Basler Electric BE1‑59N‑A5E‑E1L‑N0S1F Neutral Overvoltage Relay

The Basler Electric BE1‑59N is a solid‑state neutral overvoltage relay designed to detect ground faults in resistance‑grounded power systems. It monitors the voltage developed across the neutral grounding resistor or the voltage between the transformer neutral and ground. When a ground fault occurs, the neutral voltage rises proportionally to the fault current. The relay trips when this voltage exceeds a preset pickup level, providing sensitive and fast protection for transformers and generators.

Relay Operation

The BE1‑59N compares the measured neutral voltage against an adjustable setpoint (typically 5‑300 VAC). If the voltage exceeds the setpoint for a selected time delay (0.05‑10 seconds), the relay operates its output contacts. The pickup is adjustable via a front‑panel potentiometer, and the time delay is set by DIP switches or a dial. A built‑in test circuit allows simulation of a fault condition for functional verification.

Key Features

This relay offers high sensitivity to low‑level ground faults while maintaining transient immunity to switching surges. It includes a target indicator for trip identification, a manual reset pushbutton, and auxiliary contacts for remote annunciation. The relay is housed in a compact, dust‑resistant metal enclosure suitable for panel mounting. It operates from a wide range of DC or AC control voltages.

Technical Specifications

Input voltage: 5‑300 VAC, 50/60 Hz. Pickup accuracy: ±2% of setting. Time delay: 0.05‑10 seconds, adjustable. Output contacts: 1 Form C (SPDT), 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. Dielectric withstand: 2 kV RMS for 1 minute.

Applications

The BE1‑59N is used on power transformers, generator neutrals, and industrial grounding systems. It is ideal for high‑resistance and low‑resistance grounded systems where sensitive ground fault detection is required. It can also be applied in ungrounded systems to detect a developing ground fault. The relay is frequently coordinated with ground fault overcurrent relays for selective tripping.

Installation and Commissioning

Mount the relay in a standard panel cutout. Connect the neutral voltage input, control power, and output contacts. Commissioning involves setting the pickup level and time delay based on system grounding parameters. Use a test set to inject a voltage signal to verify trip accuracy. The relay includes a test pushbutton for quick functional checks.

Reliability and Standards

Compliant with ANSI/IEEE C37.90 and IEC 60255, the BE1‑59N is built with high‑quality solid‑state components and conformal‑coated boards to resist humidity and contaminants. Its self‑monitoring circuits ensure reliable operation. Regular calibration is recommended but not frequently required due to the stable design.

Conclusion

The Basler Electric BE1‑59N‑A5E‑E1L‑N0S1F neutral overvoltage relay provides precise and dependable ground fault protection for critical power equipment. Its adjustable settings, robust construction, and ease of use make it a valuable asset in any protection scheme.