The 3NJ6930-3BG22 is the standard Class 0.5 variant in the SENTRON 3NJ6930 NH1 current transformer family. Among the 250 A options for 3NJ62/63 switch disconnectors, this model offers the largest cable accommodation (21 mm) in the slimmest depth (30 mm) — maximising conductor flexibility while minimising space behind the disconnector.

Why choose the 21 mm cable version?

Cable diameter is often the deciding factor in NH1 CT selection. The 3BG22's 21 mm bushing accepts the full range of cable cross-sections typically used with 250 A NH1 fuse holders, including conductors with thicker insulation types. The 30 mm depth — 18 mm shallower than the legal-for-trade 3BG23 — leaves more clearance behind the disconnector for wiring access and ventilation. If your conductor fits and you do not need billing certification, this is the practical choice.

What level of precision does Class 0.5 deliver for 250 A measurement?

Class 0.5 guarantees current error within ±0.5% and phase displacement within ±30 minutes at rated primary current. At 250 A, that translates to a maximum error of ±1.25 A — half the margin of a Class 1 CT. For energy management dashboards, cost allocation between production lines, and efficiency benchmarking, this extra precision means decisions are based on data, not meter uncertainty. For revenue billing, however, precision alone is not enough — the legal-for-trade 3BG23 adds the required conformity assessment.

Frequently Asked Questions

Will this fit in a standard 150 mm deep panel?

Yes. With a 30 mm depth behind the disconnector, the 3BG22 adds minimal projection into the cable compartment. Combined with the 3NJ62/63 disconnector depth of approximately 90 mm, the total assembly fits comfortably within a 150 mm deep enclosure.

Can I use this CT with the 3NJ6940 larger disconnectors?

No. The 3NJ6930 series is mechanically designed for 3NJ62/63 (NH1) disconnectors only. The bushing geometry and mounting interface differ from the 3NJ6940 series, which fits the larger 3NJ6 platform. For NH2 or NH3 applications above 250 A, specify a 3NJ6940 series CT.