Innovative technologies for safe handling of electrical power to achieve high availability

We offer you first-class quality and safety combined with global service and every support in resolving your monitoring problems.

  • 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


The residual current monitoring module RDC104-4, with patented measurement method, is used in combination with a measuring current transformer W15BS…, CTBC17 and a type A RCD which has to be provided in the installation for DC fault current monitoring of AC charging systems for electric vehicles in which AC or DC fault currents can occur. The rated voltage Un is 250 V and the rated current (charging current) In = 1 x 48 A/3 x 32 A. The RDC104-4 is suitable for integration into a charging unit Mode 3 (AC) as a RDC-M module according to IEC 62955.

The RDC104-4 is only intended for purchase by the manufacturer of the charging system and not for end users!

More information:


  • Three outputs (DC1, DC2, Error)
  • Patented measurement method (Patents: EP 2 571 128 / US 9,397,494 / ZL 201210157968.6 / CN 103001175, EP 2 813 856)
  • Measuring range DC ±300 mA
  • Residual current resolution 0.2 mA
  • Load current up to 48 A r.m.s. (single-phase) or 3 x 32 A r.m.s. (three-phase)
  • Fault output (integrated self monitoring and test functions)
  • High insensitivity to external interferences
  • Wide range of use even in severe environments (e.g. in the event of external magnetic fields)
  • As a RDC-M module in applications according to DIN EN 61851 or IEC 62955, the RCD104-4 can replace a type B RCD when combined with a type A RCD and a suitable switching device (e.g. a power relay).


  • DC fault current monitoring of AC charging systems for electric vehicles

Downloads for RDC104-4

Handbücher RDC104-4 2.1 MB DE17.11.2021 06:42:04D00402
Handbücher RDC104-4 2.1 MB EN17.11.2021 06:42:04D00402
Datenblätter RDC104-4 675.2 KB DE24.11.2021 10:21:47D00402
Datenblätter RDC104-4 669.9 KB EN24.11.2021 10:21:57D00402
Datenblätter W15BS 404.8 KB DE26.02.2020 14:39:39D00371
Datenblätter W15BS 401.9 KB EN25.02.2020 11:19:47D00371
Technische Informationen Stellungnahme Prüfung 6mA DC Fehlerstrom 450.2 KB DE07.06.2022 12:37:32

Optional accessories for RDC104-4

RDC104-4 Variants

TypeDescriptionArt. No.
RDC104-4RDC-M module acc. to IEC 62955B94042483
W15BSMeasuring current transformer Ø = 15 mm,
Connection cable 1470 ±30 mm
W15BS-02Measuring current transformer Ø = 15 mm
Connection cable 180 ±30 mm
W15BS-03Measuring current transformer Ø = 15 mm
Connection cable 325 ±25 mm