The AC and pulsed DC sensitive residual current monitor RCM420-D (Type A) from Bender is designed for fault and residual current monitoring in earthed power supply systems (TN and TT systems) where an alarm is to be activated in the event of a fault, but disconnection must be prevented. In addition, the device can be used to monitor single conductors, such as PE conductors, N-PE connections and PE-PAS connections.
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.

• Residual current monitoring in earthed 2, 3 or 4-conductor systems
• Current monitoring of, in the normal case, de-energised single conductors
• Socket-outlet circuits for devices which are operated unattended for a long time and which may not fail
• Alarm systems, safety devices
• Air conditioning systems, EDP systems
• Cooling equipment with valuable frozen goods
• Canteen kitchens
• Monitoring of earthed power supplies for stray currents
• Impact on N conductors
• Trace heating systems

• AC and pulsed DC sensitive residual current monitor Type A according to IEC 62020
• r.m.s. value measurement (AC)
• Two separately adjustable response values
• Frequency range 42…2000 Hz
• Start-up delay, response delay and delay on release
• Restart function
• 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
• Password protection for device setting
• Device self monitoring
• Sealable transparent cover
• Two-module enclosure (36 mm)
• RoHS compliant
• Push-wire terminal (two terminals per connection)