EREA have a number of Dossena brand Type B differential current relays in our range. 

Unlike the standard Type A differential switch (aka a residual circuit-breaker (RCB) or a residual current device (RCD), formerly called ELCBs) which are found today in nearly every electrical installation, a Type B RCD will also respond to DC fault currents, which can be caused by electronic equipment like frequency converters.

The Dossena DER3B-DUAL series can detect AC and DC as well as combined fault currents. Two coils are used, placed around the cables to be monitored. It is possible to set an alarm threshold and a tripping threshold. 

Dossena's device comes in two formats, one type for installation in the door of an electrical cabinet (DER3B-DUAL/2I) and another type for DIN rail installation (DER3B-DUAL/6D).

Type B RCDs outside the industrial context

The importance of Type B RCDs outside of industrial contexts has increased significantly with the emergence of electric vehicle charging stations for use at home or at the workplace. The majority of charging stations need to be protected with a Type B RCD.