The Siemens 3NJ6920-3BE13 is a pluggable bushing current transformer designed as a direct-fit accessory for 3NJ6 in-line switch disconnectors with fuses. It combines a 150/1 A ratio, Class 0.5 accuracy, and legal-for-trade calibration — purpose-built for revenue-grade energy measurement where the CT and billing meter are separated by extended cable runs.

Application

This calibrated CT supports billing-grade measurement on 150 A circuits in low-voltage distribution. The 1 A secondary is the preferred choice when the metering device is located at a distance from the switchgear — lower secondary current means proportionally lower resistive losses in the signal wiring, preserving measurement accuracy end-to-end. The 14 mm bushing opening targets branch circuits with compact conductor cross-sections. Typical deployments include utility sub-metering, tenant billing in multi-tenant facilities, and energy cost allocation in commercial and light industrial buildings.

Installation

The pluggable design enables tool-free installation directly onto compatible 3NJ6 in-line switch disconnectors. The 14 mm bushing opening routes the primary conductor through the transformer core. The CT snaps into the dedicated accessory port on the switch disconnector body — no additional wiring or mounting hardware is needed.

Decision Parameters