Strain gauge selection for measurement in electromagnetic field
In electromagnetic field, there is DC magnetic field where a constant magnetic force is always generated and variable or AC magnetic field where the field moves or varies. In case that the relation between strain gaugea and magnetic field does not vary (strain gauges do not move in the DC magnetic filed), inductive voltage is not generated, so no counter-measure against induction is basically needed.
In case that the relation between the magnetic field and strain guatges moves in the AC and DC magnetic fields, inductive voltage is generated and any counter-meausre is required. The QMF/MF series non-inductive strain gauges use a material with small magnetic resistive effect as the sending element and has construction resistive to the influence of induction using two identical strain grids with one stacked directly above the other and twisted leadwires. In addition to the gauges for metal, non-inductive gauges with long gauge length are also available for concrete specimen.
Non-inductive gauges according to measuring objects
*Shielded twisted leadwires are also available.