| A passive lowpass 1st order filter can be used to suppress noise on measuring signals at the analog outputs of a MICROMASTER or SINAMICS so that measurements using an oscilloscope can be made.|
The 500 Ohm (0.5 K) resistor is a load resistor and is used to convert the current (0…20 mA) into a voltage (0…10 V).
Fig. 1 – Noise suppression of measuring signals at the DAC in the MM4/G120
A phase current r0069.0 (phase U) is shown in Figs. 2, 3 and 4, that is measured at the analog output of the drive SINAMICS G120 (CU240S & PM250 45 kW). The drive is operated at its rated load. The phase current is measured without / with, unshielded / shielded, filter.
Fig. 2 – Phase current r0069.0 (phase U), without filter
The result of the filter can be seen in Fig. 3:
Fig. 3 – Phase current r0069.0 (phase U), with the filter (non-shielded)
The filter with shielded housing provides even better results (Fig. 4):
Fig. 4 – Phase current r0069.0 (phase U) with the filter, with shielded housing
Written by: SD CST