ABB NINT-43C Main Circuit Interface Board

Overview

The NINT-43C is a core interface board used in high-power variable-speed drive platforms from ABB. Installed within ACS-series drive frames, this board forms the electrical and logical boundary between the high-energy power section and the low-voltage control system.
By combining galvanic isolation, signal conditioning, protection feedback, and internal communication paths, the NINT-43C enables stable and safe drive operation under demanding industrial conditions.

Unlike generic I/O boards, this module is purpose-engineered for ABB drive architectures and works as a real-time interface for power-stage supervision and control interaction.

Functional Role in the Drive System

The NINT-43C is positioned directly between the main circuit and the control electronics, where it performs three critical tasks:

Safe isolation of control circuitry from high-voltage power components
Acquisition and transmission of electrical measurement signals
Fast propagation of fault and status information to the drive controller

This architecture ensures that protection events in the power stage are detected and acted upon without delay, reducing the risk of secondary damage.

Key Technical Capabilities

High-voltage to control-level galvanic isolation
Continuous monitoring of DC-link and main-circuit signals
Support for drive-internal communication channels
Protection feedback for overcurrent, overvoltage, and thermal events
High EMC immunity suitable for high-power inverter environments
Plug-in board design optimized for ACS drive frames

Technical Specifications

The following specifications reflect consolidated data from ABB documentation and field experience. Values may vary slightly by hardware revision.

Electrical Characteristics
Control supply voltage: 24 V DC nominal
Operating voltage range: 18–30 V DC
Isolation strength: ≥ 3.5 kV AC, 60 s test between power and control domains
Typical power dissipation: < 4 W

Signal and Interface Functions
Main-circuit measurement signal interface (ABB proprietary)
Internal drive communication links to control and protection boards
Support for dual-channel or redundant signaling in specific variants

Mechanical Data
Board format: Plug-in PCB module
Dimensions: 170 × 110 × 22 mm
Weight: 0.22 kg
Mounting method: Card slot installation inside drive cabinet

Environmental Limits
Ingress protection: IP20 (standard cabinet installation)
Operating temperature range: –25 °C to +60 °C
Humidity: Non-condensing, control cabinet environment

Typical Applications

Medium- and high-power ACS-series drives
Industrial motor control systems above 160 kW
Energy, metals, pulp and paper, and heavy manufacturing drives
High-EMI environments requiring robust signal isolation

System Architecture Context

Within the drive, the NINT-43C connects:

The power stage, including IGBT or thyristor assemblies and DC link
The low-voltage control unit responsible for regulation and logic

This placement allows accurate feedback, reliable protection coordination, and stable control performance even during transient or fault conditions.

FAQ

Is the NINT-43C a standard I/O board?
No. Although sometimes described as an I/O or communication board, the NINT-43C is a dedicated main-circuit interface designed specifically for ABB drive platforms.

Can the NINT-43C be used outside ABB drives?
It is not intended for general automation use. Signal definitions and interfaces are ABB-specific.

Are there multiple hardware variants?
Yes. Different revisions may exist depending on drive frame size and protection architecture, but the functional role remains the same.