The RCMA423-D-1 is a Type B AC/DC sensitive residual current monitor designed for earthed systems (TN and TT systems). It measures residual currents via external W…AB series measuring current transformers . 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 IEC 60755 Type B standards .
Technical Specifications
· Order No.: B74043023 (push‑wire terminals) / B94043023 (screw‑type terminals)
· Supply voltage (Uₛ): DC 9.6…94 V; AC 16…72 V, 42…460 Hz
· Frequency range: 0…2000 Hz
· Response value range (IΔn₂): 30 mA…3 A (adjustable)
· Pre‑warning value (IΔn₁): 50…100 % of IΔn₂, min. 15 mA
· Response time: at IΔ = 1 × IΔn₂ ≤ 180 ms; at IΔ = 5 × IΔn₂ ≤ 30 ms
· Measuring principle: True RMS measurement (AC+DC)
· 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…99 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, IEC 60755 (Type B)
Key Features
· Type B full current sensitivity: Detects smooth DC, pulsating DC and AC residual currents, fully compatible with modern power electronic systems such as frequency converters, battery chargers, and construction site equipment with variable‑frequency drives
· Two independent alarm stages: Pre‑warning (IΔn₁) and main alarm (IΔn₂) for staged alarming
· External measuring current transformer: Non‑invasive measurement via W…AB series current transformers (W20AB, W35AB, W60AB, W120AB, W210AB)
· True RMS measurement (AC+DC): Ensures measurement accuracy even in harmonic‑rich environments
· Adjustable response delay: 0…10 s, prevents nuisance tripping due to transient disturbances
· 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
· Password protection: Prevents unauthorised parameter changes
· Sealable transparent cover: Prevents unauthorised parameter changes
Typical Applications
· Ground fault monitoring in earthed systems (TN/TT systems)
· Loads with six‑pulse rectifiers or one‑way rectifiers with smoothing: Converters, battery chargers, construction site equipment with frequency‑controlled drives
· Single‑conductor current monitoring: PE conductors, N-PE connections
· 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
· Residual current monitoring in fire‑hazard locations
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