Utility can remotely find power disturbance

In years past, it may have taken Progress Energy hours to find the fallen tree, leaning crane or other disturbance that was causing the power outage. The utility workers sometimes had to conduct foot patrols along highways, wetlands or mountainsides to root out the problem.

Now the utility can pinpoint the disturbance from downtown Raleigh, North Carolina and dispatch technicians to the precise location for repairs.

The remote technique has been in use for five years but was kept confidential until patented this year. Now Progress Energy hopes to market it to other utilities.

"We make money based on kilowatt hours," said Steve Turner, the senior engineer who came up with the idea. "So the customer minutes that are interrupted are lost revenue."

The solution that evaded the utility industry came in a flash to Turner during his job interview at Progress Energy five years ago. While interviewing with the transmission department, Turner offhandedly suggested an automated method of finding line disturbances. Some were skeptical, but Turner was hired, and soon had an opportunity to try his idea.

A transmission line between Greenville and Wilson had been shorting out for months. Technicians could never find the source of the problem.

Turner's system gave the crew coordinates to scout. There, near the transmission line, they saw a tree charred black. The tree had not fallen and ripped down the lines. Instead, it had had repeated contact with the 230,000-volt power line every time the winds had whipped its limbs. But when the winds died down, the limbs would be freed from the line, leaving no evidence for the utility crews patrolling.

"Within a half-hour, I told them where it was," said Turner, 43, a senior engineer in the transmission department.

Since then, the remote locator has never failed, he said. "It's always within a half a mile, which is excellent," Turner said.

The commercial value of the product depends on an estimate of how much time it saves in finding outages. That calculation is being made for Progress Energy by graduate students at N.C. State University, giving the company an idea of the product's market value. Progress Energy owns the rights to the product.

Turner's solution doesn't apply to most outages. It only works on transmission lines, which run from power plants and between substations and can span 20 or 30 miles or more. It doesn't work with distribution lines, which carry electricity from substations to customers. Progress Energy has about 6,000 miles of transmission line in the Carolinas, compared with 62,450 miles of distribution lines.

The key to Turner's system is calculating the distance to the disruption. The distance can be calculated by the amount of electricity the line carries.

The shorter the line, the less resistance to electrical flow, which means more electricity can flow through. When a transmission line is disrupted, it is effectively truncated at the point of contact, increasing the amount of electricity that passes through.

Engineers could figure out the length of the disrupted power line if it weren't for the tree or other object resting on the power line. The object making contact also conducts electricity, which makes the line appear longer than it is, throwing off the calculation.

Before Turner arrived at Progress Energy, the company measured power output only from the point where the electricity entered the grid.

Turner also suggested measuring power from where the line ends. When a tree touches a line, the electricity reverses direction from the other end of the transmission line, allowing for two readings.

Such a creative solution calls for a creative name.

Turner has dubbed his invention "the double-ended fault locator."