The AC/DC sensitive residual current monitor RCMA420 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 be monitored too.
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 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, in the normal case, de-energised single conductors
(e.g. N and PE conductors)

• 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 10…500 mA
• 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 selectable
• Continuous self monitoring
• Multi-functional LC display
• Password protection for device settings
• Sealable transparent cover
• Two-module enclosure (36 mm)
• RoHS compliant
• Push-wire terminal (two terminals per connection)