Named after a red brick schoolhouse, the Klondike Wind Farm is located in Sherman County, Ore. When the wind farm opened in December 2001, it had 16 turbines producing a peak output of 24 MW. Phase II opened in December 2005 with a peak output of 75 MW.
The Klondike wind farm was placed in Sherman County because of the location’s commercial-grade wind. Proximity to the Columbia River Gorge gives the area Class 4 Wind Power, which is categorized as a “good” potential resource.
The 50 additional turbines that were added in Phase II to harness more of that good potential resource needed to be grounded. Northern Electrical Contracting Inc. was hired to install the ground ring and achieve 2 ohms of resistance.
The Klondike wind farm was sited in Sherman County, Ore., a location that offers commercial-grade wind. Photo courtesy of ERICO Inc.
To achieve the required resistance, the engineering company specified exothermic connections on all below-grade connections. “I think the industry standard for a utility is exothermic because they don’t want to take a chance (on the connections failing),” says Larry Henick, project manager and principal at Northern Electrical Contracting.
For all below-grade connections, Northern Electrical Contracting used Cadweld Plus exothermic connections, a simplified method of performing exothermically welded electrical connections. The connections simplify installation by eliminating the ignition materials. The weld metal is electronically ignited using a simple battery powered control unit with a six-foot lead. Because welds can now be completed up to six feet away, welding in hard-to-reach areas is much easier.
“The connection, if it’s done properly, is a good-looking connection and you know it’s 100 percent,” Henick says. “Occasionally, we had to get back in and do some digging and the backhoe would get a piece of ground wire. We didn’t have any problems with failures on the connections. The cable broke before the connections.”
The easy-to-use system-which “timewise is as quick as a crimp,” Henick says-withstands repeated fault currents without failing during operation. Cadweld Plus exceeds IEEE Standard 837 requirements and makes a permanent, molecular bond that will not loosen or corrode, resulting in a connection that lasts the lifetime of the conductor.
In the past, Henick used compression connections, a competing method to exothermic. “With compression, corrosion can be an issue,” Henick points out. In addition, crimped connections have high start-up costs. “Your outlay [for Cadweld Plus] is basically $90 for an ignitor [control unit] and that’s it, other than the price of the molds and the shot price,” he says. “It can be anywhere from $2,000 to $3,000 for an initial cash outlay to do crimp (compression) connections.”
The combined use of 2,500 Cadweld Plus exothermic welded electrical connections and Eritech ground rods helped Northern Electrical Contracting achieve a resistance of lower than 2 ohms.