The Siemens 3NJ6920-3BD21 is a pluggable bushing current transformer that serves as a direct-fit accessory for 3NJ6 in-line switch disconnectors with fuses. Its Class 1 accuracy and 2.5 VA burden make it a cost-effective choice for general-purpose current measurement where standard accuracy is acceptable.

Application

Rated 100/5 A, this CT converts primary current to a standard 5 A secondary signal compatible with most panel meters, transducers, and protection relays. The 2.5 VA burden rating provides sufficient drive capability for multiple secondary devices or longer cable runs. Typical use cases include load monitoring, non-billing energy tracking, and basic overcurrent supervision in low-voltage distribution panels.

Installation

The pluggable design enables tool-free installation directly onto compatible 3NJ6 in-line switch disconnectors. The 21 mm bushing opening accommodates larger conductor cross-sections. The CT snaps into the dedicated accessory port on the switch disconnector body — no additional wiring or mounting hardware is needed.

Decision Parameters