ABB 1MRS050644

Description

Detailed parameter table

ABB 1MRS050644

Product introduction

The 1MRS050644 is a compact motor protection relay from ABB, designed to monitor and protect low-voltage AC motors against electrical faults and abnormal operating conditions. As a critical component in motor control circuits, it continuously measures motor current, voltage, and phase balance, triggering protective actions (such as contactor tripping) when dangerous conditions are detected.

This relay combines comprehensive protection functions with user-friendly operation, making it suitable for a wide range of applications—from pumps and fans in HVAC systems to conveyor motors in manufacturing facilities. The 1MRS050644 features a clear LCD display that provides real-time motor data and fault diagnostics, simplifying troubleshooting and reducing downtime. Its Modbus RTU communication capability allows integration into larger automation systems, enabling remote monitoring and control of motor status.

With a current range of 0.1 A to 63 A, the 1MRS050644 offers flexible protection for small to medium-sized motors, ensuring reliable operation and extending motor lifespan by preventing damage from overloads, phase failures, and other common electrical issues.

Core advantages and technical highlights

Comprehensive protection coverage

The 1MRS050644 provides a full suite of protection functions that address the most common causes of motor failure. In a wastewater treatment plant, for example, it protects pump motors by:

• Detecting overload conditions caused by clogged pipes
• Identifying phase loss that could damage windings
• Monitoring earth faults to prevent electrical hazards

This multi-layered protection reduces unplanned downtime by up to 30% compared to basic thermal overload relays.

Flexible installation and configuration

With both DIN rail and panel mounting options, the 1MRS050644 adapts to various control cabinet layouts. Its adjustable trip characteristics (Class 10, 20) allow precise matching to motor types—Class 10 for motors with high starting currents (like centrifugal pumps) and Class 20 for applications with longer acceleration times (such as conveyors). The intuitive menu system, accessible via front-panel buttons, enables quick configuration without specialized software.

Seamless system integration

Equipped with Modbus RTU, the 1MRS050644 easily connects to PLCs and SCADA systems. In a food processing facility, this allows the relay to transmit motor status data to an ABB AC500 PLC, which coordinates production lines based on real-time equipment health. Maintenance teams can remotely monitor motor performance via HMI screens, enabling predictive maintenance and reducing unnecessary site visits.

Typical application scenarios

In a commercial building’s HVAC system, the 1MRS050644 protects air handling unit motors from damage. It monitors fan motor current to detect filter blockages (indicated by increased load) and triggers an alarm before overload occurs. The phase loss protection feature prevents motor burnout if a wiring fault develops in the three-phase supply, while the underload function alerts maintenance if the fan belt breaks—ensuring continuous climate control and energy efficiency.

In a manufacturing plant’s packaging line, the 1MRS050644 safeguards conveyor motors against the stresses of variable production demands. During peak periods, it allows temporary overloads within safe limits (adjustable via trip settings) while preventing sustained overloads that would shorten motor life. The Modbus RTU interface integrates with the plant’s SCADA system, providing operators with real-time motor current readings and enabling them to adjust production speed to avoid motor strain.

ABB 1MRS050644

Related model recommendations

• 1MRS050645: Higher-current version of 1MRS050644, covering 1 A to 250 A for larger motors.
• 1MRS050646: Advanced variant with Ethernet/IP communication, ideal for smart factory integration.
• Tmax XT: ABB’s molded case circuit breaker that pairs with 1MRS050644for complete motor protection.
• RLM01: Remote I/O module that connects 1MRS050644to PLCs in distributed control systems.
• CM-MPS: Current transformer set optimized for use with 1MRS050644in 0.1-63 A applications.
• AC500 PLC: ABB’s programmable logic controller that communicates with 1MRS050644via Modbus RTU.
• 1MRS050643: Basic version of 1MRS050644with fewer protection functions, for cost-sensitive applications.

Installation, commissioning and maintenance instructions

Installation preparation: Mount the 1MRS050644 on a clean, dry DIN rail or panel, ensuring proper grounding. Connect current transformers (if required for currents > 10 A) with correct polarity to the relay’s current inputs. Wire the supply voltage (24 V DC or 110-240 V AC) to the designated terminals, using a fused circuit (0.5 A). For communication, connect the RS-485 bus to terminals A and B, ensuring proper termination (120 Ω resistor) at the end of the bus.

Maintenance suggestions: Inspect the 1MRS050644 quarterly by checking the LCD display for error codes and verifying all connections are tight. Clean the front panel with a dry cloth to maintain display visibility. Test protection functions annually by simulating faults (e.g., phase loss) and confirming the relay trips within specified time limits. Update firmware via the Modbus interface when new versions are available. If the relay fails to trip or communicate, check power and wiring first; replace with an ABB-approved unit if necessary, transferring settings to the new device.

Service and guarantee commitment

The 1MRS050644 is backed by a 2-year warranty covering defects in materials and workmanship under normal operating conditions. ABB’s technical support team provides assistance with configuration, troubleshooting, and integration into motor control systems, including guidance on setting appropriate trip parameters for specific applications.

Customers receive access to detailed user manuals and application notes for the 1MRS050644, including wiring diagrams and protection setting recommendations. ABB maintains a global inventory of replacement units to minimize downtime. Our commitment to quality ensures the 1MRS050644 delivers reliable motor protection, helping customers maintain safe and efficient operation of their electrical systems.