text.skipToContent text.skipToNavigation


Littelfuse — Western Automation Residual Current Monitor (RCM)




Littelfuse Western Automation RCM (Residual Current Monitor) Technologies

The latest innovation for EV Charging designs and more

The Western Automation RCM (Residual Current Monitor) technologies help to minimize the risk of electrical shock while charging an electric vehicle. The RCM products can detect AC and DC ground fault currents, quickly triggering a fault output to disable the charging current and remove the shock hazard. There are five RCM models with integral RCM technology available to comply with the global UL and IEC standards for EV charging applications.

The Residual Current Monitor (RCM) module’s current transformer monitors the AC supply current flowing to an EV and will provide an output signal if ground leakage currents exceed 56mA DC / 20mA AC (UL standard models) or 30mA AC / 6mA DC (IEC standard models). This output can be used to operate an RCD, a circuit breaker, or a contactor to remove the AC supply to the EV.


  • Multiple models to support global standards for Level 2 (UL2231-2), Mode 2 (IEC62752) and Mode 3 (IEC62955)

  • AC EV chargers Protects against both AC and DC leakage currents that can present serious shock risks

  • One component for both single-phase and three-phase designs


  • Packaged RCM models with integral current transformer for chassis mount applications

  • 2pc RCM system for board-level applications, PCB assembly and horizontal-mount or vertical-mount current transformer

  • Supports single phase load and three phase load currents


  • Electric Vehicle AC charging stations

  • Energy Storage Systems (ESS)

  • PV/Solar Inverters