The second challenge with monitoring power cables involves the type of sensor that’s used. Mamishev suspects that a combination of sensors can find problems in cables better than one single method can. Therefore, his team’s robot includes a thermal sensor to locate hot spots; an acoustic sensor to locate the quiet snap, crackle, and pop of sparks from a partial electric discharge; and a dielectric sensor to measure the presence of moisture that may have seeped into the insulation. In addition, the robot has a video camera so that its progress can be monitored remotely.
Mamishev and his team recently took the robot to New Orleans to test it at Lockheed Martin’s Michoud NASA Assembly Facility. The goal was to find damage that could have been caused by Hurricane Katrina, as salt water from the floods can seep into cable insulation. They did not find damage in the facility’s wires. However, this first field test was a good proof of concept, Mamishev says, and the robot successfully navigated three miles of cable.
The researchers’ “technology looks very exciting and promising,” says Dave Hawkins, project manager for the integration of renewable resources at the California Independent System Operator, a nonprofit organization that manages the majority of the state’s high-voltage power grid. The robot could “improve electrical reliability by identifying cables that have reached the end of their useful life,” he says. “By forecasting potential failures, cables can be removed from service in a planned way,” saving time and money.
EPRI’s Von Dollen says the research is on the right track to tackle part of the industry’s cable-monitoring problem. “It’s an interesting approach,” he says. However, because the robot sits a few inches taller than the pipes, it might have a difficult time navigating the tight spaces in the ducts and pipes where some cables are housed.
Mamishev says that the robot has the potential to shrink down to a height of about one inch, but no thinner. Yet even at three inches, it can still crawl unimpeded along a number of underground cable systems, he says.
In the coming months, the researchers plan to replace the current rigid stabilizers with new ones that are flexible and adaptable. Then, if the robot encounters a tight space, the arms can bend out of the way; if it tips, the arms can right the robot more precisely. In addition, Mamishev will add more batteries, perhaps by adding more segments to the robot train.
The robots have the potential to be commercialized relatively soon, he says. However, the timeline would completely depend on the interest of commercial partners. “If we had good partners,” he says, “in one year we could offer a cable-checking service.”