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The ABB 1TNA900141R0185 is a 185/4 dual-winding current transformer suitable for 12kV medium-voltage systems. It features one 0.5 class winding for high-precision measurement and one 5P10 class winding for relay protection, making it a well-balanced and widely used industrial standard product.
Product Introduction
Brand: ABB
Model: 1TNA900141R0185
Product Series: KORC 4L
Type: Window-type / Through-type Current Transformer. This type of CT has no primary winding; the power cable or busbar is directly passed through the central round hole to act as the primary side.
Primary Purpose: Typically installed in metal-enclosed switchgear for:
Measurement: Provides a secondary signal proportional to the primary current for devices like ammeters and energy meters.
Protection: Provides a signal to relay protection devices, triggering circuit breaker tripping during abnormal currents (e.g., overcurrent, short circuit).
Key Features: ABB's KORC series is renowned for its compact design, high accuracy, and reliability, and is a standard component in various ABB medium-voltage switchgear such as UniGear.
Detailed Technical Parameters
According to ABB official documentation, the specific parameters for this model are as follows:
Parameter Category Parameter Item Detailed Specification
Basic Information Full Model 1TNA900141R0185
Product Series KORC 4L
Description Window-type Current Transformer
Primary Side Parameters Rated Primary Current (Ipr) 185 A
Installation Method Through-type (Cable/Busbar pass-through)
Secondary Side Parameters Rated Secondary Current (Isr) 4 A
Output 2 independent cores and secondary windings
Core 1 (C1) Accuracy Class 0.5 (For precise measurement)
Rated Burden 15 VA
Accuracy Limit Factor (ALF) -
Core 2 (C2) Accuracy Class 5P (For protection)
Rated Burden 15 VA
Accuracy Limit Factor (ALF) 10
Accuracy Limit Current 10 x Ipr = 1850 A
General Parameters Frequency 50/60 Hz
Rated Insulation Level Typically 12/24/36 kV (Refer to official datasheet for specifics, but KORC 4L series is generally suitable for 12kV systems)
Power Frequency Withstand Voltage Typically 28 kV / 1 min
Impulse Withstand Voltage Typically 60 kV
Window Diameter Refer to specific drawings; commonly around 70-80mm for passing cables or busbars.
Standard Complies with IEC 61869-1, IEC 61869-2, etc.
Model Code Interpretation
1TNA900141R0185: This is ABB's internal material number, containing all product characteristics.
KORC 4L: This is the product series name.
KORC: Refers to ABB's specific current transformer series.
4L: Usually indicates that the CT has 4 secondary windings (or cores). However, for this specific model, documentation shows it is configured with 2 windings (one 0.5 class, one 5P10 class). Therefore, "4L" here likely refers to the design framework of the series, with the specific configuration determined by the full model number.
185/4: This is the most crucial technical code.
185: Rated primary current is 185A.
4: Rated secondary current is 4A.
Application and Selection Considerations
System Voltage: Confirm that your switchgear's system voltage (e.g., 12kV) is within the CT's rated insulation level.
Primary Current: Ensure the normal operating primary current is around 185A, and continuous overload should not exceed the CT's allowable value.
Secondary Circuit Burden: The total impedance of the wires, meters, and protection devices connected to the CT secondary side must not exceed the CT's rated burden (15 VA for both windings in this case). Excessive burden will lead to a decrease in CT accuracy.
Protection Class (5P10): "5P10" means the composite error of this protection winding does not exceed 5% at 10 times the rated primary current (10 x 185A = 1850A). This ensures the protection device operates reliably under fault currents.
Installation: During installation, pay attention to the position of the busbar or cable within the window and ensure the secondary side is never open-circuited, as this can generate dangerous high voltages.
