DEIF MDR-2 Multifunctional Digital Relay

The DEIF MDR-2 is a compact multifunctional digital relay designed for protection, measurement, and control of electrical power systems. This versatile device combines multiple protection functions into a single unit, making it ideal for generator sets, transformers, feeders, and motors. The MDR-2 offers a cost-effective solution for applications requiring comprehensive electrical protection without the complexity of larger protection systems.

Protection Functionality

The MDR-2 provides a comprehensive suite of protection functions configurable to meet specific application requirements. Overcurrent protection features selectable time-current curves including standard inverse, very inverse, and extremely inverse characteristics, enabling coordination with upstream and downstream protection devices. Earth fault protection is implemented using either residual current measurement or core balance CT configuration. Voltage protection includes both undervoltage and overvoltage functions with adjustable time delays.

Measurement and Monitoring

In addition to protection functions, the MDR-2 continuously measures key electrical parameters for system monitoring:

• Phase voltages and line voltages

• Phase currents and neutral current

• Frequency

• Active power, reactive power, and apparent power

• Power factor

• Energy measurement (kWh, kvarh)

• Harmonic distortion up to the 15th order

All measured values are displayed on the integral LCD and accessible via communication interfaces.

Configuration and Programming

The MDR-2 is configured using the DEIF MDR-2 Configuration Tool software, which provides a user-friendly interface for setting protection parameters, defining input and output functions, and establishing communication settings. The software enables offline configuration, which can be uploaded to the device or saved for documentation. Multiple configuration files can be stored and deployed across multiple units, simplifying commissioning of installations with several relays.

Communication Capabilities

The MDR-2 supports Modbus RTU communication over RS-485, enabling integration with supervisory control and data acquisition systems, programmable logic controllers, and building management systems. The communication interface provides access to all measured values, status information, and alarm conditions. The relay can also receive remote control commands for breaker operation and reset functions.

Technical Specifications

• Power Supply: 24 V DC or 110-230 V AC/DC

• Voltage Measurement: Up to 690 V AC directly

• Current Measurement: 5 A or 1 A CT secondary

• Frequency Range: 40 to 70 Hz

• Digital Inputs: 3 to 6 configurable

• Relay Outputs: 3 to 6 configurable

• Analog Outputs: 1 optional (0-20 mA or 4-20 mA)

• Operating Temperature: -25°C to +70°C

• Protection Rating: IP40 (front panel)

Applications

The DEIF MDR-2 is suitable for a wide range of power system protection applications:

• Generator protection for standby and prime power applications

• Transformer protection in distribution systems

• Feeder protection for industrial facilities

• Motor protection for critical rotating equipment

• Renewable energy system interconnection protection

• Marine and offshore electrical systems

User Interface

The front panel features a graphical LCD display with backlight, providing clear visibility of measured values and configuration menus. Navigation buttons allow users to scroll through measurement screens, view event logs, and acknowledge alarms. Status LEDs provide immediate visual indication of relay health, alarm conditions, and output status. The intuitive interface reduces training requirements for operators and maintenance personnel.

Event Logging

An integrated event log records protection operations, configuration changes, and system events with time stamps. This information is essential for post-fault analysis, helping engineers understand the sequence of events leading to protection operations and identify potential system weaknesses. The event log can be accessed locally through the display or remotely via the communication interface.

Certifications

The MDR-2 complies with IEC 60255 series standards for measuring relays and protection equipment. It meets CE requirements for electromagnetic compatibility and safety. The relay is manufactured under ISO 9001 quality management systems.