ABB 1TNA900341R0235 Current Transformer KORC 4S 235/4

ABB 1TNA900341R0235 Current Transformer KORC 4S 235/4

 ABB 1TNA900341R0235 Current Transformer KORC 4S 235/4 is an ABB KORC Series, Ring Core (Window-Type) Current Transformer designed for electrical measurement and protection in medium-voltage switchgear (like ABB's ZS1 Unigear type).

Its primary function is to scale down a high primary current to a safe, standardized lower secondary current that can be easily measured by instruments (like ammeters, energy meters) and used by protective relays.

Part Number Decoding: 1TNA900341R0235

This is the unique article number. Let's dissect it:

1TNA: This is a common prefix for ABB's primary components and distribution automation products.

900341: This is the specific base part number for this CT's core and electrical characteristics.

R0235: This is a revision or variant code. "R" often stands for Revision.

Technical Designation: KORC 4S 235/4

This is the most informative part of the code, describing the physical and electrical properties.

KORC: Stands for KOre (the German/Danish word for "core") Ring Current Transformer. This indicates it's a window-type or ring-type CT, meaning the primary conductor (e.g., a busbar or cable) simply passes through the hole in the center.

4S: Indicates the Insulation Level and Accuracy Class.

4: Refers to the rated voltage class. In this system, "4" typically corresponds to a 7.2 kV or 12 kV system voltage. (You would need to confirm from the specific datasheet, but 12kV is very common for this type).

S: Stands for "Measurements/Protection" (from the German "Schutz"). It signifies that this CT core is designed for Protection purposes. Protection cores are designed to be accurate up to high overcurrents (e.g., during a fault) and have a high "Accuracy Limit Factor" (ALF).

235/4: This defines the Current Ratio and the Accuracy Class.

235: The Rated Primary Current is 235 Amps. Because it's a window-type CT, this value is often standardized, and the actual ratio is determined by the number of times the primary cable is passed through the window.

4: The Accuracy Class for this protection core. According to the IEC 61869 standard, a class 5P is common, where the '5' indicates a composite error of ±5% at the rated accuracy limit current. The "4" might be an internal ABB designation that maps to a standard class like 5P10 or 5P20 (where 10 or 20 is the ALF). You must consult the datasheet for the exact specification.

Key Features and Specifications (Summary)

Feature Specification / Description

Manufacturer ABB

Type Ring Core (Window-Type) Current Transformer

Model Series KORC

Rated Primary Current (Ipr) 235 A (Nominal)

Rated Secondary Current (Isr) Typically 1 A or 5 A (Must be confirmed from datasheet)

Rated Voltage Likely 7.2 kV or 12 kV

Core Function Protection (Class S)

Accuracy Class Likely 5P (with a specific Accuracy Limit Factor)

Mounting Designed to be installed over a primary conductor in a compartment of medium-voltage switchgear.

Common Applications

This specific current transformer is commonly used inside ABB's UniGear ZS1 and similar medium-voltage switchgear panels for:

Feeder Protection: To detect overcurrent and short-circuit faults on outgoing power lines.

Transformer Protection: To protect the main power transformer.

General Circuit Protection: Providing a current signal to the main protective relay for the circuit breaker.