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Dielectric IV

June 22, 2012

Dielectric IV

In Dielectric I, I provided the first part of a four-part answer to a query—the summary question: To what extent does the introduction of injection equipment into energized devices impact the safe operation of medium-voltage circuits? We learned that there are great differences in the extent of this risk depending upon the injection paradigm employed. In fact there are three injection paradigms and at Novinium we use only the safest processes. With Novinium’s patented Sustained Pressure Rejuvenation (SPR) there is zero additional risk. With Novinium’s Improved Unsustained Pressure Rejuvenation (iUPR) process the risk is many times less than the legacy approach used by others. The legacy paradigm is called UPR (unsustained pressure rejuvenation). In Dielectric II, I provided data and analysis that showed why the feed end of an iUPR injection is simply not a safety issue. In Dielectric III, I examined the design issues associated with the vacuum tank utilized for iUPR and the features that make iUPR the second safest injection approach, just behind Novinium’s SPR method. Both SPR and iUPR are available only from Novinium and our partners, as these injection paradigms require the application of patented technologies.

Direct answers are provided below. The answers for (1) through (5) are taken from the previous posts.

(1) What is the insulation rating of the fluid(s) that you use for injecting?

Answer:  Several inches of Cablecure 732/733 [Ultrinium™] fluid are enough to prevent substantial leakage current. The minimum amount of fluid between an energized device and a potential ground plane is 36 inches. There is at least a two order of magnitude overdesign.

(2) What is the insulation rating of the hose(s) you use from your canisters to the injection point?

Answer: The AC breakdown strength of the tubing we use is greater than 80 kV.

(3) What is the insulation rating of the canisters themselves?

Answer: The AC breakdown strength of the Novinium’s iUPR feed tank and iUPR vacuum tank is greater than that of the tubing in question (2).

(4) What is the insulation rating for the combination elbow/canister?

Answer: The tubing has the lowest AC breakdown strength at about 80 kV.

(5) Do you have the test data for these pieces of equipment? Will you share the test data with the group?

Answer: Novinium is all about transparency. We will share the relevant test reports with the writing group. The most important data has been provided in the previous posts.

(6, 7 & 8) Have you looked at the electrical separation distance from your canisters to the cover or live bushing? Have you looked at the electrical separation distance from your canisters to ground wires in the equipment? Have you looked at the electrical separation distances from your canister connected to one phase and to the other phases in a three phase installation?

Answer: Of course, all of Novinium’s iUPR equipment is designed to be placed in dead-front enclosures and live-front applications—enclosed and exposed. As you look at the photographs of the iUPR equipment you will notice that they are made up of mostly dielectric materials. There are a few conductive brass fittings, but no conductor length is greater than an inch or two. With that design feature the components can be set into any high voltage environment without having a material impact on safe separation distances. Furthermore the equipment is typically deployed for only 12 to 48 hours.

Summary

Novinium’s SPR method completely eliminates the risks we have been discussing in these four posts. Novinium’s iUPR is a substantial improvement over the older UPR method. The elimination of the soak period reduces the exposure of potentially energized equipment over 60-fold. On the feed side, iUPR equipment is inherently unable to become energized beyond a nominal static charge. On the vacuum side, iUPR equipment is designed to contain within its bowels at least 80 kV. Even with these inherent advantages and engineered safety factors Novinium assumes that the equipment is “potentially energized” and we handle the iUPR injection equipment with hot sticks. With Novinium’s iUPR process we have observed exactly zero occasions where the equipment is energized. Many of the Novinium masters of reliability have over a decade of field experience, some have over two, and have been involved in operations with the legacy UPR process. Those masters have witnessed events where equipment was actually energized. This safety issue with UPR is explicitly acknowledged by the sole purveyors of the UPR process in their U.S. Patent 7,704,087 dated April 27, 2010. Read the patent yourself, or check out the excerpt in my April 15, 2011 post, “Soaking II: Safety First.”

What remains confusing to me is why anyone would accept the risks inherent in the UPR process. I wouldn’t want to be the defendant explaining why I chose the least safe approach. A comprehensive analysis of the safety differences between the various injection paradigms and fluid choices are presented in “A Comparison of Rejuvenation Hazards.”