ISKRA NFIB are type B residual current circuit breakers (RCCB) for which tripping is ensured as for type A and in addition for smooth d.c. residual currents, residual d.c. currents which may result from rectifying circuits and high frequency a.c. residual currents.
Intended for use in applications with frequency inverters, medical devices, UPS, mobile installations, elevators
The type B residual current circuit breakers are not intended for use in d.c. systems and networks with operating frequencies other than 50 or 60 Hz.
For type B tripping conditions for frequencies up to 1 kHz are defined.
Functions of detection, evaluation and interruption for type A residual currents do not depend on the line voltage. For evaluation of smooth d.c. residual currents supply voltage greater than 50 V is required which can be applied to any two poles only.
Versions: NFIBK: short-time delay tripping
NFIBS: selective type
Surge current withstand capability with current waveform 8/20 µs is 3 kA.
When designing and installing electrical installations, electrical loads that can generate d.c. residual currents in the event of fault, must be assigned a separate electrical circuit.
Optional operating position
Degree of protection IP20; after installation in a distribution box IP40
Assembly to a 35 mm wide mounting rail in accordance with EN 60715...