Types 

• Type A (designated NFI) – sensitive to alternating and pulsating dc residual operating currents  

• 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.  

• 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 version:  

Type S: A switch with delayed break enabling selectivity regarding a general type and a short-time delayed type (type G) connected on the load side. Break time is longer than 40 ms. The switches excel in high resistance to surge currents (up to 3 kA), which prevent unwanted trippings. Their rated currents are from 25 to 100 A, and rated residual operating currents are 100, 300 and 500 mA. This is type A, and a customer can choose between NFI2S two-pole and NFI4S four-pole switches. 

Type G: A short-time delayed breaking characteristic (min. non-actuating period is 10 ms). The switches are resistant to unwanted trippings at current impulses or
when built-in in special critical conditions. They excel in high resistance to surge currents (up to 3 kA) and a reliable operation in case of high making currents. Rated currents are from 25 to 100 A, and rated residual operating currents are 30, 100, 300 and 500 mA. This is type A, and a customer can choose between NFI2K two-pole and NFI4K four-pole switches. Versions S and G comply with the EN 61008 standard. Regarding tripping times, type G also complies with ÖVE/ÖNORM E 8601 (supplement to ÖVE EN 61008). Both types are VDE approved.