Basler BE1-81O Over/Under Frequency Relay (UT3EE1YA9S0F)

The Basler BE1-81O model UT3EE1YA9S0F is a variant of the BE1-81O digital frequency relay, offering precise overfrequency and underfrequency protection for generators, motors, and power system interconnections. This relay is designed to detect abnormal frequency conditions and initiate corrective action, such as tripping the generator or initiating load shedding, to prevent equipment damage and maintain system stability.

Like all BE1-81O relays, this unit features a microprocessor‑based design with high accuracy (±0.02 Hz) and excellent thermal stability. It provides independent overfrequency and underfrequency elements with adjustable pickup levels and time delays. The relay includes a front‑panel LCD and keypad for local settings, and supports Modbus communication for remote monitoring and control.

Technical Specifications

• Model: BE1-81O (UT3EE1YA9S0F)

• Nominal frequency: 50/60 Hz (selectable)

• Overfrequency pickup: 50‑65 Hz

• Underfrequency pickup: 45‑60 Hz

• Time delay: 0.1‑30 seconds (definite time)

• Accuracy: ±0.02 Hz

• Input voltage: 120/240 V AC (from PT)

• Output relays: 2 form C (1 for over, 1 for under)

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

• Communication: Modbus RTU (RS‑485)

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

• Enclosure: Panel mount

• Certifications: CE, UL, RoHS

Functional Features

• Pickup and dropout ratio: Hysteresis adjustable to prevent nuisance trips near setpoint.

• Time delay characteristics: Definite time or inverse time (selectable).

• Target indicators: Seal‑in target flags for over and underfrequency trips.

• Self‑diagnostics: Continuous monitoring of internal circuits and power supply.

Typical Applications

• Steam and gas turbine generators: Overfrequency protection to prevent overspeed.

• Diesel gensets: Underfrequency protection to avoid engine stall.

• Utility interconnections: Detection of frequency deviations for islanding detection.

• Industrial plants: Protection of sensitive motor loads.

Installation and Configuration

Mount the relay in a standard panel cutout. Connect the PT voltage to the input terminals and the DC/AC power supply to the appropriate terminals. The output contacts are wired to the trip circuit. Set the nominal frequency and pickup values using the keypad; the display shows the measured frequency and setpoints. The relay can be tested with a variable frequency source.

Compliance

This relay complies with IEEE C37.90, IEC 60255, and relevant EMC standards. It carries CE and UL approvals.

Conclusion

The Basler BE1-81O (UT3EE1YA9S0F) delivers dependable frequency protection with flexible settings, suitable for a wide range of generation and distribution systems.