High level of immunity against leakage and residual currents due to operational conditions from frequency 1 kHz and higher, AC/DC sensitive for residual currents with frequencies and mixed frequencies of 0 Hz (smooth direct current) up to 150 kHz, high availability even of voltage-independent detection of smooth DC residual current and AC residual current with frequencies not equal to 50/60 Hz thanks to full functional compatibility with mains voltages from at least 50 V AC on any two active conductors, mains-voltage-independent tripping when type A residual currents occur , compact design for all rated currents, high short-circuit resistance, double-sided two-tier terminals for large conductor cross-section and busbar, switch position indicator, viewing window for labels, multifunction switch toggle with three positions: "on", "off" and "tripped", Neutral conductor position left

Residual current circuit-breakers (RCCB) switch the power supply off if dangerous high residual currents occur. DFS 4 are two-terminal or two-terminal pair residual current circuit-breakers for single- or three-phase networks. In the standard design, the compact devices are just four module widths wide. They are available with many different residual current types and variants for rated currents up to 125 A. The large two-tier terminals can also accommodate large conductor cross-sections. The trip position of the multi-function toggle switch simplifies fault-finding. The free label software helps in the labelling process. Type B switches are AC-DC sensitive at frequencies of 0 Hz (smooth residual currents) to 150 kHz. They have increased resistance to surge currents and lightning. 

Quick fastening to mounting rail, any installation position, supply preferably from above. For installation instructions, click here

1. Fault protection:

Reliable operation for automatic disconnection of supply in TN, TT & IT systems for all electrical installations in compliance with Cl. 4.2.11.4.4, Cl. 4.2.11.5.3 & Cl. 4.2.11.6.4 (IS 732:2019) 

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2. Fire protection:

Specially designed for locations with risks of fire due to the nature of stored or processed materials (e.g warehouses, paint shops, carpentry workshops etc.) in compliance with Cl. 4.3.2.3.9 (IS 732:2019)​

NEC 2023 (BIS SP 30:2023)  mandates the use of Type B RCCBs for the following applications:

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1. Inverters, battery backup and UPS systems:

Cl. 5.4, Section 10, Part 1, SP 30:2023 requires the use of type B RCCBs for fault protection where inverters may create smooth d.c. residual current (transformerless inverters).

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2. Variable frequency drives including lifts and escalators:

Cl. 5.4, Section 10, Part 1, SP 30:2023 requires the use of type B RCCBs for fault protection in three-phase variable frequency drives.

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4. Solar PV Arrays:

Cl. 4.12.3.2, Part 8, SP 30:2023 requires the use of Type B RCCBs for fault protection in Solar PV arrays.