Bender RCMA420-DM3C-2 Residual Current Monitor

The Bender LINETRAXX RCMA420-DM3C-2 Residual Current Monitor is a single‑channel, AC/DC sensitive device designed to supervise earth‑fault currents in TN and TT electrical systems. It monitors residual current IΔn from 10 mA to 500 mA, including pulsed DC fault currents, using an external measuring current transformer (CTUB101 or CTBC20–60) and presents the live value on an LC display. Two independently adjustable ranges provide a prewarning and an alarm threshold, with programmable ton1/ton2 delays and a release delay ton‑off; when thresholds are exceeded, the K1 and K2 changeover contacts switch and AL1/AL2 LEDs illuminate, and they reset when the current falls below the release value unless fault memory is activated. The unit supports RMS current measurement, selectable N/C or N/O operation, and password protection for parameter changes, with a test button for function verification and optional fault memory that can be disabled. The DM variant denotes an analogue interface for integration with control systems. The RCMA420 family includes CT connection monitoring to detect CT faults and supports installation in safety circuits and protective schemes.