Device Features
The LINETRAXX® RCM420 is a residual current monitor designed for AC and pulsed DC current monitoring in TN and TT systems. Key features include adjustable switching hysteresis, r.m.s. value measurement, and a multifunctional LC display for measured value display. It offers alarm indication via LEDs and changeover contacts, selectable N/C or N/O operation, password protection, and a fault memory function that can be disabled. The device also includes CT connection monitoring.

Intended Use
The RCM420 is intended for fault and residual current monitoring in earthed power supply systems, where alarms are activated without disconnection. It can monitor single conductors and distinguish between prewarning and main alarm through two adjustable response ranges. Custom parameter settings are necessary to meet local standards and conditions.

Function
Upon applying supply voltage, a starting delay is activated. Residual current measurement is conducted via an external transformer, with values displayed on the LC display. If response values are exceeded, alarm relays switch after a delay, and LEDs light up. The device includes a test button for functionality checks and allows parameterization via the display and function keys.

Connection Monitoring
CT connections are continuously monitored. In case of a fault, alarm relays switch immediately, and LEDs flash. Faults can be reset manually if the fault memory is activated.

Wiring and Terminal Connections
The device should be connected according to the wiring diagram. Key terminal connections include supply voltage, measuring current transformers, and alarm relays.

Technical Data
The RCM420 offers different models with varying rated insulation voltages and supply voltage ranges. It supports a frequency range of 42-2000 Hz and a measuring range of 3 mA to 16 A. The device features protective separation and has specific response values and delays for alarms.

Environmental and Mechanical Conditions
The device operates within a temperature range of -25 to +55 ºC and is classified under various climatic and mechanical conditions according to IEC standards. It is designed for continuous operation and features a polycarbonate enclosure with specific protection classes.

Standards and Certifications
The RCM420 complies with standards such as UL508 and UL1053, with specific certifications for industrial control equipment and safety ground-fault sensing.

Dimensions and Ordering Information
The document provides detailed dimensions and ordering information for different models and accessories, including external measuring current transformers and mounting clips.