To UV or not to UV

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 second of five sub-posts, we will explore the role of the ultra-violet absorbers (UVAs) and hindered amine (pronounced a-mean) light stabilizers or HALS.  The primary UVA is BASF^®’s Tinuvin^® 1130.  Additionally ferrocene (pronounced fair-O-seen), which was discussed in my last post, Voltage Stabilizer, is not only a voltage stabilizer, but also absorbs ultraviolet photons in the appropriate wave length.  In the vernacular, ferrocene is a “two-fer” or a “two-for-one” ingredient, because it fulfills two independent and important life-extension functions.

As you know, frog skin is very sensitive, and so I slather on the UVA (sunscreen) every time I am out in the sun – doing so helps keep me beautiful.  Cables buried one meter underground do not need protection from the sun’s relentless ultraviolet onslaught.  They do need UV protection, however, from UV that is created when space charges recombine near the ends of water trees.  Consider for example the work of Bamji, Bulinski, Chen and Densley in the Proceeding of the 3^rd International Conference on Properties and Applications of Dielectric Materials, held in Tokyo in July 1991:

“… at points of electric stress enhancement in the polymer, the light emitted during the initiation phase of electrical treeing is … due to the recombination of electrons and holes injected into the material.  The spectra of the emitted light is in the visible and ultraviolet ranges.  The ultraviolet light can photodegrade the polymer and lead to electrical treeing.”

It is easy for us all to understand how UVA materials work.  They are opaque to UV light.  The potentially damaging UV photon strikes a resonance stabilized structure in the UVA molecule, is safely absorbed, and is converted to harmless heat.  That’s how sunscreens for our skin work too.  On my skin, if I want to stop 100% of the UV photons I need to apply unattractive zinc-oxide in a thick pasty layer – yuck!  In insulation if I want to stop 100% of the UV photons, I need to apply clay – we call those insulations EPR, EPDM, et al.  So UVA materials cannot intercept 100% of the damaging UV photons.

Unlike the common experience we all have with UVA materials, HALS are not within our normal experience.  HALS are free radical scavengers and they are beneficial, because the mechanism of photodegradation involves the creation of a free radical by errant UV photons – a photon strikes an electron and imparts so much energy to the electron that the molecule, to which it was bound, can no longer hold on to it.  A free radical (an unpaired electron in the molecule) and a free electron are created.  Electrons don’t like to be unpaired, and so, they search out other electrons and try to borrow them from their parent molecules.  As they do this, they tear apart innocent molecules and generally there is still an unpaired electron after the damage from the first encounter.  The free radical survives (or spawns a daughter) and creates cascading systemic damage.  HALS quench free radicals, and here is the cool part, they auto-regenerate to a HALS after they kill the free radical.  How cool is that?  I wish they would make HALS for amphibians, because I could take a HALS pill and snack on crickets all day without worrying about the consequences of free radicals ravaging my DNA.

It gets even better.  The word “synergy” is overused in business circles and promised synergies are often quixotic.  The poster tadpole for synergy is the interaction between UVA and HALS components.  Alone, each has a positive effect on cable life, but together they work better than the sum of their parts – one plus one equals three!  Ultrinium™ 732 and 733 fluids and Perficio™ 011 fluid utilize BASF^®’s state-of-the-art Tinuvin^® 123 HALS.  As we learned in the previous post, DMDB Doubts, Tinuvin 123 also stabilizes aluminum strand patina, which all but eliminates the potential for strand corrosion suffered by older injection technology.  Tinuvin 123 provides another formulation two-fer.

For over two decades, UVA and HALS have been included in TRXLPE (tree retardant cross-linked polyethylene) formulations.  See for example U.S. Patent 4,870,121, "Electrical Tree Suppression in High-voltage Polymeric Insulation,” September 26, 1989.  With the introduction of Ultrinium™ 732 and 733 fluids, Novinium delivers improved UV stabilization using the best available technology.  Novinium’s UV package is protected by U.S. Patent 7,658,808 and other pending patents and their foreign equivalents.  Only Novinium rehabilitation technology provides UV stabilization in the proper UV range.  To learn how first generation technology fails to address the UV photons created by space charge recombination, see Section 8 of the CIGRÉ Canada paper of October 18, 2010, “Cable Rejuvenation Mechanisms: An Update.”

To UV or not to UV, that is the question.  Answer:  Come out of the sunlight into the shade; live longer and with greater reliability,

Thermonuclear

 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 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 Novinium has 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 sub-posts that would explain the functional improvement of the five kinds of ingredients in Ultrinium™ 732 and Ultrinium™ 733 fluids.

In this first of five sub-posts we will explore the role of voltage stabilizers and partial discharge suppressers, geranylacetone (pronounced ger-an-ILL-ass-e-tone) and ferrocene (pronounced fair-O-seen), which are included in all Ultrinium™ fluids.

Ketone-type (pronounced KEY-tone) voltage stabilizers like geranylacetone have been studied in depth by several researchers.  Most prominent among those researchers is Johann Wartusch.  His work culminated in German patent DE 3017442 of August 3, 1983 and is described in his paper “Increased Voltage Endurance of Polyolefin Insulating Materials by Means of Voltage Stabilization” (IEEE 1980).  Wartusch demonstrated that the presence of geranylacetone increased tree inception voltage over three-fold, and due to its affinity for the polymer, it persists in the insulation for many years.

EPRI studied the tree inhibition properties of ferrocene in TD-145 EPRI Project RP 7830-1, “A new class of additives to inhibit tree growth in solid extruded cable insulation” of March 25, 1976, and concluded:  “Ferrocene completely suppresses treeing and increases the breakdown strength of polyethylene by [at least] 100%.”  Kato and his colleagues obtained similar results and the culmination of their effort was U.S. Patent 3,956,420, Polyolefin (pronounced poly-OLE-e-fin) Composition for Electrical Insulation, May 11, 1976.

In short, geranylacetone and ferrocene are proven tree retardants that can each provide 100% improvements in the dielectric breakdown strength of polymers in which they are dispersed.  Both materials persist in treated insulation for decades and both are found only in Novinium^® rejuvenation fluids.  The use of ferrocene in rejuvenation fluids is protected by Novinium's U.S. patent 7,658,808 and its foreign equivalents.  Other patents are pending.

Occasionally in polymeric insulation, free electrons are created by one of two known mechanisms.

1.    Recombinant space charges near the tips of water trees may generate enough energy to knock electrons out of their orbitals.

2.    Cosmic ray bombardment is the second source of ionization energy that can create free electrons.  For a 1 mm³ cavity such ionization is likely to occur every five minutes. (See Boggs, “Partial Discharge in the Context of Distribution Cable Testing”, ICC minutes.)

Whatever the source of the free electron, in the absence of a voltage stabilizer, the electron will almost certainly be accelerated by the electrical field and may inflict damage to the surrounding polymer.  Voltage stabilizers scavenge these free electrons and let them resonate within their structure.  The resonation allows the excess energy of the electron to be bled off in small, non-damaging quanta. (i.e. infrared photons, which do not have enough energy to damage the polymer.)  When a suitable and stable receptor for the electron (most likely a cation [pronounced KAT-eye-on] generated when the electron was knocked out of its orbital) is found, the voltage stabilizer gives up the excess electron and returns to its original state, ready to deal with the next errant electron.

Stable and able,

Thermonuclear

DMDB Doubts

In my December 29, 2010 post at …

Crazy-Competitor-Claims

Wonderer in the Wilderness inquired …

Question 5. A new fluid, DMDB, has been introduced.  Will this improve injection performance on my URD cables?

In that first post I provided an abbreviated answer.  We learned from the abbreviated answer that DMDB is not appropriate for URD cables in particular, because of two inherent inefficiencies.  One inefficiency is by design; the other … well it’s not by design.  I illustrate the first problem nearby.  We call this property of the fluid, “stoichiometric efficiency.”  (Pronounced stoyk-E-O-meh-tric)

Stoichiometry defines the quantitative relationships that exist between the reactants and products in chemical reactions.  When any of the six monomers in the figure nearby react with water they form desirable products and some undesirable by-products.  The percentage of desirable products compared to the total is the stoichiometric efficiency.  The stoichiometric efficiency can be calculated knowing only the chemical composition.  In the graph titled “Hydrolyzate Concentration in Condensate,” this math has been performed for all alkoxysilanes of commercial significance as a function of the number of alkoxy carbon atoms, from one to twelve.  The six globally significant alkoxysilanes are each illustrated on the figure and their positions within the hydrolyzate concentration continuum are pinpointed.  The table nearby defines the acronyms and provides commentary on each monomer.

Methanol, a one-carbon alcohol, is an undesirable by-product of the first three fluids, which are generally deployed in small diameter URD cables.  At very high operating temperatures (i.e. conductor temperatures above 55°C), methanol can corrode aluminum.  Fortunately, the methanol generally diffuses out of the system very quickly and small diameter cables do not routinely experience 55°C conductor temperature.  As a consequence the risk of methanolic corrosion is quite low in applications where these fluids are properly deployed.  All Novinium fluid formulations include Tinuvin^® 123, which stabilizes the patina on aluminum strands and further reduces the risk of methanolic corrosion.  Patina (pronounced pa-TEE-na), is the natural corrosion resistant coating that forms on metals such as aluminum.

To address methanolic corrosion in larger conductor cables CableCURE^®/DMBD fluid was introduced.  DMDB’s undesirable by-product is butanol, a four-carbon alcohol.  The good news is that butanol is unlikely to cause aluminum to corrode; the bad news is that it comes at the price of stoichiometric efficiency.  In the figure nearby, I have circled in blue the portions of the silane monomers, which yield undesirable by-products.  For the DMDBS monomer, about two-thirds of the molecule provides no benefit to the cable.  Because of its low stoichiometric efficiency, you won’t find this frog suggesting that it be used for small diameter cables – especially when there are much better solutions in wide commercial application.

How about larger conductor cables?  Does DMDB do the trick with those?

In the 1980’s the guys at Du Pont discovered that alcohols with 6 to 24 carbon atoms are “tree growth inhibitor[s] capable of imparting at least a thousand-fold increase in electrical endurance as measured by an accelerated test procedure.” (See U.S. Patent 4,206,260.)  In the figure nearby my green laser is pointing to a lightly-green-shaded region of the graph that falls within the Du Pont discovery.  Instead of undesirable by-products, these longer-carbon-chain alcohols are superb dielectric enhancement fluids.  In other words, with Novinium’s Ultrinium™ 733 fluids there are no undesirable by-products, and hence the stoichiometric efficiency is 100%.  Like the 4-carbon alcohol by-product of DMDBS, the 8-carbon alcohol will not corrode the aluminum.  High performance – no compromises!

Finally, to get the total efficiency, it is necessary to consider other efficiencies including catalytic efficiency.  In my January 3, 2011 post, Catalytic Considerations – Component I, I shed some frog wisdom on that subject.  There is also a technical paper in the Novinium library titled Considerations for Injecting Cable with High Conductor Temperature, which provides even more detail.  The bottom line is DMDBS is definitely not appropriate for small conductor URD cables.  For large conductor cables the best choice is Ultrinium™ 733 fluid which enjoys 100% stoichiometric efficiency and a much higher catalytic efficiency.

Always state-of-the-art,

Thermonuclear Bull Frog

Catalytic Considerations – Component I

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 the previous post, I provided an abbreviated answer; in this post I will provide a more comprehensive answer.  We learned from the abbreviated answer 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 chose to provide long life.  In the figure nearby, I show diffusion data that demonstrate that the monomer diffuses about six times faster than the catalyst.  I also show two-dimensional scale representations of these two molecules.   From what we learned in Size Does Matter, one can see that the larger and less flexible titanium(IV) isopropoxide (TIP) molecule would diffuse slower than the PMDMS and it does.

This diffusion mismatch was a tragic mistake, because the monomer does not condense to a longer molecule in the absence of a catalyst.  As a consequence, a substantial portion of the PMDMS diffuses out of the cable shortly after injection without adding to the long-term reliability of the cable.  In fact, about 39% diffuses out prematurely.  This premature exudation is caused by catalytic inefficiency.  We cleverly fixed that problem with U.S. Patent 7,700,871, and I will explain the elegance of that solution in a subsequent post in this series …

Catalytic Considerations – Component II

It isn’t just how much fluid is delivered to the cable strands.  Even more important than the fluid quantity injected are:

1.    The amount of fluid that persists in the cable insulation over its post-injection life, and

2.    The capabilities of the molecules that are delivered to …

a.    interfere with the growth of water trees,

b.    interrupt the conversion of water trees to electrical trees, and

c.    disrupt the inception of partial discharges.

However, it is true that when using Unsustained Pressure Rejuvenation (UPR), more fluid can be delivered into the cable strands with longer soak periods.  Novinium is not dead-set against soak periods.  We employ soaking for special cases.  For example, we sometimes employ a soak period on submarine cables with constrained geometries.  A soak period, however, to compensate for a catalyst error is unforgiveable.  Soak periods compromise safety and operational efficiency and should only be utilized where technical or economic considerations preclude the use of sustained pressure rejuvenation or for unusual cases such as the aforementioned constrained geometry submarine cable.  The figure nearby provides a summary of laboratory measurements of the amount of PMDMS fluid that is supplied during a typical 60-day soak period for 1/0 AWG and No. 2 AWG cables.  Each experiment was performed in triplicate.  The amount of PMDMS provided during the soak period is about the same as the amount of fluid lost from catalytic inefficiency.  Perficio™ 011 fluid uses a patented catalyst system that enjoys a 2% catalytic inefficiency compared to the 39% inefficiency suffered by the TIP catalyst.  Therefore, Perficio fluid delivers about the same amount of active ingredient in the cable insulation without a soak as the older technology delivers with a 60-day soak period.

An even better option is to use Ultrinium™ 732 fluid, which not only uses the same state-of-the-art catalyst used by Perficio, but also includes five other ingredient types (both water reactive and not water reactive), which all increase cable life well beyond that possible with the venerable PMDMS fluid utilized in the Perficio formulation.  In future posts, I will examine each of these ingredients in more detail to shed light on how they function to extend cable life.  The table nearby will be updated to provides the links to the post for each of the five ingredient types.

In the mean time check out Cable Rejuvenation Mechanisms: An Update from the 2010 CIGRÉ Canada Conference on Power Systems.

Smarter each day,

Thermonuclear