Looking for URD Design Class or literature

[2banee]

Does anyone have any info on a URD design class or some good literature worth it's weight? I'm a new engineer and I need to come up to speed. Class/text should cover all aspects of design from a utility compmany's perspective; loop feed vs radial, design considerations for locating pad mount switchgears, backup contingency feeders, etc. This is an entirely new city all underground. 16,000 homes, industrial, commercial, schools, etc. Please advise.

 

[jbartos]

Suggestion: Before anyone undertakes this kind of responsibility, one progresses from the Junior Engineer (several years) to Intermediate Engineer (several years) and perhaps to senior engineer (maybe another year or two). Then, one has some proficiency and specialized know-how to undertake this type of mature engineering responsibility. Else, many reworks may be pending.
If you are looking for a textbook, this may be condensed in Standard Handbook for Electrical Engineers, Electrical Power Engineers Handbooks, etc. A visit to technical library could provide a good start since it is not possible to determine what kind of coursework you have taken and what prior experience you had had. Therefore, it may be better to look for book in the library on your own or surf web for specialized trainings on your own.

 

[busbar]

There is applicable material in the IEEE C37, C57 and C62 standards "collections."

 

[SphincterBoy]

You might want to contact the University of Wisconsin, as I am constantly receiving flyers in the mail for power-related short courses. Lehigh University has sent out short course flyers, but not as frequently. I've also seen courses offered by APPA (American Public Power Association). Regretfully, I don't have the links to any of their websites. You can perform a search on Google for these sites and make contact from there.

As far as underground-specific reference textbooks are concerned, I have yet to see a good, comprehensive text.

Jbartos is correct.........don't attempt to layout URD or transmission lines w/o apprenticing first.

Also, you should search this forum for threads relating to which or what type of underground cable to use (XLPE vs. EPR).

 

[2banee]

Thanks to all for your suggestions, wisdom, and knowledge. Unfortunately, due to a sudden death of one of our senior engineers, I'm not able to get the mentoring that I truly need and want. For now, until we can hire another more proficient engineer the ball is in my court. I’m going to have to do the best I can.

As far as what type of materials are approved and can be used we have a standards book that dictates my options. However, you brought up a good question. Our present standards have XLPE as our standard insulated cable. I’ve been approached by sales reps that keep trying to push us to EPR. I thought the cost difference still doesn’t warrant this. Is it really that much better?

 

[electrifire]

In answer to your XLPE vs. EPR the answer is yes to EPR being worth the difference for 12kV and higher systems. It is primarrily because XLPE is more porone to corona and water damage in URD application reducing cable life.

I have seen some good design guides on this subject from REA. These are available through the government printing house. They have a different guide depending on the voltage class being used ie.. 12kV, 34Kv etc. The Navy also has some Technical literature that is fair.

 

[SphincterBoy]

Electrifire is correct: EPR is the best. We use Kerite.

We also (based on experience) spec. 133% insulation level, with jacketed, 1/3 neutral (substation feeders). For URD single phase feeders, we specify full neutral.

If a portion of the cable is inside a conduit, then you'll have to reduce (derate) it's ampacity according to the charts. This may force you to increase the size of the cable.

We also sectionalize long runs (> 1000 ft.) by terminating three-phase main trunks into S&C PME series dead-front (safety) padmounted switches. Bt doing this, we can quickly restore power to 'downstream' areas if a 1000 ft. section becomes faulty or accidentally cut. When sectionalizing long single-phase runs, we use Nordic fiberglass enclosures with load-break junctions (four-point). Just make certain you break up the long runs.

Make sure your padmounted transformers are dead-front, loop-fed types (primary configuration) with Bayonet fuses.

On rubber products, we spec. RTE (Cooper Power Systems) and Elastimold only for elbows, etc.

When we trench, our depth of burial is below the frost line (about 6 ft. minimum). We also make certain there are no rocks, stones, or other sharp objects on or under the new cable. If possible, place sand below and above the new cable. We also place a yellow marker tape on top of the cable to ease future locating of the cable, if the need arises.

Conduit: Underneath roadways or pole risers....use schedul 80 PVC. Everywhere else: schedule 40 PVC.

 

[wilber]

We have some literature at

http://www.electricsmarts.com/catalog/catalog.aspx?rid=5&tid=7

There are also "catlog data sheets " at

http://www.southwire.com

We have both EPR and XLPE
I'm at our technology center not the sales group.