Mersen NH1 Fuse link, 500V, 250A

The Mersen NH1 Fuse link you mentioned is part of the NH system, which is a plug-in fuse system consisting of a fuse-base (which may include terminal covers and phase barriers), a fuse-link with blade contact, and a fuse-link replacement device (LV HRC fuse puller). As you noted, it is important to handle this system by a qualified professional, as the design cannot guarantee non-interchangeability of rated current.

The NH fuse-links, specifically the type "gG," are full-range breaking capacity fuse-links used to protect cables and equipment. They can interrupt any current surge from the lowest fusing current up to their breaking capacity and can be used alone as protection. Additionally, they protect electrical devices and industrial set-ups from the electrodynamic effects of very high short-circuit currents.

The NH system's dimensions conform to DIN 43 620 Parts 1 to 4, and the NH fuse-links feature isolated metal gripping lugs (SGL), a double indicator, and 0% cadmium, which is good for the environment.