Description
Detailed Parameter Table
| Parameter Name | Parameter Value |
| Product Model | ABB IEMMU21 |
| Manufacturer | ABB |
| Product Category | Motor Protection Relay |
| Protection Functions | Overload, phase unbalance, locked rotor, earth fault |
| Current Rating | 0.5-6.3A (adjustable) |
| Supply Voltage | 24-240V AC/DC |
| Inputs | 3-phase current (CT inputs), 1 RTD input |
| Outputs | 2 changeover relays |
| Communication | Modbus RTU (RS485) |
| Display | LCD with status indicators |
| Operating Temperature | -20°C to +60°C |
| Enclosure Rating | IP20 |
| Dimensions | 90mm × 70mm × 60mm |
| Mounting | DIN rail (35mm) |
ABB IEMMU21
Product Introduction
The ABB IEMMU21 is a compact yet powerful motor protection relay designed for small to medium-sized three-phase motors. Part of ABB’s comprehensive motor management portfolio, this device provides essential protection functions while offering simple installation and operation.
With its adjustable current range from 0.5A to 6.3A, the IEMMU21 is particularly suitable for protecting pumps, fans, compressors, and other motor-driven equipment in industrial applications. The integrated Modbus communication allows for easy integration into automation systems, enabling remote monitoring and control.
The relay’s clear LCD display provides real-time motor status information and simplifies parameter setting, making it an ideal choice for applications where space is limited but reliable motor protection is essential.
Core Advantages and Technical Highlights
Comprehensive Protection:
The IEMMU21 offers complete motor protection including overload, phase unbalance/loss, locked rotor, and earth fault protection, significantly reducing motor failure risks.
Flexible Configuration:
With adjustable current settings and multiple protection curves, the relay can be precisely tuned to match specific motor characteristics and application requirements.
Integrated Communication:
Modbus RTU interface enables seamless integration with control systems for remote monitoring of motor status and operating parameters.
Compact Design:
Despite its small footprint, the relay packs all essential protection features, making it ideal for space-constrained installations.
User-Friendly Interface:
The clear LCD display and intuitive navigation buttons simplify commissioning and operation, reducing setup time and potential errors.
Wide Power Supply Range:
The ability to operate from 24-240V AC/DC makes the relay adaptable to various installation environments.
Typical Application Scenarios
The ABB IEMMU21 is widely used in:
HVAC Systems:
Protecting fans, pumps, and compressors in commercial and industrial heating, ventilation, and air conditioning systems.
Water Treatment Plants:
Safeguarding pumps and mixers in water purification and wastewater treatment processes.
Manufacturing Equipment:
Providing reliable protection for motors in conveyor systems, mixers, and packaging machinery.
Food Processing:
Monitoring and protecting motors in processing lines where consistent operation is critical.
Building Automation:
Integrating with building management systems to protect essential motor-driven services.
ABB IEMMU21
Related Model Recommendations
ABB EMMU20: Basic version without communication
ABB EMMU22: Advanced version with additional I/O
ABB EMMU23: Version with PROFIBUS communication
ABB EMM10: Compact thermal overload relay
ABB EMM11: Electronic overload relay with communication
ABB EMS: Motor starter combination units
ABB CM-MPS: Modular motor protection system
ABB M102: Motor protection relay for larger motors
Installation, Commissioning and Maintenance Instructions
Installation Preparation:
Ensure proper DIN rail mounting in a well-ventilated enclosure. Verify correct CT installation with proper shorting when not in use. Ensure power supply matches relay requirements.
Commissioning:
Set motor rated current and protection parameters according to motor nameplate data. Test each protection function using the test mode before putting into service. Verify relay operation by simulating fault conditions.
Maintenance Suggestions:
Regularly check relay display for warnings or alarms. Verify tightness of electrical connections annually. Test protection functions periodically (recommended every 6 months). Keep ventilation openings clean and unobstructed.
Service and Guarantee Commitment
ABB provides a standard 24-month warranty for the IEMMU21 motor protection relay. Technical support is available through ABB’s global service network, offering assistance with installation, configuration, and troubleshooting. Software updates and configuration tools are available through ABB’s website and authorized distributors.
For critical applications, extended warranty options are available. The relay undergoes rigorous testing during manufacturing to ensure reliable operation in demanding industrial environments. ABB’s service centers offer calibration and repair services throughout the product lifecycle.
