Moving-iron measuring instruments
for alternating current and alternating voltage
Moving-iron measuring instruments for alternating current and alternating voltage
Moving-iron measuring instruments are mainly used in heavy-current installation for the measurement of alternating currents and alternating voltages (direct measurement via current or voltage transformer). Moving-iron measuring instruments also indicate the rms value in case of non-sinusoidal quantities within a frequency range of 40-100 Hz. With direct current and direct voltage, additional indication errors of approx. 1 % may occur due to magnetization errors inside the iron. As compared to moving-coil measuring instruments, the energy consumption is relatively high ranging between 0,6 VA and 2,5 VA. They are thus not suited for measuring small currents or voltages, like e.g. at shunts, speed sensors, thermocouples, measuring transducers.
Moving-iron 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. The graduation of the scale of standard ammeters disposes of a 2-fold overload scale and starts at approx. 10% (20% for voltmeters) of the full scale. The measuring elements are mounted in a shock-resistant housing from polycarbonate. The housing dimensions comply with DIN 43 880 for built-in equipment for electrical installations. Connection is made to touch-proof captive M5 screws (max. 10 mm²).