The CBS-400B monitors and protects four fully independent circuits for earth leakage, each through its own external toroidal transformer of the Circutor WGB range, and it does so to type B. Circutor rate it to IEC 62020, with type B sensing to IEC 60755. It carries five output relays: four to trip the breaker of each protected channel and one for the adjustable pre-alarm, so a rising leakage can be acted on as a maintenance item instead of as an outage. The leakage current of each of the four channels is measured and displayed separately, and integrated RS-485 Modbus/RTU allows all four to be logged. Sensitivity is adjustable from 30 to 3000 mA. It occupies three DIN modules. It is a type B device: it responds to all forms of residual current — AC, pulsating DC and smooth DC. Smooth DC leakage is the case that matters, because it magnetically saturates the core of a type A or type AC device and blinds it to any further fault. Type B is therefore the correct and often the mandatory choice downstream of frequency converters, rectifiers, EV chargers and photovoltaic inverters. Manufactured by Circutor (Spain) and supplied under the Function brand; the Circutor catalogue reference is CBS-400B. Supplied by cBallast on quote-to-invoice terms; lead time and freight are quoted per RFQ against the destination Incoterm.