Basler BE1-81O Over/Under Frequency Relay (UT3ED1LA7N0F)

The Basler BE1-81O model UT3ED1LA7N0F is a versatile digital frequency relay used for protection of synchronous generators, motors, and utility interconnections. It monitors the system frequency and trips the circuit breaker if the frequency exceeds or falls below the preset thresholds. This variant offers specific firmware and hardware options tailored to utility and industrial requirements.

The relay employs high‑precision frequency measurement using a digital phase‑locked loop (PLL), ensuring accurate and stable readings even under noisy conditions. It includes two independent output relays – one for overfrequency and one for underfrequency – each with its own pickup and time delay settings. The relay is housed in a compact, panel‑mountable enclosure.

Technical Specifications

• Model: BE1-81O (UT3ED1LA7N0F)

• Nominal frequency: 50/60 Hz

• Overfrequency pickup: 50‑65 Hz (adjustable)

• Underfrequency pickup: 45‑60 Hz (adjustable)

• Time delay: 0.1‑30 seconds

• Accuracy: ±0.02 Hz

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

• Output contacts: 2 form C (NO/NC)

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

• Display: 2‑line alphanumeric LCD

• Communication: Modbus RTU (optional)

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

• Certifications: CE, UL, RoHS

Key Features

• High accuracy: Frequency measurement with 0.01 Hz resolution.

• Two independent elements: Separate settings for over and under frequency.

• Time delay settings: Definite time or inverse time (depending on model).

• Event memory: Stores frequency excursions and trip events.

• Analog output: Optional 0‑10 V or 4‑20 mA proportional to frequency.

Typical Applications

• Generator sets: Protection against overspeed and stalling.

• Utility tie lines: Monitoring frequency for stability.

• Industrial motors: Preventing damage from abnormal frequency.

• Load shedding schemes: Underfrequency tripping of non‑critical loads.

Installation and Commissioning

Mount the relay on a panel; connect PT inputs to the voltage terminals. The power supply can be any DC/AC from 24 to 240 V. Output relays are wired to trip coils. Configure the setpoints via the front‑panel menu, and verify using a frequency calibrator. The relay includes a test mode for simulation.

Compliance

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

Conclusion

The Basler BE1-81O (UT3ED1LA7N0F) is a reliable, precise frequency protection relay ideal for diverse power system applications.