Acoustic carrier signal transmission technology and its potential for in-site monitoring of sliding electrical contact used in gas-insulated switchgear/gas-insulated transmission line

A wireless signal transmission technology based on acoustic carrier is proposed, which overcomes the limitation of electromagnetic signal shielding and shows great potential for in-site monitoring of sliding electrical contact used in gas-insulated switchgear (GIS)/gas-insulated transmission line (GIL). Here, the state parameter of the sliding electrical contact is modulated onto the frequency domain of an ultrasound wave. As a mechanical wave, the ultrasonic wave is immune to electromagnetic shielding, so that it could carry the sensing signal to penetrate the metal shielding layer and transmit to the external terminals of GIS/GIL. The principle and signal modulation process of the acoustic carrier based transmission system have been demonstrated in detail. Both simulation and experiment have been conducted to analyse the system characteristics as well as optimise the system configuration. As a proof-of-concept application, the in situ and on-line monitoring of the thermal rise of a slide electrical contact both in a current loading equivalent model and a prototype of GIS is demonstrated. Experimental results fit well with the physical process, and show a good measurement accuracy of 0.6% and temperature sensitivity of 400 Hz/°C.