Seismic safety switch provides high-integrity protection

Written by: Tom Austin-Morgan | Published:

Sensonics has released an SA safety seismic switch range that is claimed to offer accurate detection of structural vibration in conjunction with safeshut-down procedures. The range is suited to applications where high integrity seismic protection of critical assets such as oil, gas, nuclear and hydro-electric installations, pharmaceutical and medical facilities are required.

The SA-3 seismic safety switch is said to provide triaxial vibration detection and is suited for protecting vulnerable structures from ground borne vibration events and incorporates a range of safe shutdown options.

The switch features three high-integrity low-noise piezoelectric seismometers positioned at 90° to each other along with the associated alarm circuitry housed within a robust weatherproof steel enclosure.

It is said to be seismically qualified to IEEE-344 and utilises technology operationally proven in harsh environments. The switch operates on seismic events and when the signal from any axis exceeds the pre-set alarm level, the alarm relay is activated.

The sensors consist of a unique system of matched piezoelectric elements arranged in a ‘reciprocal’ configuration providing a functional test capability. Application of a 1Hz signal to the calibration crystal element mechanically excites the measuring elements resulting in a defined signal output which can be used to perform a full loop check of the seismic switch. Such a facility is essential for applications where the switch is located in a hazardous area and requires full-proof testing on a regular basis.

As well as the usual seismic and EMC approvals the SA-3 switch is also available for functional safety applications up to SIL-2 and can also be provided in an explosive-proof housing for intrinsically safe applications.

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