Basler Electric BE1-59N Ground Fault Overvoltage Relay

The Basler Electric BE1-59N is a solid-state relay specifically designed to detect ground faults in the stator winding of synchronous generators by monitoring the voltage across the neutral grounding resistor or transformer. Under normal conditions, the neutral voltage is nearly zero. When a ground fault occurs, the neutral voltage rises proportionally to the fault location and grounding impedance. The BE1-59N continuously measures this voltage and trips when it exceeds a preset threshold for a selected time delay, providing sensitive and reliable protection against stator insulation failures.

Key Features

• Solid-state design for high repeatability and long life

• Adjustable pickup voltage from 1 to 120 VAC

• Adjustable time delay from 0.1 to 10 seconds

• Frequency tracking for 50/60 Hz systems

• Built-in test points for calibration and verification

• LED indicators for power, pickup, and output

• Output relay with Form C contacts for tripping and alarm

• Compact panel-mount case with rear terminal block

Technical Specifications

The relay accepts a voltage input of 0-150 VAC from the neutral grounding transformer. Pickup accuracy is ±2 percent of setting. Time delay accuracy is ±5 percent. Auxiliary power: 120/240 VAC or 24 to 125 VDC. Burden: less than 5 VA. Output contacts: 10 A at 250 VAC. Operating temperature: -20 to +65 degrees Celsius. The relay meets IEEE C37.90 and IEC 60255.

Protection Principle

The BE1-59N uses a high-impedance voltage measurement circuit to sense the fundamental frequency component of the neutral voltage. A filter rejects harmonics and noise to prevent nuisance tripping. The pickup setting is adjustable to accommodate different grounding methods and fault current levels. The time delay allows coordination with other protection devices.

Installation and Calibration

Mount the relay in a standard panel cutout. Connect the neutral voltage signal and auxiliary power. Calibration is performed using a variable AC source to simulate fault voltage. The pickup potentiometer and time delay switch are adjusted to the desired values. A test button is provided for functional verification.

Applications

Primary application is stator ground fault protection for generators in utility, industrial, and marine power plants. It is also used for transformer neutral overvoltage protection and as a backup for differential protection schemes.

Reliability and Compliance

The BE1-59N is manufactured under ISO 9001 and has approvals from UL, CSA, and CE. Its robust design ensures reliable operation in harsh electrical environments. Regular testing is recommended to maintain calibration.

Conclusion

Basler Electric BE1-59N ground fault overvoltage relay provides cost-effective and dependable detection of stator ground faults. Its adjustable settings, solid-state reliability, and ease of installation make it a standard choice for generator protection worldwide.