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AC/DC sensitive residual current monitoring module with integrated split-core measuring current transformer

The RCMB330 residual current monitoring modules are intended for measuring AC and DC fault currents in earthed systems (TN and TT systems). The modules are able to measure residual currents IΔ = 10…500 mA in a frequency range of DC…100 kHz.

Two separately adjustable response values allow a distinction to be made between prewarning and main alarm.

The modules feature an RS-485 interface with Modbus RTU which can be used to transfer measured values and alarm values. Setting parameters is also possible via this interface.


  • Continuous residual current monitoring in compliance with DGUV Vorschrift 3 (German Accident Prevention Regulation 3)
  • Easy DIN rail or screw mounting
  • RS-485 interface with Modbus RTU (reading out measured values/setting parameters)
  • Frequency range DC…100 kHz
  • Multicolour LED for operation and status messages
  • Digitally adjustable filters for AC/DC sensitive measured value acquisition (lowpass filters, type B acc. to IEC 60755, type B+ acc. to VDE 0664-400)
  • Separate evaluation of the AC and DC components as well as the RMS value of the residual current possible
  • Installation without mechanical separation of the primary conductors
  • Extension or modification of functionalities through software updates via Modbus
  • Insensitive to load currents due to magnetic screen
  • Supply voltage DC 24 V

Downloads for LINETRAXX® RCMB330

CE Declarations of Conformity RCMB33x 86.7 KB 2022/08/12 06:17:2512.08.2022 06:17:25
Quickstarts RCMB330 1.1 MB EN2020/11/06 14:39:1606.11.2020 14:39:16D00389
Manuals RCMB330 1.7 MB EN2020/12/11 10:21:4611.12.2020 10:21:46D00389
Datasheets RCMB330 381.7 KB EN2021/01/04 09:24:1904.01.2021 09:24:19D00389

Optional Accessories for LINETRAXX® RCMB330

DescriptionArt. No.
RS-485/USB interface converterB95012045

Voltage supply

TypeMax. connected current transformersArt. No.
STEP-PS/1 AC/24 DC/0.54B94053110
STEP-PS/1 AC/24 DC/1.7514B94053111
STEP-PS/1 AC/24 DC/4.234B94053112


TypeSupply voltage USVarianteArt. No.
RCMB330DC 24 V (19.2…28.8 V)Modbus RTUB74043160