Measurement is not just measuring. The quality of the measurement setup is decisive for measuring data to be reliable. This can be considerably improved by the following points:
? Avoiding ground loops
If measuring signal, DAQ system, PC, and power supply have a different ground reference, a compensating current occurs. In the most harmless case, only the signal will be distorted. Not separating potentials, however, is often the cause for destroying the measurement system. Isolation is the suitable method here.
? Suppression of common-mode voltages
It-s a popular fallacy to think differential measurement is the solution for noise-free measuring results. In this case, -only- the voltage difference between two analog connections is measured. A static or dynamic increase of the real signal potential ? the so-called common-mode voltage ? adds up to the measuring signal. The permitted input voltage of the DAQ system can easily be exceeded.
When testing a battery, for example, the (low) voltage of each single cell is measured. Common-mode voltages generated by the other battery cells and not being separated can make the measured signal useless or be a serious danger to the DAQ system. Again galvanic isolation is the answer.
? Signal conditioning
Sensors often provide signals in the millivolt range. A pre-connected measuring amplifier allows for optimum signal adjustment to the whole input range of a DAQ system. The system is used to its full extent and tiniest signal changes can be detected.
These criteria mentioned before are met right away if connecting an isolating measuring amplifier. The 5B measuring amplifiers of the MA series by BMC Messsysteme GmbH (bmcm) feature triple galvanic isolation between measuring signal, PC data acquisition system, and power supply. This provides maximum interference resistance and maximum protection for the measurement system. Noisy environment, e.g. caused by industrial machines, does not influence the measurement result.
The measuring amplifiers feature sensor supply as well as various measuring ranges and filter cut-off frequencies set with DIP switches at the module. Offset and Gain are calibrated via potentiometers.
The measurement specialist bmcm offers three versions of measuring converters:
Due to the high bandwidth (50kHz) of the voltage amplifier MA-U, even slightest peaks of extremely small signals do not remain undetected.
The MA-UI featuring many selectable measuring ranges allows for optimum adjustment to voltage and current signals.
–> http://www.bmcm.de/us/prgr-measamp.html
To easily connect the 5B series to sensors and the PC data acquisition system, bmcm offers different amplifier boxes (AMS series) and backplanes (AP series).
–> http://www.bmcm.de/us/prgr-connect.html
MA-UNI, MA-UI, MA-U: A strong team ranging from universal to unique.
Further information is provided on the website of BMC Messsysteme GmbH (bmcm): http://www.bmcm.de/us
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