Class B residual current circuit breakers

As is well known, the residual current circuit breaker is a protective device that automatically interrupts the power supply if it detects the passage of a current to earth above a given threshold. There are various types of residual current circuit breakers on the market, which differ according to numerous parameters. One of the most important parameters is the "class" of the differential. This is related to its ability to detect certain waveforms of currents. The most commonly used differentials are those of class AC and A. Class AC RCDs are only sensitive to sinusoidal fault currents, while Class A RCDs are sensitive to both sinusoidal currents and "one-way pulsating" currents. The latter can occur, for example, in systems including electronic devices for rectifying current, which can generate pulsating fault currents with direct components that AC residual current circuit breakers would not be able to recognise.

Italweber, in addition to the classic class AC and A residual current circuit breakers, now also offers class B residual current circuit breakers, manufactured in compliance with the IEC / EN 62423 standard. These differentials are able to detect all waveforms normally detectable by AC and A class differentials, and in addition they also detect DC earth fault currents. Their use is highly recommended in the presence of drives, UPSs and inverters, devices capable of generating continuous fault currents, and increasingly present in every work environment, and beyond. For example, on the AC side of photovoltaic systems, the class B differential should be used.

Type B differentials represent the ideal protection for Inverters used in Elevators, Machine Tools, and in the power supply of pump motors in general.

The proposed range is complete, and includes four-pole class B residual current circuit breakers with three levels of differential sensitivity (30mA, 100mA or 300mA), and with rated currents up to 63A.

A similar range of class B+ differentials is also available. The latter, compared to class B ones, are able to detect fault currents with frequencies up to 20kHz.