RCCB 4P 40A A[IR] 30mA 4M Three-Phase Residual Current Circuit Breaker

Overcurrent-Protected MDC Compact Residual Current Circuit Breakers

Overcurrent-protected MDC 45, MDC 60, and MDC 100 compact residual current circuit breakers are available for the overcurrent and residual current protection of devices and services.

MDC compact miniature circuit breakers with residual current coils feature a thermomagnetic element with the same characteristics as MTC breakers. The residual current coil, factory-mounted within the same modular housing, is available in AC, A, A[IR], pulse-resistant A[S], selective A[S], and F versions with rated residual currents of 30, 100, and 300 mA.

Overcurrent-Protected MDC 45 – 60 – 100 Compact Residual Current Circuit Breakers

Some Recommendations for Selection and Installation

By design, RCCBs are sensitive devices and are therefore more exposed to events that can cause unintended trips (i.e., the RCCB trips without an actual fault).

Unintended trips are generally caused by atmospheric disturbances such as lightning-induced electrical discharges, operations in the electrical distribution network, interference from industrial equipment, and the presence of electronic filters in the electrical circuit (also found in common household appliances) that create permanent leakage currents to earth.

Problems caused by the unintended tripping of a residual current breaker can range, in a domestic environment, from the limited inconvenience of having to reset the RCCB, to significant economic damage caused by the loss of contents in a freezer.

In industrial and tertiary sectors, where systems are extended and service continuity must be more guaranteed, the amount of damage is certainly greater. To understand the critical role of electrical service continuity for economic return on investment, efficiency, and public safety, one can consider application areas such as photovoltaic systems, telecommunications, electronic data processing, public lighting, or monitoring systems.

One possible measure to prevent improper tripping of circuit breakers is the installation of GEWISS reinforced immunity RCCBs, identified by the letters IR, which show greater resistance to the causes of unintended tripping compared to standard versions.

More specifically, IR RCCBs can:

• Not trip under atmospheric and operational overvoltages, since the immunity level to impulse residual currents with a normalized 8/20 μs waveform reaches 3000 A (standard versions peak at up to 250 A).

• Not trip in the presence of transient earth leakage currents generated when electronic devices equipped with filters in power supplies of the most common equipment—such as PCs, decoders, and variable-speed electronic household appliances (air conditioners, washing machines, etc.), lamps, and dimmers—are switched on.

F-type RCCBs, in addition to the features of IR types, also guarantee protection against indirect contacts caused by variable-frequency earth faults generated in the presence of single-phase frequency converters or inverters, i.e., devices used in household and industrial appliances such as washing machines, vacuum cleaners, dishwashers, ventilation systems, pumps, etc., that adjust an electric motor’s speed according to the voltage and frequency of the supply. Inverter technology is increasingly common in modern equipment because it improves electric motor performance and reduces energy consumption.

Unlike IR types, selective RCCBs (S-type) have a fixed delayed tripping action, as the relationship between fault current and trip time is defined according to CEI EN 61008 and 61009 standards. Thanks to S-type RCCBs, in the event of a leakage fault, vertical selectivity is established between upstream breakers of lower sensitivity and downstream breakers of higher sensitivity, minimizing the portions of the system that are taken out of service.