Basler BE1-87T Solid‑State Transformer Differential Relay

The Basler BE1-87T is a solid‑state differential relay designed for protection of power transformers. It provides fast and reliable protection against internal faults such as turn‑to‑turn, winding short circuits, and core faults. The relay employs percentage differential with harmonic restraint to ensure stability during inrush and overexcitation.

The relay features adjustable pickup, slope, and harmonic restraint settings. It is housed in a rugged enclosure for panel mounting in substations and industrial control rooms.

Technical Specifications

• Model: BE1-87T

• Protection type: Percentage differential

• Current sensing: 1/5 A CT inputs

• Pickup range: 0.1‑2.0 A (adjustable)

• Slope: 0‑40% (adjustable)

• Harmonic restraint: Second harmonic (15‑30%)

• Response time: < 20 ms

• Output contacts: 2 form C

• Power supply: 24‑240 V AC/DC

• Operating temperature: -40°C to +70°C

• Certifications: CE, UL, RoHS

Functional Features

• Fast operation: Trip times less than one cycle.

• Harmonic restraint: Prevents maloperation during inrush.

• Adjustable settings: Field‑adjustable pickup, slope, and restraint.

Typical Applications

• Power transformers: Two‑winding and three‑winding.

• Generator step‑up transformers.

• Industrial transformers.

Installation and Configuration

Mount on panel, connect CTs, power supply, and outputs. Configure settings via front‑panel controls.

Compliance

Complies with IEEE C37.91, IEC 60255, CE, UL.

Conclusion

The BE1-87T offers reliable high‑speed differential protection for transformers.