Basler Electric PRS250 Veri‑Sync Relay

The Basler Electric PRS250 (part number 9088800102) is a high‑precision solid‑state synchronism‑checking relay designed to ensure that two AC power sources are within acceptable limits of voltage magnitude, phase angle, and slip frequency before permitting breaker closure. This relay is essential for generator paralleling, bus transfer, and co‑generation applications where out‑of‑phase closure could cause catastrophic mechanical and electrical damage. The PRS250 is known for its accuracy, reliability, and ease of configuration.

Measurement and Setting Windows

The relay independently measures the voltage, phase angle difference, and slip frequency between the two sources. Each parameter has an independently adjustable window: voltage match typically 5‑20% of nominal, phase angle 1‑20 degrees, and slip frequency 0.05‑0.5 Hz. When all conditions are satisfied for a programmable dwell time (0.1‑10 seconds), the relay closes its output contact, enabling the breaker close circuit. A built‑in voltage‑matching output can automatically adjust the generator AVR to reduce phase error, speeding up the synchronizing process.

User Interface and Configuration

The PRS250 features a front panel with LED indicators for source presence, synchronism status, and relay health. DIP switches and potentiometers allow easy setting adjustments without the need for external software. The relay includes one Form C output contact (rated 5 A at 250 VAC), a test pushbutton for functional verification, and a manual reset button. The unit is housed in a rugged metal enclosure suitable for standard panel mounting.

Technical Specifications

Input voltage: 100‑480 VAC, 50/60 Hz (single‑phase or three‑phase sensing). Accuracy: ±2% for voltage, ±1 degree for phase angle. Output contact: 1 Form C, rated 5 A at 250 VAC. Power supply: 24‑250 VDC or 120‑240 VAC. Burden: less than 5 VA. Operating temperature: –20°C to +65°C. The relay meets IEEE C37.90 surge withstand capability and is CE marked.

Applications

The PRS250 is widely used in emergency generator sets, marine propulsion systems, utility interconnections, and industrial co‑generation plants. It is also employed in automatic transfer switch schemes to verify synchronism before returning load to the preferred source. The relay can be used with both synchronous and induction generators with appropriate settings.

Installation and Commissioning

Mount the relay in a standard panel cutout. Connect the voltage inputs from both sources (line and bus), and connect the output to the breaker close coil circuit. Commissioning involves setting the voltage, phase, and slip windows according to system requirements, then testing with a synchronizing test set. The relay includes a built‑in simulation mode for functional verification without live sources.

Reliability and Quality

Basler Electric’s PRS250 is built with high‑reliability components and subjected to rigorous environmental and electrical testing, including temperature cycling, vibration, and transient immunity. Its solid‑state design ensures long life and minimal maintenance. The relay is backed by Basler’s technical support and comprehensive documentation.

Conclusion

The Basler Electric PRS250 Veri‑Sync relay (9088800102) is a dependable, accurate, and easy‑to‑configure synchronism‑checking device that enhances safety and reliability in power system paralleling operations.