Basler BE1‑87G Generator Differential Relay

The Basler BE1‑87G is a solid‑state differential relay specifically designed for generator protection. This model, identified by configuration BE1‑87G‑G1E‑A1K‑A0N0F (also referenced as BE187GG1EA1KA0N0F), provides high‑speed fault detection by comparing currents entering and leaving the protected zone. It is essential for rapid isolation of internal faults to prevent damage to the generator and associated equipment.

Key Features

The relay features adjustable pickup settings, harmonic restraint to prevent maloperation during generator startup or external fault recovery, and a high‑speed output for tripping. It includes a target indicator for fault identification and test points for calibration. The relay is housed in a rugged draw‑out case for easy maintenance. This configuration includes reactor application settings for optimized performance.

Technical Specifications

CT secondary rating: 5 A or 1 A. Pickup current range: 0.1 to 2.0 times rated. Operating time: less than 25 milliseconds at 2 times pickup. Harmonic restraint: adjustable second‑harmonic blocking from 15% to 40%. Output contacts: 2 form‑C rated at 5 A at 250 VAC. Operating temperature: -20°C to +55°C. Auxiliary supply: 120/240 VAC or 48/125 VDC.

Operating Principles

The relay continuously monitors the current on both sides of the protected generator. Under normal conditions, the currents are balanced. When an internal fault occurs, the differential current exceeds the pickup threshold, and the relay initiates a trip. The harmonic restraint circuit prevents tripping during transient conditions by blocking on second‑harmonic content, ensuring security against false operations.

Applications

This relay is used for protection of generators, reactor banks, and large motors in utility and industrial power systems. It is essential for ensuring the integrity of critical assets and is commonly applied in power plants and substations.

Installation and Configuration

Mount the relay in a standard panel cutout. Connect the CT leads and auxiliary power. Adjust the pickup and restraint settings using the front‑panel controls. A secondary injection test is recommended to verify the operating characteristics and trip timing.

Maintenance and Reliability

Solid‑state design ensures long‑term reliability. Periodic testing with injection equipment is recommended to confirm calibration. Routine visual inspection of connections is sufficient.

Conclusion

The Basler BE1‑87G generator differential relay provides dependable high‑speed protection for generators and reactors, ensuring safe and reliable operation of power systems.