An example of this is the RCMB35-30-01 AC/DC differential current module (toroidal with integrated electronics), designed for mounting on the power supply of variable frequency drives (VFDs), with an inner diameter of 35 mm. The alarm relay is activated when the differential current exceeds 30 mA. The application of this RCMB35-30-01 module in combination with a trip coil meets all the requirements of DIN EN 60947-2 Annex M for a Modular Differential Current Monitor (MRCD).
The RCMB35-30-01 modules, immune to load currents due to their magnetic shielding, include a test and reset button, and multi-color LEDs for indicating service status, alarm exceeded value, and internal error. The response is calibrated for IΔn ≤ 30 mA (0…1 kHz).
Differential protection in converters, drives, inverters and UPSs is conditioned by the existence of possible superimposed direct currents or a high number of harmonics.
