The Janitza RCM 202-AB is a two-channel residual current monitoring device, specifically designed for continuous measurement and monitoring of fault currents in earthed AC systems, particularly in TN and TT networks. It detects and monitors residual currents of types A, B, and B+ in accordance with IEC 62020 standards, and is also capable of detecting sinusoidal alternating fault currents up to 20 kHz (type B+). The device is compatible with two connectable current sensors, enabling precise measurement in the range of 10 mA to 20 A (AC/DC). The integrated sensor connection monitoring detects wire breaks or short circuits per channel, preventing false alarms and enhancing system reliability.

Operation is performed via an intuitive 3-button control and a dual-color LED display with a resolution of 128 x 64 pixels, which shows measurement values and status information. The user interface is available in German, English, and Spanish, facilitating use in international environments. For integration into higher-level monitoring systems, the device features an RS485 interface with Modbus RTU protocol, enabling communication with all communication-capable Janitza Modbus master devices. Measured values and extreme values are stored with timestamps to ensure subsequent analysis and documentation.