Basler BE1-51/27R Voltage-Controlled Overcurrent Relay

The Basler BE1-51/27R is a multifunction digital relay that combines overcurrent protection with under-voltage control, providing coordinated protection for generators, motors, and transformers. This relay features phase overcurrent (51) and ground overcurrent (51N) elements that can be blocked or conditioned by voltage (27) signals, enabling advanced protection schemes such as voltage-restrained overcurrent and breaker failure protection.

The relay offers high accuracy and flexibility with programmable settings for pickup, time-current curves, and voltage thresholds. It includes a front-panel display and keypad for local operation, and supports Modbus communication for remote monitoring. The BE1-51/27R is housed in a rugged enclosure suitable for panel mounting in industrial and utility substations.

Technical Specifications

• Model: BE1-51/27R

• Protection functions: Phase overcurrent (51), ground overcurrent (51N), voltage-controlled/restrained (27), under-voltage (27)

• Current sensing: 1/5 A CT inputs

• Voltage sensing: 3-phase, 0-600 V AC

• Time-current curves: Definite time, IEC, IEEE

• Pickup range: 0.05-20.00 A (adjustable)

• Voltage threshold: 0-120 V (adjustable)

• Output contacts: 4 form C (trip, alarm, etc.)

• Communication: Modbus RTU (RS-485)

• Power supply: 24-240 V AC/DC (universal)

• Display: 2-line LCD with keypad

• Operating temperature: -40°C to +70°C

• Certifications: CE, UL, RoHS

Functional Features

• Voltage-controlled overcurrent: Overcurrent pickup can be blocked or modified by under-voltage conditions for coordinated protection.

• Voltage-restrained overcurrent: Enhances sensitivity during voltage dips.

• Under-voltage protection: Independent under-voltage element for motor and generator protection.

• Programmable logic: Allows custom logic equations for advanced protection schemes.

• Event recording: Stores fault events with time stamps.

Typical Applications

• Generator protection: Voltage-restrained overcurrent for backup protection.

• Motor protection: Under-voltage and overcurrent protection for large motors.

• Feeder protection: Overcurrent protection with voltage supervision for distribution feeders.

• Breaker failure protection: Overcurrent supervision with voltage logic.

Installation and Configuration

Mount the BE1-51/27R on a panel. Connect CT and PT inputs, power supply, and output contacts. Configure the protection elements, voltage thresholds, and communication settings using the front-panel keypad. The relay includes a test mode for commissioning.

Compliance

Complies with IEEE C37.90, IEC 60255, CE and UL approved, RoHS compliant.

Conclusion

The Basler BE1-51/27R provides advanced voltage-controlled overcurrent protection, offering flexible coordination and enhanced security for complex power system applications.