Switching industries-moving to Transmission & Substation 1

[oengineer]

Hello,

I am a structural engineer with oil & gas experience designing refineries (steel structures & reinforced concrete foundations). I recently got a job in the power & utilities (EHV) industry working as a civil/structural engineer for a Transmission-Substation department.

I wanted to get some information on structural engineering for Transmission & Substation work. Has any one else made this switch from oil & gas to power & utilities (EHV) industry? If so what are the similarities regarding the structural engineering? What are the differences between the two industries?

I have found some information regarding foundation design for transformers but not much else. I am also aware of a program called LPile, but i have never used it before. In oil & gas I used STAAD quite often.

Are there any books, websites, or any information that would be helpful for someone new to this field. I am just wondering what type of information I should be looking into to hit the ground running. Any comments or suggestions in the right direction would help.

 

[BUGGAR]

ASCE has substation design guides. If you are in earthquake land, electrical equipment generally has to be seismically qualified so you will know the equipment periods, etc. to plug into your staad dynamic model (at least SDG&E uses Staad seismic dynamics). LPile is great (my opinion). Wear wool shirts at the substations, learn about monopoles, take a Valmont salesman to lunch, and take a Valmont salesman out to lunch.
Structurally, we designed to IBC, AISC, and ACI.
Design your baseplate with double nuts and no grout below (make sure there is 5/8" or less of bolt between concrete and nut and you can ignore anchor bending. Don't forget to design your baseplates with drain holes cut into the corners so someone here has something to write about. Galvanize everything, no field welding. And if they send you out to wash insulators, that's not a joke.

 

[Lomarandil]

Also look into the RUS guide (

http://www.rd.usda.gov/files/UEP_Bulletin_1724E-300.pdf).

That's a good overall primer. I also picked up a copy of the Standard Handbook for Electrical Engineers (old editions are fine,

http://www.amazon.com/gp/product/007020974X?psc=1&redirect=true&ref_=oh_aui_search_detailpage)

when I was just starting out. Helped me understand some of the basics of what the sparkies wanted.

Typically, we designed anything outside the substation fence to loads from the NESC (very similar to ASCE 7-05, in terms of design philosophy, but with some extra provisions), and anything inside the fence was ASCE 7/RUS. Structural design provisions per AISC/ACI/RUS.

For transmission lines, you'll probably be working with (or having someone model for you in) PLS-CADD. Not just a CADD program, the different modules will help with analysis, etc too. Very powerful for an advanced user, but I always found it to be a bit of a black box. Of course, many of the transmission poles and towers will be actually designed by the manufacturer. Don't expect to have to design a lattice tower from scratch.

Lpile is great for complex deep foundations, although if quick and dirty you might want to look into Broms' method for hand calcs. You'll have a good number of shallow foundations inside substations of course.

Definitely all steel will be galvanized (so bolted connections, as Buggar mentioned), and use closed shapes wherever possible -- keeps the birds from nesting and accumulating debris.

Side note: Buggar, have you seen that 5/8" codified anywhere? Or just a rule of thumb? I couldn't remember where to find it recently.

 

[BUGGAR]

Sorry, it's 5/8 times the diameter of the anchor. I think it's in the ASCE guide. I'll try to find it because the guide is also an excellent reference for designing concrete anchors based on non-contact lap splicing with dowel bars.
I have a whole library of bird screen details - what utility cadd operators work on when not busy.

 

[oengineer]

Thank you Buggar & Lomarandil for your post. They have been very helpful.

I was told that I will be using STAAD. I assume it is for the transmission and substation structures. I am not familiar with the structures used in substations.

Also do either of you have any information/recommendations regarding the use and design of Hilti bolts for Transmission & Substation foundations? What programs are used for Hilti bolt design.

Since grout is not used for base plates, does this mean that the design of the base plates differ greatly from the AISC Base Plate design guide?

How much interaction does the civil/structural engineer have with the electrical engineers? In oil & gas I never really interacted with the Process/Chemical Engineers.

Have either of you been in this industry for a long time? If so how stable is it? How is it in terms of compensations and career growth/opportunities?

 

[BUGGAR]

I can shoot you a set of the Sampson Street Substation structure I did for SDG&E here in S.D. (Yes I have an agreement). It's twelve pages but I have to figure out how to attach it. Zip O.K.?
Electrical structures are nice because there are no Architects involved, just pure function. There's no electrical magic - the electrical dudes give you the equipment data sheets with the seismic data and anchor bolt layout and you just plug and chug. Most of the stuff I did was pretty simple but you can get some great seismic situations with the stuff electrical guys like to stick up in the air.
Google Earth, Sampson Street, San Diego and take a look. I did the handsome one.

 

[Lomarandil]

Exactly right. Electrical engineers will determine the equipment needed and a general layout. You will probably collaborate to determine spacings, height of bus , etc. After that, very much plug and chug.

Most substation structures are simply poles or frames meant to hold a piece of electrical equipment at a specific height (to have adequate clearance to the ground or other structures). All based on the voltage -- higher voltages require larger air gaps for insulation. You'll also have dead end structures (which take the lines from a transmission structure, and therefore have to carry a lot of horizontal tension), lightning protection (very tall to attract lightning), and generator pads (mostly straight forward, but you may need to design it for oil containment). Generators are getting so difficult to replace that I've also seen walls and structures built to protect them.

Hilti has a software package called Profis. Black box, but widely used. Otherwise, hand calcs using manufacturer's tables. I didn't see too many Hilti's being used though, I didn't do a lot where a post-installed anchor was needed. We used a lot of newly cast-in anchor bolts.

I've not used the AISC base plate guide. But I suspect it's different, yes, because all the load is transferred through the bolts. Simpler, I suspect.

I was only in the industry for about a year before my wife's career required a move. But many of my friends are still in it. The compensation is good, higher than most civil due to rubbing elbows with the highly paid EEs (probably similar to O&G). Lots of demand -- I still get calls pretty regularly asking if I want to go back to power. The industry is going through a huge retirement spike right now (even more so than other areas of engineering), so that can increase opportunities for advancement.

 

[BUGGAR]

I haven't worked on it for a while but Staad was compatible with Risa - Excellent! I may have my old Staad files for Sampson but it was under the '97 UBC. It showed how we modeled insulators (I forgot why but we had to make assumptions for some reason).
With SDG&E, their substation engineers (electrical and structural) got to go out and deal with the Contractor, which is good training; they point out your errors faster than your boss can.
SDG&E being investor owned was very tight and everyone always worked on yesterday's AutoCAD. Their Staad was old but still Code current. I was a consultant to them so I don't know how they paid their employees. They did all they could to avoid building permits (ref.: helicopter landing pads for the Sunrise Power Link), but that's not unusual.