NMW / MWQ .. DIN
Bimetal measuring instruments
with slave pointer, combined with moving-iron ammeter (maximum and instantaneous current ammeter)
Bimetal measuring instruments with slave pointer, combined with moving-iron ammeter (maximum and instantaneous current ammeter)
Bimetal measuring instruments are used for monitoring the load ratios and conditions of electrical distribution installations. Due to their thermal inertia, the displayed measured values equal the rms value of the current, a built-in slave pointer is used to show the maximum values.
Bimetal measuring instruments are manufactured according to EN 60 051 as well as pursuant to the other relevant VDE and EN regulations. The accuracy amounts to 3 % referred to the full scale. The scale graduation starts at approx. 15 % of the full scale and has a 1,2-fold overload scale. Bimetal measuring instruments show the square mean value of the current, the measured value equals the rms value and is independent of the waveform. Due to the extremely high torque, a slave pointer showing the maximum current may be used. Using a sealable reset button, the maximum pointer (slave pointer) may be reset up to the measuring element pointer. Another model combines bimetal measuring system with moving-iron measuring system (class 1,5) inside one housing. This allows for measuring maximum value, mean value and instantaneous value of the current on one scale at the same time. The standard type allows for measuring currents within a frequency range of 15 Hz to 100 Hz. Moving-iron measuring elements are provided with a shielding against external magnetic fields up to a strength of 4 kA/m. The connection is made using M4 screws (back-of-hand-proof).