ABB 1TNA900241R0400 Current Transformer KORC 4SL 400/4

ABB 1TNA900241R0400 Current Transformer  KORC 4SL 400/4

This is the unique manufacturer's part number.

• 1TNA: Standard prefix for ABB's low-voltage instrument transformers.

• 900241: The specific article number for this model. The change from the previous example's "900341" indicates a different product variant.

• R0400: A revision or variant code, likely indicating the specific primary current rating (400A) is a key feature of this version.

Technical Designation: KORC 4SL 400/4

This segment contains the core technical specifications.

• KORC: This indicates the type of current transformer.

◦ KO: Standard ABB series for ring-type (window-type) current transformers.

◦ R C: Part of the model family designation.

• 4SL: This specifies the accuracy class and burden.

◦ The number 4 indicates the accuracy class is 1%.

◦ The letters SL indicate a specific burden. In ABB's nomenclature, "SL" typically corresponds to a burden of 1 VA (Volt-Amperes). This is a lower burden than the "4S" (2.5 VA) from the previous example.

• 400/4: This defines the current ratio.

◦ 400: The rated primary current is 400 Amperes.

◦ 4: The rated secondary current is 4 Amps. The full ratio is 400/4 A.

Summary of Key Specifications

Feature

Specification

Meaning & Comparison

Manufacturer

ABB

Type

Ring/Window Type Current Transformer

Same physical style as the previous model.

Rated Primary Current (Ipn)

400 A

Key Difference: Designed for a much higher current circuit.

Rated Secondary Current (Isn)

4 A

Same secondary standard.

Ratio

400/4

Key Difference: When primary is 400A, secondary is 4A.

Accuracy Class

1%

Same high accuracy for measurement.

Rated Burden

1 VA

Key Difference: Can only drive a smaller load (wiring, meters) while maintaining accuracy compared to a 2.5 VA model.

Mounting

On a busbar or a single core cable.

Typical Application

This CT is used for precise electrical metering and protection in low-voltage systems with higher current levels, such as:

• Main incoming feeders in a commercial or industrial distribution board.

• Supply lines to large motors or other high-power equipment.

• It accurately steps down the 400A primary current to a safe, standardized 4A secondary current for connection to ammeters, energy meters, and protection relays.