Catalytic Considerations—Component I
Catalytic Considerations—Component I
In my December 29, 2010 post, the question was asked…
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 …
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 unforgivable. 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. Cablecure iXL [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, Cablecure iXL 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 Cablecure 732 [Ultrinium™ 732] fluid, which not only uses the same state-of-the-art catalyst used by Cablecure iXL, 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 Cablecure iXL 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.
|Short Name||Long name||Comment||Link|
|GA||geranylacetone||voltage stabilizer and PD suppression in Cablecure 732 [Ultrinium™ 732] fluid||Voltage Stabilizers|
|Ferrocene||ferrocene||voltage stabilizer and PD suppression and UVA in all Novinium® fluids|
|TEMDMS||tolylethylmethyldimethoxy silane||silane in Cablecure 732 fluid||ChainEntanglement|
|CBMDMS||cyanobutylmethyldimethoxy silane||silane in Cablecure 732 fluid||Really Long-term Life|
|KV10||Irgastab® Cable KV10||anti-oxidant in Cablecure 732 fluid||AO, AO|
|T1130m||Tinuvin® 1130 monomer||UVA in Cablecure 732 fluid||To UV or not to UV|
|T1130d||Tinuvin® 1130 dimer||UVA in Cablecure 732 fluid|
|T123||Tinuvin® 123||HALS and methanolic corrosion suppression in Cablecure 732 and Cablecure iXL [Perficio™ 011] fluids|
In the meantime check out Cable Rejuvenation Mechanisms: An Update from the 2010 CIGRÉ Canada Conference on Power Systems.