RXHL/RAHL – Compact Overcurrent Relays RXHL 4xx and Line Protection RAHL 4xx

The RAHL/RXHL 401, 411, 421, and 422 are overcurrent and earth-fault protection relays designed for various power system applications. They also provide backup protection for terminals such as the 650 and 670 series across all voltage levels, including Extra High Voltage (EHV) systems.

Furthermore, these relays support time-current characteristics according to IEC 60255-3. They also offer a thermal replica overload function, RI curve, and a special logarithmic curve for earth faults in EHV systems. Additionally, they detect intermittent phase and earth faults to improve protection reliability. Their flexible design also makes them suitable for retrofitting and replacing older electromechanical and static relay designs.

RXHL/RAHL 422 for Solidly Earthed or Low-Impedance Earthed Systems

The RXHL/RAHL 422 provides comprehensive protection for solidly earthed and low-impedance earthed power systems. It combines overcurrent, thermal overload, and earth-fault protection with additional circuit breaker monitoring functions.

• Two-Phase Overcurrent Protection: Provides three time-delayed or instantaneous protection stages (I>, I>>, I>>>) with alarm and trip functions.

• Thermal Overload Protection: Monitors three-phase thermal conditions through the Q> alarm and trip functions.

• Directional and Non-Directional Earth-Fault Protection: Offers three time-delayed or instantaneous protection stages (IN>, IN>>, IN>>>) for effectively earthed networks, with alarm and trip functions.

• Low Polarising Voltage: Supports polarising voltage levels down to 0.5%, ensuring reliable earth-fault protection.

• Adjustable Characteristic Angle: Allows users to set the operating characteristic angle between 0° and 90° to suit system requirements.

• Circuit Breaker Failure Protection: Detects breaker failures through three-phase and neutral current measurements, with selectable timing logic.

• Pole Disagreement Protection: Identifies pole disagreement by monitoring individual phase current levels.

• Automatic Reclosing: Supports up to four reclosing attempts as an optional function, helping restore power supply after temporary faults.

• Additional I/O Module: Supports an optional expansion board with four optocoupled inputs and four relay outputs for greater control and monitoring flexibility.