Basler PRS 250 Veri-Sync Relay

The Basler PRS 250 is a Veri‑Sync synchronization relay designed for paralleling generators with the utility grid or with other generators. This relay monitors voltage, frequency, and phase angle between the generator and the bus, and provides a closure signal to the circuit breaker when synchronization conditions are met, ensuring safe and reliable parallel operation. The relay operates with 120 V or 240 V AC inputs, providing flexibility for various generator control applications.

The relay features high‑precision measurement with adjustable synchronization window settings (voltage difference, frequency difference, and phase angle). It includes a front‑panel display and pushbuttons for local configuration, and supports communication for remote monitoring. The PRS 250 is housed in a rugged enclosure suitable for panel mounting in generator control rooms and substations.

Technical Specifications

• Model: PRS 250

• Function: Synchronization / paralleling relay

• Voltage sensing: 120/240 V AC (generator and bus)

• Frequency difference: 0.05‑1.00 Hz (adjustable)

• Voltage difference: 0.5‑20.0 V (adjustable)

• Phase angle: ±1° to ±20° (adjustable)

• Accuracy: ±0.5% (voltage), ±0.01 Hz (frequency)

• Output contacts: 2 form C (close and alarm)

• Communication: Modbus RTU (optional)

• Power supply: 120/240 V AC (from sensing)

• Display: 2‑line LCD with keypad

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

• Certifications: CE, UL, RoHS

Functional Features

• Accurate synchronization: Ensures safe paralleling by monitoring voltage, frequency, and phase angle.

• Adjustable thresholds: Voltage, frequency, and phase angle windows can be field‑adjusted.

• Breaker close output: Provides a closing pulse to the circuit breaker.

• Alarm outputs: Indicates out‑of‑sync conditions or relay faults.

• Event logging: Records synchronization events for post‑operation analysis.

Typical Applications

• Generator paralleling: Synchronizing diesel, gas, or hydro generators with the grid.

• Multiple generator sets: Paralleling generators in islanded power systems.

• Utility interconnections: Safe connection of distributed generation.

Installation and Configuration

Mount the PRS 250 on a panel. Connect the generator and bus voltage inputs, the power supply, and the output contacts. Configure the synchronization thresholds 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 PRS 250 provides reliable and accurate synchronization for generator paralleling, ensuring safe and seamless connection to the grid.