It comes as a set of three — one per phase for a three-phase motor branch circuit. The aM curve means it tolerates motor inrush without nuisance blowing, but clears short-circuit faults fast. At 400 A and 690 V AC, it's sized for large motor loads — think 200+ kW induction motors on 400 V lines, or high-current feeders in heavy industrial switchgear.
Lifecycle reality — obsolete, sourced on request
This part is marked obsolete by Schneider Electric. The TeSys DF range is a mature line; if you're maintaining existing gear, this fuse set is the exact fit for the NH3 holder. Any substitution requires checking the holder's rated voltage and the fuse's breaking capacity against the panel's SCCR — not a casual swap.
Physical fit and packaging
NH3 is the standard DIN blade size for high-current fuses — 400 A class. The DIN form factor means it slots into a matching NH3 fuse base or switch-disconnect holder without adapters. The set-of-3 packaging matches a three-phase line; order one set per motor branch.