This is a Vigi add-on module for ComPact NSX 400/630 that provides a residual current alarm. It is used for 4-pole circuit breakers. The operating voltage is between 200 and 440 VAC 50/60 Hz. The differential current sensitivity is adjustable from 30 mA to 30 A. It is installed directly on the device connection terminals and gives an alarm without tripping in the event of a fault due to residual current. This Vigi add-on module is internally powered by the voltage of the distribution network, even if it is only powered by 2 phases. It is compliant with the IEC 60947-2 standard, Annex B.