Transmission crew replaces 2,500-pound crossarms to improve system reliability.
Working on a live circuit demands certain safety precautions, but it can help to ensure the reliability of the electric system. On a recent project, Ameren (St. Louis, Missouri) linemen demonstrated how they could improve the security of the transmission system, minimize risk of customer load interruption and safely get the job done.
This summer, Ameren replaced the crossarms on 17 H-frame structures while the 138-kV line remained energized. According to the seven-person crew, Ameren is the only utility performing this type of job while the line is hot.
The linemen replaced some crossarms that were broken. Others were being replaced because of age and the weather had weakened them. The crossarm replacements were needed to keep the structures safe and the lines reliable.
From late August to mid-September, the crew led by Ron Politte, supervisor, replaced the 34-ft-long, 2,500-lb crossarms at the rate of one per day. Attached to the crossarms are three insulator strings each holding two conductors. Politte estimates the weight of each phase is nearly 1,500 lbs.
“I came up with this system of changing crossarms and poles while keeping the line energized about 15 years ago,” Politte said. “We've changed lots of crossarms and poles since then. This job is harder because we have two conductors per phase so it is heavier.”
The job is difficult for several reasons: the line is energized, the crossarms and phases have a significant combined weight, the clearances are tight, and the right-of-way runs through a neighborhood in South St. Louis County.
Journeyman linemen Ken Carroll and Ted Walsh worked from one pole while apprentice Nick Beilsmith and journeyman lineman Jeff Fleming worked from the other. B.J. Volz and Jorden Drummond operated the two cranes that were brought in for the job.
Volz operated the crane holding the temporary fiberglass crossarm with the hot phases so service from Meramec Plant to the Watson Substation to the Ringer Substation was uninterrupted. Drummond manned the crane that removed sections of the old H-frame. The linemen on the poles used chain saws to remove the broken crossarm. The second crane also moved the new crossarm into place.
“It's more involved to take the old crossarm down only because we're taking it down in pieces,” Carroll said. “When we take the new crossarm up, we're taking it up as one complete unit.”
Lineman Bill McAllister worked the ground for the crew. As the crew on the H-frame called for hotsticks, slings or drills, McAllister gathered the necessary items and worked the hand lines to hoist the items up.
The rigging in transmission was the most important part of the job because the linemen were dealing with so much weight and trying to make everything fit perfectly. Two of the linemen had to piece the arm with chain saws in a very precise manner to make it work. They also had to use the boom to remove the arms rather than letting them fall down to the ground. When it got into the energized phase, this would have posed a hazard for the linemen on the pole.
It took the linemen about 45 minutes to transfer the phases to the temporary fiberglass arm and remove the old crossarm. About 35 minutes after the transfer, Drummond carefully maneuvered the new crossarm in between the phases. Nearly two-and-a-half hours after the linemen made their way up the two poles, Fleming and Beilsmith used hotsticks to pin the last of the two phases into place on the insulator.
Focus on Safety
For the seven-person crew that worked the job energized, completing the job safely was the top priority. If something happened, the line would have stay locked out for the safety of the crew.
The transmission department prides itself on doing all jobs safely and also helping to ensure reliability and minimize power interruptions.
“If we didn't do this job energized, Meramec Plant would have to do some switching just to transfer all this power to somewhere else,” Politte said.
Brian Bretsch works for the communications department for AmerenUE (St. Louis, Missouri). He wrote this article for his company's publication, the Ameren Journal.