Siemens Current transformer, 50/5A, 1.2VA Part number 4NC5112-2CB21

Product Overview

The Siemens 4NC5112-2CB21 is a window-type current transformer (CT) from the SENTRON/4NC series, used to measure or monitor current in low-voltage (up to 0.72 kV) power circuits. It converts a primary current (e.g. 50 A) to a standardized secondary current (5 A), enabling measurement devices, meters or protection relays to safely monitor currents. The transformer is designed for compact mounting and is suitable for integration into switchboards or distribution panels where current measurement or metering is required.

Key Features

• Window-type current transformer (SENTRON 4NC series)
• Primary rated current: 50 A
• Secondary rated current: 5 A — standard output for metering / protection devices
• Rated burden (secondary): 1.2 VA — suitable for standard current measurement loads
• Accuracy class: Class 1.0 — adequate precision for metering and monitoring applications
• Screw-terminal connection for secondary output — simple, stable wiring
• Suitable for insertion of single conductor or busbar up to 20 mm width through the window opening
• Compact mechanical design — facilitates retrofit or panel-mount integration
• IP20 protection rating — intended for use inside enclosed switchgear or control cabinets

Technical Specifications

• Article Number: 4NC5112-2CB21
• Product Type: Window-type current transformer (CT)
• Primary Current Rating (In): 50 A
• Secondary Current Rating (Is): 5 A
• Rated Secondary Burden: 1.2 VA
• Accuracy Class: 1.0
• Rated Insulation Voltage: up to 0.72 kV (suitable for low-voltage networks)
• Window Opening (for conductor / busbar): Accepts bar/conductor up to 20 mm width, ~19 mm opening diameter
• Secondary Connection: Screw-terminal
• Protection Rating (Housing): IP20
• Design Type: Bushing/window-type (not split-core) — requires disconnection before installation on live conductor

Compliance & Standards

• Part of Siemens 4NC SENTRON series — designed for low-voltage current measurement applications
• Accuracy and burden ratings compliant with standard CT performance requirements for metering and protection
• Intended for use in enclosed switchgear or control cabinets (IP20 protection) to ensure user safety

Applications

The 4NC5112-2CB21 CT is ideal for current measurement, energy monitoring, metering, protective relay feeding, or any application requiring a standardized 5 A secondary current derived from a higher primary current (50 A). It can be used in switchboards, distribution panels, control cabinets, energy metering installations, or automation systems — particularly where retrofitting or compact installation of a measurable CT is needed.