The RCM420-D-1 is a Type A residual current monitor designed for earthed systems (TN and TT systems) to monitor AC and pulsating DC residual currents. When an earth fault is detected, the device triggers an alarm without disconnecting the power supply, providing advanced warning of developing ground faults. The device complies with IEC 62020 and can also be used to monitor single conductors (e.g., PE conductors, N-PE connections, and PE-PAS connections).
Technical Specifications
· Order No.: B94014001 (screw‑type terminals) / B74014001 (push‑wire terminals)
· Supply voltage (Uₛ): AC 16…72 V, 42…460 Hz; DC 9.6…94 V
· Frequency range: 42…2000 Hz
· Response value range (IΔn₂): 10 mA…10 A
· Pre‑warning value (IΔn₁): 50…100 % of IΔn₂
· Response time: at IΔ = 1 × IΔn₂ ≤ 180 ms; at IΔ = 5 × IΔn₂ ≤ 30 ms
· Measuring principle: True RMS measurement
· Alarm outputs: Two independent changeover contacts (SPDT), AC 250 V / 5 A
· Adjustable time delays: Start‑up delay 0…10 s, response delay 0…10 s, delay on release 0…30 s
· Display: Multi‑function LC display
· LED indicators: Power On, Alarm 1, Alarm 2
· Operating temperature: -25 °C … +55 °C
· Protection class: Internal components IP30, terminals IP20
· Mounting: 35 mm DIN rail (2-module enclosure, 36 mm width)
· Weight: ≤ 150 g
· Standards compliance: IEC 62020
Key Features
· Type A residual current monitoring: Detects sinusoidal AC and pulsating DC earth fault currents, compliant with IEC 62020
· External measuring current transformer: Non‑invasive measurement via W…, WR…, WS… series current transformers; measurement largely unaffected by load current and system voltage
· Two independent alarm stages: Pre‑warning (IΔn₁) and main alarm (IΔn₂) for staged alarming
· Adjustable response delay: 0…10 s, prevents nuisance tripping due to transient disturbances
· True RMS measurement: Ensures measurement accuracy even in harmonic‑rich environments
· Selectable fault memory: Latching or non‑latching mode
· Self‑test and reset: Built‑in TEST/RESET button; supports external push‑buttons for remote operation
· Transformer connection monitoring: Alarms immediately on wire break or system fault
· Sealable transparent cover: Prevents unauthorised parameter changes
· Password protection: Prevents unauthorised parameter changes
Typical Applications
· Residual current monitoring in earthed systems (TN/TT systems)
· Single‑conductor current monitoring: PE conductors, N-PE connections, PE-PAS connections
· Residual current monitoring in fire‑hazard locations
· Leakage monitoring in industrial automation production lines
· Data centres: Monitoring earth leakage in server racks and critical IT equipment
· Medical locations: Leakage current monitoring in operating theatres, ICUs and other critical areas
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