Transmission Insulators 2015 Year in Review

2015 showed continued growth in Transmission including Transmission Insulators (TI). The outlook remains strong for 2016 and MPS is well positioned to see continued growth from investments in both equipment and people. With the addition of a Project Manager and Transmission Specialist in 2015, MPS strategically used advantages with:
• New Line Post designs
• High Strength designs for compact line applications
• Integration of Toughened Glass insulators to the MPS Transmission product family
• Testing and product development

New Molding Presses
MacLean Power added new state-of-the-art injection molding presses to improve efficiency and capacity within the molded Line Post line. Injection molded insulators continue to be MPS’ largest volume family of products covering intermediate to high strength applications from 46kV – 230kV. Standard lengths are molded in volume and stocked to provide customers with consistent lead times and allow MPS to respond to larger spikes in volume.

The Transmission Team has worked closely with customers on specification reviews adding new MPS designs to standards where applicable. Modular constructed insulators continue and allow us to expand for engineered solutions, heavy leakage, and higher strength EHV applications.

High Strength Mechanical Applications
The transmission marketplace continues to change and evolve with many customers shifting to more compact line designs. By using tubular steel poles and line post or braced post insulators, the user can reduce the line corridor size and visual impact, while maintaining or increasing strength performance. MPS has taken a leadership position in this application through extensive mechanical testing, refinements in multi-axis performance charts and ability to present detailed mechanical data in a usable format. Special yoke designs for bundled conductor and bases that transfer more of the load to the structure allow full utilization of the strength properties of fiberglass core material. With accurate and detailed mechanical data, line designers can optimize structure heights and placement. Longer spans with fewer structures or shorter pole height have huge impact project costs where poles and conductors account for the largest portion of project material costs.

MPS extra high strength (3.5″ core) braced posts were supplied on several renewable projects in 2015. A major investor-owned utility is doing their first full scale (30 mi) 345kV line with MPS braced posts.

Toughened Glass
2015 was the first full year of having toughened glass insulators. Many customers select TG due to reduced maintenance and long mechanical performance record for certain applications, in some cases, applying a mix of polymer and glass on a single line. MPS is the only supplier to the industry that can offer a complete package of ceramic and non-ceramic insulators along with all of the string hardware and conductor attachments. This allows MPS to provide a complete package where customers are assured of proper fit and function of material to operate as a system. This year, MPS gained approvals at six of the largest utilities in the country, and supplied to a range of customers’ numerous projects, most recently, a 60 mile 765kV project that begins construction in Indiana in 2016.

Testing
As the “new guy” in glass insulation, MPS has had to demonstrate product performance through extensive testing. Even with complete testing to ANSI C29.2B (2013), many customer standards have additional testing requirements to weed out weaker designs. Although there were already three suppliers on standards, MPS was the first supplier to complete AEP’s updated disk test specification. Over a month, all four strength class designs were subjected to a series of mechanical and electrical tests including steep front, which hits disks with a voltage rise of 2500kV per microsecond. Testing also required surviving a drop to the floor that went from 2 to 8 feet as well as heat cycle testing from (+70 to 30 C). Visible corona and radio interference voltage (RIV) testing is currently ongoing for MPS 765kV designs.

Technology
New molding equipment is a very visible use of new technology. MPS has also enhanced their electronic field modeling capability with the addition of a new computer using Coulomb Software. E-Field models show detail of voltage stresses on insulators and hardware and can replicate field conditions showing influences of tower clearances and other phase positions. This is a key design tool to quantify corona free designs and shorten development of grading devices used on EHV.