Basler Electric BE1‑50/51M Overcurrent Relay

The Basler Electric BE1‑50/51M is a solid‑state overcurrent relay that provides both instantaneous (ANSI 50) and time‑overcurrent (ANSI 51) protection in a single unit. It is specifically designed for motor protection and feeder applications where fast fault clearing and coordinated time grading are required. The relay offers adjustable pickup settings, independent time delays, and a choice of inverse‑time or definite‑time characteristics.

Instantaneous Element

The instantaneous element (50) operates without intentional time delay when the current exceeds a high‑set pickup level. It is typically set above the motor starting current or feeder maximum load to provide rapid protection for severe short‑circuit faults. The pickup is adjustable from 2 to 80 times the nominal current, with accuracy within ±2%.

Time‑Overcurrent Element

The time‑overcurrent element (51M) features an inverse‑time characteristic with adjustable time dial (0.5‑10 seconds at 10x pickup). This allows coordination with downstream protective devices. The motor‑specific version (51M) includes thermal memory and a stall protection feature to prevent motor burnout during prolonged overloads. The pickup is adjustable from 0.5 to 20 A secondary.

Key Features

The relay includes a front‑panel selector for choosing the characteristic curve (e.g., extremely inverse, very inverse, or standard inverse). It has LED indicators for trip and alarm, a target reset button, and a test jack for secondary injection testing. Output contacts include two Form C (SPDT) for tripping and signaling. The relay is housed in a rugged metal enclosure suitable for panel mounting.

Technical Specifications

Input CT secondary: 1 A or 5 A. Frequency: 50/60 Hz. Instantaneous pickup: 2‑80 A (adjustable). Time pickup: 0.5‑20 A. Time dial: 0.5‑10 seconds. Accuracy: ±3% for pickup, ±5% for timing. Output contacts: 2 Form C, rated 5 A at 250 VAC. Power supply: 24‑250 VDC or 120‑240 VAC. Operating temperature: –30°C to +65°C.

Applications

This relay is used for protection of induction motors, synchronous motors, and distribution feeders in industrial plants, pumping stations, and renewable energy systems. It provides primary protection for phase faults and backup protection for ground faults when used with additional relays.

Installation and Commissioning

Install the relay in a standard panel cutout. Connect CT leads, control power, and trip circuits. Commissioning involves setting pickup values and time dials according to coordination studies, then verifying operation with a relay test set. The relay includes a built‑in test button for quick functional checks.

Reliability and Standards

Compliant with ANSI C37.90 and IEC 60255, the BE1‑50/51M is built with high‑quality components and is fully sealed against dust and moisture. Its solid‑state design ensures long life and low maintenance. Basler Electric’s quality assurance guarantees dependable performance in critical applications.

Conclusion

The Basler Electric BE1‑50/51M overcurrent relay offers comprehensive, high‑speed protection for motors and feeders in a single, reliable package. Its adjustable settings and robust construction make it a versatile and trusted solution for power system protection.