Residual current circuit breakers (RCCBs) are components for implementing the protective measure 'protection by automatic shutdown of the power supply' in accordance with the requirements of VDE 0100 Part 410 or corresponding international installation regulations. Devices in the DFS 4 series are compact two- or four-pole residual current circuit breakers. In the standard version, they only take up four division units. While the DFS 4 version for alternating and pulsating direct residual currents is designed for three-phase networks, but can also be used in single-phase networks, there are special versions for single- or three-phase operation in the universal current sensitive versions (type B, type B+). Despite the compact dimensions, a large number of different tripping currents and characteristics are available for rated currents - depending on the version - up to 125 A. All devices are available in the 'HD' version, which is particularly suitable for use in harsh environments (tunnels, swimming pools, etc.). They also have large double-level terminals for accommodating large conductor cross-sections, a practical multi-function switch toggle and can be labeled with pre-made labels using free software. Switches with residual current characteristic A enable the detection of sinusoidal alternating and pulsating direct residual currents independent of the mains voltage. Any additional functions may be voltage-dependent. Due to a response delay, residual current circuit breakers of the KV design only react to residual currents with a duration of more than half a period of the mains frequency. They are considerably less sensitive to short-term pulse-shaped residual currents than switches with no delay and enable trouble-free operation - even if switching or lightning surges in the system cause capacitive surge residual currents or insulation flashovers with a follow-on current up to the zero crossing of the mains voltage. They therefore also meet the requirements for storm-proof RCCBs in accordance with the Austrian standard ÖVE E 8601. The tripping times for instantaneous RCCBs required in national and international building regulations are also met by the KV version devices. They can therefore generally be used instead of a standard switch. Standard version devices are designed for monitoring circuits with a rated voltage of 230 V or 400 V and a rated frequency of 50 Hz. Properties: - high immunity to surge fault currents and mains voltage-driven follow-on current pulses, - mains and auxiliary voltage-independent tripping, - sensitive to alternating and pulsating direct fault currents (type A), - small size for all rated currents, - high short-circuit strength, - double-sided double-deck terminals for large conductor cross-sections and busbar connections, - switch position indicator, - viewing window for labels,- Multifunctional switch toggle with three positions: 'on', 'off', 'tripped', - Neutral conductor in standard version on the left, with every four-pole device optionally N on the right available at no extra cost, Mounting type: - Quick fastening on mounting rail, - Installation position as desired, - Feed direction as desired, Areas of use: - Power supplies for residential and commercial buildings as well as industrial plants with TN-S, TT and TN-CS networks in which conventional RCCBs trigger undesirably as a result of transient leakage currents, such as systems with long cable lengths behind the RCCB, lighting systems with many fluorescent lamps (> 20 units), computer systems, solariums and X-ray systems., - Use in TN-C networks and for protecting systems in which electronic equipment can cause smooth DC residual currents or residual currents with frequencies other than 50 Hz is excluded. Comprehensive protection is not provided here. For such applications we recommend