Catalogues - seismic-monitoring-protection-systems

Catalogue Seismic Monitoring & Protection Systems

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GEOPHYSICAL PRODUCTS

The Willmore Mklll range of Seismometers are velocity sensing devices suitable for field, vault or observatory use. Available in both broadband and short period configurations, the Mklll sets a standard that is hard to beat.

The mass is a permanent magnet suspended on ligament springs, which achieves friction less axial movement. The output is derived from two coils fixed to the frame, one at each end of the mass. Auxiliary coils are provided for feedback and calibration. The natural period of oscillation of the mass is adjustable so that the instrument can be optimally matched to the required operating conditions.

The broadband response is achieved by adding a low noise capacitive displacement transducing system to the basic Mklll suspension. A current proportional to the mass displacement is fed back to the 'moving coil' to maintain the mass at equilibrium. Adjustable electronic feedback damping is included to give the user, besides the noise reduction of the technique, an instrument capable of detecting earth motion from the micro-seismic to the strong motion range.

Standard Output Responses Available:-

-1 '* Ty^-Lt^vv-.- " '^i

• Acceleration - DC to 25Hz, lO'Wm/s³

• Broadband Velocity - 20s to 20Hz, lOW/m/s²

• Long Period Narrow Band - 2xl0⁶V/m/s² at 20s ! Short Period -SxlO^V/m/s², Is to 3s

Dynamic Range

Noise Level

Movement Range

Temperature Range

Sensitivity Vj Over Tempera tu

Inertial Mass

Housing

Auxiliary Coils

l40dB

10^-9 m/s² per root +/- 2mm ultimate -40°C to 50°C

Less than I %

l-2Kg

Polished Stainless Steel

I OKohm Primary. SOOohm Secondary

Mass can be clamped for transportation and position adjusted from outside of sealed case.