jueves, 11 de octubre de 2007

Is live-line work with non-ceramic insulators safe?

When considering worker safety, the power industry very seldom develops any earth-rattling technology. Rather, gains seem to be relatively small, such as taller manlifts with handier jibs, or hand tools that can make the lineman's job easier and safer.
For years we've had test instruments and standards that help perform live work tasks on or around ceramic insulators. When it comes to non-ceramic, or polymer, insulators, there is no commercially available instrument to field test energized NCIs and no standard to test by.
How can we spot an imminent failure?
If we don't have a tester or a method to identify the electrical and/or mechanical integrity of an NCI before working on or near it in an energized state, how do we then know that when the electric field is disturbed when tools or men are placed in the electric field, the NCI will not fail?
When this subject was first discussed at an industry meeting about a year back, I was rather surprised at the broad spectrum of approaches taken when working on energized NCIs. The live line safety coordinator of a large utility in New Jersey was asked how they treat NCIs when doing barehand work.
He said, "If they [the insulators] visually look all right then we go ahead and perform our work. In fact, we have done this for a long time."
Rethinking work practices
When I pressed him a little more and asked him how he knew they wouldn't fail at that precise moment when workers disturbed the electric field, he thought a little bit and said, "We may have to rethink our policy on this issue."
No longer does this large utility assume that NCIs will not fail at the moment in time that the electric field is disturbed in live work situations.
At the panel session I sponsored on this subject at ESMO in Orlando, the senior work methods specialist from California's largest utility stated that he felt strongly about not working on NCIs under energized conditions "because you don't know the condition of the insulator like you do when you test and work on ceramic insulators." But he added, "System demands for no outages were making it difficult to keep this policy of 'no energized work on NCIs' enforceable."
I talked to a former craft supervisor, who is now a field division director of a large Midwest utility who put it in these terms: "Addressing the t-line constraints we are dealing with today and tomorrow—coupled with the fact that these insulators are not electrically tested from the manufacturer, and the fact that we will not ask our craftsman to work on polymer insulators under energized conditions without positive proof test indicating the insulator integrity—limits our ability to respond to specific kinds of outages. This lack of live-line maintenance capability could severely reduce our system reliability and greatly increase our outage requirements."
All these people are very familiar with barehand and hotstick procedures. In fact, they are experts in the field, and I for one listen to what these guys have to say!
Weighing trade-offs
So where do we go from here? There are two main questions that the electric industry needs to address concerning NCIs and live work. One concerns the apparent advantages of NCIs—lightweight, easy to install and good for areas of high contamination. Are they worth the apparent disadvantages—the inability to test in an energized state, difficulty of cleaning under energized conditions and susceptibility to handling, storage and installation damages?
The second question is whether we as an industry, with the help of insulator manufacturers, are willing to step up to the issue and do the research necessary to overcome the disadvantages and reap the rewards and advantages of NCIs. We may also ask if we, the workers, are willing to take a stand and refuse to perform work under energized conditions on or near NCIs.
One firm is doing research that may produce a field tool for identifying mechanical defects on energized NCIs. Another has done some promising work using thermography techniques.
EPRI has a project looking at developing a field test tool. This research is now looking at shunting a portion of an in-service NCI and reading leakage current. In some ways, this approach is similar to today's ceramic insulator tester. The Positron tool is available and has been used with some success.
From what I understand, all these technologies are promising in their own right. But none seems to be the answer that field staff will accept as they have accepted the insulator tester used by utilities to test ceramic insulators.
What's next?
So, where should we go from here and where do the responsibilities lie? I firmly believe we will gain by continuing research to find a practical way to test and or identify NCIs for safe use in live work. I also believe that the industry has a responsibility to its employees to reduce potential risks.
The manufacturers, the utilities themselves and the people asked to work on these insulators should band together and develop the standards to promote a
safe work environment around in-service NCIs. This is a slow process. Today only a handful of utilities are participating in any research or creating standards for safe work practices.
I encourage each individual to take an active role in contributing something to research, standard development or new ideas for testing. We all have a responsibility for safety to ourselves and our co-workers. If nothing else, I hope I have raised the awareness to a need that may take years to answer.
Let me leave you with two final questions. First, are we as an industry ready for the technology that has been presented before us in the form of NCIs? If the answer is yes, then are we—the people required to work on these insulators—willing to demand that the manufacturers and the utility companies develop the technology and work methods to create a safe work environment for the people in the trenches?
Remember safety is everyone's responsibility. We owe it to our families to return home in one piece every night. Don't take shortcuts. Often, it's the unknown that gets us in trouble.


(Note: Ed Hunt is a foreman III in the RM Region. The views in this article are those of the author and do not necessarily represent his organization or Western. This article was originally prepared for submission to Transmission and Distribution. The Closed Circuit welcomes letters and articles on issues of interest to our employees. Send your submissions to Corporate Communications.)

martes, 9 de octubre de 2007

Qué podemos hacer?

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