New from Bestech Australia is a range of vibrating wire strain gauges and sensors for geophysical applications where the prime requirement is to monitor changes in structural integrity and stress over long periods of time. Potential mining applications are numerous, including the monitoring of stress and crack propagation in dam walls, tunnels, bridges, large diameter pipes, embankments, and mounting pads for heavy machinery and high voltage pylons.

The Encardio-Rite vibrating wire technology is described as ideal where it is necessary to run long cables between the sensor and the controlling instrument. Changes in cable resistance and conductivity due to temperature and moisture ingress have no effect on the integrity of the frequency-based signal where it can also be used for embedment in soil or concrete. All Encardio-Rite EDS-20V strain gauges supplied by Bestech Australia comprise a pretensioned high tensile steel wire strain gauge element with thermistor temperature sensor as to measure temperate changes at the same time, and a permanent magnet and induction coil assembly. Both components are factory sealed to prevent the ingress of water, corrosive substances and gases.

The induction coil assembly is either mounted over the strain gauge assembly, or both components form one assembly. To complete a basic system, a vibrating wire strain indicator, such as the Encardio-Rite EDI-51V also available from Bestech Australia, is connected by a 4-core, screened cable to the induction coil assembly to display measured strain that is proportional to the frequency output. Multichannel signal conditioners are also available.