Insulated Conductors Committee

 E4- Minutes

Spring 2008

Minutes of Education Session: IEEE Presentation on Standards Draft Development (Editorial) and the Standards Word Template (Style Manual) & Utility Perspective: Real-Time Thermal Rating Applications for Underground Cables

Chair: Sudhakar Cherukupalli

Co-Chair: Carol Liu;

70 participants


1. IEEE Standards Publishing, Lorraine Patsco, IEEE

Q: What's the process if somebody wishes to expand the scope, how long would it take and is it difficult?

A: You have to revise the PAR and match it exactly and be re-approved by standards committee.

Q: To insert a table or figure, we need to obtain a written permission. What do we do with this written permission? Do we send it in or do we keep it?

A: You send it in.

Q: If some individual has developed some kind of Excel spreadsheet to calculate something not in the process of writing the standards but from an external research project, and that becomes an important aspect of the standard. If that person is a member of the working group, does IEEE demand a letter from this individual or the chair to say it is not copyright material and it is okay to use it in the standards?

A: If that person is a member of the working group, it is part of the agreement in anything resulting for the standards. If the source is not clear, it is better to get a written permission.

2. IEEE-SA Word Template for Working Group Document Development, Jennie Steinhagen, IEEE-SA

Q: When we are revising an existing standard, do we start from scratch or can you give us a document template?

A: You are not required to use the template, but we suggest that you do. We do ask the working groups to put the information into the templates.

Q: When people send in documents written in different versions of Word, formatting could cause a lot of trouble. Does the template strip the existing format of the text when it is inserted?

A: Yes, just copy and paste, the template handles the formatting.

3. Ampacity Evaluation of High-Pressure Gas-Filled (HPGF) Pipe-Type Cables Under Bridgeport Harbor, Mohammad Pasha, United Illuminating Co. & Rusty Bascom, Power Delivery Consultants, Inc.

Q: The number of hours that you predict for fiber optic cables, using temperature sensors, how does that compare to the manufacturers' specifications?

A: The lifetime of fiber optic cables depend on the operational environment. Typically for this case, if you operate the cable at 90 degrees C continuously, you will probably see the temperature of the fiber within the cable at around 60~70 degrees C. Not every manufacturer can warranty or guarantee the cable for 10 years of 70 degrees C operation. In some cases, when the cable is not operating at 90 degrees C continuously, that means the fiber is operating at below 70 degrees C and its lifetime would be longer. However, there is no fiber installation so far that is more than 7~10 years at this moment, so we don't have any proven operational experience.

Q: When you have electrical cable and you've got a failure, you know about it. Do you have any idea when the fibers reach the end of their life (because you are depending on that for reliable and accurate temperature measurements)? Do you have just a general fault and these things stop transmitting?

A: It certainly a function of temperature - at higher temperatures, it would lose its characteristics faster, even if you don't load it fully. You are correct in saying that the characteristics will decay in time, in fact many utilities do not even thinking to use fiber inside their cables for that very reason. So you just rely on what is best available on the market, as we cannot yet predict what will happen.

4. Underground Transmission Capacity Increases from Dynamic Rating Analysis, Erich Schoennagel, CenterPoint Energy

Q: Just a question about the assumption of maximum conductor temperature (lowered to 75 degrees C from 85) - after installing the operating system, you did not raise it back to 85 degrees? And this gives you basically the 20% rise in ampacity?

A: At 85 degrees C, the operating current would be 1035 Amps (static normal rating). We showed the worst-case current is around 1311 Amps, when we have another 138 kV pipe type circuit.

Q: In regards to the ambient soil temperature, it seems kind of low for Houston, what time of the year was that measurement taken?

A: It was taken just about this time of the year, around March. We were out at the substation just last week and it was 21.5 degrees C. On the average, it would be around 25 degrees C.

Q: How does the dynamic normal rating work and why is it changing? Are you changing the load or the earth temperature day-to-day? Is it somewhat load dependent?

A: It is load dependent and it is also load-cycle dependent. In addition to that, it is taking in key input from the thermal couple measurements. That's why you see the dynamic normal rating fluctuate.

Fall 2008

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