DYNAMOMETER INSTRUMENTATION

How to power a dynamometer

The necessary equipment to supply voltage, collect and process the output signal and display usable values constitutes the electronic element connected to the load cell. Traditional electronic instruments – stabilised power supply and multimeter– can be used. Transducer manufacturers have developed specific electronic equipment allowing the optimization of settings, measurement conditions and accuracy.

Technical progress of the dynamometer

The latest advances in dynamometer techniques comprise integrating the electronic equipment associated with the digitalisation of the signal and the transducer in order to constitute a single device which, powered by 220 V, releases an output digital signal according to the force applied to the load cell.

Dynamometers are often used as the sensitive element of weighing instruments. In this case, the shape of the proof body is determined so as to obtain an output signal that is exactly proportional to the mass of the specimen placed on the instrument loading tray.

Applications

When the relationship between the force applied to a dynamometer and the measurement of its output signal cannot be accurately determined by means of a calculation, it is necessary to calibrate the dynamometer. This involves establishing the exact relationship between the force applied to a dynamometer – input – and the electrical signal it releases – output. In essence, the operation consists of applying forces that can be accurately measured to a dynamometer and registering the values provided by the electronic equipment connected to the transducer. This operation is generally performed by applying the protocol established by the international standard ISO 376. This one provides for the classification of the dynamometer according to precision criteria. The results of the calibration of a dynamometer lead to determination of a mathematical polynomial of 2nd or 3rd degree, which enables the calculation of the value of the force applied to the dynamometer based on the indication provided by the electronic equipment. The formula allowing the level of uncertainty of this value to be calculated is also part of the calibration.

Another application for dynamometers involves testing machines used to characterise the resistance of materials or products. This field is largely covered by standards such as ISO 7500-1 covering uniaxial static tests for metallic materials, or EN 12390 section 4, dealing with hardened concrete.

NOTE : Spanish version /en/tecnologia/instrumentacion-sensores-de-fuerza/instrumentacion-de-un-dinamometro