Moving-coil measuring instruments
for direct current
Moving-coil measuring instruments for direct current
Moving-coil measuring instruments serve for measuring direct current and direct voltage. For extending the measuring range, shunts, series resistors or voltage dividers are used. The energy consumption of moving-coil measuring instruments is very low; they may thus be connected to shunts, speed sensors, thermocouples, measuring transducers or similar. Moving-coil measuring instruments with rectifier serve for measuring alternating current and alternating voltage. They measure the arithmetic mean value, but are designed in a way to indicate the rms value in case of sinusoidal variables. In case of non-sinusoidal variables, an rms-value rectifier is provided. It is able to still process crest factors of max. 8 without problems. The max. error amounts to less than 1% in this case.
Moving-coil measuring instruments are manufactured according to EN 60 051 as well as according to the other relevant VDE and EN regulations. The accuracy amounts to 1.5 % referred to the full scale. When adjusting moving-coil measuring instruments for their connection to shunts, an input lead resistance of 0.06 Ω is principally accounted for, this corresponds to an input lead of 1.3 m, 2 x 0.75 mm².