ABB INSUM MCU2 | Motor Control Unit for MNS Switchgear

The ABB INSUM MCU2 (Motor Control Unit 2) is the primary intelligent component of the INSUM (Integrated System for User-optimized Motor Management) architecture. Designed specifically for integration within MNS (Modular Low Voltage Switchgear), the MCU2 provides comprehensive protection, monitoring, and control for low-voltage motors. It acts as a bridge between the physical motor hardware and the higher-level Distributed Control System (DCS), offering high-resolution diagnostic data that goes far beyond standard thermal overload protection.

Product Specifications and Datasheet

• Model Designation: MCU2
• System Series: INSUM / MNS Switchgear
• Protection Functions: Thermal overload, phase failure, stall protection, earth fault, and underload monitoring.
• Control Modes: Local/Remote, manual/automatic, and various starter types (DOL, Reversing, Star-Delta).
• Communication: LonWorks protocol (standard for INSUM) or Profibus/Modbus via gateways.
• Input Voltage: 24V DC control power (typical).
• Current Measurement: Interface for external current sensors (Rogowski coils or CTs).
• Mounting: Designed for internal drawer installation in MNS switchboard modules.
• Dimensions (Depth): 145 mm
• Dimensions (Height): 90 mm
• Dimensions (Width): 75 mm
• Weight: 0.48 kg

Application Areas

The MCU2 is predominantly used in large-scale industrial plants where motor uptime is critical for process continuity. Key application areas include:

• Oil & Gas Refineries: Monitoring high-duty pumps and compressors.
• Chemical Plants: Managing motor-driven agitators and mixers in hazardous environments.
• Power Plants: Coordinating auxiliary motors for cooling fans and fuel handling.
• Mining & Metals: Protecting heavy-duty conveyors and crushers.
• Water & Wastewater: Controlling large submersible pumps and aeration systems.

Product Operating Instructions

The MCU2 should be installed by a qualified electrical technician within the MNS drawer assembly. Ensure the communication bus (LonWorks) is properly terminated and that the node address is correctly set via the INSUM OS (Operating Station) or the MMI (Man-Machine Interface). Wiring for current and voltage sensing should follow the specific schematic for the motor starter type (e.g., Direct-on-Line or Soft Starter). Once installed, parameters such as nominal motor current (In​) and trip class must be configured. During operation, use the front-panel LEDs or a connected HMI to monitor status; a steady green light typically indicates the unit is “Ready” and communicating.

Common Questions & Answers

Q: What is the main improvement of the MCU2 over the original MCU? A: The MCU2 offers enhanced memory for event logging, more precise measurement of electrical variables (including power factor and energy consumption), and improved diagnostic capabilities for preventative maintenance.

Q: Can the MCU2 be used with a standard Profibus DP network? A: Directly, the MCU2 communicates via LonWorks. To interface with Profibus, an ABB CI851 or CI854 communication module (for AC 800M) or a specialized INSUM gateway is required.

Q: How does the “Thermal Memory” function work? A: The MCU2 calculates the heat buildup in the motor based on current and time. If a trip occurs, the thermal memory prevents an immediate restart until the motor has cooled sufficiently, protecting the insulation from permanent damage.

Q: Is the MCU2 compatible with all MNS drawers? A: It is specifically designed for the MNS modular system. However, ensure the drawer mechanical footprint and backplane connections are configured for INSUM components.

Recommended Similar Models

• ABB INSUM MCU (Legacy)
• ABB MNS iS (Integrated System)
• ABB MCU3 (Next Generation)
• ABB CI857 (INSUM Communication Interface)
• ABB MMI (Man-Machine Interface for INSUM)