NW / WQ .. DIN
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 15-100 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 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. Voltmeters and ammeters up to 5 A are provided with a shielding against external magnetic fields up to a strength of 4 kA/m, ammeters of 6 A up to 60 A offer a shielding up to a strength of 2 kA/m. The connection is back of hand proof and is realized using M4 screws (max. 6 mm2) for voltmeters and for ammeters up to 15 A or M5 screws (min. 2,5 mm² – max. 16 mm²) for ammeters to 60 A.