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  • Electrical safety for unearthed power supplies (IT systems)
  • Insulation monitoring equipment, insulation fault location systems
  • Power supplies for medical applications
  • Measuring and monitoring relays
  • Electrical safety for earthed power supplies (TN systems)
  • Using renewable energies efficiently: wind power, photovoltaics
  • Test systems for electrical equipment and medical technology


  • AC/DC sensitive measured value acquisition type B
  • Adjustable response values
  • For protection of persons, fire protection, plant protection

The AC/DC sensitive residual current monitor RCMA423 is designed for monitoring earthed power supply systems (TN and TT systems) where smooth DC fault currents or residual currents continuously greater than zero may occur. These are in particular loads containing six-pulse rectifiers or one way rectifiers with smoothing, such as converters, battery chargers, cons­truction site equipment with frequency-controlled drives. Currents in single conductors can also be monitored by RCMA423.

The prewarning stage (50…100 % of the set response value IΔn2) allow to distinguish between prewarning and alarm. Since the values are measured with measuring current transformers, the device is nearly independent of the load current and the nominal voltage of the system.


  • AC/DC sensitive residual current monitor Type B acc. to IEC 62020 and IEC/TR 60755
  • r.m.s. value measurement (AC+DC)
  • Two separately adjustable response values 30 mA…3 A
  • Frequency range 0…2000 Hz
  • Start-up delay, response delay and delay on release
  • Digital measured value display via LC display
  • Measured value memory for operating value
  • CT connection monitoring
  • LEDs: Power On, Alarm 1, Alarm 2
  • Internal/external test/reset button
  • Two separate alarm relays (one changeover contact each)
  • N/O or N/C operation and fault memory behaviour selectable
  • Continuous self monitoring
  • Multi-functional LC display
  • Password protection for device settings
  • Sealable transparent cover
  • Push-wire terminal (two terminals per connection)
  • Two-module enclosure (36 mm)


  • AC/DC sensitive residual current monitoring in earthed two, three or four conductor systems (TN and TT systems)
  • Monitoring of variable-speed drives, UPS systems, construction site equipment, printing machines, battery systems, laboratory equipment, wood working machines, MF welding systems, furniture industry, medical electrical equipment, etc.
  • AC/DC sensitive current monitoring of single conductors de-energised under normal conditions (e.g. N and PE conductors)

Downloads for LINETRAXX® RCMA423

Datasheets RCMA423 530.3 KB ZH13.05.2019 10:31:33D00063
Manuals RCMA423 1.7 MB DE07.05.2021 10:08:37D00063
Manuals RCMA423 1.7 MB EN07.05.2021 10:08:27D00063
Datasheets RCMA423 362.9 KB DE10.01.2020 10:34:46D00063
Datasheets RCMA423 332.7 KB EN10.01.2020 10:35:03D00063
Datasheets RCMA423 334.5 KB ES04.09.2020 05:48:55D00063
Quickstarts RCMA423 1,019.8 KB DE07.05.2021 10:09:08D00063
Quickstarts RCMA423 1,019.8 KB EN07.05.2021 10:09:08D00063
Datasheets XM420-Schnittstellenoptionen 264.1 KB DE13.05.2019 10:31:35
Datasheets XM420 interface options 223.5 KB EN13.05.2019 10:31:36D00051
Technical information Changed variants of relays from goldplated to silver-plated contacts 166.3 KB EN27.06.2022 09:03:08
Technical information Geänderte Relaisvarianten von vergoldeten Kontakten auf versilberte Kontakte 166.3 KB DE27.06.2022 09:03:08

Optional accessories for LINETRAXX® RCMA423

Measuring current transformers

TypeInternal diameter (mm)Art. No.
CTUB101-CTBC20ø 20B78120010
CTUB101-CTBC20Pø 20B78120020
CTUB101-CTBC35ø 35B78120012
CTUB101-CTBC35Pø 35B78120022
CTUB101-CTBC60ø 60B78120014
CTUB101-CTBC60Pø 60B78120024
CTUB101-CTBC120ø 120B78120016
CTUB101-CTBC120Pø 120B78120026
CTUB101-CTBC210ø 210B78120018
CTUB101-CTBC210Pø 210B78120028

Connection cable measuring current transformer – RCMA423-D

TypeLength/mArt. No.


TypeArt. No.
Mounting clip for XM420 enclosureB98060008


TypeResponse range IΔnFrequency rangeSupply voltage US*Art. No.**
RCMA423-D-130 mA…3 A0…2000 HzDC 9,6…94 V /
AC 16…72 V, 42…460 Hz
RCMA423-D-230 mA…3 A0…2000 HzDC 70…300 V /
AC 70…300 V, 42…460 Hz

* Absolute values
**(B7… = push-wire terminal / B9… = screw-type terminal)