Overview:

The ABB Relion REJ603 is a self-powered protection relay designed for secondary distribution networks, where access to an auxiliary power source may be unavailable. It is primarily used in Ring Main Units (RMUs) and compact switchgear, offering reliable overcurrent and earth-fault protection. Powered by Current Transformers (CTs), the REJ603 ensures protection even when external power is absent, making it an ideal solution for remote locations and installations with limited power supply.

Key Features:

• Self-Powered Operation: The REJ603 generates the necessary operating energy from the primary circuit’s current transformers (CTs). It ensures protection during fault conditions, even at startup (cold start).

• Protection Functions:

• Three-Phase Overcurrent Protection: Covers both low-set (I>) and high-set (I>>) overcurrent protection stages, providing selective coordination and fast response to faults.

• Earth Fault Protection: Detects leakage currents to ground with both phase current summation and optional use of a core balance CT (CBCT).

• Current Transformer Compatibility: The relay is optimized for dual-core CTs that have two windings—one for measurement and protection, and one for energy harvesting to power the relay.

• Measurement and Monitoring:

• Monitors phase currents and earth current for a comprehensive fault analysis.

• User Interface:

• LCD Display: Shows fault information and operational status.

• LED Indicators: Provides visual feedback for fault types (overcurrent, earth-fault).

• Communication Options:

• Modbus RTU (RS-485) for remote monitoring.

• Optical Port for local communication.

• Environmentally Robust: The REJ603 operates in temperatures ranging from -25°C to +70°C, ensuring reliability in a variety of environments.

Technical Specifications:

Variants:

• Version 1.5: Standard for basic RMU applications.

• Version 3.0: Enhanced version with better communication protocols and upgraded hardware interfaces.

Applications:

• Secondary Substations: Protects transformers and feeders in secondary distribution networks.

• Remote Sites: Ideal for areas without a stable DC power supply or UPS.

• Retrofits: Replaces older mechanical or thermal relays in existing switchgear, upgrading the protection system with modern features.

Frequently Asked Questions (FAQ):

Q1: What is the main advantage of the self-powered feature of the REJ603?

The REJ603 eliminates the need for an external power supply, drawing energy directly from the current transformers (CTs), ensuring continuous protection even if the external power fails.

Q2: Can the REJ603 be used in remote locations without auxiliary power?

Yes, the self-powered design makes the REJ603 ideal for remote sites where stable DC battery systems are not available.

Q3: How does the Earth-fault protection work in the REJ603?

The REJ603 utilizes phase current summation or can integrate with a core balance CT (CBCT) for accurate detection of leakage currents to ground, ensuring reliable earth-fault protection.