Basler Electric PRS‑250 Veri‑Sync Relay

The Basler Electric PRS‑250 Veri‑Sync relay is a solid‑state synchronism‑checking device that ensures two AC sources are within safe limits of voltage, phase angle, and frequency before allowing breaker closure. It is widely used in generator paralleling, automatic bus transfer, and co‑generation applications to prevent out‑of‑phase closures that can cause severe mechanical and electrical damage.

Operating Parameters

The relay independently measures the voltage magnitude, phase angle difference, and slip frequency between the two sources. Each parameter has an 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 met for a preset 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 difference.

Design and Interfaces

The PRS‑250 features a front panel with LED indicators for source presence, synchronism status, and relay health. DIP switches and potentiometers allow easy setting adjustments. The relay includes both normally open and normally closed output contacts, a test pushbutton, and a reset button. It is housed in a rugged metal enclosure for 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. Output contact: 1 Form C, rated 5 A at 250 VAC. Power supply: 24‑250 VDC or 120‑240 VAC. Burden:<5 VA. Operating temperature: –20°C to +65°C. Meets IEEE C37.90 surge withstand.

Applications

The PRS‑250 is used in emergency standby generator sets, marine propulsion systems, utility interconnections, and industrial plants with multiple generators. It is also employed in automatic transfer switches to verify synchronism before returning load to the preferred source.

Installation and Commissioning

Installation is standard panel mounting. Connect voltage inputs from both sources and the output to the breaker control circuit. Commissioning involves setting the windows and dwell time, then verifying operation with a test set. The relay includes a simulation mode for functional testing.

Reliability and Quality

Basler Electric’s PRS‑250 is built with high‑reliability components and is fully tested for temperature, humidity, and electrical noise. Its solid‑state design ensures long life and low maintenance.

Conclusion

The Basler Electric PRS‑250 Veri‑Sync relay is a precise and dependable synchronism‑checking device that enhances safety and reliability in power system paralleling operations.