Basler Electric BE1-27/59 Undervoltage and Overvoltage Relay

The Basler Electric BE1-27/59 is a solid-state voltage relay that provides both undervoltage (27) and overvoltage (59) protection in a single unit. It continuously monitors the three-phase voltage of a generator, motor, or transformer and operates when the voltage falls below or rises above predetermined setpoints. This relay is essential for protecting equipment from voltage excursions that can cause thermal damage, instability, or loss of synchronization.

Key Features

• Independent undervoltage and overvoltage pickup settings

• Adjustable time delay for each function

• Single-phase or three-phase sensing options

• Definite time or inverse time characteristics selectable

• Wide voltage range for 120 or 240 VAC systems

• Output relays for tripping and alarm

• LED indicators for status and operation

• Test points for calibration and functional testing

Technical Specifications

Voltage sensing inputs are rated for 0-300 VAC, 50/60 Hz. Undervoltage pickup range is 10 to 120 VAC, and overvoltage pickup range is 60 to 300 VAC. Time delays are adjustable from 0.1 to 10 seconds. Auxiliary power is 120/240 VAC or 24 to 125 VDC. Output contacts are rated at 10 A, 250 VAC. Operating temperature is -20 to +65 degrees Celsius. The relay meets IEEE C37.90 and IEC 60255 standards.

Protection Functions

Undervoltage protection guards against voltage sags that can cause motor stalling, generator loss of excitation, or contactor dropout. Overvoltage protection prevents insulation damage and overexcitation of transformers. The relay can be set for phase-to-neutral or phase-to-phase voltage measurement, and includes a loss-of-voltage detection feature to differentiate between fault and normal zero voltage.

Installation and Calibration

Panel mounting with rear connections. Calibration involves applying reference voltage and adjusting the pickup potentiometers. The time delay is set via rotary switches. Commissioning requires verifying operation at both undervoltage and overvoltage thresholds using a variable transformer.

Applications

Used in generator protection panels, motor control centers, transformer protection, and industrial power distribution systems. It is also applied in automatic transfer schemes to initiate transfer during undervoltage conditions.

Reliability and Compliance

Manufactured with high-quality solid-state components, the BE1-27/59 offers long-term stability and resistance to electrical noise. It carries UL, CSA, and CE approvals. Regular testing is recommended to ensure accuracy.

Conclusion

Basler Electric BE1-27/59 undervoltage/overvoltage relay provides complete voltage protection in a compact, reliable package. Its dual-function design simplifies protection schemes and reduces panel space requirements.