Asix-man maintenance crew working for Tennessee Valley Authority (TVA; Chattanooga, Tennessee) invented a new way to support the overhead ground wire while performing energized work. By supporting the static line with a crane's boom tip, workers can now reach taller structures and keep the static line in a more natural position.
The SLL-60 Static Line Lifter, from Diversified Product Development (Waco, Texas), allows a crane to support the ground wire during energized work, which frees up bucket trucks to perform other functions.
The product also maintains the static line's relative position above and ahead of energized conductors. By using the attachment, linemen can then keep the ground wire insulated from the working piece of equipment and minimize the strain on the ground wire when it's moved to a temporary location.
The attachment maximizes utilities' investment in their equipment and requires fewer operators and linemen to be on the job site, says Ray Fritel, president of Diversified Product Development, an engineering firm that partnered with TVA to design the product.
One of TVA's crews discovered a better way to support the ground wire while doing energized work by using a crane truck to support the conductor. John Kile, a transmission maintenance specialist for TVA, turned to the engineering firm two years ago to help transform the TVA crew's concept into a workable design.
During the design process, engineers created 3-D models of different product designs for Kile to review, and Fritel flew to Tennessee to meet with the line crews.
Following beta testing, the engineering firm and TVA finalized the design, and the utility began using the prototype in its three service areas. TVA's 26 crews now use the device when performing energized work.
Installation: A One-Person Job
To increase productivity, the firm designed the attachment so that it can be installed by one worker in less than five minutes. The worker needs to lower a crane's boom tip down to the ground, pin the lifting adapter to the tip, and pin the jib to the adapter.
The three-part design consists of an adapter bracket for the end of the crane, a jib that attaches to the base adapter plate and a line holder. The jib is constructed of continuous roving, filament-wound fiberglass, and the attachment bracket is powder-coated and constructed of high-strength steel. The product's total weight is 95 lbs, and the heaviest component is 50 lbs.
TVA advised the firm to make the product lightweight for two main reasons — to make it easy for a worker to handle and install and secondly, to reduce the load on the crane. Once a crew breaks down the device into three pieces, each component can be easily lifted, which is the reason for the three-part design.
The compact size and light weight allows the unit to be placed in a toolbox, storage container or the service body. Keeping the weight of the product down to a manageable size also helps to ensure workers' safety. The crews work in right-of-way, which can be wet, muddy and slippery. Kile didn't want his workers compromising their safety by lifting unnecessarily heavy pieces of equipment or tools.
After beta testing one of the prototypes, the field crews advised the engineering firm to extend the reach of the lifter by 1 ft. Otherwise, the crews would have to use another piece of equipment to move the static line over to the jib.
The engineers also designed a vinyl-padded cover to protect the fiberglass arm while in storage or in the toolbox. This ensures that the fiberglass isn't damaged or contaminated while it's being transported.
Having insight from an industry professional on a daily basis was helpful, according to Corey Rasmussen, a project engineer who spent two years designing the lifter.
During the design process, Rasmussen wanted the lifter to be nonconductive, have angular adjustments and be able to lift 1000 lbs at 5 ft. To keep the cost of the product down, he also tried to find a way for it to adapt to any crane. While the jib and line holder are designed for universal use, each bracket is designed for the crane model it's mounted on. Each of the four line lifters that were shipped to TVA had adapters for two different types of cranes.
The engineering firm designed the product to help utility companies make better use of their cranes and have more flexibility.
Extending the Reach
TVA's need for a device to support the static line served as a springboard for a line of new products.
When the engineering firm launched the product, utilities requested an attachment that was bigger, longer and had better capacity. The company listened to their requests and is now developing an energized line lifter called ELL 161kV, which has more than 8 ft of reach and 2500 lbs of capacity. The firm is also developing two other versions, and one goes all the way up to 500 kV and 19 ft of reach.
Kile is pleased with the end product, which more than met his expectations. “They came up with an idea to help us, and in the process, they improved the work practices of other crews,” Kile says.
Editor's Note: Diversified Product Development will display the Static Line Lifter at the International Construction and Utility Equipment Exposition show Oct. 16-18, 2007, in Louisville, Kentucky.
SLL-60 PRODUCT SPECS
- SLL-60 1000-lb vertical lift
- Weighs less than 95 lbs
- The attachment's total length measures 60 inches long, and the fiberglass section is 26 inches long
- Tested to 13.5 kV and exceeds the applicable requirements of ANSI A92.2 and ASME B30.5
- The line holder/jib has angular adjustments