Residual Current Circuit Breakers FI, NFI

With a residual current circuit breaker (RCCB) the following protective measures are available: fault protection, protection against fire and additional protection in case of direct contact.

FEATURES:

• Isolating function

• Additional colour display of the position of main contacts (red – contacts closed, green – contacts open)

• A terminal shape prevents connection of a conductor outside the connection area
   

• Types:

1. Type A (designated NFI) – sensitive to alternating and pulsating dc residual operating currents
    
2. Type AC (designated FI) – sensitive only to alternating residual operating currents of a sine wave form
    
3. Type F (designated NFIF) – tripping is ensured as for type A and in addition for residual currents with mixed frequencies that can result from single-phase electrical loads with frequency inverters.
    
4. Type B (designated NFIB) – 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.
    

• Special versions:

1. Type S: A switch with a delayed break enabling selectivity regarding a general type and a short-time delayed type (type G)
         connected on the load side
    
2. Type G: a short-time delayed breaking characteristic (a min. non-actuating period is 10 ms)
    
3. FIR-FIT combination: It is used for a protection in circuits where operational currents are higher than rated currents of residual current circuit breakers.

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