Temperature measurement with SAW sensors

One of the most important safety aspects of overhead power lines is their distance to the ground. If the temperature of a power line increases due to heavier load, the line expands and the safe distance between the line and the ground is reduced, which may limit the load that can be transmitted. Until now, only theoretical limit values for power line loads have been available. The newly developed surface acoustic wave sensors (SAW sensors) mean that the network can soon be utilized with real measured values.

SAW sensors are a by-product of telecommunications engineering. When the developers of this technology set out, they did not expect it to be used for high-voltage engineering. Manfred Hudasch, project manager for basic research into high voltage technology at EnBW, however, immediately realised that the component was suitable for wireless temperature measurement of overhead power lines. The technology affords a brilliantly simple way of measuring a physical variable which - apart from the size of the overhead conductor current - is meaningful but difficult to measure: temperature. For in addition to pressure and torque, SAW sensors can also measure temperature. What is fascinating is that the SAW sensor is a completely passive instrument which is as small as a chip in a radio and doesn