Basler Electric L301KC Protective Relay

The Basler Electric L301KC is a versatile protective relay designed for overcurrent protection in medium‑voltage and low‑voltage power systems. It provides reliable detection of phase and ground faults, with adjustable pickup settings and time‑delay characteristics. The L301KC is part of Basler's family of electromechanical and solid‑state relays, offering a cost‑effective solution for distribution protection.

Key Features

The relay features a wide pickup current range, selectable time‑current curves (inverse, definite time), and high reset ratio. It includes a target indicator for fault identification and a test point for easy calibration. The construction is robust, with a transparent cover for visual inspection of contacts and settings.

Technical Specifications

Current rating: 5 A or 1 A secondary. Pickup range: 2‑20 A (for 5 A CT). Time delay: 0.1‑10 seconds. Operating temperature: ‑20°C to +55°C. Contact rating: 5 A at 250 VAC. Frequency: 50/60 Hz. Dimensions: 150 x 100 x 80 mm. Weight: 1.5 kg.

Operating Principles

The L301KC continuously monitors the current from CTs. When the current exceeds the pickup setting, the timing circuit starts. After the preset time delay, the output contact trips the breaker. The inverse‑time characteristic provides faster tripping for higher fault currents, ensuring selective coordination.

Applications

This relay is used in feeder protection, motor protection, and transformer protection. It is suitable for industrial plants, commercial buildings, and utility substations. The L301KC is often retrofitted into older switchgear as a reliable replacement.

Installation and Configuration

Install the relay on a panel or in a relay rack. Connect the CT leads and breaker trip circuit. Adjust the pickup and time dial settings using the front‑panel knobs. A primary injection test is recommended to verify the settings.

Maintenance and Reliability

The L301KC's electromechanical design requires occasional contact cleaning and timing verification. However, its proven technology ensures decades of dependable service. Spare parts are readily available.

Conclusion

The Basler Electric L301KC protective relay combines simplicity, reliability, and performance for essential overcurrent protection in power distribution networks.