SMUD personnel X-ray high-voltage lines while suspended from a helicopter

Transmission Line with Blue Sky and Clouds

SMUD’s high-voltage transmission lines, in Sierra, deliver large amounts of power from SMUD’s hydroelectric facilities to SMUD customers. Critical to the lines’ capability are the splices that enable the lines to be continuous. As transmission lines are strung or repaired over time, the splices–tubular metal sleeves that connect long sections of conductor–can degrade and fail. A fault can significantly impact the electrical system, potentially leaving thousands of customers without power. Failure of splices can also lead to unsafe situations especially if a line would separate and fall.

To find potential faults, a SMUD line worker can use portable X-ray photography to inspect these major transmission lines even suspended in a chair connected by a long tether to a helicopter. Simultaneously on the ground, a crew can look at the live X-ray pictures and data and can identify any potential problem immediately. The worker can then assign it for prompt repair to prevent future failure.

SMUD has been using this technology for several years, covering transmission lines from across its territory.

These high-voltage lines are strung atop high lattice-style towers. Maintenance and repairs on them can involve a lot of work, sometimes more than one hundred feet above the ground.

The work is part of many ongoing SMUD grid projects to improve and enhance safe and reliable power delivery. The transmission lines in El Dorado County deliver power from the SMUD’s Upper American River Project (UARP), the huge system of hydroelectric power plants in the Sierra. The UARP’s nearly 700 megawatts (MW) of clean power can provide about 20 percent of SMUD’s power in a normal water year, which can be crucial especially in summer months when market power is more expensive.

“This work is part of our ongoing year-in, year-out maintenance to harden the SMUD grid,” said SMUD Chief Energy Delivery Officer Frankie McDermott. “This tool enables us to see issues that could lead to line failure and power outages, or worse, a compromise in the safety of our infrastructure which we dutifully work to prevent.”

SMUD uses a line worker suspended from a helicopter to take X-ray photos of splices that bind high-voltage transmission lines in El Dorado County. Simultaneously, a crew on the ground views the X-ray photos and data live to promptly identify any potential problem immediately so it can be repaired. The work is part of SMUD’s annual maintenance work to harden the SMUD grid to enhance electrical safety and prevent power outages.

The main focus for DISTRIBUTECH+‘s November Series is Grid Resiliency: Planning and Response. Register for the sessions here so you don’t miss out!

Previous articleAmeren and EPRI showcase 10 energy startups during “˜Demo Day’
Next articleCalifornia braces for renewed fire threat from windy weather
The Clarion Energy Content Team is made up of editors from various publications, including POWERGRID International, Power Engineering, Renewable Energy World, Hydro Review, Smart Energy International, and Power Engineering International. Contact the content lead for this publication at

No posts to display