ABB 1TNA900111R0250 Current Transformer KORC 4L 250/1

Here is a detailed breakdown of the part number ABB 1TNA900111R0250 and its description KORC 4L 250/1.

This is another model from the same product family, differentiated by its higher current rating.

Part Number Breakdown: 1TNA900111R0250

This follows ABB's standard coding structure:

1TNA: The standard prefix for ABB's measurement and protection devices.

900111: The consistent unique article number, confirming this is the same base product as the 150/1 and 200/1 models.

R0250: This suffix now clearly indicates the variant with a primary current rating of 250A.

Description Breakdown: KORC 4L 250/1

This technical description defines the product's key characteristics, with one changing value.

KORC: Product Series.

Unchanged. This is part of ABB's KO series of resin-insulated, ring-type (window-type) current transformers. They are designed for reliability in switchgear, panel boards, and substations.

4L: Accuracy Class.

Unchanged. The 4L class is for metering applications.

'4' signifies an accuracy within ±4% at the rated current.

'L' denotes a low burden, making it ideal for connection to modern, low-power-consumption energy meters.

250/1: Current Ratio.

This is the defining difference for this model.

250: The Primary Current (I_p). This CT is designed for circuits with a normal current of 250 Amps.

1: The Secondary Current (I_s). The standardized, safe output current remains 1 Amp.

Summary of Key Specifications

Feature Specification Meaning & Context

Manufacturer ABB A leading global technology company.

Product Series KORC Identical series: resin-insulated, ring-type current transformer.

Type Window Type (Ring Type) Identical design. The main conductor passes through the center.

Primary Current (I_p) 250 A The key specification. Used for measuring a 250A circuit.

Secondary Current (I_s) 1 A Same standardized, safe output current for instruments.

Ratio 250/1 For every 250A in, 1A comes out.

Accuracy Class 4L Identical. For metering, with ±4% accuracy and a low burden.

Insulation Resin Cast Identical. Robust for industrial environments.

What is this used for?

The ABB 1TNA900111R0250 (KORC 4L 250/1) is used for energy metering and current measurement in low-voltage electrical installations where the expected load is higher.

You would select this 250/1 model for applications such as:

The main service entrance for a medium-sized commercial building.

A large industrial machine or a group of machines on a single feeder.

A distribution panel feeding multiple smaller circuits.