Description

RXHL/RAHL – Compact overcurrent relays RXHL 4xx and line protection RAHL 4xx

The four overcurrent and earth-fault relays RAHL/RXHL 401, 411, 421 and 422 are intended for power system applications and as backup to, e.g., the 650 or 670 series terminals at all system voltage levels, including EHV. All time-curves are provided according to IEC 60225-3; the thermal replica overload function and the RI, and a special logarithmic curve for earth faults in EHV systems are also available. It can detect intermittent phase and earth faults. The relays are also intended for retrofit and replacement of earlier electromechanical and static relay designs. 

RXHL/RAHL 421 for high-impedance earthed systems

• Three stages of two-phase time-delayed or instantaneous overcurrent protection, I>, I>>, I>>> alarm and trip functions
• Three-phase thermal overload protection, Q> alarm and trip functions
• Three stages of time-delayed or instantaneous directional earth-fault protection, IN>, IN>>, IN>>> alarm and trip functions. – Neutral point voltage stage, enabling criteria for directional earth-fault stage. Definite time delay, serves also as back-up protection. – Uni- or bi-directional operating characteristic and manual or remote change of characteristic angle, 0° or -90°. Definite time delay.
• Neutral point time-delayed overvoltage function (one step)
• Logic for detection and clearance of intermittent faults
• Breaker failure protection, three phases and neutral current detection, selectable timing logic
• Pole disagreement function based on separate phase current level measurement
• Autoreclosing, up to 4 attempts (option)
• Extra I/O board with 4 optocoupled inputs and 4 relay outputs (option)