Page 31 - Catalogue ANGLAIS 2016_Neat

Description:

The force sensor ASG Load Cell is machined in the mass of a rod made of chrome silicon steel called
"Spring steel" which has undergone machining and then heat treatment and aging cycles after mounting
the sensors to reduce and relax The residual mechanical stresses. The ASG Load cell is fully waterlight and
is therefore an Intrinsic Safety (SI), an ATEX qualification request can be requested as an option.

The own geometry of the ASG Load cell allows the cable or the tie rod to be centered with the
combination of two large-sized distribution plates to place above and below the instrumented block. This
central stack mounting ensures a better distribution of the internal load in the sensor.

The geometry of the ASG Load cell is the result of numerous studies and the experience and know-how of
more than 25 years Of the Geo-Instrumentation team. Moreover, the combination of the new
technologies that DAO brings and the direct machining on digital machines from digitized drawings allows
optimizing the unit production of the ASG Load Cell and guarantees the accuracy of the angular
distribution of the vertical mounting of the eight vibrating wire extensometers with double coils.

The measuring base for each strain gauge is more than 100 mm, thus integrating a large area of steel
which is subjected to reversible deformation. The homogeneous assembly in the force sensor ASG Load
Cell of 8 acoustic extensometers in series, makes it possible to measure Eight zones in compression of the
block under the evolution of the load applied, which compensates the imbalance of the descent of charge
in the event of ex-centration of the applied mass. The sixteen coils in individualized circuits, all benefit,
Technological and dimensional developments, for the optimization of the electromagnetic efficiency.
"PhD thesis of the ESCPCI: Optimization of the magneto-mechanical couplings of vibrating wire
extensometers for the monitoring of the aging of strategic constructions University PIERRE and MARIE
CURIE Paris Geo-Instrumentation" with a high performance piano wire. Each of the eight vibrating wire
acoustic extensometers is thus read independently in sustained mode to determine the evolution of the
sectoral deformation and then averaged for the ASG Load Cell force sensor. (Note: Sustained mode it is
this same electromagnetic principle which has been used for more than 60 years as a guarantee of quality
of listening for the head of the cell "mobile magnet" reading on the "HI FI high-end" Vinyl records.)

Functioning:

ASG Load Cell is activated by a calibration under load by a press in a Cofrac test laboratory. Geo-
Instrumentation measures during this test the eight measurements of deformation of the block through
the eight vibrating wire extensometers and at the same time the measurement of the load applied to the
block. This calibration results in the direct conversion of deformations (microns) into Tons.
Glossary: GEO INSTRUMENATION Vibrating Wire Acoustic strain Gage
Reminder: sustained Mode: the loop circuit of a sensor with acoustic vibrating wire consists electrically of two coils and a specific
operational ampli " Geo-instrumentation with optional a loudspeaker.
The ampli geo-instrumentation injects a current in tension between 190/120 mV in one of the two coils.
Oscillation of the high-performance steel wire Geo-instrumentation leads in the 2nd coil an alternating current between 6 and 30
mV.The operator can hear on a loudspeaker associated with the circuit of measure the sound of the continuous sensor " Acoustic
vibrating wire and continuous sound in audible frequencies 450 in 2500 Hz "
Geo-instrumentation uses the measure of the frequency on "sustained" said continuous mode. The measure is so repetitive.
The stability and metrological performance in sustained mode have been validated by a Cofrac French
Laboratory. The calibration results confirm a better linearity and reproducibility in sustained mode
(Geo-Instrumentation sensors) than the plucked mode used by Anglo-Saxon manufacturers. It can be
used in ATEX zone due to its weak level of power.

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