For years, large supervisory control and data acquisition (SCADA) systems have suffered from an annoyingly simple vulnerability: backup batteries in radio-signal extenders can die, causing a loss of communication. One large utility says a new monitoring device from Ventev Wireless Infrastructure solves the issue.
The SCADA for Southern Co.'s electrical grid is a series of devices that sends signals to each other via radio, says Bob Cheney, team leader for the power-delivery test lab at the utility, based in Atlanta. If two of these devices, called "preferred sources," are close enough physically, they can communicate directly with one another. If not, they need repeaters, or radio boosters, to extend the signal. If a preferred source loses power, the grid loses power, says Cheney. So, preferred sources are heavily monitored. "When the batteries are dead, we'll know," he says.
But the signal repeaters' batteries are not monitored, making them the weakest link in the communication chain, says Cheney. "The signal can go down all because of a silly battery that costs $5.15," he observes.
And when the power goes down, Cheney hears about it from Southern's 1.4-million Alabama-based customers and the five large manufacturing plants in the utility's service area.
"Mercedes Benz's manufacturing plant doesn't like it when they lose power," notes Cheney.
Everything changed when Ventev Wireless Infrastructure, a division of TESSCO Technologies, Hunt Valley, Md., custom-developed its Outdoor Wireless Enclosure system for Southern's repeaters. The enclosure includes a Battery Test Remote Monitor (BTRM) that also monitors the repeater's battery life, protects from radio interface and provides environmental protection, says Cheney.
"The battery test monitor removes AC power to the source and tests the battery load, and if the power lags or drops, it will tell us," says Cheney.
If there is a battery failure, the Ventev system sends text or email alerts to Cheney's team via Ethernet or DNP3 communication protocols. The BTRM also can monitor for other conditions, such as a door opening or a status change in a system.
After working with Ventev, Southern has ordered, to date, 400 Ventev enclosures, 100 with BTRM. Southern's SCADA system has expanded to more than 4,000 devices over the past three years, doubling the system's size.
"I want other utilities to know. This was my problem, and it can be solved," says Cheney. The system varies in cost and is now available to other utilities, such as oil and gas companies.
