Q.bloxx A116 – the compact 8-channel measurement module
Fatigue test of structures like wind plates usually needs hundreds of strain measuring points to learn the material and structural behavior of the specimen. Strain gauges are located along the test subject, sometimes over a distance of 100 m or more. Dynamic test like alternating bending require a perfect correlation of all measurements and don’t accept a jitter. Otherwise the results are not representing the real behavior of the specimen.
The bridge measurement module Q.bloxx A116 provides for flexible strain gauge bridge measurement 8 real parallel input channels for the universal connection of strain gauge quarter-, half- and full bridges with DC voltage supply. The connection of the bridges are in 3/4 or 5/6-wire circuit to compensate cable influences. But even when connecting single strain gauges in ¼-bridge circuit of the cable will influence of long cables by a parallel reference measurement because the voltage drop within the cable is perfect evaluated. This method avoids to use more expensive and more complex 4 wire strain gauge connection. A fully compensation of the influence of long cables on the sensitivity of the measurement is given with 3 wire connection.
To adapt the excitation to the measurement (specimen material, strain gauge size) the transducer excitation can be set to 2 VDC or 4 VDC.
The bridge completion is a very sensitive item because the deviation of this resistor will fully effect the quality of the measurement. To reach a temperature stability of 0.0025%/K a completion resistors of 120 O or 350 O with a temperature coefficient of 0.05 ppm/K are implemented. Temperature fluctuations have thus only a very small influence.
The input ranges 2,000 µm/m and 20,000 µm/m cover all applications. For small strain application the range of 2000 µm/m is a good choice, for high strain test until material cracking 20.000 µm/m, optional 50.000 µm/m is suitable.
The module has 8 parallel A/D converter with 24 bit resolution for a sampling rate of 10 kHz per channel. It is possible to connect more than 500 channels to one controller that ensure a jitter less than 1 µs between all measured. Other features are shunt calibration, digital filter 4th order, min/max storage, arithmetic, alarm, accuracy class of 0.05.
