RCM420-D-2 Bender

Product descriptionThe AC and pulsed DC sensitive residual current monitor RCM420-D (Type A) from Bender isdesigned for fault and residual current monitoring in earthed power supply systems (TNand TT systems) where an alarm is to be activated in the event of a fault, but disconnectionmust 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 ofthe system.Applications• 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 andwhich 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 systemsFunctionOnce the supply voltage Us has been applied, the start-up delay “t” starts. Measured valuesexceeded during this time do not influence the switching state of the alarm relays.Residual current monitoring takes place via an external measuring current transformer.The actual measured value is indicated on the LCD. In this way any changes, for examplewhen circuits are connected to the system, can be recognised easily.If the measured value exceeds one or both response values, the response delays ton1/2begin. Once “ton1/2” have elapsed, the selected alarm relays switch). If the release value isnot reached before the response delay “ton” has elapsed, the alarm LEDs “AL1/AL2” donot light up and the alarm relays do not switch. The set release time “toff” begins whenthe measured value again falls below the release value (response value minus hysteresis)after the switching of the alarm relays. When “toff” has elapsed, the alarm relays switchback to their initial position. If the fault memory is enabled, the alarm relays remain in thealarm state until the reset button is pressed or until the supply voltage is interrupted. Thedevice function can be tested using the test button. Parameters are assigned to the devicevia the LCD and the control buttons on the front panel; this function can be password-protected.Connection monitoringThe CT connections are continuously monitored. In the event of a fault, the alarm relaysK1/K2 switch without delay, the alarm LEDs AL1/AL2/ON flash. After eliminating the fault,the alarm relays return to their initial position either automatically or by pressing the resetbutton (fault memory behaviour).Restart functionIf an alarm is pending after resetting the alarm relay and restarting the system being monitored,this reset process is repeated until the preset number of restart cycles is completed.As soon as the preset number of restart cycles is completed, the fault memory is set to ON.