The 3NJ6900‑4HD21 is a no‑nonsense panel ammeter for mains cubicles. It hooks directly into a 100 A single‑phase busbar or cable, moving the pointer with the magnetic force of the flowing current, no auxiliary supply needed. The 96 × 96 mm front plate drops into a standard switchboard opening and is held by a single clamp from the rear, with a small locating pin to stop rotation.

Moving‑Iron Movement

• Irons in the coil produce a magnetic field proportional to the current; the deflected pointer moves over a 60 mm scale.
• Inherent r.m.s. response handles distorted waveforms without extra electronics.
• Accuracy class 1.5 (±1.5 % of full‑scale value) for monitoring, not for billing.