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Smart Device Delivers Operational Information on High-Voltage Transmission Lines

April 3, 2012
Lindsey Manufacturing Co. has introduced the Transmission Line Monitor (TLM).

Lindsey Manufacturing Co. has introduced the Transmission Line Monitor (TLM). This transmission line clearance monitor assists with real-time rating and forecasting of high-voltage line capacity.

Developing in conjunction with the Idaho National Laboratory (INL), the TLM enables electric utilities to maximize their transmission resources by calculating each line’s dynamic capacity. By knowing the conductor’s height clearance history for a load under specific weather conditions, operators can forecast the line capacity for similar future weather conditions with a high degree of confidence.

According to Lindsey Manufacturing President Keith E. Lindsey, the TLM will change the way electric transmission and distribution infrastructure is maintained and managed worldwide. “This is the first ‘smart’ device of its kind delivering valuable operational information on high-voltage transmission lines,” said Lindsey. “Based on the initial INL design, our company developed ways to measure line sag, conductor temperature, and tilt & roll of the conductors, as well as the distance to any object beneath the line. We also tasked the sensors to detect Aeolian vibration, which is an indication of wind blowing across the conductor, and ‘galloping.’

“By gathering weather history from locations around an installed TLM, line current history and exact conductor height history, utility operators can forecast 24-hour in advance how much additional line capacity is available without violating clearance regulations," he said.

The TLM uses Light Detection and Ranging (LIDAR) technology to accurately measure the height of the transmission line relative to crossing conductors or vegetation below the line. Its onboard sensor package incorporates two temperature sensors: one measures conductor temperature up to 250 degrees C in real-time, and the other measures ambient temperature. A pair of dual-axis MEMS accelerometers measures the vibration characteristics of the transmission line and determines its tilt and roll.

Each TLM is remotely programmable, has a Global Positioning System (GPS) address, and communicates in a self-healing wireless mesh network over the 915 MHz band. Data from the device are encrypted compliant with the National Institute of Standards and Technology (NIST) AES 256-bit standard, and are available at the end-point ground location in DNP3 format, which integrates to most installed “Smart Grid” communication systems.

Manufactured in Azusa, California, the TLM is corona-tested in compliance with IEEE P1829 , is corona-free at 500 kV and installs on live lines with hot sticks or bare hand live line techniques.

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