Raising the Roof: Device Jacks High Wires
January 29, 2014
A new system to increase the capacity of transmission lines is being used for the first time by members of Syracuse, N.Y. Local 1249.
The Ampjack is a portable set of hydraulic jacks that allows a small work crew to increase the height of transmission towers without disrupting power flow on the high-voltage lines they carry. Utilities raise tower height to increase a power line’s ground clearance, either to put it in compliance with regulations or because they want to increase the amount of energy they send through a line, which can cause a line to sag more. Traditional methods of increasing tower height were much more expensive, required power to be turned off and were often impractical in remote areas.
Since October, an eight-man crew working for Northline Utilities has been jacking up 13 double-circuit towers between seven-and-a-half and 15 feet. They’ve been using a tool called the Ampjack --invented by Luke Chaput, formerly a member of Winnipeg, Manitoba Local 2034—that puts the work crew entirely within the column of the tower, far enough away from the wires that they can remain energized.
By attaching the lattice frame to four hydraulic jacks, they can cut it free from the base and slowly raise the nine-to-11-ton towers up to 5 feet at a time. A new level of lattice work is built into the gap and the process is repeated until the tower reaches the desired height. Because the crew stays inside the tower stack, the transmission lines never have to be deenergized.
“Raising towers was a pretty common job to be called out on,” said Chaput who was a journeyman lineman from 1988 to 1998. “We’d have to bring in a crane, de-energize the wires at the substation, lift the tower with the crane and then build a new base for it.”
High-voltage wires always have slack built into the run between towers to let the wires expand and contract as their internal temperature is changed by air temperature and the amount of electricity flowing through them. Hot summer days and higher electricity flows heat wires up, increasing sag. Regulations in the U.S. and Canada set minimum clearance heights to prevent lines from snapping or snagging on trees, leaving a live wire on the ground and a cutting off power downstream.
If a line sags too low, or regulations tighten and older lines towers don’t meet the standard, often the simplest solution is to use the existing towers and, in effect, put them on stilts. Companies also raise towers when they want to increase how much electricity flows through a line. That raises the line’s internal temperature and can cause lines to sag more.
When Chaput went back to school to get an electrical engineering degree, some of his first jobs were designing transmission upgrades he used to work.
“If everything is right, you can increase capacity by 30 to 40 percent using the existing lines,” Chaput said.
But he soon found that everything was rarely right. In remote, hilly or heavily wooded sites -- of which there are many in Canada – using a crane wasn’t practical. It was also expensive and left the utility scrambling to make up for the lost transmission capacity. Chaput set out to find a better way, using equipment small enough to fit on the back of a truck, but robust and flexible enough to handle the variety of tower shapes and locations.
His answer has evolved from an idea into a company and, a decade later, the Ampjack system has left the prototype phase.
“We’d done tower raising from time to time in the past and more of them recently, but it was such a process. This this is a whole lot slicker,” said Bill Boire, business manager of Local 1249. “The guys who were working on the job were real proud to be doing something that’s never been done before.”
When a tower is finished, the Ampjack is taken apart and moved to the next tower. It can be moved by truck, skid loader or, if access is extremely limited, by helicopter.
“It’s cool stuff. It’s so small, not a lot of machines, but real labor intensive and requires very skilled linemen,” said Ryan Youngman, assistant business representative for Local 1249. “This is a great demonstration of what the IBEW is capable of.”