the circuit for most of 2010 in 30 minute increments.  The lowest curve on this graph is the ambient soil temperature at cable depth.  The temperature of the individual cables for phases A, B, and C, are displayed as fine red, grey and blue lines respectively.  The flux weighted temperature, that is the equivalent constant temperature that provides the same permeation of fluid through a cable, are the three heavy horizontal lines using the same red, grey, and blue color scheme.  I described this process generally in my previous post and I have promised a future post to examine in more detail what flux weighting means.

The next illustration of three graphs stacked on top of each other shows the extrapolation of the Carrollton AM-1215 data with 1%, 2% and 3% annual load growth.  First allow me to explain the common elements of each graph.  The x-axis is the year.  The red, grey, and blue dashed lines are projections of flux weighted amperage for phases A, B, and C respectively.  All dashed lines are plotted against the left-y-axis.  The corresponding flux weighted annual temperatures are like-colored solid lines and are plotted against the right-y-axis.  The top-most horizontal dashed line (purple) at 603 amperes is the rated ampacity of each cable.  The lower horizontal dashed line (violet) at 469 amperes is the maximum flux weighted load.  Based upon the historical difference between the peak and flux weighted temperatures for all three phases, when the flux weighted current grows to be greater than or equal to the flux-weighted maximum load, the circuit will experience significant thermal excursions above the maximum operating temperature during periods of peak load.

In the top graph of 1% annual growth, the cable is approaching its ampacity limit in the year 2050 – 40 years from now.  All is well.  In the middle graph of 2% annual ampacity growth, constraints are experienced in about 2031 or 20 years from now.  The doubling of the growth rate halved the ampacity-life of the circuit.  In the bottom graph of 3% annual ampacity growth, constraints are experienced in about 2025 or 14 years from now.

Einstein was right – the compounded growth rate is the most powerful force in the universe!  The difference between 1%, 2%, and 3% is bigger than my belly.  For the Carrollton AM-1215 circuit, 40 years of life is simply not possible in the 2% and 3% load growth scenarios unless a portion of its load is transferred to another circuit.

If you don’t expect to keep a circuit in service for 40 years, don’t ask Steve to warrant it for that long.  Ask him for a shorter life and a discount.  The cost of the technology to obtain 40 years of life is more than the cost to reach 20 years.

Compounding my own growth,

Thermo

P.S.  As for me I have never really gotten used to Steve.  His skin lacks any camouflage pattern.  I am pleased that you have learned to look the other way.  I will endeavor to be more tolerant.