The RCM470LY‑7121 is a Type A residual current monitor designed for earthed systems (TN and TT systems). It measures residual current non‑invasively via an external measuring current transformer. When an earth fault is detected, the device triggers an alarm without disconnecting the power supply, providing advanced warning of developing ground faults and effectively preventing nuisance tripping. This model is specifically designed for 50/60 Hz AC power systems.
Technical Specifications
· Order No.: B94012050
· Response range: AC 6…600 mA, 50/60 Hz
· Supply voltage: DC 9.6…84 V
· Power consumption: 3.0 VA
· Alarm output: 1 DPDT potential‑free changeover contact, AC 250 V / 5 A
· Display: LED bar graph (0‑100%), Power On LED, Alarm LED
· Response delay: 0…10 s (adjustable)
· Hysteresis: approx. 25 % of the response value
· Fault memory: Selectable latching (manual reset) or non‑latching
· Test/Reset: Built‑in TEST/RESET button, supports external push‑buttons
· Transformer connection monitoring: Alarms on wire break or system fault
· Protection class: Housing IP30, terminals IP30
· Mounting: 35 mm DIN rail or screw mounting
· Data sheet: 401003-mod
Key Features
· Type A residual current monitoring for 50/60 Hz pure AC systems
· External measuring current transformer (W…, WR…, WS… series) – unaffected by load current and system voltage
· Steplessly adjustable response value 6…600 mA
· LED bar graph shows measured value as percentage of set value
· Adjustable response delay 0…10 s prevents nuisance tripping
· Selectable fault memory (latching / non‑latching)
· Built‑in TEST/RESET button, supports external push‑buttons for remote operation
· Transformer connection monitoring – alarms on wire break
· Sealable transparent cover prevents unauthorised parameter changes
Typical Applications
· Residual current monitoring in earthed systems (TN/TT systems)
· Motor and motor control systems
· Portable and stationary generators
· Alarm systems, safety devices
· Cooling equipment (e.g., refrigerators storing valuable frozen goods)
· Socket outlet circuits for permanently unattended equipment (air conditioning, EDP systems)
· Industrial control and heat tracing systems
· Busbar systems
· Off‑line single‑conductor current monitoring (PE conductor, N‑PE connection, etc.)
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