Basler Electric BE1-50 Instantaneous Overcurrent Relay

The Basler Electric BE1-50 is a solid‑state instantaneous overcurrent relay that responds to phase or ground currents exceeding a preset pickup level. It operates without intentional time delay, making it ideal for fast fault clearing in short‑circuit conditions. The relay is widely used in feeder protection, transformer backup protection, and generator protection schemes.

Design and Performance

The BE1-50 uses a precision current transformer input and a fast‑acting comparator circuit. When the measured current exceeds the pickup setting, the relay trips within one cycle (20 ms at 50 Hz). This ultra‑fast response minimises fault energy and reduces damage to cables and equipment. The relay includes a dropout ratio of approximately 95% to prevent contact chatter near the threshold.

Adjustable Pickup Setting

The pickup current is adjustable from 0.5 to 80 A (primary or secondary depending on CT ratio). The setting is made via a front‑panel dial with a locking mechanism to prevent accidental changes. A built‑in test jack allows injection of test current for verification without applying high power.

Technical Specifications

Input current: 1 A or 5 A secondary (user‑selectable). Pickup accuracy: ±2% of setting. Operating time:<20 ms. Output contacts: 1 Form C, rated 5 A at 250 VAC. Power supply: 24–250 VDC or 120–240 VAC. Operating temperature: –30°C to +65°C. The relay meets ANSI C37.90 surge withstand requirements.

Applications

The BE1-50 is used in distribution substations, motor control centres, and industrial power systems to provide instantaneous protection against phase‑to‑phase, phase‑to‑ground, and three‑phase short circuits. It is often coordinated with time‑overcurrent relays (ANSI 51) to provide a complete overcurrent protection scheme.

Installation and Integration

Mounting is simple with a standard panel cutout. Wiring connections accommodate CT inputs, control power, and trip outputs. The relay can be installed in new panels or retrofitted into existing switchgear. Its compact size saves valuable panel space.

Reliability and Maintenance

With no moving parts, the BE1-50 offers high reliability and virtually no wear. Periodic testing is recommended to verify pickup accuracy and trip timing. The relay’s solid‑state design ensures consistent performance over its service life, reducing maintenance costs.

Conclusion

The Basler Electric BE1-50 instantaneous overcurrent relay is a fast, dependable, and easy‑to‑use solution for short‑circuit protection. Its instantaneous operation and robust construction make it a cornerstone of modern power system protection.