DIS-TRAN Steel Blog

Two ASCE Must-Have References for Transmission & Substation Design

Posted by Brooke Barone on May 29, 2013 4:28:00 PM

Whether you’re a seasoned Engineer or still working on your P.E., there are a few ASCE must-haves when it comes to designing substations and transmission structures.

The first reference, Substation Structure Design Guide, also referred to as ASCE Manual 113, was first published in 2008 and is the first of its kind for substation design. The second must-have is the Design of Steel Transmission Pole Structures, also known as ASCE Standard 48-11.

Now let’s see how good you are…

Do you know the main difference in the two? (Besides the obvious that one is intended for substation design and the other for transmission pole.)

Well, if you said one is a guide and the other is a standard then you are correct! It should be addressed that while guides, standards and codes are all used, there is a difference between them.


There is a level of importance that falls with these, meaning that if a guide contradicts a standard, the standard typically wins, and if a standard contradicts a code, the code typically wins.

The substation design guide is currently being updated along with a handful of other design guides, standards and codes.  Jennifer Gemar, Vice President of the Engineering Department at DIS-TRAN Steel, is on the ASCE 113 Design Committee which is responsible for revising the guide, and has a few updates from the latest meeting that was held in the Houston area last month. 

The plan is to have the revision ready for submittal to ASCE by late 2015.  Since this is the guide’s first time going through a revision, it will remain a design guide with the thoughts that it will eventually become a design standard through enough revisions and time.  Overall, it seems the guide has been well received throughout the industry, especially being the first time published.  It has quickly become a “go-to” book, and a great reference and training tool for newer engineers.  It’s pretty much straight forward, and has general definitions of equipment and types of structures found inside a substation.  The fundamentals are basic, and while it points in the right direction when designing, it doesn’t actually give the formulas to design the steel structures.

 The second book, ASCE Standard 48-11, was published in 2012 as a revision to the ASCE Standard 48-05, that was first published in 2005.  This standard replaced the ASCE Manual 72, which at the time, was the main design reference for transmission pole structures.  The standard outlines the minimum criteria that must be considered in the structural design, fabrication, testing, assembly and erection of these type structures.  Unlike the substation guide, ASCE 48-11 explains how to design steel poles and their corresponding connections.  There is a committee currently updating this standard as well.

It’s important that these references stay updated as knowledge and experience permits.  It’s also beneficial to be active on one of the committees responsible for these updates.  Though it can be hard work, it can also be a very educational with opportunities to contribute and shed light on problems or issues that need addressing.

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Tags: steel structures, DIS-TRAN Steel, transmission, asce manual, asce 113, pole structures, substation design, asce standards, asce, high voltage substation structure design

Wood Structures: Still in the Game or Ancient History?

Posted by Brooke Barone on Jan 18, 2013 2:04:00 PM

While many say “Out with the old and in with the new,” this might be true for hairstyles, tube socks or shag carpet, but with over 130 million wood utility structures across America that are still in service today, this is simply not the case.

Wood utility structures have an undeniable reputation for being reliable, versatile and cost-effective.Wood distribution and transmission structures remain highly preferred in the utility industry due to their ease of construction, climbability and design flexibility.

Wood Transmission Structures

Reliability Wood transmission structures have higher Basic Insulating Levels (BIL), which can help reduce lightning flashovers, cutting down on power outages.

Cost-effective With economical initial costs and low overall life cycle costs, wood can directly reduce the impact of operating expenses.

Safety Since wood transmission structures have been around for decades, utilities and lineman are very familiar with proper use and handling of the products.

Why use wood transmission structures?

  1. Lower cost
  2. Long and proven service life
  3. Adaptable to many different applications
  4. Easy to handle and store the structures
  5. Natural flexibility providing  high performance under load
  6. Can be easily modified in the field
  7. Can be supplied quickly in times of crisis

trans pic green

The general standards that wood transmission structures must meet include ANSI, RUS, NESC, WCLIB and AWPA. And just like steel, concrete and other materials, there are countless configurations for wood transmission structures. 

Just to name a few, there are:

  • Single Pole with Traditional Crossarms
  • Wishbone Structures
  • Two Pole H-Frame Structures
  • Multi-Pole H-Frame Structures

trans 2 green

When considering which manufacturer to choose, you might want to consider their history in the supply of products in the utility market, the location and number of facilities, in-house design capacity, access to raw materials and available inventory for standard items, especially when time is critical. All of these factors could make or break your recovery response when natural disasters strike.

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Tags: utility industry, wood distribution crossarms, wood crossarms, utilities, transmission, wood crossarm, wood transmission structures, wishbone structures, H-Frame structures, wood structures

Behind the scenes look at Substations and Transmissions

Posted by Brooke Barone on Oct 26, 2012 10:29:00 AM

Turning on a light happens within a blink of an eye. But it’s a little more complicated than just flipping a switch. P1020296 resized 600

Transmission and substations work coinciding with one another in order to bring the electricity from the distribution station, into your home.

Transmission lines move high voltage power across the country, while substations basically take the higher voltage down to lower voltages.  Let’s say a 230kV line comes into a substation, the power is then transformed into a lower voltage, or multiple lower voltages, and then carried out by distribution lines into your home or business.

A good way to remember the difference between the two is to think of transmission lines as interstates or freeways, and distribution lines as smaller state or county highways.

There are three components that make up a transmission line:

  • Conductors
  • Insulators
  • Transmission Structures

Transmission structures are typically taller than substation structures because they carry a higher voltage and require a greater phase separation. Transmission structures can be made with either wood, concrete or steel. Lower transmission voltages are more commonly constructed with wood or concrete, while steel is used for higher voltage structures.

Transmission structures are built in a number of different designs, but the two most common that you will see are tapered tubular poles or lattice structures.  Other transmission structure types include:

  • Dead-end                           
  • Embedded
  • Base-plate
  • Tangent
  • Guyed
  • Unguyed

The transmission lines deliver power to transformers, which are located inside the substation. The substation is where the voltage is either increased or decreased. The power is then carried out by either overhead lines or underground potheads. (A device that connects overhead conductors to underground)

The main structures found in a substation are:

  • Dead-Ends
  • Static Poles
  • Equipment/Bus Supports

The circuits are connected by buses, which connects different  circuits within a substation, providing flexibility.  Buses can be made with either aluminum tubing, copper or other materials.

All electricity travels in three phases, or three separate lines, to make up one circuit. It depends on the voltage as to how far apart each line should be spaced. The higher the voltage, the further apart they should be in order to avoid arcing. If the wires get too close to the metal or any object, it will arc, finding the path of least resistance. This is vital with both transmission and substations.

For FREE Steel Sturcture Design Templates, click on the link below!

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Tags: substations, transmission, tapered tubular steel poles, transmission structures, substation structures, distribution line, high voltage, transmissions

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